[MPaulHolmes]

I have some 1200 ounce*inch stepper motors directly driving my x and y axis of a Harbor Freight geared head mill. 50v power supply, Gecko 540B driver. About once every 2 months or so of nearly daily use, while it's moving with the G00 command, the x-axis suddenly locks up and starts making that honking noise. Could it be a controller issue? Has anyone had this problem as sporadically?

[strohkirchw]

Do you have backlash comp turned on?

[MPaulHolmes]

Yes. 0.021 x, 0.017 y. That gives a perfect plus sign when I test it.

[eartaker]

How often do you oil everything?

[MPaulHolmes]

Oh, I'm starting to think not often enough (oiling it). I'll go try that. Right now every few months or so :rainfro:

[strohkirchw]

Only time I've had that issue is when using backlash comp. It's usually encountered though when you try to jog another axis when one is currently moving. If this is what is happening then it's likely that your backlash comp speed or shuttle speed is set too high. If it's just one axis moving and it locks up then it's probably not the problem.

[eartaker]

I use backlash comp on my little mill and it never causes it. It is almost always caused by harmonics or it is binding up. If you are using it DAILY then you should be oiling it daily. You can pickup some chainsaw bar oil at Lowes by the gallon and it works great. Just a little before you start.

[pete from TN]

are you sure you are driving it with enough power? Not sure what the limits are for the G540b really.... did you use the G540b XML file for Mach3? I am assuming you are using mach3 here of course.... do you have a build thread or some pictures somewhere? Peace

Pete

[MPaulHolmes]

The motors could take double the current, but it works well. I don't have a build thread, just bought a bunch of little plates, lovejoy couplers, spacers, and stepper motors from ebay and stuck them on. 1.5 years with ALMOST no problems. I think it's an oiling issue perhaps. On a separate note, does anyone know where I can get a replacement drawbar? I think mine is slightly bent. It came that way. Go HF!

[eartaker]

MPaulHolmes,

I was moving the head of ZX-45 and doped the whole thing one say and the drawbar was in the spindle but not attached to any collet. Luckily it landed on the drawbar that was hanging out of the top first cushioning the fall.... Bent the drawbar at a 90deg angle. The threading on the end of a R8 drawbar is 7/16 X 20TPI. you could buy a piece of hex rod and make a new one. Gd.marsh suggested using hardened all thread rod and placing 2 nuts on the top, but I don't know how you would grip it to tighten/loosen it as this idea was for use with a pneumatic cylinder style power drawbar.

[SCzEngrgGroup]

The motors could take double the current, but it works well. I don't have a build thread, just bought a bunch of little plates, lovejoy couplers, spacers, and stepper motors from ebay and stuck them on. 1.5 years with ALMOST no problems. I think it's an oiling issue perhaps. On a separate note, does anyone know where I can get a replacement drawbar? I think mine is slightly bent. It came that way. Go HF!

Running those big motors on a G540 you are certainly giving up at least half the rated torque. Since you are experiencing sporadic, random position loss, the problem is likely you're simply pushing too hard. The "right" way to setup steppers is to push them to higher accelerations and higher speeds, until you start seeing position loss. Then back off by 30-50% on BOTH top speed and acceleration. Any less than that, and you're likely to get exactly what you're getting.

And, running over-sized motors with under-sized drivers is just a bad combination all around. You'd almost surely get significantly better performance all around by swapping out for some motors that are better matched to the capabilities of the G540. Either that, or sell the G540 and buy some G201s or G203s so you can actually drive those motors properly. But, 1200 oz-in is more than ANY benchtop machine needs....

Regards,
Ray L.