Stepper Motor Calibration

1

So I’ve been playing around with my X-Carve for about 6 months now, doing basic signs, a few boxes. cut outs, etc. neat stuff, but nothing that needed to be dead accurate until now.

I was using the X-Carve to make some blind holes for some cam connectors to be placed in (you know, like you have in IKEA furniture). When I went to place the cam in the hole, I noticed that it wasn’t quite circular, but was actually slightly oval.

It’s supposed to be 15mm diameter, but is more like 14.99 x 15.27 (h x w), so my X-axis calibration seems to be off.

I switched to one of the engraving bits (has a nice fine point) and laid out the tape measure on the waste board and told the X-Carve to move 20" in the +X direction, and it moves just over 20 1/8", but returns exactly to its starting spot when I move it to the left.

I’ve searched thru the forum, and found Phil’s stepper motor calculator, and an online one from John, but can’t seem to find the actual stepper motor calibration procedure. I need to know what machine variables to look for to get my current X steps, and need to know how many steps were sent so I can adjust my X-Axis (Y is just fine), probably should check Z too.

Can anyone provide a link to (or post the actual procedure) to calibrate the steppers in a Step 1, Step 2, Step 3 fashion?

Thanks,

Don

2

There are calculators on the forum, but it is just a matter of changing the values by the percentage error you get when you jog your machine.

$100=40.000 (x, step/mm)
$101=40.000 (y, step/mm)
$102=188.947 (z, step/mm)

The formula would be New (steps/mm) = (requested move in mm * current steps/mm) / (actual move in mm)

For your X 20in = 508 mm
your actual move 20.125 = 511.175 mm

new steps/mm would be (508 mm * 40 steps/mm) / 511.175mm = 39.752 steps/mm

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3

Best Stepper Motor Calibration I have seen

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4

@LarryM and @GlennMDutcher,

Thanks!! That should sort it out and it’s easy enough to do. I’ll give it a go tomorrow and let you know how it turns out.

Don

5

For a true circle to be carved into a true circle the give on both X/Y (any machine has some degree go give" need to be even. If there is difference or excess slack on one of the axises the circle will be deformed / the “sides” will tend to be straight.

This image will show the defect I talk about:

If this is the case with your system then recalibration will not cure it.