Y axis lost postions

I am lost at this point. Tried everything i can think of.

I will set my XYZ zero’s and run my first program. Next, after a tool change. I will run my second operation. However, my Y position is always off my +.03 - .070", every time.

I removed G28 from my programs so the machine does not home, hoping it was a limit switch issue, but it still happens.

Currently i am unable to use my machine without probing Y at every tool change. X and Z are fine.

Any help would be appreciated.

Sounds like you’re losing steps. Something is in a bind, too tight, or you’re taking off too much material at once.


I am cutting .020" deep into soft plastic.

Just figured out it is the boring tool path. Removed it and the problem went away. It is very odd though, it will even lose steps when cutting 1" above the part too. Doesnt even start the hole at the correct position.

After a while my machine settled and had a slight bit of twist in it. It had dropped maybe 0.15" in the right rear and nearly as much in the left front. Can’t remember the angle it was putting into the table but I want to say 1.6 degrees sounds about right. It was putting the Y axis in a bind about half way through its travel. Could have been the adjustable feet settling, or the whole assembly.

After getting it level again I went back through the steps of loosening the X axis gantry, broke the Y axis bolts loose and jogged the Y axis back and forth a few times to let the rails align, then tightened the Y axis bolts down while Y was about mid travel. Resquared the X axis and it took care of the missed steps.
May not be your issue here, but something to think about.

Thanks, I will try this.

I think I’ve got a similar problem. My machine has started to make a single popping sound during Y travel. Doesn’t happen all the time but something’s getting thrown off when it does as a re-zero then shows different machine coords. I’m thinking I need to check the level. How did you accomplish this? Just a level on the machine bed?

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Level on the bed, I used a Starrett 199 Master Level. It’s a spendy bugger for hobbyists but I’ve got more machines to level than the MR-1 so it’s priceless at times.


I was able to resolve this by upgrading the Y drivers. I followed the instruction on another post using stepper online drives instead of the pricey ones.

No issues so far. Thinking about doing the same for the Z drive. The machine audibly sounds smoother.


I used a digital level on the bed, but any precision level will do.
Check in line with X and Y and diagonal in a few places to see if it’s got some twist in it from settling.
I think Benj is onto something too with the upgraded drivers. The regular drivers on the Y axis aren’t incredibly strong, so a little bit of misalignment could be the cause.
After loosening the cap screws and letting the Y rails realign I haven’t had any more pops. What you describe is exactly what I was getting too. Anything from a single pop leaving home position, or half way through Y travel, up to sounding like a machine gun and the Y axis on the DRO was way off afterward.
Upgraded Y drivers is still on my list of things to do. It’s just not as much of a necessity as of now.

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Thanks a bunch for the details. I checked my levels and they were actually fine - 1 degree toward the front, but even for both sides. I actually set it up at 1 degree toward the front in the beginning to flow at bit toward the front for easier cleaning. I ended up loosening jet the right side of the y rails and cycled it a few times and then re-tightened. Now it runs smooth with no pops and no lost positioning. Thanks again for all your help! Now if I could just get the Langmuir touch probe to be more accurate, I could flip my parts (and mate them with other parts) with more success :wink:


No problem, glad you got it sorted out.
Unfortunately I dont have any tips for the LS probe. Mine has been apart a few times and has a repeatability of around .003" most days. Sometimes it misses that mark too though.