On Friday 20 November 2009, dave wrote: >On Fri, 2009-11-20 at 16:39 +0000, Andy Pugh wrote: >> 2009/11/20 Gene Heskett <gene.hesk...@gmail.com>: >> > A cube of dry ice sitting on >> > it would help, but would raise the available oxygen too. >> >> I am fairly sure it would displace the oxygen (being heavier) and so >> would both cool and reduce oxide formation. >> >> You might have hit on a cunning plan, and it would look cool too. > >Carbon Dioxide doesn't disassociate easily but will if pushed hard. >It cannot be used in heat-treating furnaces for that reason but for >cooling/shielding Al machined parts I think it will work just fine. > >I'm not sure the kinetics of Al oxidation are as aggressive as Gene >states but cannot find any evidence to support or disallow such a claim. >The oxidation curve, at least at high temps (600 F), is parabolic so it >limits fairly quickly. > >A couple of alternatives for small orifices come to mind. Diesel rebuild >shops should always have a supply of used injector nozzles. I understand >the newer ones are carbide. > >IIRC Gene had a tap remover (crude edm) running at one time. That should >fab almost any small hole he wants. :-)
But what to use for the electrode? That is the 64k$ question. Even tag wire is too big for this. I have since built a better power supply, but using the same idea. I needed to bore some holes in some 10" table saw blades so I could turn them on the table and sharpen them a wee bit. With the new supply, 400 watts worth of 25 ohm resistor, and about 80 volts charging a 10 uf oiled paper capacitor across the gap, I can set a tape spool ring into modeling clay for a dam, put 1/2" of k1 in the ring and blow a nice clean hole through a saw blades .090" thick web in about 10 minutes. But not without fishing a set of 32 db rated shooting muffs out of the range box in the pickup, it is that noisy. It would obviously have to be scaled back considerably to do real teeny hole drilling. And as I found out while tap removal was in progress, the inability to keep the gap flushed was a major problem, I had to back out of the hole, blow it as clean as my air compressor could, and put fresh k1 in the hole at about 1 minute intervals as it got so sludgy it shorted. >Small volumes of oil/mist might be available by using model airplane >engines as pumps. > >Just thinking out loud. Usually dangerous. Chuckle, same here Dave, but so far I've managed to live through some pretty interesting times in my 75 years. >Dave > > > > >--------------------------------------------------------------------------- >--- Let Crystal Reports handle the reporting - Free Crystal Reports 2008 > 30-Day trial. Simplify your report design, integration and deployment - > and focus on what you do best, core application coding. Discover what's > new with Crystal Reports now. http://p.sf.net/sfu/bobj-july >_______________________________________________ >Emc-users mailing list >Emc-users@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/emc-users > -- 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 NRA is offering FREE Associate memberships to anyone who wants them. <https://www.nrahq.org/nrabonus/accept-membership.asp> If money can't buy happiness, I guess you'll just have to rent it. ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
