On Wednesday 28 March 2007, John Kasunich wrote: >Gene Heskett wrote: >> On Wednesday 28 March 2007, Roland wrote: >>> At 10:35 AM 28/03/2007 -0400, you wrote: >>>> over half an hour per pass though. MCS is selling a little air >>>> grinder rated at 70k rpms, >>> >>> we removed the milling head entirely and mounted a Pferd >>> air-tool. >> >> I wasn't aware the air bearings could be that sloppy. > >(snip) > >> I guess what I'm saying is that air bearings can be quite precise, >> >> to buy a spare was more >> like $3k or more. That, compared to the $100 tool I'm looking at in >> the MSC catalog, says the MSC device is pretty sloppily made. Your >> comment re the air compressor tends to back it up. > >I think you two are talking about completely different things. > >The "air tool" is basically a die grinder. It is _powered_ by air, >which explains the heavy air consumption. But its bearings are just >plain old-fashioned ball bearings, and probably not very good ones at >that (certainly not ABEC 7 spindle bearings). > >Air bearings are a whole 'nother ball of wax, and as you say, an air >bearing spindle is gonna cost a lot more than $100.
I'd expect such a cheaply made device to skip the ball bearings entirely John, and rely instead of a moderate level of precision so that it could be driven at a good speed, and be running on the air bearings full time. This would of course require the bearings to be getting air full time, and the trigger only controlling the driving turbine. The headwheel of course was driven by amplifiers, with the air only supplying the bearings. Frankly, relying on roller skate bearing quality stuff at 50+K rpms would be very risky. The other consideration would be environmental cleanliness, relatively easy in a tv control room environment, very difficult on the factory floor. >Regards, > >John Kasunich > >------------------------------------------------------------------------ >- Take Surveys. Earn Cash. Influence the Future of IT >Join SourceForge.net's Techsay panel and you'll get the chance to share > your opinions on IT & business topics through brief surveys-and earn > cash > http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVD >EV _______________________________________________ >Emc-users mailing list >[email protected] >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) Nothing ever becomes real till it is experienced -- even a proverb is no proverb to you till your life has illustrated it. -- John Keats ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
