I understand flushing is important but nothing about how ot adapt speed.
> On Friday 26 February 2016 05:07:20 Nicklas Karlsson wrote: > > > > >Anybody familiar with EDM who could tell me how to adjust the feed > > > > rate for EDM operations? > > > > > > Not a very trivial task but it can be done. There is a youtube video > > > showing and EDM running on linuxcnc. Do a search. The problem comes > > > in when you have to backup as some EDM machines do. > > > > Programming I could solve. Then controlling speed and backup what do > > they try to achieve: A certain average gap voltage? Ignition voltage? > > Power in each pulse? > > > I have only used edm 3 times, in each case in blind holes. The first time > I drove it by hand from the arrow keys, but found the blind holes lack > of the electrolite fluid circulation to be a major problem as the juice > in the hole would gradually get conductive & short it out. I did get the > first broken tap removed but it was an all day job. I found also that > if the electrode was rotating at 50 to 100 revs, that induced > circulation seems to help. So I wrote a loop that drove it to a fixed > very small increment farther each time, doing g0 moves so the > electrolite was somewhat pumped in and out of the hole, and the second > busted tap was cut out in about 1/3rd of the time. But I felt the power > supply was a bit puny, so the next time I traded the 2uf capacitor out > for a 10 uf (both oil filled paper caps) and doubled the voltage to > around 75 volts while reducing the resistor from 50 ohms to 25, lots > more power per pulse. > > Later, needing mounting holes in a 10" carbide tipped saw blade so I > could mount it on a rotary table to sharpen it, I used hollow brass > tubing as the electrode, rotating in the mills chuck to help circulate > the juice. With more power it was faster, but even with 29db shooting > earmuffs on, the noise was still in the 130 db area and a bit painfull. > That saw blade made a great sounding board and I expect it could be > easily heard 3 to 6 blocks away. It also drilled the cleanest holes I > have ever seen in that hard chrome plated steel. > > So the importance of being able to circulate the juice to keep the > metalic debris flushed from the working area is at last as important as > the height control. As for active height control, one might be able to > use one of the thc modules for that but I've not tried it. > > With very short, heavy leads between the capacitor and the workface, a > diode to rectify the peak voltage reached at the capcitor would seem to > be the measurement method of choice, but that, even with very short > leads, might need some r/c filtering because the discharge IS going to > induce some resonant ringing, likely sufficient to cause micro-arcing in > a common bulk carbon resistor, which will manifest itself as an initial > lowering of the filtering resistors measured resistance, and a drift in > the desired operating voltage until the resistor is destroyed. For the > same reason, the diode needs to be a very fast recovery diode and rated > at least to 1 kilovolt. > > Not hugely helpfull Nicklas, but that is what I learned based on 65+ > years of making electrons do useful work. > > > Nicklas Karlsson > > > > ---------------------------------------------------------------------- > >-------- Site24x7 APM Insight: Get Deep Visibility into Application > > Performance APM + Mobile APM + RUM: Monitor 3 App instances at just > > $35/Month Monitor end-to-end web transactions and take corrective > > actions now Troubleshoot faster and improve end-user experience. > > Signup Now! > > http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 > > _______________________________________________ > > Emc-developers mailing list > > Emc-developers@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-developers > > > Cheers, Gene Heskett > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > Genes Web page <http://geneslinuxbox.net:6309/gene> > > ------------------------------------------------------------------------------ > Site24x7 APM Insight: Get Deep Visibility into Application Performance > APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month > Monitor end-to-end web transactions and take corrective actions now > Troubleshoot faster and improve end-user experience. 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