Why would a machine suddenly start losing steps?

[CaptainVee]

Hi Guys,

I'm a bit puzzled.

When my mill has been running fine for a while it sometimes starts to lose steps. Yesterday it did so again and it was the same program I had been running all week, doing several hours of more or less non stop work, where yesterday it was less than one hour of milling time.

The only difference was that most of the week I had been milling mdf and yesterday it was ocoume plywood.

Can it be that the machine needed to work harder because of the stronger material?
The steps were lost during a G00 move on the x axis, so no load. I have 6.4 Nm steppers and G00 was probably about 6000-8000 mm/minute.

[adprinter]

I too, experienced problems with lost steps on my machine. Except that in my case, it was on the Z axis. Which prompted me down a path to cure the problem, which ended up being an improvement to my machine. (But did NOT correct the initial problem of the lost steps). In my case, it wound up being the mounting bolts for my Z axis Nut assembly had vibrated loose. I simply retorqued the bolts, and have not had any problems since! Since you mention in your post, that your problems are with the X axis, the first thing I would look for is worn bearings (or perhaps mounting bolts, or even a loose set screw on the motor couplings). You might even go to the extreme, of removing the motor coupling from the drive, and try turning the drive by hand. If you can't, then you have some type of binding issues in the mechanical drive on that axis. Again, look for worn bearings, etc. I once had this issue to appear on my Y axis, and discovered that it had been dragging a shattered bearing around (instead of it smoothly rolling along, as it was designed to do). Hope this helps!

[Christian Knüll]

Hello,

sometimes the problem is just too much dust on the spindles. Wood dust and grease can get pretty sticky over time. This is especially bad with ballscrew splindles as the dirt is collected inside the nut. Just clean the spindles and guides, put some petrol on them to get rid of old, sticky oil, clean again and relube with oil.

If it still happens from time to time - even if everything is clean and all bolts and bearings are OK you may just be running a bit too close to maximum speed. In this case just decrease G00 speed by 10% and it is very likely to never happen again.

If you're well below maximum speed just try selecting a slightly different speed - maybe you've just picked a speed close to the spindles resonance frequency which may also cause loosing steps from time to time.

Christian

[nobel]

Yes this could be, because as name indicates that this is a machine so any type of fault can be occurred. Although all the participants above perform well according to their knowledge...

[CaptainVee]

Hey guys, thanks for the suggestions.
It has not happened since but these are good remarks to keep in mind for all axis.

[Claude Boudreau]

Same thing happen here.
Try sqweezing your motor coupling a bit with the motor turning at full speed.
If its loosing step easily, lower your speed .
P.S.dont loose a finger...