Calibrate stepper control (steps / mm)

[dbenamy]

http://reprap.org/wiki/Triffid_Hunter's_Calibration_Guide

[dbenamy]

We'll likely need to tackle this for milestone 1.

[dbenamy]

I'm trying to calibrate y using measurement. I put a c clamp on the rail and measure the distance from there to a bolt on one of the long axis mounts using a caliper. Then I manually told it to move 100 (presumably mm) and measured again. It moved 54.6mm.

The second (presumably y) DEFAULT_AXIS_STEPS_PER_UNIT is 78.7402. If I'm doing this math right, I want 100 / 54.6 * 78.7402 = 144.2128. I didn't take super precise measurements and the second side isn't sliding right which may skew things, but this should get us into the right ballpark.

X moved 61.49mm when I told it to move 100. 100 / 61.49 * 78.7402 (which is the x default) = 128.0537.

With this change, the x is definitely much closer to right. I can't retest y at the moment because of of the motor mounts is missing a set screw :-( But I'm assuming it'll be close enough to continue and we can find tune further later.

I'll put a note about this in http://opensourceecology.org/wiki/CNC_Torch_Table_2/Control_Overview#Marlin

To do: calibrate z

[dbenamy]

Fine tuning: x should have drawn 203.2 and drew about 205. So I think it's 203.2 / 205 * 128.0537 (which is the steps per unit right now) = ~126.9.

Y: 100 / ~101.2 * 144.2128 = ~142.5 - this turned out wrong. i'll do it again. maybe i had the numbers backward.