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Author Topic: a axis as a linear axis  (Read 2095 times)

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a axis as a linear axis
« on: May 20, 2010, 04:35:14 AM »
Hi All
I am trying to do some engraving on a circumference for a machine dial. I set my A axis as a linear axis in general set up and calibrated it so 144 mm linear movement gives 1 rotation on my rotary table (800 steps per mm x 72 assuming a 2mm ptch leadscrew). The G0 commands work perfectly but as soon as I do an MDI G1 command it seems to revert to angular motion and feed rates. I thought I might be able to do this without axis swapping as my Y motor is hard wired to the stepper driver and it seemed an elegant solution. I have also tried slaving the A axis to the Y axis and disabling the Y axis but the rotary table motor just jitters and screams...not good. any suggestions . I know I should work in degrees for rotary axes but going through my code and converting all Y moves to A angular moves seems really tedious. I have tried CNC wrapper but  on conversion the feed rates in A axis are way to slow so you have to move the  A axis move to a seperate line and and add a seperate feed rate...clunky at best!

any help appreciated

Iain

Offline Greolt

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Re: a axis as a linear axis
« Reply #1 on: May 20, 2010, 05:33:28 AM »
I have tried CNC wrapper but  on conversion the feed rates in A axis are way to slow

CNCWrapper does not alter feedrates.   They are left unchanged.

Go to Toolpath Configuration and set "Use Radius for Feedrate"

Then set whatever the Z axis zero height is in "Rotation Radius" DRO, found on the Settings page.

If using the centre of rotation as Z zero, then put a very small number in that DRO, not zero. (zero will turn it off)

Greg
Re: a axis as a linear axis
« Reply #2 on: May 20, 2010, 05:55:35 AM »
Thanks Greg..I'll give that a whirl