Z axis losing depth

[jeff]

Ok guys.. been a while since I've been here.. but.. I have an older PRS standard with a 4g control box..when doing a longer carve: 45 mins or longer, at the end of the cut, the Z is between .25 and .5 inch higher.. the software states that it is still at the original level. Called SB, and we are working through it.. Did an air cut... same issue... checked cables... checked for binding of the rollers, adjusted spring tightness, adjusted speed, machine is grounded.. all checked, no luck.. This all seemed to begin, when a computer problem stopped the bot during the cut.. the bit stuck in the wood. I had to manually pull it up.. since then. It seems to gradually raise throughout the cut.. Could it be a motor? levelness of the router? control box problem.. need this thing up and running fast! Business depends on it.. and I'm already behind.. Please help!
Thanks in advance..

Jeff

[ssflyer]

Hi Jeff,

The first thing I would suspect is the collet - particularly since you've checked everything else! :cool:

Ron

[Gary Campbell]

Z Pinion grub screw?

[ken_rychlik]

The first thing I would do is to drop the motor off of the z axis and move it up and down by hand to see how free it is.

If it does it on air cuts, I can't blame the collet or bit slipping.

There were a few rare times where someone had their move distance and jog distance get messed up. If by chance a move z,4 command would move it 4 and a Jog z 4 would move it 4.1 then that would explain it.

When you pull the motor you can check the set screw on the pinion gear and move the z to see how easy or hard it moves all at the same time.

If all that fails, I would swap with another motor on the machine. Swap gears too when you do it.

[jeff]

thanks guys.. Definitely not the collet..
Ron.. I'm not sure what the Z pinion grub screw is.?

Ken.. the moves and jogs both go equal distance.. it is in the long cuts that have the gradual change in depth...I'll take the motor off today and check how free everything moves..
I tried to adjust the tightness of the rollers and spring last night, but did not remove the motor. I'll also switch drivers to rule out a weak driver per Frank at SB... and give resistance during a move..

I appreciate all your advice.. Gotta get it up and running! As you know.. time is money!

[asteude]

Hey, Jeff - did you get your issue fixed? I'm having the exact opposite problem. My z axis gradually loses height.

[asteude]

It appears my drooping z-axis is related to running unnecessary software while cutting. I disabled Norton antivirus and firewall and my wireless printer software and tonight's 45min aircut was right on the money. Hopefully that was the only problem.

[robtown]

Andy, make sure you aren't plunging into your material too fast or that you aren't trying to do your carving too fast in X and Y.

When doing long carves the movement of the Z will dictate how fast you can actually move in X and Y.

If you are trying to use speed values that are too high it will result in lost steps usually starting with the Z axis...