Re: gEDA-user: Putting holes in hard steel - was - Re: the joy and sadness of new boards

[Gene Heskett <gene.heskett@xxxxxxxxxxx>]

On Friday 03 April 2009, andrewm wrote:
>> If anybody has a better idea, yelp.
>
>EDM ?
>
Humm, hadn't thought of that, but I did that a couple of years ago, removing 
some broken 6-32 taps from some blind holes about 3/4" deep. This was while 
building a new z axis drive for my micromill. PIMA to do, but it worked just 
fine if my time was only worth a nickle an hour, but when you are retired its 
sorta hard to place a value on time since nobody is paying me.  And I've since 
acquired some much healthier transformers and rectifiers, so it shouldn't take 
2 days per hole either.  They change my ability from .35 amps at 28 volts to 
about 5 amps at 65 volts, but my resistors 50 ohms, 400 watt, will limit that 
to a bit over an amp under short circuit.  Should make more better smoke that 
way. :)

Thanks for reminding me of that.  In this case, how about I get some of that 
brass tubing that's a bit over 7mm from the hobby shop and use that for 
electrode.  No use removing the plug in the middle .000001" at a time. :)  
Maybe I could even drill a porthole in it, and run it through a tee with o-
rings to seal, and have a continuous kerosene flush, which would speed it up 
even more.  I also found it seemed to help if the spindle was turning the 
electrode about 50 rpm to stir the dielectric. Yeah, come some warmer weather 
I'll do just that.  Too cold for a diabetic with poor feet circulation to 
fiddle with now.  That shop building has very little heat, just enough to keep 
it above the dew point _most_ of the time.

Thanks!
>
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-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The road to ruin is always in good repair, and the travellers pay the
expense of it.
		-- Josh Billings



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