Homebrew PCBs

Hello everyone.My name is Nick from Sydney Aust. My first post to 
this group.So this is probably a dumb question to you guys.I have 
managed to etch my first board after a few failures, but I came up 
with a real beauty(I think anyway).I drilled a board last week and i 
nearly went blind tryin to line up the bloody drill to the pads.So 
is there a way i can use a mirror or something to give me a better 
view of tiny drill to tiny pads. I am using a dremell mounted on a 
stand .The drilling is easy but lining up whilst looking through the 
magnifying glass is hard.Any tips would be appreciated.Thanks.

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

From: "Nick" <njacovou@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, August 26, 2004 5:52 AM
Subject: [Homebrew_PCBs] Drilling Pcb's


> Hello everyone.My name is Nick from Sydney Aust. My first post to
> this group.So this is probably a dumb question to you guys.I have
> managed to etch my first board after a few failures, but I came up
> with a real beauty(I think anyway).I drilled a board last week and i
> nearly went blind tryin to line up the bloody drill to the pads.So
> is there a way i can use a mirror or something to give me a better
> view of tiny drill to tiny pads. I am using a dremell mounted on a
> stand .The drilling is easy but lining up whilst looking through the
> magnifying glass is hard.Any tips would be appreciated.Thanks.

I had the same problem which I solved by buying a pair of 3.5 diopter
reading glasses.

Leon

On Thu, 26 Aug 2004 04:52:24 -0000, Nick <njacovou@...> wrote:

> Hello everyone.My name is Nick from Sydney Aust. My first post to
> this group.So this is probably a dumb question to you guys.I have
> managed to etch my first board after a few failures, but I came up
> with a real beauty(I think anyway).I drilled a board last week and i
> nearly went blind tryin to line up the bloody drill to the pads.So
> is there a way i can use a mirror or something to give me a better
> view of tiny drill to tiny pads. I am using a dremell mounted on a
> stand .The drilling is easy but lining up whilst looking through the
> magnifying glass is hard.Any tips would be appreciated.Thanks.

It helps if you etch a small hole in the copper. This small hole catches
the drill and centers it.

The professinal approach is to use a viewing apparatus, a optical system  
looking
at the PCB from the other side. this apparatus has concentric rings on the  
screen which
helps to align the pad.
Normally those machines feed the drill from below, and have a foot holding  
down the pcb
so it doesn't get lifted up. A optical system looks from top, and has a  
screen.
A "cheap" homebrew solution could be a small camera module and a old tv  
screen.
Monunt the camera under the drill table, facing up through a hole.
(use a mirror and/or glass plate to keep the dust away from the cam lens).
I reckon this is easier to align for a electronics guy than a real optical  
system and those
camera modules go for well below 50eur/usd. A tv can probably be found  
somewhere.
It also allows for a unmodified drill stand with the drill fed from above  
(and no pressure
foot needed).

Perhaps you will need compressed air or a fan to keep the dust away from  
the mirror or glass plate.
You must ensure alignment is solid so the cam doesn't move relative to the  
drill.

For around 500bucks you could buy a cnc drilling machine(-kit), and if you  
are good with mechanics
you could build your own for a lot less. You put the pcb in and the  
machine does the rest.
Of course a CNC is only useful if you have a certain number of PCBs,  
otherwise is is too
expensive. (Also keep in mind setting up the machine will take time,  
learnig how to generate
the drill files, aligning and chucking stuff etc. I believe for a small  
imple PCB nothing beats
hand drilling (of course 100pcs./months with 200holes ea. are another  
story).

ST

Hi Nick,
I am up in Brisbane  and can sympathize with your problem.

Over the last thirty years or so I have drilled thousands upon thousands of 
holes by hand.

Make sure you have decent holes in the pad before you start drilling. I 
usually set the hole size in the PCB design program to 20 thow. This acts 
like a center pop mark and the drill finds its own center.

Use only the tungsten carbide bits as the normal HSS drills go blunt after 
about thirty holes. The tungsten bits are more expensive but last for ages. 
However if you look at them the wrong way they snap.

I use a Desk Mount Magnifier Lamp (Jaycar QM 3525) to look through. If I 
can't use this I wear a head magnifier.

I also have a jet of compressed air blowing on the drill tip to clear the 
swarf away.

Be careful with the Dremell on its drill stand. The Dremell stand I used to 
use was very sloppy and if one used all its travel the last couple of 
millimeters went sideways and broke the drill. I now use a Toyo drill press 
and it works without problems.

David


At 02:52 PM 26/08/2004, you wrote:
>Hello everyone.My name is Nick from Sydney Aust. My first post to
>this group.So this is probably a dumb question to you guys.I have
>managed to etch my first board after a few failures, but I came up
>with a real beauty(I think anyway).I drilled a board last week and i
>nearly went blind tryin to line up the bloody drill to the pads.So
>is there a way i can use a mirror or something to give me a better
>view of tiny drill to tiny pads. I am using a dremell mounted on a
>stand .The drilling is easy but lining up whilst looking through the
>magnifying glass is hard.Any tips would be appreciated.Thanks.
>
>
>
>
>
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David Hopkins (VK4ZF)
Queensland
AUSTRALIA
davhop@...
S 27, 22.294  E153, 11.008

Hello Nick,

Welcome. Before I started using CNC to drill pcb holes, I came up 
with something that improved my results immensely, but took a bit 
more time, and requires a decent drill press (as one reply mentioned, 
if your drill press goes all over the place as you bring it down, 
you're fighting a losing battle.)

Anyways, here's what I useta do. Use a piece of .100 perfbord UNDER 
the pcb--on the drill table. Then use a dual inline header strip as 
a "fence" to guide the PCB. By using this fence system to control the 
front to back, your eyes only need to determine left and right 
placement. As long as you use a .100 layout, this can be pretty quick.

Start with the FRONTMOST holes in your PCB. This means the "fence" 
will be the farthest away from the bit. Go from left or right and 
when that "row" is drilled pull the header forward one row and repeat.

As I said, moving the header "fence" takes a bit more time than 
without, but the straight even holes are worth it, IMO.

Hope this helps,

Ballendo
 

--- In Homebrew_PCBs@yahoogroups.com, "Nick" <njacovou@o...> wrote:
> Hello everyone.My name is Nick from Sydney Aust. My first post to 
> this group.So this is probably a dumb question to you guys.I have 
> managed to etch my first board after a few failures, but I came up 
> with a real beauty(I think anyway).I drilled a board last week and 
i 
> nearly went blind tryin to line up the bloody drill to the pads.So 
> is there a way i can use a mirror or something to give me a better 
> view of tiny drill to tiny pads. I am using a dremell mounted on a 
> stand .The drilling is easy but lining up whilst looking through 
the 
> magnifying glass is hard.Any tips would be appreciated.Thanks.

Thank you all for your responses.Most usefull.I liked the cam idea, 
i also experimented with a light from below through a pinhole which 
is drilled in place in a piece of laminex. As i move the pcb over 
the pinhole when im lined up, the light beam lights up the 
pad.Problem is the board tends to disperse the light.I sure would 
like to use CNC to mill the boards but this is what got me on to 
this group in the first place! Yes these boards are for a 
router/mill  LOL. I have never tried making a complex(to me)pcb 
before.So in the last few weeks I have learned how do toner transfer 
and driven my wife nuts ,cause she has access to photocopier at 
work .Problem is unless you have your own laser/copier it is hard to 
experiment.So not being allowed to adjust the settings of the 
photocopier is a major drawback.I was printing with our Epson inkjet 
onto Kodak presentation paper at 1440 Dpi and then this was used to 
photocopy onto various paper and transparancies.My results were good 
but not consistent.I also learned how difficult it is to line up 
transfers for double sided boards.I still reckon its a great cheap 
system and my kids have applied it to their craftwork.Enter Phase2.I 
bit the bullit and bought Kinsten presensitised PCB .  Also got the 
Jetstar Inkjet transparancies.I printed  at 1440 Dpi   I made 4 
copies 2 for the top 2 for the bottom.I stuck the ink side to the 
ink side lining them up perfectly.This also gave me a darker 
black.Then I used double sided tape to stick the top to the bottom 
leaving a pocket on one side.So 4 pieces alltogether shiny sides 
out.Then I slide board in and expose in front of fluro lights for 8 
minutes and develop.Not enough exposure on one side(I think).I etch 
the board ,one side good other side bad.So I etch longer.This pitted 
good side.Start again new board.Exposed in front of mercury 
vapourlight for 2 minutes.Developed excellent result!Etch again this 
time overcautiously and I only checked with my magnifying glass 
should have checked with my eyepiece,I had 7 short circuits!I 
cleaned it up.My third attempt turned out great.I'll try and post a 
pic. I realise you guys have been there done that.Also most of the 
credit goes to guys on this group and others.So back to 
drilling.Bye .

_Very_ clever trick, Ballendo!  But I hope I won't have to ever use 
it, because with luck I'll have one of your new machines soon!  Can't 
wait to see what other clever tricks you have imcorporated into your 
products....

- Steve

--- In Homebrew_PCBs@yahoogroups.com, "ballendo" <ballendo@y...> 
wrote:
> Hello Nick,
> 
> Welcome. Before I started using CNC to drill pcb holes, I came up 
> with something that improved my results immensely, but took a bit 
> more time, and requires a decent drill press (as one reply 
mentioned, 
> if your drill press goes all over the place as you bring it down, 
> you're fighting a losing battle.)
> 
> Anyways, here's what I useta do. Use a piece of .100 perfbord UNDER 
> the pcb--on the drill table. Then use a dual inline header strip as 
> a "fence" to guide the PCB. By using this fence system to control 
the 
> front to back, your eyes only need to determine left and right 
> placement. As long as you use a .100 layout, this can be pretty 
quick.
> 
> Start with the FRONTMOST holes in your PCB. This means the "fence" 
> will be the farthest away from the bit. Go from left or right and 
> when that "row" is drilled pull the header forward one row and 
repeat.

> 
> As I said, moving the header "fence" takes a bit more time than 
> without, but the straight even holes are worth it, IMO.
> 
> Hope this helps,
> 
> Ballendo

In article <cgjqa8+10gud@...>,
   Nick <njacovou@...> wrote:
> Hello everyone.My name is Nick from Sydney Aust. My first post to 
> this group.So this is probably a dumb question to you guys.I have 
> managed to etch my first board after a few failures, but I came up 
> with a real beauty(I think anyway).I drilled a board last week and i 
> nearly went blind tryin to line up the bloody drill to the pads.So 
> is there a way i can use a mirror or something to give me a better 
> view of tiny drill to tiny pads. I am using a dremell mounted on a 
> stand .The drilling is easy but lining up whilst looking through the 
> magnifying glass is hard.Any tips would be appreciated.Thanks.

Being very short sighted I remove my glasses and can then get quite close.

I do use goggles though!

I have a small halogen spotlight, you know the dichoric ones they use for
display lighting, small lamp about 2" diam? I place this to one side and
it gives a very good illumination. It also casts a shadow of the drill bit
onto the pcb. Placed so that the shadow is due "east-west" I use this to
give me a fore and aft indication of the drill position.

As the drill comes down I can see the shadow getting closer and closer to
the pad centre and I know I'm right before the drill contacts.

Stuart

--- In Homebrew_PCBs@yahoogroups.com, "Nick" <njacovou@o...> wrote:
> Thank you all for your responses.Most usefull.

Nick,

Here's another technique I useta use, which I didn't have time to 
post before...

It also involves using a perf board and laying out your board at .100

First make an accurately sized photocopy of your final PCB layout.
Then--using light from behind, as you described for a different use-- 
line this up with a piece of perfboard at least as big as the entire 
board. Now peeling back one "half" at a time, use a stick adhesive 
(UHU is one common brand) to fasten the paper TO the perfboard 
(Actually, I used to do it all in one shot, with spray adhesive (3m77 
or 90) first, but if you're not used to doing that type of "gotta get 
it right the first time", it will be easier to do one half at a time)

However you do it, you now have "guide holes" for your bit. Just 
drill carefully the first time, and/or punch through the desired 
locations with a pin, resistor lead, etc.

Depending upon th eperfboard you use, there may be some "slop" 
because cheap perf board has relatively big holes. The holes you need 
to drill which are BIGGER than the perf board holes will be "created" 
by the first use of this "drill jig".

I used this method awhile back to do some limited "production" runs 
of boards, and it worked extremely well. I DID still have the etched 
central "dot" which helps reduce the slop effect for samll holes.

Drilling PCB's by hand is all about feel, and with a good "feel", you 
can use the described drill jig to get an .042 hole over your desired 
hole location VERY quickly, and then let the centering depression 
etched into the board do the rest... More importantly, you'll NEVER 
have MORE than the perf board error in any of your drilling...

Hope this helps,

Ballendo

P.S. I used perf board larger than my desired board, and set up 
a "sandwich" with:

1) a lower "exit" board--which has "fences" to "corral" the target PCB
(these are just scraps of PCB material the same thickness as your 
target board) Be sure to leave spaces between these fence pieces so 
that drill swarf can be EASILY blown out after each board is drilled

2) the undrilled but etched target board

3) the perfboard drill jig

I used mylar as a "hinge" to allow target board insertion and removal.

The syatem overall was fast, accurate, and simple enough to set uyp 
to be worth doing--IMO--for "runs" of boards as small as 5 or ten.

Here is another technique that I did when I started.

I took a DIP socket and with a small drill, 25 thou or whatever you 
have, drill out all the pins.  this lines up the drill with the 
proper holes.

Then drill the #1 hole on the DIP on your board.
place a pin of the same diameter as the drill into the #1 pin of the 
DIP socket and then line up the opposite hole, the #8 on a 14 pin DIP 
and drill thru the DIP socket into the board, using the DIP socket as 
the guide.

Put a pin in that hole and then the rest are easy and aligned 
properly.

This will eventually wear out the DIP socket and you'll need to make 
a new one.  But, you do get past the horror of mis-dilling a hole on 
a 28 pin DIP board.

Also, if you did leave a hole in the pad, the first holes are good. 
and if you mess up the first hole you have 3 other corners to use to 
get it right.  : )

Dave