Homebrew_PCBs

How 'bout this little thing? Too much weight to put in a plotter,
but maybe in a homebuilt router/engraver.

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=43155

58,000rpm no load. There is a Harbor Freight Tools about 1/2 mile
from my house.

How are you guys measuring runout? Drill with a stiff bit then
measure the size of the hole? I don't have a micrometer that can
measure the inside of a round hole.

Steve Greenfield

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Hi Steve,
Put a 1/8" bit in your motor tool. A ball mill is
fine. Turn the tool on. Look at the tip of the bit as you
increase the speed. You will see the tip of the bit grow
larger. Even if you hold the motor tool tight the tip will
spin out of round. Under a florescent the Think and Tinker
bit seems to have two tips. As I slow the tool down the tip
becomes one point again. I hope to buy a new Dremel tool.
I am curious if the bearing is worn or if all Dremels are this bad.
The problem showed up when I started milling circuit boards at 20,000
RPM with a feedrate of 8" a minute. For now I dropped back to
running the Dremel on number 3 only. The Dremel has 100 hours on
it and it owes me nothing.
I bet other tools have the same problem. There is a reason
cheap machines have a top speed of 10,000 to 15,000 rpms. Going
higher gets expensive.

John

--- In Homebrew_PCBs@y..., Steve Greenfield <alienrelics@y...> wrote:
> How 'bout this little thing? Too much weight to put in a plotter,
> but maybe in a homebuilt router/engraver.
>
> http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?
itemnumber=43155
>
> 58,000rpm no load. There is a Harbor Freight Tools about 1/2 mile
> from my house.
>
> How are you guys measuring runout? Drill with a stiff bit then
> measure the size of the hole? I don't have a micrometer that can
> measure the inside of a round hole.
>
> Steve Greenfield
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Tax Center - online filing with TurboTax
> http://taxes.yahoo.com/

At 10:12 AM 4/11/02 -0700, Steve Greenfield wrote:

>How 'bout this little thing? Too much weight to put in a plotter,
>but maybe in a homebuilt router/engraver.
>
>http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=43155
>
>58,000rpm no load. There is a Harbor Freight Tools about 1/2 mile
>from my house.

That is probably the same as the unit I mentioned from Princess Auto. I
think that its cheaper here in Canada, though ($30.00 Canadian vs $36.00 US).

>How are you guys measuring runout? Drill with a stiff bit then
>measure the size of the hole? I don't have a micrometer that can
>measure the inside of a round hole.

I've done it that way (although that method includes any error resulting
from an off-balance drill bit). I also just stick a solid carbide shaft
into the chuck and measure both play and run-out when rotating the shaft by
hand.

dwayne




Dwayne Reid <dwayner@...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax

Celebrating 18 years of Engineering Innovation (1984 - 2002)
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Dwayne Reid wrote:

> At 10:12 AM 4/11/02 -0700, Steve Greenfield wrote:
> >How 'bout this little thing? Too much weight to put in a plotter,
> >but maybe in a homebuilt router/engraver.
> >
> >http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=43155
> >
> >58,000rpm no load. There is a Harbor Freight Tools about 1/2 mile
> >from my house.
>
> That is probably the same as the unit I mentioned from Princess Auto. I
> think that its cheaper here in Canada, though ($30.00 Canadian vs $36.00 US).
>
> >How are you guys measuring runout? Drill with a stiff bit then
> >measure the size of the hole? I don't have a micrometer that can
> >measure the inside of a round hole.
>
> I've done it that way (although that method includes any error resulting
> from an off-balance drill bit). I also just stick a solid carbide shaft
> into the chuck and measure both play and run-out when rotating the shaft by
> hand.
>
> dwayne

If you can see the out of roundness with your eye or feel play with your finders
then its a pretty bad drill. I wouldn't trust it at all for carbide bits. The
small air powered die grinders look like a cheap solution, but are you prepared
to have a big thumping compressor to go with them ? These things suck a lot of
air for there size!

Alternatively you could use a professional electric die grinder, but these
usually are quite heavy and powerful for drilling boards. The grinder I used is a
BOSCH GGS 27 (see link below), runs at 27k RPM, has precision ground collet so
the round out is superb, compared to a Dremel at least. Normally a dial indicator
is used to measure out of roundness.

http://www.bosch.com.au/productcatalogue/spt3/grinders.htm

At 09:16 AM 4/12/02 +1000, Adam Seychell wrote:

>Dwayne Reid wrote:
>
> > I also just stick a solid carbide shaft
> > into the chuck and measure both play and run-out when rotating the shaft by
> > hand.
> >
> > dwayne
>
>If you can see the out of roundness with your eye or feel play with your
>finders
>then its a pretty bad drill.

Sorry - I should have said: measure both play and run-out WITH A DIAL
INDICATOR when rotating the shaft by hand. I can measure deviation down to
about 0.0002" or so.

dwayne


Dwayne Reid <dwayner@...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax

Celebrating 18 years of Engineering Innovation (1984 - 2002)
.-. .-. .-. .-. .-. .-. .-. .-. .-. .-
`-' `-' `-' `-' `-' `-' `-' `-' `-'
Do NOT send unsolicited commercial email to this email address.
This message neither grants consent to receive unsolicited
commercial email nor is intended to solicit commercial email.

Dwayne,
My Dremel passes that test. My runout shows up
above 16,000 rpms. The bits are balanced so one of my
bearings must be bad. I changed the collet and got
the same results.

John

--- In Homebrew_PCBs@y..., Dwayne Reid <dwayner@p...> wrote:
> At 09:16 AM 4/12/02 +1000, Adam Seychell wrote:
>
> >Dwayne Reid wrote:
> >
> > > I also just stick a solid carbide shaft
> > > into the chuck and measure both play and run-out when rotating
the shaft by
> > > hand.
> > >
> > > dwayne
> >
> >If you can see the out of roundness with your eye or feel play
with your
> >finders
> >then its a pretty bad drill.
>
> Sorry - I should have said: measure both play and run-out WITH A
DIAL
> INDICATOR when rotating the shaft by hand. I can measure deviation
down to
> about 0.0002" or so.
>
> dwayne
>
>
> Dwayne Reid <dwayner@p...>
> Trinity Electronics Systems Ltd Edmonton, AB, CANADA
> (780) 489-3199 voice (780) 487-6397 fax
>
> Celebrating 18 years of Engineering Innovation (1984 - 2002)
> .-. .-. .-. .-. .-. .-. .-. .-. .-. .-
> `-' `-' `-' `-' `-' `-' `-' `-' `-'
> Do NOT send unsolicited commercial email to this email address.
> This message neither grants consent to receive unsolicited
> commercial email nor is intended to solicit commercial email.

At 12:20 AM 4/12/02 +0000, crankorgan wrote:

>Dwayne,
> My Dremel passes that test. My runout shows up
>above 16,000 rpms. The bits are balanced so one of my
>bearings must be bad. I changed the collet and got
>the same results.

You are probably right. Another possibility is that the armature may have
become unbalanced. That will also show up as increased vibration as well
as excess run-out.

The thing I like so much about these little air tools is that the rotor is
so tiny that balance is less of a problem.

I've fired up both die grinders and the tip of a #65 carbide drill bit does
NOT appear to grow larger as the speed increases. I think they will work
just fine!

dwayne


Dwayne Reid <dwayner@...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax

Celebrating 18 years of Engineering Innovation (1984 - 2002)
.-. .-. .-. .-. .-. .-. .-. .-. .-. .-
`-' `-' `-' `-' `-' `-' `-' `-' `-'
Do NOT send unsolicited commercial email to this email address.
This message neither grants consent to receive unsolicited
commercial email nor is intended to solicit commercial email.

Hi Dwayne,
I added a thin strip to each bearing. I was
hoping one bearing was loose in the body. Looks like
the wear on the commutator is causing the armature
to run out of round. I learned my lesson, speed kills.
The next Dremel will be kept on Number 3.
A mechanical etching bit is very light. If your tool
is spinning true with a drill bit you are all set. Keep an
eye on the tool as it gets old. The air tools are the way to
go if you can afford it. I will go that route if sales continue
to increase.

John

--- In Homebrew_PCBs@y..., Dwayne Reid <dwayner@p...> wrote:
> At 12:20 AM 4/12/02 +0000, crankorgan wrote:
> >Dwayne,
> > My Dremel passes that test. My runout shows up
> >above 16,000 rpms. The bits are balanced so one of my
> >bearings must be bad. I changed the collet and got
> >the same results.
>
> You are probably right. Another possibility is that the armature
may have
> become unbalanced. That will also show up as increased vibration
as well
> as excess run-out.
>
> The thing I like so much about these little air tools is that the
rotor is
> so tiny that balance is less of a problem.
>
> I've fired up both die grinders and the tip of a #65 carbide drill
bit does
> NOT appear to grow larger as the speed increases. I think they
will work
> just fine!
>
> dwayne
>
>
> Dwayne Reid <dwayner@p...>
> Trinity Electronics Systems Ltd Edmonton, AB, CANADA
> (780) 489-3199 voice (780) 487-6397 fax
>
> Celebrating 18 years of Engineering Innovation (1984 - 2002)
> .-. .-. .-. .-. .-. .-. .-. .-. .-. .-
> `-' `-' `-' `-' `-' `-' `-' `-' `-'
> Do NOT send unsolicited commercial email to this email address.
> This message neither grants consent to receive unsolicited
> commercial email nor is intended to solicit commercial email.