On Thursday 03 March 2016 01:47:27 TJoseph Powderly wrote: > 50A/in^2 > very crude rule fro Gr/St ( graphite to steel ) > Surprisingly high, but I've very little experience.
> the 'current density' is NOT linear > maximum is near 400amperes even if area is yds^2 > becasue the process is not controllable at extreme currents > and is seemingly high at very low areas 50 amps supplied to 1mm dia > bras tube > and 12 amps 'draw' seen on meter I've not approached that. Worst case, 75 volts dc, 25 ohms limit R, and a 10 uf oil filled cap. Using a 1/4" od brass tube in the drill chuck, working in a clay dam holding 1/8" deep puddle of k2 around the hole, it was painfully noisy even with 29db rated muffs on my ears, and it cut a 1/4" diameter hole in the center web area of a 10" circular saw blade, in perhaps 5 or 6 minutes. Beautiful holes, never ever drilled anything that cleanly before. I had the spindle turning about 100 revs to help circulate the k2. Spark rep rate seemed to match our 60 hz power, or 120 pps. No clue what I was doing but it sure drilled nice holes in steel the best drill bit would not make a mark on. > and that rule is only for roughing ( creating net form ) > not for finishing > > during roughing the 'frontal area (Fp) is the governing factor > in finishing, the Peak to valley of the craters is the governing > factor for engraving graphite or copper is commonly used > the choice is oftern determined by experience > > experience of... do i want a dirty shop and cheap electrodes ( > graphite) or a clean shop and expensive electrodes ( copper) Chuckle, OTOH I'd have to say the level of dirt is relative. That k2 turned into black, conductive mud & had to be changed about every 1 or 2 minutes as I'm not rigged to pump it. > hth Yes, its good guidance. > tomp Thanks TomP.> 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. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
