Homebrew PCBs

http://www.delorie.com/pcb/dremel-stand/

My big drill press has too much runout for the tiny drill bits, and my
hand isn't steady enough to drill manually with the dremel.  So, I
made something simple that would just hold the dremel steady so I
didn't snap any more drill bits.  I drilled a couple of 13 mil holes
with it, seems to do the job (although there's some runout even still,
partly due to the bits vibrating).

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

From: "DJ Delorie" <dj@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, April 15, 2007 5:32 PM
Subject: [Homebrew_PCBs] home-made dremel "drill press"


>
> http://www.delorie.com/pcb/dremel-stand/
>
> My big drill press has too much runout for the tiny drill bits, and my
> hand isn't steady enough to drill manually with the dremel.  So, I
> made something simple that would just hold the dremel steady so I
> didn't snap any more drill bits.  I drilled a couple of 13 mil holes
> with it, seems to do the job (although there's some runout even still,
> partly due to the bits vibrating).

Milford Instruments sells a CNC machine that can be used for drilling PCBs:

http://www.milinst.com/

It's the 3-axis Machine in the Robotics section.

It's mostly made from wood.

I just noticed that DXF files of the components are provided, perhaps it 
could build a copy of itself. 8-)

Leon
--
Leon Heller
Amateur radio call-sign G1HSM
Yaesu FT-817ND and FT-857D transceivers
Suzuki SV1000S motorcycle
leon355@...
http://www.geocities.com/leon_heller

--- In Homebrew_PCBs@yahoogroups.com, DJ Delorie <dj@...> wrote:
>
> 
> http://www.delorie.com/pcb/dremel-stand/
> 
> My big drill press has too much runout for the tiny drill bits, and my
> hand isn't steady enough to drill manually with the dremel.  So, I
> made something simple that would just hold the dremel steady so I
> didn't snap any more drill bits.  I drilled a couple of 13 mil holes
> with it, seems to do the job (although there's some runout even still,
> partly due to the bits vibrating).
>

Another great example of simple woodwork providing an elegant solution. 

The design, heavy dremel on the end of long flexible arms, is going to 
show vibration components but there are techniques to try that may 
dampen them. 

Assuming the dremel is a snug fit it the arms, I would try the mass 
weight technique used to stop flutter on aircraft control surfaces. 
Bluetac a large-ish lump of steel just behind the dremel on the lower 
arm and see if a large mass here will dampen the vibration, at the 
drill speed you need. This weight may bend the lower arm and this may 
attempt to set the dremel free so tape the arms together for the 
experiment.

Once the weight gets up a bit you may need to arrange a counterbalance 
for the weight. Perhaps fit a bungee from the top of the uprights to 
the area the weight is sitting or alternatively temporarily install 
some compressible rubber between the lower arm and base board.

All the best, great job.

"warrenbrayshaw" <warrenbrayshaw@...> writes:
> Assuming the dremel is a snug fit it the arms,

It is.  I made the holes a tad small, then spindle sanded them until
it just fit.

> Bluetac a large-ish lump of steel just behind the dremel on the
> lower arm and see if a large mass here will dampen the vibration,

I can try that.  I have a 2lb anvil.

I originally thought of having two sets of arms, at 90 degrees to each
other.  That would further reduce any chance of movement, but would
further limit the ability to pull the drill down too.

> Once the weight gets up a bit you may need to arrange a counterbalance 
> for the weight.

If I'm lucky, it will bring the dremel down closer to the board,
making my job easier ;-)

> All the best, great job.  

Thanks!