On Thursday 14 February 2013 04:51:03 Erik Christiansen did opine: > On 13.02.13 16:17, Pete Matos wrote: > > I have actually looked at Mcmaster carr as I usually do but did not > > see > > > > what I needed. I actually like the looks of those cut bodied couplers > > but I am not too sure of their misalignment ability. A quality > > oldham in the right size should work fine I think....peace > > I've never done any measurements, but figure that the "helical beam", or > whatever you want to call them, couplings ought to have the lowest > backlash. An Oldham coupling must wear out, Shirley? > > Erik
I made several sets of these from old mine shafting, about 1.4" in diameter, quite a few years ago, and installed them between the 225 oz double stack nema 23's on my toy mill, and the OEM 20 tpi square screws, nearly a decade ago. My miss-alignments are on the order of 1/32", and I slobber a little vactra on them when I think about it. They went together originally with perhaps 2 thousandths of an inch between the tenons and fins, and may have worn an additional thousandth since. The are not shielded from dust and swarf. With the motors running micro stepped at /8, screw reversals can still be felt within 2 steps of a reversal command. The piss poor nuts (and I'm being kind with that description) it uses are a far larger source of backlash than these couplings will ever be. I may eventually put ball screws in the thing, but my inclination is to get a bigger, much more beefy machine, this toy has far too many design compromises I fight with daily, like the extremely short and easily bound up Z ways. Not helped a bit by a tiny post like a willow tree branch. 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) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! My views <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> You will stop at nothing to reach your objective, but only because your brakes are defective. I was taught to respect my elders, but its getting harder and harder to find any... ------------------------------------------------------------------------------ Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
