2009/6/10 Steve Blackmore <[email protected]>: > What a childish response - is your dad bigger than mine too??
No, he is a tiny little chap, he would hardly stretch a timing belt at all. > In practical terms there is no stretch, provided the design criteria is > not exceeded. Let us back up a bit here. It was me who first suggested a toothed-belt drive for this application. I wouldn't have done it if I thought it was a bad idea. The physical layout of a toothed-belt drive means that it is a relatively logical replacement for a rack-and-pinion system. It will also be relatively short, and so belt stretch will probably not be a problem. I am less concerned about accuracy in the proposed application than about chatter and vibration. As the original rack and pinion didn't cause a problem there then one could assume that this would not be a problem. However the spindle or table hanging on an elastic belt _will_ be more springy than the same weight sat on a leadscrew. It would still be the first thing I tried, as the modifications required to the machine would be minimal. I have designed and worked on toothed-belt drive systems where it didn't matter (seat belt arrestor mechanism tester, pick and place systems, high-speed stage for a bond tester[1] and ones where it did (the camera motion system for an X-ray microscope). The main differences being the length of the belt and the accuracy of positioning needed (the camera needs to not wobble by more than 1 CCD pixel after stopping, and the belt was 2m long) [1] A bond tester is for pulling the solder balls and little gold connection wires off of microchips. A rather specialised and tiny sort of tensile/shear testing machine. http://www.dage-group.com/node/10 -- atp ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
