The Dreaded X axis stepper error using UC400ETH and UCCNC !!!

[dachopper]

UC400 ETH controller, UCCNC software

I don't know, I can turn the ball screws by hand from end to end..... what more could cause the X axis to seemingly bind, not get noticed by the 822, and then immediately unbind in reverse direction?

Next step is GOPRO an entire cut in the air, and see if it jams unloaded under inertia or no jam and program telling it to move?

[Doddy]

Have you checked the pulse width from the UC400 ETH?, I don't know how but I've noticed its an option in the UCCNC software. The AM882 needs >2.5us for reliable operation. Worth a look?

[ptjw7uk]

Does the power supply have enough output!

Peter

[Ger21]

Have you checked the pulse width from the UC400 ETH?, I don't know how but I've noticed its an option in the UCCNC software. The AM882 needs >2.5us for reliable operation. Worth a look?

Pulse width is not an option. It's a function of the kernel frequency. I believe that you need to use 200Khz or less to get 2.5us pulse width.

[dachopper]

Using 50 khz , .1 sec com buffer, and 300 line look ahead

[A_Camera]

Driver PSU voltage: ???
Micro stepping: ???
Stepper current: ???
Speed and acceleration: ???

The AM882 seems to be pretty complex compared with the traditional analogue drivers, are you sure it is been configured right, according to the manual?
Have you checked the signal levels at the AM882 end? How about wiring?

[A_Camera]

Using 50 khz , .1 sec com buffer, and 300 line look ahead

No benefit in using 50kHz and it is too low if you have a fast machine. Raise it to 200kHz.

[Ger21]

What's the benefit of 200Khz?
50Khz gives you a longer pulse width, which can be a benefit with some drives.

The fact that he's had this issue with both Geckos and Leadshines, means it's probably not the drives.

That would point to maybe the power supply, an issue with accel/velocity settings, or a mechanical issue.

You said the motors are very hot? What are the motor specs, and what do you have the drive current set at?

[routercnc]

You said the motors are very hot? What are the motor specs, and what do you have the drive current set at?

My thoughts exactly. I've machined lots of parts often taking an hour or more and motors are never boiling hot. Warm to the touch is the hottest they get. Try turning the current down.
My understanding is that voltage is doing the work and turning down the current will help the other parts of the chain such as drivers and psi. If they are browning out under the load that is easily on the list of lost steps suspects.

[A_Camera]

What's the benefit of 200Khz?
50Khz gives you a longer pulse width, which can be a benefit with some drives.

...that depends on his settings, which I still have no idea about.

50kHz means maximum 50,000 pulses per second.

So, here is my calculation for my machine:

If a motor, like most steppers, takes 200 steps/rev, using 10x micro stepping means 2,000 step pulses for one rev. The speed is 9000 mm/min which is 150mm/s. To move 150mm with my 1605 I need to turn the screw 30 times, so 30 x 2000 = 60,000 which is obviously more than 50,000 meaning that my MINIMUM should be 100kHz.

In other words, it is not possible to say if 50kHz is enough or not, that depends on his speed, screw pitch and micro stepping settings, but those questions are not answered yet, or I missed that part.

The fact that he's had this issue with both Geckos and Leadshines, means it's probably not the drives.

That would point to maybe the power supply, an issue with accel/velocity settings, or a mechanical issue.

Yes, that could be the issue as well, but even the kernel frequency if it is too low, or in fact, the current settings. Of course, if the kernel frequency is too low then lowering speed and acceleration might hide the actual issue when the solution should actually be raising the frequency. If the current is too low then acceleration and deceleration may occasionally be a problem, while at other times it may work. Can also be that it works on one axis but not another. Of course, if the PSU is not able to deliver the necessary current then that might also be an issue...

You said the motors are very hot? What are the motor specs, and what do you have the drive current set at?

I don't think motor temperature is a problem. In fact, I think most people draw the wrong conclusion, put their hands on the motor and "decide" that it is too hot, when in reality, you can't really hold your hand on anything for a longer period which is above 40-50 C. Steppers can get as hot as 60-80C so I would really not worry about that, assuming the drivers are set up right and the motors are designed for that current. In any case, "motors too hot" says nothing without stating the MEASURED temperature.

I had similar issues once and the solution was simple: raised the motor current and the kernel frequency. Problem gone immediately after and never seen it again. Of course, motors got hotter but that doesn't matter, I measured and is still well below the limit.