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General Mach Discussion / Why do large files cause lost steps?
« on: April 02, 2008, 05:20:21 PM »
I've been trying to do 3d contouring on a 4-axis stepper/gecko machine we built recently, and I'm experiencing strange behavior, which I'm at a loss to account for. While a combined move in the X and A axes works perfectly with the X axis set at 300 ipm and the A axis at 790 dpm (degrees per minute), when I try to run my large (11mb) finishing pass, which calls for multiple tiny moves in Z at the same time as it rotates in A, I have to slow down to a crawl (75 Z, 150 A) in order not to miss steps. At this rate, the motors sound very odd (the A axis groans, and the Z axis clicks) and of course the progress of the cutting operation is practically nil; the cutter basically burns its way through the wood.
I'm trying to figure out what's going on. Is memory overhead from the file size interfering with pulse generation? Is it the graphic redraw that's slowing things down? (How do I turn that off?) I haven't had nearly as much trouble when combining tiny moves in X and Z; is there an issue with combined rotary and linear moves? Should I set a different plane of movement? (X/Y is called by default) Or is it the Constant Velocity function that's messing things up? (When I've tried Exact Stop, things get very herky-jerky). I've used Mach for a while without having problems like this; is it something to do with Version 2.63? Why is there such a huge difference between the speeds that work reliably in testing and the ones that I have to use when running my program? What is it that's causing this massive loss of steps, particularly in A? Any suggestions would be much appreciated - I haven't got much more hair to tear out...
Andrew Werby
www.computersculpture.com
I'm trying to figure out what's going on. Is memory overhead from the file size interfering with pulse generation? Is it the graphic redraw that's slowing things down? (How do I turn that off?) I haven't had nearly as much trouble when combining tiny moves in X and Z; is there an issue with combined rotary and linear moves? Should I set a different plane of movement? (X/Y is called by default) Or is it the Constant Velocity function that's messing things up? (When I've tried Exact Stop, things get very herky-jerky). I've used Mach for a while without having problems like this; is it something to do with Version 2.63? Why is there such a huge difference between the speeds that work reliably in testing and the ones that I have to use when running my program? What is it that's causing this massive loss of steps, particularly in A? Any suggestions would be much appreciated - I haven't got much more hair to tear out...
Andrew Werby
www.computersculpture.com