Random Z-Axis plunge

[gomako]

Thanks for the quick replies guys! Thanks for all the info jazzcnc, I have a lot to learn.

I have followed your advice and I think there might have been a couple of solutions in both posts.

I had a look and some of the connections in the terminals of the drivers were looking a bit strained, so I pulled the cable back to relieve the stress. Hopefully that'll minimise any noise.

I also had a look at the movement speed that was set on the tools ( the guy that we got the machine from gave me this advice too after I'd posted here ) and the plunge and movement speed was set pretty high, and could well be causing the machine to miss steps as you suggested John. It does seem odd that it was pretty much exactly 10mm every time, so what you say makes sense.

Having done all that, the machine seems to be behaving itself! Thanks very much! I'm looking forward to being part of the forum.

[JAZZCNC]

Did it do it every time you ran the same code at the same point in G-code or occsionally and randomly with the same code.? If the later then I'd be surprised if it's missing steps.
Esp has it's exactly 10mm, missed steps from overtuning tend to be random amounts resulting in random offset distances.?

Seen has it's a constant figure It could also be backlash.? Backlash would give exact offset distances.!
Check all mechanical connections on the ballscrew, you should if built correctly have a fixed end where the ballscrew comes thru the thrust bearings and is fasten with a lock nut to stop end float. If this nut works lose(which does happen) it will have the same effect has backlash and give a constant movement amount when changing direction.!

EDit: The movement amount can be tiny but it accumlates with lots of moves resulting in an exact amount at a set point in the job so check carefully because even a tiny amount is bad news.!!

It's the constant 10mm amount that concerns me, missed steps thru overtune don't often give same error amounts.?