Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

----- Original Message -----
From: starsnstripes_2003
To: Homebrew_PCBs@yahoogroups.com
Sent: Friday, July 25, 2003 3:14 PM
Subject: [Homebrew_PCBs] Re: laptop drill press


Thanks for the ideas, Dave ;-)


I already had thought about a simple footswitch, But it would only
turn on the Dremel.
MCM? or Mouser? has a footswitch with phono plug for about $7.00.
I can mount a phono jack in a cheap power strip and plug the
footswitch into it to enable foot operation for the whole power
strip. I think Dremel gets about $45 for their footswitch...Ouch!

You don't need the spring to pull down on the Dremel. You might need
it to provide counter-balance for a true-gravity feed, though.
Gravity does the job fine. (Adjust the pivot bolt just snug enough
to remove "play" in the arm). I used a little melted candle-wax to
lubricate the pivot points.
The feed arm on mine has the feel of a regular drill press with just
about 80 deg. arc providing the full 1/4" travel. Works just fine
for my purposes :-)

I chuckled with your suggestion of an auto-tool changer! I came from
a CNC production environment with over 500 various CNC machine tools.
Most had tool changers. They are a pain in the A$$...(I was CNC
Maintenance Leader there.)
My Dremel set came with Hex and Knurled collet nuts.
The knurled collet nut allows pretty fast changes just using "finger-
tight" if you stick to the Carbide drills with 1/8" shanks. They are
only about $4.25 for a pack of 5 (resharpened) at Drill Bit City.

As for auto-feed and retract, I suppose if you were really serious,
you could mount a stepper motor w/controller to a modified feed arm,
and provide a limit / microswitch to do the retract.

Not sure if the solenoid would work, but it might if you let the arm
free-fall and the solenoid do the lift.

I'm not THAT serious, though!

Well, maybe if I find an old printer that I can scrap...Hmmm...So
much fun in such a small Yahoo Group!
Next up: X/Y Table ?


--- In Homebrew_PCBs@yahoogroups.com, "Dave Mucha" <dave_mucha@y...>
wrote:
> --- In Homebrew_PCBs@yahoogroups.com, "starsnstripes_2003"
> <bwatson@a...> wrote:
> > I was so impressed with your Laptop Drill that I made a tabletop
> > version. (I told ya I liked it!)
> > Elegant simplicity...
>
> Nice pic, and it looks good.
>
> I thought about the unit and if I were to modify it, I would add
an
> articulating arm magnifying light to see the hole locations
better,
>
> AND....
>
> I would add a foot operated lever. spring load the lever so when
you
> stepped on it, the drilling arm drilled the hole and only the
spring
> pulled the dremel, not the power of your foot.
>
> alternatly, mount a solenoid and a foot switch.
>
> now, to design a fast change chuck for a Dremel.......

If you do use a phono plug, make sure you put a relay and transformer with it to avoid running the mains current on a phonoplug.

In the US, it seems about 20% of residential buildings are wired backwords, and as such you could end up with 120V on the phonoplug shell, so I'd make sure that a low voltage signal was running through the footswitch which would enable a relay to turn on the dremel. Make sure to use a decent relay, as the inductive kickback from the dremel can fry contacts pretty easily if you don't have the proper snubber.

Another solution is a foot switch designed for mains operation such that there are no safety concerns. Sometimes you can find them surplus for under $10.

Thanks
Ron

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