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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