Re: Gavztheouch's Mk2 Laser
Posted: Wed Jul 18, 2012 7:08 pm
Hi Gav
Just noticed your new setup - looking really good ! Loved the anti- whip support for the ballscrew end machining - looks like my old music stand
50um, I wish that was what I had
Regarding the snake data to show up backlash, I swapped to 'waves' of half arcs - the backlash showed up instantly - it's amazing how accurate your eyes are.
Anyway, regarding the dsp and 'backlash' (although this isnt realyl backlash). On my system, I had to set the Y axis steps/um different from the X (X was as calculated using the pitch circle diameter of the pulleys - bang on) - to date, I haven't found out why (I did actually swap drive pulleys and drives to see if that was a cause). Both axes now use exactly the same steppers and belts - the belts are even from the same reel.
I did the settings over 500mm on both axes - checked the diagonals were equal too. I also measured multiple square test pieces. All dead nuts on, but the axis steps are different. I began to think like you ,that there was some issue in the pulses from the dsp. I no longer have access to any decent test equipment - a pulse counter would be a good thing to hang on the step outputs during a 45deg diagonal move with the same steps/um on each axis. I also tried a change in step polarity
I don't remember having this issue using the lasersaur board, but I had a lot of backlash at that time caused by those split couplers which may have masked it I no longer have the board, I mailed it to a friend for his laser.
Hopefully, you'll get to the bottom of it using mach - look forwrd to yourr results.
Cheers
Neil
Just noticed your new setup - looking really good ! Loved the anti- whip support for the ballscrew end machining - looks like my old music stand
50um, I wish that was what I had
Regarding the snake data to show up backlash, I swapped to 'waves' of half arcs - the backlash showed up instantly - it's amazing how accurate your eyes are.
Anyway, regarding the dsp and 'backlash' (although this isnt realyl backlash). On my system, I had to set the Y axis steps/um different from the X (X was as calculated using the pitch circle diameter of the pulleys - bang on) - to date, I haven't found out why (I did actually swap drive pulleys and drives to see if that was a cause). Both axes now use exactly the same steppers and belts - the belts are even from the same reel.
I did the settings over 500mm on both axes - checked the diagonals were equal too. I also measured multiple square test pieces. All dead nuts on, but the axis steps are different. I began to think like you ,that there was some issue in the pulses from the dsp. I no longer have access to any decent test equipment - a pulse counter would be a good thing to hang on the step outputs during a 45deg diagonal move with the same steps/um on each axis. I also tried a change in step polarity
I don't remember having this issue using the lasersaur board, but I had a lot of backlash at that time caused by those split couplers which may have masked it I no longer have the board, I mailed it to a friend for his laser.
Hopefully, you'll get to the bottom of it using mach - look forwrd to yourr results.
Cheers
Neil