On 24/10/2013, Tomaz T. <[email protected]> wrote: > Does anyone here have any experience with chinese motorized rotary stages, > like this one: > http://www.alibaba.com/product-gs/615993083/LSDH_100WS_Worm_gear_motorized_rotary.html > > I'm a bit worried about actual accuracy and amount of backlash. If it would
That device has a resolution and a repeatability specifications but no accuracy which worries me. A few years ago I measured some rotary tables and found most of them were useless for the job we were doing due to periodic error due to the worm to wormwheel engagement, a basic sawtooth error which in one case was nearly .75 of a degree. Currently on my 5 axis I use a Vertex brand rotary (Taiwan) which has a 90-1 worm. So far for clock gears it has been good enough but I have not measured the accuracy beyond checking the resulting manufactured gear pitches. To provoke the error from a worm cut a gear of much higher number number than the internal worm. Simple check is, get a digital vernier, pick a number of teeth to measure over, measure , zero the vernier, then step around the gear, any time the vernier reads negative zero it, repeat till you get a lap just positive and record the peak distance, should be very small for a good rotary. I have seen some terrible variation from some rotaries. Backlash in these low cost rotaries I avoid by writing directional gcode. Dave Caroline ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60135991&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
