On Tuesday 21 August 2007, Dave Engvall wrote: >Hi Gene, > >On Aug 20, 2007, at 11:19 PM, Gene Heskett wrote: >> On Tuesday 21 August 2007, Jon Elson wrote: >>> Gene Heskett wrote: >>>> Understood. In playing tonight with 25 volts & probably 100 ma >>>> average, I >>>> found that spinning the electrode at around 1k rpms seemed to add >>>> enough >>>> agitation to the oil that I could use it all up and go about 30 thou >>>> before I had to vacuum it out and refresh it, with about 1/2 cc in a >>>> modeling clay dam around the hole. A 100 rpm spin would short in >>>> just a >>>> thou or two. >>> >>> That is way too low a current for any serious metal removal. >>> You want at least an amp, and it will still be really slow. You >>> need an insanely fine feed. I have .000025" per encoder count >>> on the Z axis of my mill, so I could get a pretty slow feed, >>> about .0001" every second. It still took all evening to burn >>> out one tap. I think with a hollow electrode with a drip feed >>> scheme through the electrode it would go a lot faster. >> >> Theres always that 'yabut' Jon, in this case yabut where can I find >> one of >> those? :) > >I always thought 'yabuts' were those things with long ears. :-) > :-)
>Try your local or not so local 30 miles one way. >Model Airplane shop. The typically >have multiple sizes of >brass tubing that just slip inside each other. Except the smallest is about 3/16". A bit large. >The fancy stuff with internal structure is available off the web. > >IV tubing should work for dielectric delivery if it doesn't curl up >and die from the solvent. I have lots of that, the wife has COPD. >Being able to flush a cavity in EDM is VERY important. Not much else >will do as much for erosion speed. So I'm finding. Question though: Working in a blind hole today, I found the electrode sharpening itself like a bullet, and to get part of the 2nd tap out, (the first one was easy once I figured out I needed more voltage & stacked my battery charger on top of the other supply, which will have to do till the new transformers get here) I've had to replace it it, and clip it back square several times. The bottom of the tap is still in the hole and I don't seem to be able to 'get at' the outside of it while the electrode is still square. I'm getting shorts real easy, like the tap is moving around in the hole, but its sitting solid when I try to pick it. >Real edm systems also filter ( 5 um ) and reuse the dielectric. For >the small amounts you use it is probably a throw away. I made a dam out of modeling clay, about 1/2" high, with a malt straw down the middle, filling it with kerosene and sucking it out and replacing it when the feed rate at 30 volts slows down. With fresh kero I can run down at about .009"/minute. But at about -.6" I'm hitting the wall, it just shorts beyond that point even at .0001"/minute feed. >>> The alum-tap is a really light fluid, maybe just a little higher >>> viscosity that water. It worked MUCH better than #20 oil, which >>> I also tried. Try a couple different fluids to see what works >>> best, it makes a big difference. >> >> I have some other stuff too besides the fuel oil (#1 I think), >> paint thinners >> etc could be tried too. Aluma-tap would be a foreign language here >> in WV >> unless I ordered it from someplace I suspect... > >I just checked my lamp oil container: "Lamplight" ultra-pure, >Menomonee Falls, WI Aka kerosene. >> Q? Does distilled water carbon up like the hydrocarbons do when >> doing this? > >Nope, no carbon there to muck up; just hydrogen and oxygen. That sounds as if it might not short so easy then? I'll see if I can clean it up and try that tomorrow then. -- 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) Wherever you go...There you are. - Buckaroo Banzai ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
