Z height changes on execute

[axeman]

Hello Folks,
When I begin running some G-code I have a problem with the Z-axis resetting 1mm higher than it was zeroed at before starting the program, resulting in it cutting 1mm deeper into the stock.
This is not consistent, it will run the same program fine sometimes and other times it will reset the Z-axis position as seen in the attachment.
Any ideas why this might be happening?

Here's a link to a video that shows the issue:
https://youtu.be/lgTcxx-f5xk

[TomKerekes]

Hi ace man,

Sorry for the delay I thought we responded.

I don’t understand the video.

I think there might be some confusion with Tool length compensation. Are you using it? You might read this thread.

https://www.cnczone.com/forums/dynomoti ... 4-cnc.html

[axeman]

Yes, that was it!
Tool length compensation was set by default for T1 at 1mm, I guess by way of example but it took me a while to find it.
This little machine does not have any tool changer so I didn't consider tool length offsets and assumed they would be all zero by default. I will be more careful to check in future.
Everything is working well now, thanks!

[TomKerekes]

Great. Thanks for taking the time to post back.