On Wednesday 11 December 2013 21:00:21 Leonardo Marsaglia did opine: > 2013/12/11 Gene Heskett <ghesk...@wdtv.com> > > > Huge yabut there. Co$t... The precision of the ball screw apparently > > isn't needed, and keeping it clean for long life could be a problem, > > particularly when the nylon nut can be replaced several times during > > overnight maintenance for 2% of the cost of the ball screw and nut > > that size. Assuming reasonably clean screws, and a heat formed > > acetal/delrin nut I'd think screw/nut life would be quite reasonable > > and its lower friction compared to nylon, a win-win. And heat molded > > acetel can have backlash under .001". Just shield it if you can from > > the induction heating. External air coming it would lower it 100F or > > more, doing wonders for any "cold flow" the constant weight might > > induce. So would gun drilling the screw and running room temp > > recycled water through it if the screw gets too hot to touch. Easy > > if the nut is driven and the screw mounted rigidly. > > Yes, it would cost a lot and as you said keeping it clean requires some > kind of telescopical cover to be made. So that idea is not convenient.
Nor is buying them cheap, I looked at that for my lathe & came to the conclusion I can blow the screw clean if the wipers are in decent shape. So my 16x5 Z screw is right out in front, naked as a baby. > I wasn't familiar with delrin, I was checking now that you mentioned and > I have some sellers near so I can ask and replace it in the near > future. The nut and screw are almost 400 mm from the source of the heat > and also the lobes being heated are not big enough to radiate heat to > the screw or nut, so that's not a problem as I see it. > > Is this material easy to machine? When you're talking about heat molded > I assume is the way they make the long bars which they fraction later. Best I can do on that is furnish an interesting howto link: <http://bbs.homeshopmachinist.net/threads/43645-Making-Acetal-leadscrew-nuts-the-easy-way> Which pretty well explains the how to. Cutting tool wise, since tool steel can be made much sharper than carbide inserts, well tuned up tool steel should work for that. I have obtained a 1" round bar of it about a foot long, suitable for making some new nuts for my toy milling machine, but tearing up a knee the last of September has buried my round tuit now till warmer weather & a healed up knee. Possibly to be delayed by getting a herniated disc fixed too. There are times in my 79 trips around this star, when I have not been kind to my back & now its haunting me day & night. 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) Genes Web page <http://geneslinuxbox.net:6309/gene> Schlattwhapper, n.: The window shade that allows itself to be pulled down, hesitates for a second, then snaps up in your face. -- Rich Hall, "Sniglets" A pen in the hand of this president is far more dangerous than 200 million guns in the hands of law-abiding citizens. ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
