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tormach told me more than likely the gibs are loose in my machine. When moving from Z0 up to Z2.0 the machine overshoots by about .032 and when returning to Z0 is about .003 short.
I got some spanners in today and plan to tackle it this weekend. Any lessons learned from anyone that has tried this before?
I've done it a couple of times, just follow the procedure in the series II manual, even if you have a series I machine. The only thing thats not clear is how tight to tighten the adjusting end screw. I guess its a feel thing. Better to snug it firmly, then run the Z up & down a few times and recheck it. Also, I ran the machine to normal operating temps before I started. No need for the spanners... Good luck.
Thanks, for some reason I read I needed them, probably reading the ball screw adjustment tools required.Originally Posted by kprice1658
Anyway, I have adjusted till I am blue in the face. Still no solution, so will send Tormach a note back.
Mag I've had the same experience as you and it does take a little bit of investigating. I've adjusted the X Y Z gibs until I was blue in the face too (2 weeks worth). I noticed very quick that if the gibs aren't in the exact place when the machine arrived, it will act a little screwy. I'd push the gib around until you find the honey spot.
If that's not it, move on to the bearing housing & mount. Mike Henry a member here brought this one to my attention. I had to make a really long socket head style wrench to get in there and had a few that were kind of loose. (might help)
The coupling was another I spent sometime on. With a permanent marker, draw a little line on both the coupling and shaft and see it they move. If so there's your problem.
What really helped me was to adjust the gib first, then the backlash nuts, then gib, then backlash nuts. When adjusting the backlash nuts I loosened the coupling to the motor & shaft before I tighten them each time.
Last I'd check the straightness of your gib.
Since no matter what I do I get the same results, I am beginning to think it is something else, but look into your suggestions.
I have two concerns, one is my Z motor has always been a little louder that what I would think it should be moving up/down.
The second is my Mach 3 show PCNC 1100 at the bottom right and I thought it used to say PCNC 770.
If the z-axis positioning system were closed loop (servo controlled) I would say that the acceleration parameter for the z-axis is set too high in the configuration causing the overshoot. Are you sure you're running the correct software? It should say PCNC1100 and not PCNC770 (that is, if we're talking about a PCNC1100). It may be the acceleration parameter is higher in the 770 software that the 1100 can handle. I'm not entirely sure, though, how the overshoot can occur in an open loop control system. That is, it can certainly overshoot but I don't see why the powered stepper would settle back into nearly the correct position afterward. In any event I would uninstall and re-install the proper software. Interested in what you eventually learn from Tormach on this. - Terry
I actually have the PCNC770.
I installed a patch a while back for problems with the Z axis (more direct was for a noisy Z movement) for the 1100 and some 770 - which affected mine. Looks like I may have installed that patch wrong or Tormach had the wrong update.
I copied the old install as I normally do and saved it. Renaming the directory and moving the old install back the 770 shows back up and the G0 Z2 command now move within .002. I would consider that pretty close for now. Giving G0 Z1 moves in back dead on to Z1. I forgot I had installed that patch.
The parts I am making now are only 6mm x 6mm so I doubt it would matter.
I would still like to get that .002 even smaller if possible.
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