Hi Andrew, Jon Sorry I didn't get the post from Andrew. Gonna have to look at why.
Jon's right. I set up a machine in order to test several things. It was an old Grizzly Sieg. The goal was to retrofit for low cost and reasonably good benchtop quality. I measured the lash on all three of the axes because they all used the same screws and nuts. There was a little bit of difference between but not a lot. I also know that the lash was not caused or made worse by the quality of the thrust bearings because I made the ends myself and setup the preload correctly. Nor was it caused by loose linkage between the nut and the slideways. I spent a couple days with a bpt getting all that right. For the electrical system on it I used several different drives connected to a PMDX-120 breakout and very light duty MAE motors with a three to one belt reduction. These motors were about 100 inch ounce. Another fellow demonstrated the machine at a NAMES show with his own control. Someone was shaking their head and muttering that those little motors would never run the machine in a cut. The operator asked the skeptic to push against the x axis while he jogged it. He was able to push the machine across the display table but not stop the motion. HTH Rayh --- [EMAIL PROTECTED] wrote: From: Jon Elson <[EMAIL PROTECTED]> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> Subject: Re: [Emc-users] home-mad CNC machine project. Date: Fri, 14 Mar 2008 11:20:23 -0600 Andrew Ayre wrote: > Hi Rayh, > > Can you tell me or point me to a website that describes the process for > measuring backlash? Thanks. Assuming the screws are mounted on a machine, you put a dial indicator (preferably one that reads out in .0001" units -- they call that a "tenths reading" indicator) across the slide and step the control back and forth, seeing how many units you need to move the CNC control before the axis actually moves. If you want to know the backlash on a ballscrew and nut set sitting alone on a table, you'd have to build some sort of test rig to evaluate it. You'd need to hold the screw rigid and prevent the nut from turning, and then apply force to the nut and read linear free play with the dial indicator. Jon ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
