Last week when I was running my machine, when I jogged up the Z after setting zero, I noticed the Z would change and not hold. I then looked closer and when I jogged the z up, it would make a small second movement. I called and ordered a new servo motor for the machine and when it arrived, I went into the garage and the Z was working fine??? I then cut about 30 pieces with no issues and then it started again. The z would change with each jog after setting zero. That little extra up bump I would notice on the hand wheel. HAs anyone else ever had this problem. Where do you think I should start. I am at a loss here. I am using a tabeltop mill made by Townlabs and it uses servo motors for all axis. THank you for any help...................

Hard to say as I am not really sure what you are meaning, especially the small second movement bit. Could be bad servo drive tuning or could be noise, may even be step pulse active state being wrong.

Hood

Hood, thank you for the reply. The second tiny movement is what is throwing the Z height off. I jog up after finding zero and when I remove my finger from the keyboard, it jumps a tad more. I switched the cable from the Z to the X, to see what would happen and then it also did it in the X. I think that rules out a bad servo motor, as X works just fine. I am leaning towards the controller?

Is there anything inside computer that I should change values on possibly? This quirk just showed up recently and never happened before.

Thanks in advance for any other suggestions.

Maybe this bit will help, it seems this anomaly only happens on the first up jog, second or third up jogs, don't seem to be effected???

Do you have backlash comp enabled?
Hood

Yessir and properly adjusted.............I just checked that again yesterday.

As a test can you disable it and see if it makes any difference.
Hood

I am going to change the keyboard today. Thats sounds silly but I am out of options.

Keyboard problems could make it jump I suppose but if I am und3erstanding what you are saying you are actually losing axis position compared to Machs DRO. I think the keyboard would be unlikely to do that but worth a go.
I was wondering if it was maybe the backlash that was the issue as you said in a previous post it was just on first jog away from your zero.
May also be worth checking you have the Step outputs active state set correctly for your drives.
Hood

Hood,

Thank you for replying. I am having the same issue and now I am convinced its a temperature issue and a controller issue. If I swicth the plugs around the problem moves from Z to X. Now that it has been ober 90 degrees, the issue is really bad. I am sending the controller back to be checked.

One thing puizzles me is that you were the only one to respond, while another user has a ton of attempted help and its a HOT TOPIC. I know us small time contributors have little to add to the forum, but when something like this happens to you, its very much important.

I'll post a reply when the controller comes back........................

One thing puizzles me is that you were the only one to respond

Ussca,let not your heart be troubled. Certainly nothing personal as it matters not if you are big or small time on this forum.
Sometimes we just like to leave it to Hood to reply as it gives his fingers somethng to do. 

RICH