Homebrew PCBs

Hey again,

I've gotten more and more interested in throwing together a tiny press 
for the boards. I looked at some shock innards on howstuffworks and 
asked someone, but it looks like the part I was interested in isn't 
the "snug slide" part that I would want. I did however, maybe come up 
with a solution which won't be that difficult here, involving some 
fiberglass. I'm getting more interested in something extra small and 
portable that I can keep for a while, but MOST importantly, something 
that looks cool. ;)

Back to the question- Which of you have heard or used a cheap roto-
tool that was noticeably "quiet". I may get one for permanent drill 
duty. We've got the HomeDepot's and Lowes here as well as Walmart, 
Sears, etc., then there's always eBay and the net.

Also, if I can scrounge up the parts, I may go ahead and start soon 
(without the roto). What would be a safe guess on housing diameter for 
the carriage? I've got the fancy looking new one here with the gray 
rubber grip sleeves. It measures 1.85 inches diameter in the "barely 
adequate" straight cylindrical section. That area is only about 1.25" 
long and there's about 3.25" from the end of that to the end of the 
chuck. There's also that little tapered "finger" section right at the 
nose where the arbor sticks out, if that's a common clamp point. I 
guess all the clamping should be as close to the nose as possible. 
Since it really just gets adjusted and clamped in once, a generic jaw 
shape might suffice, like a "V" with stepped notches to handle 
different shapes or sizes.

Are there any tricks, etc. to getting the whole crap aligned 
perpendicular to the table? I thought about maybe a rod or something 
in the chuck which was temporarily stuck into the table right at the 
drilling point.  -???

George

PS- I just cranked my Dremel to full throttle for the heck of it. Good 
lord that thing's obnoxious!

On Wed, 14 Dec 2005 03:02:49 +0100, soffee83 <soffee83@...> wrote:

> Are there any tricks, etc. to getting the whole crap aligned
>
> perpendicular to the table? I thought about maybe a rod or something
>
> in the chuck which was temporarily stuck into the table right at the
>
> drilling point.  -???
>
>
> George


Put a rod or drill in the chuck and line it up visually with a right angle  
set at the table. That's very precise if you look against a light. You  
need to do it from at least two angles of course.

For holding the spindle, if you have no good straight section use v-clamps  
or something on two points, one near the business end and one somewhere  
above. That ought to be dead stable then.

I haven't found a quiet drill yet, the brushes seem to make much of it.  
Better quality grinders make less noise, but still not as little as a  
brushless motor.

ST

Stefan,

Yeah, the rod idea sounds right. I'll do that when the time comes. I 
can't say I'm looking forward to gripping that small part of the 
Dremel, but that would be the obvious business end. There are older 
ones (single speed maybe) which look more like a cylinder, but I'd 
have no idea what kind of noise they'd put off.

On the noise issue, I'm not really expecting a "quiet" tool, just 
"quieter". I figure there has to be some difference in one or two of 
them. On web searches, the quietest, unfortunately, looks to be the 
cordless variants. I think dogs use them to trim their nails or 
something. I also noticed that the generic laminate trimmers are very 
cheap on eBay (around the cost of a Dremel). That was what's always 
stopped me from getting one for plastics. The PorterCables & Dewalts 
are more in the $100 and over range. They are all perfect cylinders, 
not much larger than a roto, way more powerful, and run around 30k 
rpm. Could be noisy as crap though. The only times I ever run my small 
B&D router are when I'm trimming or cutting something which makes it's 
own obnoxious noise. I'm wondering if I could just bump a Dremel down 
slower. After checking my press, top speed is only in the 3k rpm range 
(!) and on top of that, I was running it at <1k this whole time, 
before I read the info here. This was with carbides, HSS, and diamond 
burrs. The belt drive motor is huge, more like the raw motors I've got 
here, and puts off nice LF noise, but I'm not expecting that from a 
roto.

I may check the woodwork newsgroup for roto recommendations, but I can 
use the available Dremel until I find a good one.

BTW- I've got a decent plan for a really small solid press involving 
some fiberglass. If it works out, I'll try to snap some pictures along 
the way. May be easier than describing or sketching it. It's not as 
complicated as it sounds, but I may make mine a bit more so, just for 
the looks and durability.

Thanks again for all the tips and help here!

                               George

Stefan Trethan wrote:

>
>
>Put a rod or drill in the chuck and line it up visually with a right angle  
>set at the table. That's very precise if you look against a light. You  
>need to do it from at least two angles of course.
>  
>
  I find right angles a bit imprecise, and even if you get this perfect, 
it doesn't tell you for sure if the travel is perfect or not without 
moving the bits.

  I load a #78 or #80 drill bit put my 1/64th" ruler behind it, and get 
it so the tip is just in front of the ruler, and visually touching the 
edge of a line, at the upper edge of the ruler.  I then advance the bit 
until the shank end of the fluted area is at the edge of the ruler, and 
check that it is also just barely touching the edge of the same line 
visually.  This way, you know for sure that the travel goes through the 
same point and the motion is aligned properly, and can get it to a 
fraction of a line on the ruler.  Check again 90 degrees off, and the 
drilling will be exactly square to the table, or at least 98%.  The only 
way I have found to make the other 2% is to then drill with one of those 
very fine bits.  As it goes through the board and advances more, any 
remaining off travel will make the bit bow out in an arc, and you can 
adjust alignment in very tiny increments and minimize this.  Then you're 
aligned.  I haven't found anything that's accurate enough to tell me 
whether the bits will bow out before drilling some holes, it's the only 
thing to check the final alignment that is an accurate indicator for the 
last little bit..  Note that this is with the very fine #78 and #81 bits 
I have.  Larger bits won't even begin to visually bow at these small 
angles, they'll just break more often because you're putting additional 
stress on them that you can't see, and will blame on other things.  
Large bits aren't an accurate indicator of their own alignment, they 
simply will not flex enough to tell what's going on.  Only the tiniest 
bits will let you really align a system well.  For sure, if you align 
with a bigger bit, then chuck up a very fine bit, you'll get a severe 
bow in that little bit when you drill some holes, that'll be a great 
indicator of just how poor that first alignment was.

  But, I do have plans to focus one of my webcams in very close, put it 
right next to the bit, and move up and down.  640 pixels from 1/4" away 
and move the bit up and down should detect if there is any off angle a 
little better than using a normal visual method, should get it very 
close to perfect on one pass.

>For holding the spindle, if you have no good straight section use v-clamps  
>or something on two points, one near the business end and one somewhere  
>above. That ought to be dead stable then.
>
>  
>

  I took mine apart, found 'roomy' areas and drilled holes through the 
case, used I think 8-32 nylon screws out through the case, and screwed 
on nuts.  That gives a secure threaded portion coming out from the 
drill, easy to hook things to it from there with another nut or two.  
Only use nylon inside of course, so you don't have problems with the AC..


>I haven't found a quiet drill yet, the brushes seem to make much of it.  
>Better quality grinders make less noise, but still not as little as a  
>brushless motor.
>
>  
>
  Brushes make a lot, and I think the little fan and bearing noise is 
most of the rest.  The Walmart off brand Handi tool I got for $18.88 is 
by far the quietest stock tool I've ever seen, still up there but 
noticably less than my Dremels, and overall seems to have less play.

  And of course brushless would be 10 times better, I have some large 
fans just for it but it's low on the totem pole..

Alan

----- Original Message ----- 

From: "Alan King" <alan@...>
>  I load a #78 or #80 drill bit put my 1/64th" ruler behind it, and get
> it so the tip is just in front of the ruler, and visually touching the
> edge of a line, at the upper edge of the ruler.  I then advance the bit
> until the shank end of the fluted area is at the edge of the ruler, and

They use dial test indicators on "real" machinery. The ruler and eyeball are 
reasonable enough substitutes. After squaring the axis to the table, you can 
swing a bent wire in the spindle to square it to the table. The height of 
the free end above the table should be the same through a full circle.

--- In Homebrew_PCBs@yahoogroups.com, Alan King <alan@n...> wrote:
>   But, I do have plans to focus one of my webcams in very close, 
put it 
> right next to the bit, and move up and down.  640 pixels from 1/4" 
away 
> and move the bit up and down should detect if there is any off 
angle a 
> little better than using a normal visual method, should get it 
very 
> close to perfect on one pass.


If you find a web cam that can do that or figure out how to adapt 
one, please let me know. I can't get any of the 4 I own to focust 
closer than about a foot and a half away. I've looked for close up 
lenses, but all I can find are for the higher end cameras.

Having the ability to do close up with a web cam is the first step 
in machine vision automation on the hobby level. The software is 
becomming available, the only real cost at this point is the high 
end cameras you have to buy.

On Thu, 15 Dec 2005 18:51:02 +0100, James Newton  
<jamesmichaelnewton@...> wrote:

>
> If you find a web cam that can do that or figure out how to adapt
>
> one, please let me know. I can't get any of the 4 I own to focust
>
> closer than about a foot and a half away. I've looked for close up
>
> lenses, but all I can find are for the higher end cameras.
>
>
> Having the ability to do close up with a web cam is the first step
>
> in machine vision automation on the hobby level. The software is
>
> becomming available, the only real cost at this point is the high
>
> end cameras you have to buy.


Mine needed removing of a plastic stop to focus closer. It will also work  
through a microscope now since it is mechanically similar to the human eye  
(in terms of lens diameter and how close in you can get).

ST

James Newton wrote:

>--- In Homebrew_PCBs@yahoogroups.com, Alan King <alan@n...> wrote:
>  
>
>>  But, I do have plans to focus one of my webcams in very close, 
>>    
>>
>put it 
>  
>
>>right next to the bit, and move up and down.  640 pixels from 1/4" 
>>    
>>
>away 
>  
>
>>and move the bit up and down should detect if there is any off 
>>    
>>
>angle a 
>  
>
>>little better than using a normal visual method, should get it 
>>    
>>
>very 
>  
>
>>close to perfect on one pass.
>>    
>>
>
>
>If you find a web cam that can do that or figure out how to adapt 
>one, please let me know. I can't get any of the 4 I own to focust 
>closer than about a foot and a half away. I've looked for close up 
>lenses, but all I can find are for the higher end cameras.
>
>Having the ability to do close up with a web cam is the first step 
>in machine vision automation on the hobby level. The software is 
>becomming available, the only real cost at this point is the high 
>end cameras you have to buy.
>
>  
>
http://www.superference.com/images/PCB/80bit.jpg
http://www.superference.com/images/PCB/80bitLED.jpg
http://www.superference.com/images/PCB/1mmRouter.jpg
http://www.superference.com/images/PCB/18f242board.jpg    Dusty 18f242 
board where I tore up a trace, focus backed out a bit..

  Those are with my bone stock Logitech Quickcam Zoom.  No need for 
anything special, just open them up, break the stop so you can unscrew 
the lens further, and you're done.  Usually the first thing I do to any 
new webcam, but I got the zoom for chatting and it already does well 
enough stock that I never broke it to work further.  Could probably do 
2x what's in that picture.  Every other web cam I have can do that or 
better after breaking the stop, even the $19 closeouts and free after 
rebate one..

  Never understood why everything doesn't just grab a pic against a 
plain background to set tool depth for CNC.  Probably a patent issue 
though..

  Grab a pic with the tip at the top, then move down until the shank end 
is at the top, and if it's within the same pixel at the top for both you 
will know your bit is drilling true.  Do that again 90 degrees off and 
you know the bit is truly running parallel with the motion in both axes 
and the bit is following behind the tip, with no sideways forces applied 
as it drills further into a material.


  Also beats the heck out of trying to eyeball SMT component markings 
and good for checking solder joints.  The board gives some idea, and it 
wasn't a really close picture.

  The small 1mm chipbreaker routers I just got look so huge now, hadn't 
directly compared them before with the 80s.  Also included a pic, they 
are all bits from toolsandtunes, tends to have the best deals.

Alan

--- In Homebrew_PCBs@yahoogroups.com, "Mike Young" <mikewhy@s...> 
wrote:
>After squaring the axis to the table, you can swing a bent wire in 
>the spindle to square it to the table. The height of the free end 
>above the table should be the same through a full circle.

That sounds good (and easy)! It sounds just like the procedure in my 
radial saw manual, where you rotate the arm with the arbor lightly 
scraping the table.

I've saved Alan's posts for later. They're a bit over my head for now, 
but I understand most of it. I figure if the pivoting presses are good 
enough for most work, this thing should be able to get straight 
enough. I'm considering incorporating some type of screws or shims in 
the tool holder to make it easier to tweak the alignment if need be.

PS - If Alan reads this- The camera technique is out of my league, but 
I got a "forbidden" error when going to look at those pictures. Not 
sure if others can see them. I'm on Opera 8.51 for Windows.

                        -Much Thanks as Usual!
George

Here's an interesting article that might help you.

http://www.photocritic.org/2005/macro-photography-on-a-budget/

It's not that hard to change the focal length of a webcam, but you'll 
need to increase the amount of light, either with a macro lens, or by 
using better illumination, or, if the cam allows for it, by using a 
longer exposure.



--- In Homebrew_PCBs@yahoogroups.com, "James Newton" 
<jamesmichaelnewton@y...> wrote:
>
> --- In Homebrew_PCBs@yahoogroups.com, Alan King <alan@n...> wrote:
> >   But, I do have plans to focus one of my webcams in very close, 
> put it 
> > right next to the bit, and move up and down.  640 pixels from 
1/4" 

> away 
> > and move the bit up and down should detect if there is any off 
> angle a 
> > little better than using a normal visual method, should get it 
> very 
> > close to perfect on one pass.
> 
> 
> If you find a web cam that can do that or figure out how to adapt 
> one, please let me know. I can't get any of the 4 I own to focust 
> closer than about a foot and a half away. I've looked for close up 
> lenses, but all I can find are for the higher end cameras.
> 
> Having the ability to do close up with a web cam is the first step 
> in machine vision automation on the hobby level. The software is 
> becomming available, the only real cost at this point is the high 
> end cameras you have to buy.
>

soffee83 wrote:

>--- In Homebrew_PCBs@yahoogroups.com, "Mike Young" <mikewhy@s...> 
>wrote:
>  
>
>>After squaring the axis to the table, you can swing a bent wire in 
>>the spindle to square it to the table. The height of the free end 
>>above the table should be the same through a full circle.
>>    
>>
>
>That sounds good (and easy)! It sounds just like the procedure in my 
>radial saw manual, where you rotate the arm with the arbor lightly 
>scraping the table.
>  
>
  It sounds good only if you want to see if your drill is perpendicular 
to the table.  I don't generally care if it's exactly perp. to the table 
or not, I want it true to the motion so it doesn't snap bits.

  Set your axis to 85 degrees instead of 90.  Set your tool back 5 
degrees to the 90.  You're back to perpendicular to the table. Get this 
to zero, then go up and down and see that it's still zero, even though 
you move over quite a bit for any change in depth.  This measurement 
doesn't begin to take out any error in axis motion alignment, it left 
that back at the initial setup for the axis.

  Errors either add, or worse than that, multiply.  All measurements 
have error.  You don't align the axis, let that have error, then only 
align the tool to flat to the table, let that have error, and then let 
the two errors add up.  You measure what you want correct directly, only 
having one source of measurement error, and minimize that error.  The 
off angle motion that that bent wire test can't even detect is way more 
important than whether the tool and axis are exactly 90 degrees to the 
table or not.

  Yes, almost all machinists use dial indicators a lot.  But there are 
still many classes of machinist, most notably the average ones, and 
those that can do truly exceptional things.  I seriously doubt any of 
that higher class would settle for the double error of the indirect 
measures mentioned, I know I don't, and I have barely scratched the 
surface of machining.  What I outlined gives a direct measure of the 
true path of the bit, trying to add up any other couple of measurements 
to get that is going to be a second class measurement.  Lots of people 
like to measure lots of things with lots of numbers and say they're 
highly accurate, but it isn't the case at all if they aren't using the 
best methods and looking through the data to select only the most useful 
and get the best answers.  The alarming thing is just how many of those 
machinists out there with 10x the tools I have can barely beat what I 
can get done with very little, when they should be able to do at least 
10x more easily.  And I find those who insist that all their tools be 
super accurate are often the least accurate themselves, not the most.  
They generally need that super accuracy of everything else to make up 
for the slop in what they do with the tools, it's why they insist on it 
so much.

  I generally don't care if the drill is at 90, or 88, or 75, or 103 
degrees to the table.  The only thing that matters to breaking the bits 
is whether the shaft follows the hole cut by the tip exactly down the 
hole or not.  The best way to measure that is directly.  After you get 
that right, then it's easy to get the whole axis very near 90 degrees, 
and you don't even have to care much if there is error in that 
measurement or not, it has no bearing on snapping bits.  Doesn't matter 
if you do that part first, but checking the tool path directly better be 
done somewhere along the line if you expect to have any sort of high 
accuracy.

  Most machinists would laugh at my setup.  But chuck up a #80 bit, and 
start drilling lots of little holes without breaking bits, and I'm sure 
I can get most of them quiet without much problem.  Especially after I 
stop drilling, wiggle the chuck back and forth probably .010" or .020" 
total with my fingers, then start drilling again and still not breaking 
bits.  Parallel motion is key, basically nothing else matters much.  But 
I'll put some videos up once things are going soon so you can see what 
it'll do for yourselves..

>I've saved Alan's posts for later. They're a bit over my head for now, 
>but I understand most of it. I figure if the pivoting presses are good 
>enough for most work, this thing should be able to get straight 
>enough. I'm considering incorporating some type of screws or shims in 
>the tool holder to make it easier to tweak the alignment if need be.
>
>  
>
    Well the pivot type press works because come out a bit and it's only 
a tiny fraction off from a line, and it's easy to take nearly all the 
play out of hinges.  If what you're doing will have much off axis travel 
or notable play it can easily end up not being as good as the simple 
hinge..  Everything is different, but simple is very good because there 
is less to go wrong.

  With $5 or $10 per 50 or 100 bits, it really won't matter that much if 
things break a bit more than they should.  Even a little sub-optimal is 
still fine for general use if you're not using the very smallest bits..  
.025 or .030 etc bits won't like the flexing and will break more 
quickly, but they don't just snap when you breathe wrong like .016 and 
smaller tend to do.  I've snapped the 80s a few times in my hands or 
while holding what they were in, and you can barely even feel them break..


>PS - If Alan reads this- The camera technique is out of my league, but 
>I got a "forbidden" error when going to look at those pictures. Not 
>sure if others can see them. I'm on Opera 8.51 for Windows.
>
>                        -Much Thanks as Usual!
>George
>  
>

  Suspect Opera for that.  Hotlinking is disabled on my web space, and 
some browsers mask the referring URL.  If your referring URL given by 
the browser is anything besides direct URL entry or link from my site, 
you won't get the file..  Could of course be several other problems 
since I haven't tested it from away lately, but that is the most likely, 
I think it's in the privacy settings of some browsers, seem to have read 
it somewhere a while back.

Alan



[Non-text portions of this message have been removed]

>  Suspect Opera for that.  Hotlinking is disabled on my web space, and 
>some browsers mask the referring URL.  If your referring URL given by 
>  
>
PS at least for now I disabled hotlink protection, that should make it 
work for anyone without a problem..

Links are copied below. 
 

http://www.superference.com/images/PCB/80bit.jpg
http://www.superference.com/images/PCB/80bitLED.jpg
http://www.superference.com/images/PCB/1mmRouter.jpg
http://www.superference.com/images/PCB/18f242board.jpg    Dusty 18f242 
board where I tore up a trace, focus backed out a bit..

I got a 'Forbidden' error on those links earlier today but they're 
working fine now. I'm using IE6, SP2.


Regards, Bob

--- In Homebrew_PCBs@yahoogroups.com, Alan King <alan@n...> wrote:
>
> 
> >  Suspect Opera for that.  Hotlinking is disabled on my web 
space, and 
> >some browsers mask the referring URL.  If your referring URL 
given by 
> >  
> >
> PS at least for now I disabled hotlink protection, that should 
make it 
> work for anyone without a problem..
> 
> Links are copied below. 
>  
> 
> http://www.superference.com/images/PCB/80bit.jpg
> http://www.superference.com/images/PCB/80bitLED.jpg
> http://www.superference.com/images/PCB/1mmRouter.jpg
> http://www.superference.com/images/PCB/18f242board.jpg    Dusty 
18f242 
> board where I tore up a trace, focus backed out a bit..
>

--- In Homebrew_PCBs@yahoogroups.com, "Bob_xyz" <bob_barr@h...> wrote:
> I got a 'Forbidden' error on those links earlier today but they're 
> working fine now. I'm using IE6, SP2.

Same here. I can see them all fine now in Opera.

-Take Care

----- Original Message ----- 

From: "Alan King" <alan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, December 15, 2005 11:24 PM
Subject: Re: [Homebrew_PCBs] Re: The verdict on the quiet Dremel?


> soffee83 wrote:
>
>>--- In Homebrew_PCBs@yahoogroups.com, "Mike Young" <mikewhy@s...>
>>wrote:
>>
>>
>>>After squaring the axis to the table, you can swing a bent wire in
>>>the spindle to square it to the table. The height of the free end
>>>above the table should be the same through a full circle.
>>>
>>>
>>
>>That sounds good (and easy)! It sounds just like the procedure in my
>>radial saw manual, where you rotate the arm with the arbor lightly
>>scraping the table.
>>
>>
>  It sounds good only if you want to see if your drill is perpendicular
> to the table.  I don't generally care if it's exactly perp. to the table
> or not, I want it true to the motion so it doesn't snap bits.

Good Lord, Alan. :)

Yeah, you're right. Square to the table is meaningless if the motion axis is 
skewed. I misread your instructions, and forgot the pivoting arm context. 
That's your fault, though, as the writer.

Truth to tell, PCBs are soft and very forgiving. Sharp carbide at speed cuts 
through it like... soft, fresh, Butternut white bread comes to mind as I 
poke at the boards. Snapping a bit seems about as likely as the White Sox 
taking the pennant next year. (Of course it's possible, but not something 
you think seriously about.)

On Fri, 16 Dec 2005 09:41:47 +0100, Mike Young <mikewhy@...>  
wrote:

>  Snapping a bit seems about as likely as the White Sox
>
> taking the pennant next year. (Of course it's possible, but not something
>
> you think seriously about.)


Oh well, i'm sure you had lotsa hands on experience to come to that  
conclusion.
And i mean the snapping bit, not the white sox.

ST

The lenses in any webcam should be capable of focussing close 
enough, but it is a case of getting enough physical adjustment. You 
will need to move the lens away from the sensor array.

I have been using cameras for close up wrk, but I run a conventional 
composite video board camera through a digitiser board.

The principle is the same tho

Chris

The principle is the same though...  lens further away--- In 
Homebrew_PCBs@yahoogroups.com, "James Newton" 
<jamesmichaelnewton@y...> wrote:
>
> --- In Homebrew_PCBs@yahoogroups.com, Alan King <alan@n...> wrote:
> >   But, I do have plans to focus one of my webcams in very close, 
> put it 
> > right next to the bit, and move up and down.  640 pixels from 
1/4" 

> away 
> > and move the bit up and down should detect if there is any off 
> angle a 
> > little better than using a normal visual method, should get it 
> very 
> > close to perfect on one pass.
> 
> 
> If you find a web cam that can do that or figure out how to adapt 
> one, please let me know. I can't get any of the 4 I own to focust 
> closer than about a foot and a half away. I've looked for close up 
> lenses, but all I can find are for the higher end cameras.
> 
> Having the ability to do close up with a web cam is the first step 
> in machine vision automation on the hobby level. The software is 
> becomming available, the only real cost at this point is the high 
> end cameras you have to buy.
>

----- Original Message ----- 

From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, December 16, 2005 4:15 AM
Subject: Re: [Homebrew_PCBs] Re: The verdict on the quiet Dremel?


> On Fri, 16 Dec 2005 09:41:47 +0100, Mike Young <mikewhy@...>
> wrote:
>
>>  Snapping a bit seems about as likely as the White Sox
>>
>> taking the pennant next year. (Of course it's possible, but not something
>>
>> you think seriously about.)
>
>
> Oh well, i'm sure you had lotsa hands on experience to come to that
> conclusion.

Shoot. Poking a hole through very thin fiberglass backed copper hardly 
requires advanced study. You won't have problems if it's rigid enough, 
straight enough, and spinning fast enough so it feeds well. Snapping a bit 
really does seem quite unlikely. Not the same for you?

On Fri, 16 Dec 2005 19:05:39 +0100, Mike Young <mikewhy@...>  
wrote:

>
>
>
> Shoot. Poking a hole through very thin fiberglass backed copper hardly
>
> requires advanced study. You won't have problems if it's rigid enough,
>
> straight enough, and spinning fast enough so it feeds well. Snapping a  
> bit
>
> really does seem quite unlikely. Not the same for you?
>


Well, as long as it seems unlikely to you you should be quite one the safe  
side then ;-)

ST

Hi, Stefan.

What's up? You sounded a little aggrieved on that one. I read that as a 
reminder that I'm still new to the list. And so I'm reminded.

But what's up with the holes? Are the bits breaking on you?


----- Original Message ----- 

From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, December 16, 2005 12:45 PM
Subject: Re: [Homebrew_PCBs] Re: The verdict on the quiet Dremel?


> On Fri, 16 Dec 2005 19:05:39 +0100, Mike Young <mikewhy@...>
> wrote:
>
>>
>>
>>
>> Shoot. Poking a hole through very thin fiberglass backed copper hardly
>>
>> requires advanced study. You won't have problems if it's rigid enough,
>>
>> straight enough, and spinning fast enough so it feeds well. Snapping a
>> bit
>>
>> really does seem quite unlikely. Not the same for you?
>>
>
>
> Well, as long as it seems unlikely to you you should be quite one the safe
> side then ;-)
>
> ST
>
>
>
> Be sure to visit the group home and check for new Links, Files, and 
> Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> Yahoo! Groups Links
>
>
>
>
>
>

On Fri, 16 Dec 2005 20:21:12 +0100, Mike Young <mikewhy@...>  
wrote:

> Hi, Stefan.
>
>
> What's up? You sounded a little aggrieved on that one. I read that as a
>
> reminder that I'm still new to the list. And so I'm reminded.
>
>
> But what's up with the holes? Are the bits breaking on you?


You just made it sound like the bits don't break, ever, unless the user is  
a klutz.
Either you haven't tried or you have other drills than most people.

ST

----- Original Message ----- 

From: "Stefan Trethan" <stefan_trethan@...>
>> But what's up with the holes? Are the bits breaking on you?
>
>
> You just made it sound like the bits don't break, ever, unless the user is
> a klutz.
> Either you haven't tried or you have other drills than most people.

It's a question of the tool, not of personal ability. If the bits are 
breaking, check that it's rigid enough, straight enough, and spinning fast 
enough. Fast enough covers a lot of sins. (Mine spins at 30k, and is loud 
when it does so. The alternatives -- going slower, or spending a few 
hundred -- aren't very attractive compared to suffering it or wearing ear 
plugs.)

My rig is gravity fed, un-counterweighted. I dropped it once from 2" up, to 
fall full force into the MDF backer. The .032 bit survived. That's about as 
klutzy as you can get, short of piercing a body part.

Is it the drills, then? I use resharpened carbide from Drill City (url 
posted a couple times this month). There's very little preceptible drag on 
new ones straight out of the box. It drags increasingly more as it dulls 
with use. I suppose they'll eventually break to mark the end of their 
service life. I haven't hit that point yet.

As strange aas it may seem, in my supporting Stefan,
bits do break and often. Stefan is not a klutz. :)

I thinks it's a difference in perspective, if you are
a machinist, with the right tools, knowing the correct
procedures and used to machining steel; drilling a few
holes in epoxy fiberglass is easy.

For the rest of use who are weekend warriors, drilling
ususally means putting few holes in a 2 x 4, it's
difficult to downsize the procedure.

what may be a 'hair off' to the weekend builder, will
look like the grand canyon to the experienced
machinist. Combined with the diffence in tool
sharpening (if ever), it all adds up to drill
breakage. At the low cost of drills, it's not a big
deal to the weekend builder.

TANSTAAFL

Myc

--- Mike Young <mikewhy@...> wrote:

> Hi, Stefan.
> 
> What's up? You sounded a little aggrieved on that
> one. I read that as a 
> reminder that I'm still new to the list. And so I'm
> reminded.
> 
> But what's up with the holes? Are the bits breaking
> on you?
> 
> 
> ----- Original Message ----- 
> From: "Stefan Trethan" <stefan_trethan@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Friday, December 16, 2005 12:45 PM
> Subject: Re: [Homebrew_PCBs] Re: The verdict on the
> quiet Dremel?
> 
> 
> > On Fri, 16 Dec 2005 19:05:39 +0100, Mike Young
> <mikewhy@...>
> > wrote:
> >
> >>
> >>
> >>
> >> Shoot. Poking a hole through very thin fiberglass
> backed copper hardly
> >>
> >> requires advanced study. You won't have problems
> if it's rigid enough,
> >>
> >> straight enough, and spinning fast enough so it
> feeds well. Snapping a
> >> bit
> >>
> >> really does seem quite unlikely. Not the same for
> you?
> >>
> >
> >
> > Well, as long as it seems unlikely to you you
> should be quite one the safe
> > side then ;-)
> >
> > ST
> >
> >
> >
> > Be sure to visit the group home and check for new
> Links, Files, and 
> > Photos:
> > http://groups.yahoo.com/group/Homebrew_PCBs
> >
> > If Files or Photos are running short of space,
> post them here:
> >
>
http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> > 
> 
> 
> 
> ------------------------ Yahoo! Groups Sponsor
> --------------------~--> 
> Get fast access to your favorite Yahoo! Groups. Make
> Yahoo! your home page
>
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> 
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>  
> 
> 
> 


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com

While I am/was a machinist and have plenty of experience drilling 
holes with a wide variety of tools, I am very new to drilling in PCB 
materal. I have only drilled a thousand or so holes so far.

However, what I have learned is that the same rules apply to 
drilling PCBs as any other thin material - with one exception which 
I will explan last....


Speed isn't that critical for PCB material - It drills fine at 800 
RPM and at 3500 RPM and at 20,000 RPM.  When drilling on my drill 
press, I use around 1500 RPM or so, it's quiet and works well.  The 
more RPM does help, but isnt' critical.  Adjust your rate of feed 
accordingly with the RPM.

Stable backer board and hold the PCB down.  MDF makes a good backer 
board to rest the PCB on and to drill into - It's cheap.  As the 
drill bit breaks through the back side of the board, it will have a 
tendancy to lift the PCB up, hold the PCB down to prevent this.

Exception -----

When drilling the PCBs on a drill press and positioning the work by 
hand, it is very natural for someone to get the spot lined up, then 
quickly pull down on the handle.  PCB is soft and drills easy so the 
assumption is to drill quickly.  As you get tired, this tendancy to 
feed quickly also increases.  This is probably the biggest cause of 
broken drill bits.  

When drilling hard woods or more so with metal, there is "feed back" 
in the lever to indicate you are feeding with enough presure, with 
PCBs this isn't very noticable. So, to help guide you a bit, try 
this the next time you sit down at the drill press.

Line up the part with the drill bit, gently pull down on the handle 
until the bit contacts the part.  Now, try to time the cut to last 1 
second - no less.  You will notice right away this is about 10 times 
longer than you naturally been doing it AND you will also notice 
that the part has much less tendancy to lift off the drill press 
table.

Practice that for a while and you should see a difference right 
away.  As for broken bits for me when drilling PCB material....

So far this is what has broken the bits for me...

1) Dropped on floor

2) Poked hole in finger while trying to get it out of the little 
box, not once, but twice.  The second time it stuck in my finger and 
when I pulled back in pain, it stuck and flew against the wall.

3) Kept drilling after I was tired (probably 40 holes or so) and 
didn't feed slowly enough and the PCB rode up the drill bit. Then in 
reaction, I pushed the board back down and bit broke

4) I tried to drill a hole free-hand with a dremel - bit broke

5) I lifted the part up off the drill press table without first 
sliding it out from under the bit - bit broke

6) I tried to drill a hole in a PCB at the drill press but with most 
of the components installed on the board. The board would not sit 
flat during drilling and the drill broke.

I believe that pretty much sums up my experience so far with 
drilling PCBs.

Chris





--- In Homebrew_PCBs@yahoogroups.com, Mycroft2152 <mycroft2152@y...> 
wrote:

>
> As strange aas it may seem, in my supporting Stefan,
> bits do break and often. Stefan is not a klutz. :)
> 
> I thinks it's a difference in perspective, if you are
> a machinist, with the right tools, knowing the correct
> procedures and used to machining steel; drilling a few
> holes in epoxy fiberglass is easy.
> 
> For the rest of use who are weekend warriors, drilling
> ususally means putting few holes in a 2 x 4, it's
> difficult to downsize the procedure.
> 
> what may be a 'hair off' to the weekend builder, will
> look like the grand canyon to the experienced
> machinist. Combined with the diffence in tool
> sharpening (if ever), it all adds up to drill
> breakage. At the low cost of drills, it's not a big
> deal to the weekend builder.
> 
> TANSTAAFL
> 
> Myc

I agree on all points.
With a large press and the friction and spring pressure involved in the  
pinion feed, and the good lever action, makes for practically zero  
feedback about the force on the drill (and that is tiny in the first place  
because of the size).
Before i put a vice as counterweight on the back of my pivoting press the  
weight of the arm and spindle would feed the drill too fast, especially at  
low RPMs, which broke a drill. Now that it is balanced i get a very good  
feedback of force from it, i guess the counterweight is a bit better here  
than a spring, and the almost frictionless thrust bearings help too.
There's definitely a difference in "drag" between a fresh out of the box  
drill and a well used one, although the holes will still be nice and clean  
with a slightly dull drill and i see no reason to stop using it.


If you feed slow enough for the RPM, and board and spindle is solid, and  
there's not too much runout, the drills won't break, of course. But  
carbide drills are about the most brittle drill one will ever work with,  
and usually the smallest too, so it takes some attention to get it right.

I have tried different arrangements, including a spindle holder for a  
drill stand inctended for normal power drills, and nothing worked really  
well. The pivoting press does what i need - hold the drill exactly upright  
and in place while allowing me to feed it freely. With it i only break  
drills when making mistakes.

Anyway, it's not a problem, but it isn't the same as drilling a 8mm hole  
in a piece of wood either.

ST

On Sat, 17 Dec 2005 13:20:24 +0100, lcdpublishing  
<lcdpublishing@...> wrote:

> While I am/was a machinist and have plenty of experience drilling
> holes with a wide variety of tools, I am very new to drilling in PCB
> materal. I have only drilled a thousand or so holes so far.
>
> However, what I have learned is that the same rules apply to
> drilling PCBs as any other thin material - with one exception which
> I will explan last....
>
>
> Speed isn't that critical for PCB material - It drills fine at 800
> RPM and at 3500 RPM and at 20,000 RPM.  When drilling on my drill
> press, I use around 1500 RPM or so, it's quiet and works well.  The
> more RPM does help, but isnt' critical.  Adjust your rate of feed
> accordingly with the RPM.
>
> Stable backer board and hold the PCB down.  MDF makes a good backer
> board to rest the PCB on and to drill into - It's cheap.  As the
> drill bit breaks through the back side of the board, it will have a
> tendancy to lift the PCB up, hold the PCB down to prevent this.
>
> Exception -----
>
> When drilling the PCBs on a drill press and positioning the work by
> hand, it is very natural for someone to get the spot lined up, then
> quickly pull down on the handle.  PCB is soft and drills easy so the
> assumption is to drill quickly.  As you get tired, this tendancy to
> feed quickly also increases.  This is probably the biggest cause of
> broken drill bits.
>
> When drilling hard woods or more so with metal, there is "feed back"
> in the lever to indicate you are feeding with enough presure, with
> PCBs this isn't very noticable. So, to help guide you a bit, try
> this the next time you sit down at the drill press.
>
> Line up the part with the drill bit, gently pull down on the handle
> until the bit contacts the part.  Now, try to time the cut to last 1
> second - no less.  You will notice right away this is about 10 times
> longer than you naturally been doing it AND you will also notice
> that the part has much less tendancy to lift off the drill press
> table.
>
> Practice that for a while and you should see a difference right
> away.  As for broken bits for me when drilling PCB material....
>
> So far this is what has broken the bits for me...
>
> 1) Dropped on floor
>
> 2) Poked hole in finger while trying to get it out of the little
> box, not once, but twice.  The second time it stuck in my finger and
> when I pulled back in pain, it stuck and flew against the wall.
>
> 3) Kept drilling after I was tired (probably 40 holes or so) and
> didn't feed slowly enough and the PCB rode up the drill bit. Then in
> reaction, I pushed the board back down and bit broke
>
> 4) I tried to drill a hole free-hand with a dremel - bit broke
>
> 5) I lifted the part up off the drill press table without first
> sliding it out from under the bit - bit broke
>
> 6) I tried to drill a hole in a PCB at the drill press but with most
> of the components installed on the board. The board would not sit
> flat during drilling and the drill broke.
>
> I believe that pretty much sums up my experience so far with
> drilling PCBs.
>
> Chris
>
>
>
>
>
> --- In Homebrew_PCBs@yahoogroups.com, Mycroft2152 <mycroft2152@y...>
> wrote:
>>
>> As strange aas it may seem, in my supporting Stefan,
>> bits do break and often. Stefan is not a klutz. :)
>>
>> I thinks it's a difference in perspective, if you are
>> a machinist, with the right tools, knowing the correct
>> procedures and used to machining steel; drilling a few
>> holes in epoxy fiberglass is easy.
>>
>> For the rest of use who are weekend warriors, drilling
>> ususally means putting few holes in a 2 x 4, it's
>> difficult to downsize the procedure.
>>
>> what may be a 'hair off' to the weekend builder, will
>> look like the grand canyon to the experienced
>> machinist. Combined with the diffence in tool
>> sharpening (if ever), it all adds up to drill
>> breakage. At the low cost of drills, it's not a big
>> deal to the weekend builder.
>>
>> TANSTAAFL
>>
>> Myc
>
>
>
>
>
>
>
>
> Be sure to visit the group home and check for new Links, Files, and  
> Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> Yahoo! Groups Links
>
>
>
>
>
>

I do like that idea of a counter balance - it adds feedback to the 
drilling process.  There are small precision drill presses that have 
some sort of device on them for very precise small hole drilling in 
metals.  I have seen them, never touched one so I don't understand 
it completely.  But, from what I gather it works something like 
this...

It has a quil like a drill press, but no arms.  To move the tool up 
and down it has some sort of collar located just above the chuck 
(this collar does not rotate).  To move the drill bit, pull this 
collar down to feed the bit into the work - very tactile and works 
pretty good from what I saw.  The operators work with stereo 
microscopes so they can see what is going on.  For me, this sort of 
work would drive me crazy in a couple of hours - probably minutes!

Chris




--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:
>
> I agree on all points.
> With a large press and the friction and spring pressure involved 
in the  
> pinion feed, and the good lever action, makes for practically 
zero  
> feedback about the force on the drill (and that is tiny in the 
first place  
> because of the size).
> Before i put a vice as counterweight on the back of my pivoting 
press the  
> weight of the arm and spindle would feed the drill too fast, 
especially at  
> low RPMs, which broke a drill. Now that it is balanced i get a 
very good  
> feedback of force from it, i guess the counterweight is a bit 
better here  
> than a spring, and the almost frictionless thrust bearings help 
too.
> There's definitely a difference in "drag" between a fresh out of 
the box  
> drill and a well used one, although the holes will still be nice 
and clean  
> with a slightly dull drill and i see no reason to stop using it.
> 
> 
> If you feed slow enough for the RPM, and board and spindle is 
solid, and  
> there's not too much runout, the drills won't break, of course. 
But  
> carbide drills are about the most brittle drill one will ever work 
with,  
> and usually the smallest too, so it takes some attention to get it 
right.
> 
> I have tried different arrangements, including a spindle holder 
for a  
> drill stand inctended for normal power drills, and nothing worked 
really  
> well. The pivoting press does what i need - hold the drill exactly 
upright  
> and in place while allowing me to feed it freely. With it i only 
break  
> drills when making mistakes.
> 
> Anyway, it's not a problem, but it isn't the same as drilling a 
8mm hole  
> in a piece of wood either.
> 
> ST
> 
> On Sat, 17 Dec 2005 13:20:24 +0100, lcdpublishing  
> <lcdpublishing@y...> wrote:
> 
> > While I am/was a machinist and have plenty of experience drilling
> > holes with a wide variety of tools, I am very new to drilling in 
PCB
> > materal. I have only drilled a thousand or so holes so far.
> >
> > However, what I have learned is that the same rules apply to
> > drilling PCBs as any other thin material - with one exception 
which
> > I will explan last....
> >
> >
> > Speed isn't that critical for PCB material - It drills fine at 
800
> > RPM and at 3500 RPM and at 20,000 RPM.  When drilling on my drill
> > press, I use around 1500 RPM or so, it's quiet and works well.  
The
> > more RPM does help, but isnt' critical.  Adjust your rate of feed
> > accordingly with the RPM.
> >
> > Stable backer board and hold the PCB down.  MDF makes a good 
backer
> > board to rest the PCB on and to drill into - It's cheap.  As the
> > drill bit breaks through the back side of the board, it will 
have a
> > tendancy to lift the PCB up, hold the PCB down to prevent this.
> >
> > Exception -----
> >
> > When drilling the PCBs on a drill press and positioning the work 
by
> > hand, it is very natural for someone to get the spot lined up, 
then
> > quickly pull down on the handle.  PCB is soft and drills easy so 
the
> > assumption is to drill quickly.  As you get tired, this tendancy 
to
> > feed quickly also increases.  This is probably the biggest cause 
of
> > broken drill bits.
> >
> > When drilling hard woods or more so with metal, there is "feed 
back"
> > in the lever to indicate you are feeding with enough presure, 
with
> > PCBs this isn't very noticable. So, to help guide you a bit, try
> > this the next time you sit down at the drill press.
> >
> > Line up the part with the drill bit, gently pull down on the 
handle
> > until the bit contacts the part.  Now, try to time the cut to 
last 1
> > second - no less.  You will notice right away this is about 10 
times
> > longer than you naturally been doing it AND you will also notice
> > that the part has much less tendancy to lift off the drill press
> > table.
> >
> > Practice that for a while and you should see a difference right
> > away.  As for broken bits for me when drilling PCB material....
> >
> > So far this is what has broken the bits for me...
> >
> > 1) Dropped on floor
> >
> > 2) Poked hole in finger while trying to get it out of the little
> > box, not once, but twice.  The second time it stuck in my finger 
and
> > when I pulled back in pain, it stuck and flew against the wall.
> >
> > 3) Kept drilling after I was tired (probably 40 holes or so) and
> > didn't feed slowly enough and the PCB rode up the drill bit. 
Then in
> > reaction, I pushed the board back down and bit broke
> >
> > 4) I tried to drill a hole free-hand with a dremel - bit broke
> >
> > 5) I lifted the part up off the drill press table without first
> > sliding it out from under the bit - bit broke
> >
> > 6) I tried to drill a hole in a PCB at the drill press but with 
most
> > of the components installed on the board. The board would not sit
> > flat during drilling and the drill broke.
> >
> > I believe that pretty much sums up my experience so far with
> > drilling PCBs.
> >
> > Chris
> >
> >
> >
> >
> >
> > --- In Homebrew_PCBs@yahoogroups.com, Mycroft2152 
<mycroft2152@y...>
> > wrote:
> >>
> >> As strange aas it may seem, in my supporting Stefan,
> >> bits do break and often. Stefan is not a klutz. :)
> >>
> >> I thinks it's a difference in perspective, if you are
> >> a machinist, with the right tools, knowing the correct
> >> procedures and used to machining steel; drilling a few
> >> holes in epoxy fiberglass is easy.
> >>
> >> For the rest of use who are weekend warriors, drilling
> >> ususally means putting few holes in a 2 x 4, it's
> >> difficult to downsize the procedure.
> >>
> >> what may be a 'hair off' to the weekend builder, will
> >> look like the grand canyon to the experienced
> >> machinist. Combined with the diffence in tool
> >> sharpening (if ever), it all adds up to drill
> >> breakage. At the low cost of drills, it's not a big
> >> deal to the weekend builder.
> >>
> >> TANSTAAFL
> >>
> >> Myc
> >
> >
> >
> >
> >
> >
> >
> >
> > Be sure to visit the group home and check for new Links, Files, 
and  

> > Photos:
> > http://groups.yahoo.com/group/Homebrew_PCBs
> >
> > If Files or Photos are running short of space, post them here:
> > http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
>

--- In Homebrew_PCBs@yahoogroups.com, "lcdpublishing" 
<lcdpublishing@y...> wrote:
> Speed isn't that critical for PCB material - It drills fine at 800 
> RPM and at 3500 RPM and at 20,000 RPM.  When drilling on my drill 
> press, I use around 1500 RPM or so, it's quiet and works well.

Yeah, I didn't know anything about the recommended higher speeds until 
I got in here. I've never counted, but I would guess I've done several 
thousand holes already, and have been running even below what you're 
talking about. I'm usually at the lowest, quietest setting on my 
benchtop press which is only 620rpm. I'm a bit careless about it at 
times, and will use anything on hand, from HSS to carbide, to diamond 
burrs.

My usual bit breakage is also with stupid stuff like repositioning the 
boards while the tip is blocked by something. The backers have been 
lots of stuff, from melamine up to soft pine, but I'm trying to get in 
a habit of keeping new clean, flat backer material (maybe tempered 
hardboard).

BTW, I've drilled 'into' my finger with a Dremel on high speed before. 
It left a perfectly cylindrical hole about 1/16" dia. by almost as 
deep. It was really gross to look at, and didn't bleed (just stung).

                          -George

Stefan Trethan wrote:

>
>If you feed slow enough for the RPM, and board and spindle is solid, and  
>there's not too much runout, the drills won't break, of course. But  
>carbide drills are about the most brittle drill one will ever work with,  
>and usually the smallest too, so it takes some attention to get it right.
>
>  
>


  Well, haven't even read all the replies yet.  But runout is not the 
only critical factor.  You can spin absolutely true, and still be 
putting a heck of a strain on a bit.  If your drill isn't 100% in line 
with the motion, and I mean well beyond what most people would probably 
consider acceptable, you'll be flexing the bit like crazy.  1/10,000th 
off is 3" of flexing back and forth per minute at 30k RPM..

  If your bit is say half a thousandth off of where it should land for 
vertical, the tip will cut a hole there.  Soon as that tip cuts a hole, 
the bit is locked in, these things have just about zero side cutting 
ability.  An X narrows the gaps between the lines as you go up, assume 
as you drill that gap narrows to .4 of a thousandth off to where it 
should be, and the tip is locked in way over at .5.  That would average 
to half of a ten thousandth off.  That's 1.5 inches per minute you're 
flexing the drill, and at 500 Hz.  Really it's 3" per minute, 
considering it goes one way then the other as it rotates.  And that's 
with zero runout to start, runout has nothing at all to do with the 
drill being even a tiny bit off line of the motion.  And compared to 
near zero if you get it much closer, which bit will fail first?

  And you're not likely to even begin to see errors of this small 
magnitude.  I can't see it myself.  But for sure, if I chuck up an 80 
bit after aligning by a .025 or .030 first, I can certainly see how 
crappy my alignment on the first bit was by how badly the 80 will flex.  
And go back up after aligning by them, and everything is that much 
smoother and nothing breaks.

  I'd personally think very very few in this group might have the tools 
to align their rigs statically to even come close to what's really 
needed for these bits now that I've done some math on it.  If you're 
just aligning your axis fairly well, and then checking runout, you 
probably aren't even that close to where you should be, at least not 
close enough for very small bits that need to have zero flexing.  It'd 
probably take a laser interferometer to do it reliably with a general 
measuring tool.  The numbers that you think of as great for machining 
aren't even close to good enough for these fine bits to not be seriously 
flexing, even if you can't see that few ten thousandths of error by 
looking at a .030 bit while it's running, it's working very hard on your 
bits.

  But with 32 boards here to round off and do some internal cutouts asap 
things just got kind of busy..  Need at least 6 or so built within a day 
or two now, have to get samples to a couple of people, hopefully before 
Christmas which will be a stretch.  While it's an anxious time waiting 
for them to get here, it's very relaxing to have a pile of excellent 
boards in your hands without having to make them!  :)

Alan

----- Original Message ----- 

From: "Alan King" <alan@...>
> close enough for very small bits that need to have zero flexing.  It'd
> probably take a laser interferometer to do it reliably with a general

:) Good one. No doubt you're right for something that small and into a 
larger chunk of something more substantial. For 24 mil holes in 1/16" FR4, 
though...

I'm having trouble forming complete thoughts this moment; running off a 
fever here in winter wonderland. Here's a dump of what flickered across the 
forebrain on reading your thoughts.

Something very tiny will break before it can cut sideways, while something 
rather larger will cut rather than break. Somewhere in between is the 
continental divide between "woefully fragile" versus "bulletproof". The 
threshold size is smaller for: faster cutter speed; thinner material; 
smaller angular misalignment; slower feed rate;  softer material; sharper 
tool edge. Small is good; it's the smallest hole your tool can drill instead 
of break. I'll put forth the notion that, various reasons, the size is 
rather sharp defined, and more or less fixed for a given tool. #73 is as 
small as I care to drill, and is on the bulletproof side of that line on my 
drill.

Flexural stress varies as the cube of the diameter for small deflections. A 
#73 is about twice the diameter of your #80. So, considering geometry alone, 
it sees about 8 times less stress for the same misalignment. It is also 
stiffer, requiring more side force to deflect a given distance, and so has 
stronger cutting action.

3" per minute sounds significantly big, but to what do we compare it? A #67 
bit at 30k rpm is moving two flutes 500 fpm on the surface. 3 ipm is next to 
nothing in comparison, if comparison is reasonable.

Radius of gyration, and buckling limits... It hurts my head to think about 
right now, but is very likely the physical failure mode.

Resonance... Definitely significant if present (but similarly impossible to 
frame into a meaningful thought this moment; will try again in the morning).

On Tue, 20 Dec 2005 02:14:57 +0100, Alan King <alan@...> wrote:

>
>
> Alan


I will try your method with watching the tiny bit flex, i have plenty of  
those to break.

ST

--- In Homebrew_PCBs@yahoogroups.com, Alan King <alan@n...> wrote:
 >Well, haven't even read all the replies yet.

Alan,

I had one a few days ago on looking for the Handi-Tool at Walmart 
(couldn't find it).

If you happen to know anywhere else, or if you think it's no longer 
available, let me know.

                             -Thanks!

Lol yes, maybe you're a bit feverish..

Mike Young wrote:

>----- Original Message ----- 
>From: "Alan King" <alan@...>
>  
>
>>close enough for very small bits that need to have zero flexing.  It'd
>>probably take a laser interferometer to do it reliably with a general
>>    
>>
>
>:) Good one. No doubt you're right for something that small and into a 
>larger chunk of something more substantial. For 24 mil holes in 1/16" FR4, 
>though...
>
>  
>
  Within this range, the thinner bit is probably quite a bit less likely 
to break as fast, bending in more of an arc due to having a bit more 
flexibility from being thin.  The 24 will try and stay more straight, 
and with the same small displacement will tend to concentrate it more in 
a single area.


>I'm having trouble forming complete thoughts this moment; running off a 
>fever here in winter wonderland. Here's a dump of what flickered across the 
>forebrain on reading your thoughts.
>
>Something very tiny will break before it can cut sideways, while something 
>rather larger will cut rather than break. Somewhere in between is the 
>continental divide between "woefully fragile" versus "bulletproof". The 
>threshold size is smaller for: faster cutter speed; thinner material; 
>smaller angular misalignment; slower feed rate;  softer material; sharper 
>tool edge. Small is good; it's the smallest hole your tool can drill instead 
>of break. I'll put forth the notion that, various reasons, the size is 
>rather sharp defined, and more or less fixed for a given tool. #73 is as 
>small as I care to drill, and is on the bulletproof side of that line on my 
>drill.
>
>  
>
  Try something.  Start a hole with your 24.  Move your drill so there 
is a little bow in the bit.  See just how long it takes you to do even a 
small sideways cut.  The flutes are to clear the hole, in the direction 
of drilling.  Carbide doesn't flex well, the normal bits are not 
designed for side cutting.  Even the routers that are designed to cut 
sideways it is stressed to let them cut, not force them into the 
material at any great rate.



>Flexural stress varies as the cube of the diameter for small deflections. A 
>#73 is about twice the diameter of your #80. So, considering geometry alone, 
>it sees about 8 times less stress for the same misalignment. It is also 
>stiffer, requiring more side force to deflect a given distance, and so has 
>stronger cutting action.
>  
>

  That's without the concentration point where the bit joins the shank.  
For sure I've drilled with 80's bowing out with displacements that will 
snap a 24 or 32 just about instantly.  To a point, you can break thicker 
wire faster than thinner wire when bending it back and forth by hand.  
The thinner wire tends to bend in more of a radius and spread the load.  
Use the same deflection and break some 30 ga wire and some 22 ga.  I 
think you'll find the 22 is far easier to break..  #80 bits are that bit 
more flexible, they will radius bend and have very little actual force 
at the tip. 24 will have most of the force concentrated at the tip and 
board, and stress where the shaft meets the shank, and considerably less 
bending in between.  The extra strength only serves to concentrate the 
stress into a tiny area.  There are many such cases where things operate 
backwards, a solid rod is weaker than a pipe of same diameter with a 
certain wall thickness.  If you stick a tight sized marble into the 
pipe, it will bend at the marble first, it is a leverage point from one 
side to the other that weakens the pipe.  And think of the solid center 
of a rod as being an infinite number of marbles, they all make the rod 
actually a little weaker than if it were hollow with thick walls..  The 
center doesn't really contribute much to the strength, what seems it 
should have been stronger is actually weaker..

  By doubling the diameter of an 80 to an .024, you'll make it 
considerably less flexible and tend to concentrate stresses while not 
increasing it's resistance to flex related damage by an equal margin.  
You have to start getting into a large bit before it can start taking a 
decent sideways cutting force instead of displacing, or pull your whole 
axis into it's alignment instead of displacing the tip..

  The real problem isn't the degree between the two anyway.  It's that 
you can run for long periods of time with .024 etc bits, thinking you're 
in near perfect alignment, while you're actually stressing them the 
whole time.  The 80s will bow noticably when starting with the exact 
same small misalignments, and you can see and correct it.  When you go 
back up to the .024 after that, they run that little bit smoother, and 
start lasting a long time, usually until you screw up doing something 
else and feed to fast or hit the bit.  You see it immediately with the 
80s and can correct, with the 24 you can run the bit and never notice 
the same small level of displacement killing the bits because they won't 
bow out so much and be as visible, you'll only see that they break now 
and then.  Don't think I've had one break from natural causes since 
doing this, mostly from hitting it with other stuff, there has been one 
or two from drilling, but was from leaving it at the same rate I use for 
jogging the drill around, not at a normal drill rate.  Another now and 
then still beyond that, but with used bits and dropping the cases now 
and then, I'm sure I have started fractures in more than a few before 
they even get chucked up..

  Note that I don't even consider all that important to actually do this 
alignment.  Bits are cheap, if you get close enough to do 500 holes it's 
sort of a who cares number.  But the same bits can likely still do 5000, 
even if they're used.  But it's important simply to understand that 
there is another level of alignment to work on that is important to 
really long life, before even considering that play etc or anything else 
is what's actually breaking the bits.  Everything else is simply a 
secondary factor, even a tiny bit of misalignment is going to be more 
important to bit life..

>3" per minute sounds significantly big, but to what do we compare it? A #67 
>bit at 30k rpm is moving two flutes 500 fpm on the surface. 3 ipm is next to 
>nothing in comparison, if comparison is reasonable.
>
>  
>

  These are applying forces in directions the bit can take. You could 
drive thousands of miles with a 10,000ft drop off on your right, but 
lets see how things work out when you turn right and then drive 10 feet 
over it..  Independent variables don't relate at all.

Alan

Stefan Trethan wrote:

>On Tue, 20 Dec 2005 02:14:57 +0100, Alan King <alan@...> wrote:
>
>  
>
>>Alan
>>    
>>
>
>
>I will try your method with watching the tiny bit flex, i have plenty of  
>those to break.
>
>ST
>
>  
>

  Hey great, another critical eye on it.  First, loosen everything in 
the axis a little, and totally realign it as best you can with a 24 or 
30 range bit.  Get it so there's no visible vibration or wobble.   Then 
chuck the 80 and see what you think.  I'm curious if your estimate of 
the initial alignment is as bad as mine after seeing what the 80 size 
does right after..

  You could actually hit on near perfect, even with still bad error in 
the general alignment, just by chance.  Or get much closer with 
different tools.  But I've never been that lucky, and it's even hard to 
move one end of the drill in small enough motions to get it good for the 
80's.  Usually takes 8-10 tries before I get it tightened back up and 
keeping the alignment I wanted..  Need to make a better screw type fine 
adjuster, but even 10 tries or more is quick enough that I haven't 
bothered.  One of the things to look at though for rebuilding the CNC, 
would be nice to have one end of the drill have X and Y adjustments (or 
maybe one on each end for simplicity of the adjuster) and be able to do 
very precise adjustments.  Right now it is just oversize holes with 
screws and nuts, and tweak around and tighten and hope it stays right 
and check after..

Alan

----- Original Message ----- 

From: "Alan King" <alan@...>

> whole time.  The 80s will bow noticably when starting with the exact
> same small misalignments, and you can see and correct it.  When you go
> back up to the .024 after that, they run that little bit smoother, and

I'll buy in that really skinny bits make useful and usable edge finders. 
That's a plenty useful observation, and a good place to leave it. We can 
pick it up again next year if you like. I have a few nits and bones to pick 
on some of your other comments, but they'll keep.

soffee83 wrote:

>--- In Homebrew_PCBs@yahoogroups.com, Alan King <alan@n...> wrote:
> >Well, haven't even read all the replies yet.
>
>Alan,
>
>I had one a few days ago on looking for the Handi-Tool at Walmart 
>(couldn't find it).
>
>If you happen to know anywhere else, or if you think it's no longer 
>available, let me know.
>
>                             -Thanks! 
>
>  
>

http://images.amazon.com/images/P/B0000302V5.01.LZZZZZZZ.jpg

"and a Handi Works Rotary Tool MHW550 (which cost the least and I like 
the best)."

http://powertoolsvault.com/B0000302V5/index.php

  May well have been a one time run sort of model.  Apparently made by 
Black&Decker and just rebadged for Walmart.  Looks like there is a newer 
B&D tool, so may not be made any longer.  I'll see if my local Walmart 
still has it next time I'm out.  Was there last time I looked, but it's 
been a year or more since I went to really check their tool aisle..

  B&D is switched variable speed, the Handi has a speed dial. 

Heck, here is a picture of mine..
http://www.modellights.com/images/temp/handiworksrotarytool.jpg

http://www.modellights.com/images/temp/handimount.jpg

  And the mounting.  Nylon screw inside the case, nut to case, and nut 
to hanger iron.  One of these on each end of tool, and into a flat 
electrical box, which is in turn screwed to the wood plate for the 
axis.  Quick and dirty (note the cobwebs) but stable in the directions 
needed and no V etc to cut.  Another temporary quick idea to get it 
mounted and testing, that worked so well that I have never fixed it.  I 
expected it to move etc while drilling, but it's quite precise under 
drilling and even routing loads.

Alan

Much thanks for the images!

I didn't realize that thing was actually a B&D. It looks old yet 
familiar. We have a B&D service center here that may be able to find 
one if you think it's quiet enough to hunt down.

The Walmart here must have had the newer model you refer to (along 
with all the Dremels). There's was the bright orange one.

                         -Take Care

soffee83 wrote:

>Much thanks for the images!
>
>I didn't realize that thing was actually a B&D. It looks old yet 
>familiar. We have a B&D service center here that may be able to find 
>one if you think it's quiet enough to hunt down.
>
>The Walmart here must have had the newer model you refer to (along 
>with all the Dremels). There's was the bright orange one.
>
>                         -Take Care 
>
>  
>

  Never can tell, the new one could be even better.  Might try and swing 
by my Walmart today, and see what they have.  If it's anywhere near the 
$19 I paid for this one, may pick up a spare and try it out, then take 
it back if it's worse and find a spare myself while it can still be 
tracked down..

  Not sure if the actual sound pressure level is all that much lower, 
but the sound itself is much less annoying.  Dremel starts being 
annoying around 2 on the 5 scale, this one at 4 on the 6 scale is quite 
decent and even all the way up isn't too terrible.  I got this as a back 
up hand tool, to mount the Dremel on the CNC.  It was quite noticably 
enough better that it got stuck on the CNC instead and the Dremel is the 
back up..  If I had much to do I'd unmount this one before using the 
Dremel much.

Alan

Thanks again Alan!

The blue version is around (used). They all have sort of a weird 
shape, but I guess if I do the body mounted standoffs like yours, it 
wouldn't make much difference. A perfect cylinder sure would look cool 
though. :) There's an older Dremel that looks like that, but it could 
sound like a chainsaw.

One complaint I saw on the blue one, was that it doesn't really allow 
for the lower speeds. I've got a varispeed box here that may work, but 
I've heard it can do nasty things to certain types of motors. You may 
have noticed the post here about the lower speeds being adequate most 
of the time. I realize that isn't the best idea for the carbides, but 
if it does OK, it would make a heck of a difference noise-wise. I tend 
to do boards late at night, usually at home. 

I'm still planning to check a newsgroup too. I'm not sure what would 
be the best group for that. It's possible there's someone out there 
who uses them all day and has owned twelve different models. I'm in no 
hurry. The Christmas junk has given me no chance of working on a press 
for at least a few days.

BTW- I do sound crap and I've got a couple dB meters here, as well as 
software that can capture spectrum and FFT shots. If I can get more 
than one roto, I may try that. It would probably give a good idea of 
who makes the more obnoxious sound.

                                      -George

soffee83 wrote:

>Thanks again Alan!
>
>The blue version is around (used). They all have sort of a weird 
>shape, but I guess if I do the body mounted standoffs like yours, it 
>wouldn't make much difference. A perfect cylinder sure would look cool 
>though. :) There's an older Dremel that looks like that, but it could 
>sound like a chainsaw.
>
>One complaint I saw on the blue one, was that it doesn't really allow 
>for the lower speeds. I've got a varispeed box here that may work, but 
>I've heard it can do nasty things to certain types of motors. You may 
>have noticed the post here about the lower speeds being adequate most 
>of the time. I realize that isn't the best idea for the carbides, but 
>if it does OK, it would make a heck of a difference noise-wise. I tend 
>to do boards late at night, usually at home. 
>  
>
  Well definitely wait until I try out the newer one.  Then if it's bad 
I'd say hunt for the old grey Walmart one, it has the dial, and was the 
reason I went ahead and got one.  While I haven't bought 50 of them, 
I've used more than a few and heard many more.  This one is the least 
annoying that I've ever seen and least vibration, they did a few things 
right.  My webcam gets the sound as well, at some point soon I'll try 
and capture this and the Dremel.  No doubt will be lacking for sound 
accuracy, but at least give some relative idea..

>I'm still planning to check a newsgroup too. I'm not sure what would 
>be the best group for that. It's possible there's someone out there 
>who uses them all day and has owned twelve different models. I'm in no 
>hurry. The Christmas junk has given me no chance of working on a press 
>for at least a few days.
>
>  
>

  Yep that and the invisible water leak have stopped about everything 
else for me for 2 days.  Gallon or two showed up in the carpet and under 
the hardwood beside, only 3 water sources within 50 feet, yet they're 
all dry.  Big spot of water with no apparent route to a source, and no 
more water coming in..  Gotta find where it came from before something 
lets go..

  Didn't get out there today, but still might wait till a bit later and 
brave the crowds tonight for Walmart and see what they have.  Open to 12 
I think so 11 should be clearing out..

Alan

Alan King wrote:

>soffee83 wrote:
>  
>

  Just got the new $25 B&D from Walmart.  While I was expecting to take 
a look, it not be any better than the Handi, and take it back, heck if 
it isn't actually as good or better.  Only has 3 speeds, but that is a 
minor limitation.  Very rarely should one ever use these at low speeds, 
about the only thing is for plastic etc to go very slow so it won't 
melt.  The rotation of the tool is supposed to do the work, not spinning 
slowly and using sideways pressure..  Low speeds are fairly irrelevant 
for most drilling with small bits.

  I will set up a direct comparison with my webcam, so everyone can 
check it out.  The new one is very smooth, at least as good as the older 
one.  Of course bearings are subject to wear, and some of the newer 
higher end Dremels may be better than mine, although it's a multipro and 
not really old or worn out.  But every Dremel I've ever heard was rather 
annoying at the top end if not by the middle range.  While Dremel has 
the name for the rotary tool, B&D is actually a much larger company, and 
if you've seen the show on the History channel with their research lab, 
they're likely able to pump 10 or 50 times as much money into R&D than a 
smaller company could afford, with lower noise and vibration being a 
major target, and with other tool lines spreading the costs.  At any 
rate, for $25, it is an excellent tool.  Only the sanding drum in the 
kit though, but I expect most here will already have a ton of bits..

Alan