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General Mach Discussion / inconsistent steps, unsure if Mach3 problem
« on: March 19, 2013, 05:50:53 PM »
Howdy 
Going through the late stages of converting my RF45 clone to CNC. I'm using DMM Technologies servo drives and 400W motors, 3:1 belt driven, with the typical 5mm lead ballscrews.
I have noticed while tramming and measuring backlash, etc, that while jogging the machine in 0.001" step increments, the axis' don't always move a full thou.. The servos have 500ppr encoders, with quadrature, which turns out to be 30480 steps per inch. Even ignoring the quadrature, it should give me step accuracy of 0.0001" or thereabouts, but I'm not seeing that. It definitely averages itself out, if I move 0.020", it'll end up fairly close, but some steps will move it 0.0015, some are right on at 0.001 and some 0.0005.
Any ideas? It could just be horrendous ballscrew accuracy, but I thought I'd check if anyone has seen a similar issue. Any thoughts appreciated
Thanks!
edit: figured I should mention that I'm also using an ethernet SmoothStepper!
Going through the late stages of converting my RF45 clone to CNC. I'm using DMM Technologies servo drives and 400W motors, 3:1 belt driven, with the typical 5mm lead ballscrews. I have noticed while tramming and measuring backlash, etc, that while jogging the machine in 0.001" step increments, the axis' don't always move a full thou.. The servos have 500ppr encoders, with quadrature, which turns out to be 30480 steps per inch. Even ignoring the quadrature, it should give me step accuracy of 0.0001" or thereabouts, but I'm not seeing that. It definitely averages itself out, if I move 0.020", it'll end up fairly close, but some steps will move it 0.0015, some are right on at 0.001 and some 0.0005.
Any ideas? It could just be horrendous ballscrew accuracy, but I thought I'd check if anyone has seen a similar issue. Any thoughts appreciated
Thanks!
edit: figured I should mention that I'm also using an ethernet SmoothStepper!