Re: intro update

Looking forward to seeing your web pages on this. I just gor a brochure for a small tap remover from Taiwan but havn't got a
price on it yet. take a look at
http://manufacture.com.tw/~joemars/p7.htm
I worked in a mold shop that had a Camman tap buster, it used molybdenum tubing for the electrode and a milky colored dialectric
coolant fluid. I had used it to remove everything from a 2-56 tap to stuck 2" shcs.
These things can save a lot of parts and I wouldn't mind making one for myself .
Jon Elson wrote:

> From: Jon Elson <jmelson@...>
>
> Oh, yes, one other thing mentioned that I did recently --
>
> I had some broken off taps in parts I was making, and decided one
> weekend to see what I could do about that. I threw together a low
> power EDM system from a large assortment of miscellaneous
> parts. I made an electrode from a piece of 1/16" brazing rod
> with one end brazed into a socket head cap screw. I threaded
> the screw into a big nylon spacer I had, and mounted that in my
> milling machine's Jacobs chuck. I was able to use the CNC
> mill's positioning system to move the electrode just where I
> wanted it. For EDM fluid, I first tried tap water, but that foamed
> and sputtered away quickly. I then went to alum-tap tapping
> fluid, which worked fantastically as an EDM fluid. I set up
> for about 30 V open circuit, and started the mill in the slowest
> backgear range (80 RPM). With the brazing rod almost perfectly
> straight, it orbited about .010 - .015", clearing out a bigger hole
> in the tap than the diameter of the rd, itself.
>
> I programmed the CNC to advance the spindle at about .006
> to .01" per minute, and used the feed override to keep EDM
> current between .25 and .5 Amp. I replenished the fluid as needed,
> and raised the electrode and cleaned out the hole when progress
> stopped (about every .020"). I got rid of each tap in about 10
> to 25 minutes, depending on how much of the tap was left down
> in the hole. Mostly, after the EDM operation, all that was left of
> the tap was the very tip of the flutes, and they could be picked
> out with a fine needle. All the holes were later tapped and
> the parts used. An earlier attempt to burn the taps out with
> Nitric Acid was not very successful, and left the aluminum
> slightly stained, but the EDM did no damage to the workpiece
> at all.
>
> I plan to put all this, including diagrams and photos on my
> web pages.
>
> Jon
>
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> welcome to CAD/CAM/EDM/DRO@..., an unmodulated list for the discussion of shop built systems in the above catagories.

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James P Crombie
Summerside PEI Canada

http://www3.pei.sympatico.ca/jpcrombie/ My Astronomy stuff
http://www3.pei.sympatico.ca/jpcrombie/RHINOFILES/ RhinoCad 3D Stuff

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