Trouble setting the correct steps for an Openbuilds Lead CNC I am building.

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(Rob Mitchell) #1

Trouble setting the correct steps for an Openbuilds Lead CNC I am building. I’m using tinyG however I have entered 8 as the distance travelled for per revolution and it’s gaining a few mm over 100mm commands when testing. Units are set to mm. My lead screw is the 8mm Acme Metric from Openbuilds with a 2pitch.

What is the right calculation to use?

I am using NEMA 23 with 1.8’ 200 steps per rev.

Thanks

(JOHN LAUER) #2

What I have tended to do in the past is do a long measurement like you did, but go to the max extent on each axis and measure the amount it’s off like you did. Then I would just divide that out and reset the CNC controller to exactly reflect the amount of movement. That would take into account any incorrections in the off-the-shelf measurements.

(carl j mcgrath) #3

With tinyG, you need to modify the axis travel per revolution parameter, don’t mess with steps. So if Y axis moves 102.5 mm when you issue G1 Y100, the set your $ytr = (100/102.5)*2 , assuming the current value is $ytr=2mm.
Calibrate X and Z similarly
See also https://github.com/synthetos/TinyG/wiki/TinyG-Configuration-for-Firmware-Version-0.97