Holes does not center on X axis?

[dahlman]

Hi!
I'am new into plasma cutting. I've managed to get a couple of
decent cuts, but also a whole bunch of bad ones.
At the moment i struggle with a strange problem.
When i try to cut a 200mm shape with two holes in it on both ends
the holes don't align to center on the x-axis. About 2 mm wrong.
I've tried this piece four times with the exact same result. Also tried another
one with the exact same problem.
The shape and hole dimensions do match the cad , but i'd like to have them centered as drawn
The holes are round and the shape it self looks fine.

Iam using:
* Sheetcam
* Mach3

Any ideas what's going on here?

Best regards

[Les Newell]

The most likely reason is that your machine is losing position. Before you start cutting move the torch to X0Y0 and carefully measure it's position on the machine. After cutting a per again move back to 0,0 and measure it's position again. I expect that you will find it has moved.

This is a common problem with stepper machines. The solution is to reduce the acceleration and/or the the maximum speed in Mach. You need to esperiment a lot with this. Make up some complex drawings with intricate shapes and cut lots of them with the torch off. Try different drawings and use the maximum feed rate override that you are likely to use. Keep playing with your settings until it no longer loses position. Once you are happy with it reduce both the acceleration and top speed by about 20% to give you some extra safety margin.

[dahlman]

Thank's for your reply!
I'll check my acc settings.

[dahlman]

Hi again!
Thank's for your reply.

I've tested some more, turns out that this problem only occurs when using the torch.
With a pen, all moved fine. So it seems like i have some interference problems when torch is firing.
I noticed that the wiring for Z axis limit and Z axis "safety" were unshielded so i removed them yesterday, i'll do some test cut's tonight.