tag:blogger.com,1999:blog-31599891.post6827589558591676023..comments2009-11-12T13:42:49.864-08:00Adrian Bowyerhttp://www.blogger.com/profile/17595509188999219420noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-31599891.post-15960593115422347722009-11-12T13:42:49.864-08:002009-11-12T13:42:49.864-08:00In case anyone is wondering, my Y-Motor-Coupling cracked and failed a couple weeks after I made this post. It likely had a small fracture, which allowed the set screw to move away from the flat on the motor shaft, introducing backlash.<br /><br />I replaced it with a 1 inch long steel spacer with 1/4 inch walls. I was able to drill two holes in it using my drill press and then tap them for M5 set screws.mccoynhttp://www.blogger.com/profile/09895019423053612239noreply@blogger.comtag:blogger.com,1999:blog-31599891.post-82296261626156261492009-08-26T03:27:18.277-07:002009-08-26T03:27:18.277-07:00Forrest,<br /><br />It&#39;s not that hard. Backlash is an unavoidable property of all reversing mechanical couplings (Wikipedia: backlash)<br />There are various effects that cause backlash.They are made visible through my simulation, where I&#39;ve exaggerated the effects:<br /><a href="http://blog.erikdebruijn.nl/archives/107-Phun-simulations-with-RepRap.html" rel="nofollow">http://blog.erikdebruijn.nl/archives/107-Phun-simulations-with-RepRap.html</a><br /><br />It has to do with belt tension, the play between the rods the X axis slides over and the, rods from the X axis. It can wiggle a bit, which causes movement of the lower part of the toolhead to be in the inverse direction of where the driving shaft is trying to push them. There are various more effects that can be mechanically mitigated, or by pre-processing the Gcode like I do with my script (discussed in the above blog post)<br /><br />Erik<br />[edit: now with correct link]Erik de Bruijnhttp://www.blogger.com/profile/09433438819279256757noreply@blogger.comtag:blogger.com,1999:blog-31599891.post-58088007985214693382009-08-25T22:56:15.401-07:002009-08-25T22:56:15.401-07:00I guess I&#39;m confused about how you are getting backlash in a belt driven Darwin. :-?Forrest Higgshttp://www.blogger.com/profile/17208965471464716174noreply@blogger.comtag:blogger.com,1999:blog-31599891.post-45091304681003028182009-08-25T11:45:37.120-07:002009-08-25T11:45:37.120-07:00It is a Darwin-style repstrap. http://www.codeerrors.com/blog/?p=81mccoynhttp://www.blogger.com/profile/09895019423053612239noreply@blogger.comtag:blogger.com,1999:blog-31599891.post-81278670078611615502009-08-25T05:53:14.071-07:002009-08-25T05:53:14.071-07:00You neglected to tell us what kind of machine you&#39;re getting backlash on.Forrest Higgshttp://www.blogger.com/profile/17208965471464716174noreply@blogger.com