Serious Y axis jump

I'm machining 2 duplicate pieces out of 6061 in 2 vises. The left vise is G54 and the right is G55. I just finished roughing the G54 part and was moving over to the G55 vise when I heard a sound and when the cutter started on the G55 vise it wasn't even touching the part. It had moved -.660 in Y which was fortunate due to my starting point that it didn't hit the part but missed it completely. I was using Tormachs modular 16mm endmill at 4500rpm and about 40imp with a .125doc and about a .250 woc. When I checked the G54 it also had jumped the same so I don't believe it was a controller error. Anyone else have this or have any ideas as to why this happened? Something loose? I've been using this machine for over a year and machining similar parts for a few months with no issues. I didn't pull the machine out to give the Y axis motor a good look but that will be first thing tomorrow.

Do you have the air compressor, or a fridge, plugged into the same line as the computer or the machine? Those have both been known to cause line interference when they startup/run, and that can mess with locations in mach.

Checking the motor is a waste of time - there's nothing wrong with it. You should check that the coupler between the motor and ballscrew is tight on BOTH shafts. Otherwise, it was probably a stall, caused by over-loading the motor, which could indicate high friction due to lack of lubrication on the Y axis ways. Could also just be a Mach3 transient glitch. Unless it happens again, I wouldn't lose any sleep over it.

Regards,
Ray L.

Or it could be the Y motor coupling slip - I have had that happen. If you find the small clamping screws are not that tight - tighten them a little - but not so much as they strip etc. . Also mark each side and the coupling with a white out pen so you can check it in future to see if it ever slips again.Keen

Quote:

---

Originally Posted by keen

Or it could be the Y motor coupling slip - I have had that happen. If you find the small clamping screws are not that tight - tighten them a little - but not so much as they strip etc. . Also mark each side and the coupling with a white out pen so you can check it in future to see if it ever slips again.Keen

---

There was a thread -or a comment in a thread- a while back (2-3 years, maybe more) about replacing the couplers in series I & II machines with a better design. Can't find it now, but if I recall correctly it was a 4 screw compression clamp rather than the set screw on a flat type. Haven't checked, but I've seen some pictures that suggest Tormach has changed the design of the coupling. Anyone have a reference to that thread, or know if the coupling design has changed?

I go to check the coupler and it seems I have to take the coolant tray off to get to two screws near the column. Not a good design imo. The movement didn't happen under load, it was during the move from one vise to the next that it happend so I'm going to run again and see what happens.
Update: After shutting the machine down and restarting, y was off the amount I corrected for after it jumped so it appears it was load that made it jump. Looks like I will adjust my feed a little.

Quote:

---

Originally Posted by sparrow

I go to check the coupler and it seems I have to take the coolant tray off to get to two screws near the column. Not a good design imo. The movement didn't happen under load, it was during the move from one vise to the next that it happend so I'm going to run again and see what happens.

---

My experience with Mach/windows has been similar, occasionally it would do something like this, I just reboot rehome and start again, this has always straightened out the problem. I always listened for any unnatural noises, usually means problems at some point in the program.
I never found any mechanical or electrical problem that could be causing this, it didnt repeat itself either, I just attributed it to a glitch in Mach or windows.

Quote:

---

Originally Posted by sparrow

I go to check the coupler and it seems I have to take the coolant tray off to get to two screws near the column. Not a good design imo. The movement didn't happen under load, it was during the move from one vise to the next that it happend so I'm going to run again and see what happens.
Update: After shutting the machine down and restarting, y was off the amount I corrected for after it jumped so it appears it was load that made it jump. Looks like I will adjust my feed a little.

---

Because the coupler is difficult to get at is not a reason to believe it's not the problem. Check it or you'll be sooooorrrrrreeeeeeeeeeeeeeee, it wont fix itself.

Phil:)

Quote:

---

Originally Posted by philbur

Because the coupler is difficult to get at is not a reason to believe it's not the problem. Check it or you'll be sooooorrrrrreeeeeeeeeeeeeeee, it wont fix itself.

Phil:)

---

Lol, for sure I will check it. I have to install/change some things around anyway so it's a good time to do a PM. I am going to grind an opening in the edge of the coolant tray that blocks the access so I can get to the screws.

My own Z-axis motor coupler experience is at http://www.cnczone.com/forums/tormac...s-problem.html

Randy