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

[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.

[dachopper]

Hi guys... Sooooooooo angry right now !!!!!!!!!!!!!

I just video'd the problem for the first time, it was a vertical travel move, with speed turned down to 50% of my tools recommended speed.

After 8 minutes, the tool lifted vertically while unloaded with a slow retract speed, and the Z height travel jammed for 1/2 a second just before getting to full retract height. then plunged into the part. on the next down shift. It wasn't accelerating, it was at travel speed when it jammed on nothing

The previous other error was not caused by the Z axis, as it was an X axis shift, that also must have had to jam and remain in mid air - and be unloaded for 3-4 seconds wile being sent an X command but remaining Dead still in the X axis, with the Z axis moving up making the tool cut vertically in mid air.

Current Peak is set to 3.5A with Pro tuner in the AM882

Stall detect will not function as my cut speeds are low while I try to figure out what is causing these issues

Motors are NEMA23 381oz/in 3.5A Single Shaft Stepper Motor KL23H2100-35-4A, 0.9 degree.

Power supply is PS-10N68 - 1000W 68V Power Supply running 4 of the above steppers, ( two of the motors would have been on 50% current hold ) when the other motor stalled also.

The final thing is that I tried as hard as I physically could to get the Z and X axis to jam, and i just physically cannot, even with the motors hot............ any ideas?

Remember, they both effectively jammed at travel speed, basically under no load, .... but y?

[m_c]

Is there anything still original from when the problem first appeared?

What BOB are you using?
I'm wondering if it's a faulty BOB causing issues with step/dir outputs.

[dachopper]

The only original parts are UC400ETH, UCCNC + PC software and hardware, Spindle, motors + wiring..

More clues, just had fault number 3 for today on video, I had everything running, but no drill bit in the spindle, ( All electrics on and running, spindle was turning but with no BIT. This time the X axis jammed during a left to right travel movement. just after reaching retract height, under no load. AM882 stall detect SHOULD have picked up this stall, it was at 450rpm, but it didn't........ some kind of electrical interference?

Did another RUN everything turned on again, but this time the spindle freewheeling ( inverter powered but no power to spindle ).....18 minutes later, no fault

Ok - I've now noticed that the X axis jam that happened in mid air snapped the coupling in half.

Just ordered some different spindle shielded cable - siemens proflex EMV

I do have the spindle running in the same 50mm cable carrier as the X / Y motors... would this normally be ok? I don't think I've seen a DIY machine that doesn't run this setup yet?

[routercnc]

The only original parts are UC400ETH, UCCNC + PC software and hardware, Spindle, motors + wiring..

More clues, just had fault number 3 for today on video, I had everything running, but no drill bit in the spindle, ( All electrics on and running, spindle was turning but with no BIT. This time the X axis jammed during a left to right travel movement. just after reaching retract height, under no load. AM882 stall detect SHOULD have picked up this stall, it was at 450rpm, but it didn't........ some kind of electrical interference?

Did another RUN everything turned on again, but this time the spindle freewheeling ( inverter powered but no power to spindle ).....18 minutes later, no fault

Ill do another run with the spindle rotating, but everything else turned off..... then I can be positive somehow spindle interference is causing the dam issue.

When I got random estops awhile ago I plugged the invertor into a socket at the other end of the workshop via a 10m cable reel. No issues since.

[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.

[A_Camera]

The only original parts are UC400ETH, UCCNC + PC software and hardware, Spindle, motors + wiring..

More clues, just had fault number 3 for today on video, I had everything running, but no drill bit in the spindle, ( All electrics on and running, spindle was turning but with no BIT. This time the X axis jammed during a left to right travel movement. just after reaching retract height, under no load. AM882 stall detect SHOULD have picked up this stall, it was at 450rpm, but it didn't........ some kind of electrical interference?

Did another RUN everything turned on again, but this time the spindle freewheeling ( inverter powered but no power to spindle ).....18 minutes later, no fault

Ok - I've now noticed that the X axis jam that happened in mid air snapped the coupling in half.

Just ordered some different spindle shielded cable - siemens proflex EMV

I do have the spindle running in the same 50mm cable carrier as the X / Y motors... would this normally be ok? I don't think I've seen a DIY machine that doesn't run this setup yet?

Normally it is not an issue to run the spindle and stepper cables in the same cable carrier. I have done that and never ever could relate any problems to that.

Right now I think you are a bit upset and inconsistent/badly structured in your efforts to finding out what's wrong. I think it would be a good idea if you could cool down a little, accept the fact that you have many problems and try to solve them one by one. I understand that you are upset and emotional but it does not help in fault finding. Remove the spindle from the loop by completely disconnecting it from the mains. At this moment milling air is perfectly fine. No need for a spindle at all. Try to solve all the other issues first since your machine is useless as it is anyway. Describe your machine, post a few pics of major parts and technical specs and settings. Answer questions instead of asking loads of new ones in a non-structured way, because at least I have problems with understanding your actual issues, there seems to be far too many and probably not related to each other, but I don't know.

The snapped coupler may be because you are using the type which is frequently sold on eBay as "flexible coupler" and basically is just a joke and they can snap and also cause other issues, but since you don't post any pictures or video it is difficult to say what can be the problem with each issue.

[m_c]

The thing that sticks out to me, is the seemingly random stalling. The fact the drivers never picked up the stall at speed, makes me think the problem is on the step/dir side.

Noise I wouldn't expect to cause a sustained stall. I'd expect more random lost/gained steps, with gradual loss of position, not just a sudden stall. It could be that there is some form of excess noise that is saturating the step signals, but I'd expect other noticeable issues if the noise really was that bad.

Wrong settings, I'd expect stalling during acceleration, or under cutting conditions. It is possible that at high speed the current drops due to not a high enough voltage, but the drives should detect the stall, and as the fault still occurs at reduced speed, it makes this unlikely.

Mechanical problem is not a likely cause, especially as this affects more than one axis, however it could be more than one problem. But again, the stall at speed should of been detected.

Given that other axes still seem to keep moving normally, I'd doubt a power supply issue.

One thing nobody has asked, is when the stall happens, is the affected axis motor making any noise?
If the motor had stalled, you would normally hear it cogging/vibrating. If it just stops with no noise/movement, the driver has stopped driving it.
If you're not sure what cogging sounds like, lock one of the stepper motors (holding the pulley by hand should be enough provided you're not using high torque steppers), and move the axis. You should feel and hear the motor cogging as it jumps steps.

I think the only way to find a definitive answer, would be to connect up a digital storage scope (or even a cheap logic analyser should do) and monitor the step signals of the affected axes, with the hope you manage to record the signals during a stall.

[Ger21]

What version of UCCNC are you using, and have you been using the same version all along? Maybe try updating it?

[dachopper]

So guys,

I am fairly confident that I have diagnosed the problem correctly.

Background - I seem to experience random jamming in the X / Z axis, where by the stepper would loose any huge amount of steps - up to 5 or 10CM of error per event.
It only happened when running parallel type operations with multiple quick Z or X axis toolpaths, or both at the same time. I can run a parallel operation in the Y direction with Fixed Z height, and have no issues whatsoever for hours, but the other direction - within 10 to 15 minutes guaranteed motorStall in Z or X

I changed the power supply from 600W switching, to 700W torroidal, to 1000W torroidal.
I tried 2 x different Gecko drive motherboards
I bought new Ethernet cabling from the laptop to ETH400
I replaced the Geckodrive with a PDMX126 + 5 x Leadshine AM882 digital stepper drivers
I ran the motors under both 3.5 Amp peak setting, and 3.5 Amp RMS setting.
I observed stalls occurring randomly 10-20 minutes in, in every single one of those tried changes
I currently have the Max speed set at 80% of motors peak torque rating, and acceleration set at 10% of the slowest acceleration speed I was able to generate an inertial induced motor stall.
I cannot physically make these motors stall no matter how hard I push / pull / sit on the gantry while it's moving, yet it still stalls mid air unloaded.

After finally videotaping 3 stall events, none of which were cause by excessive speed, loading or acceleration, and also noting the AM882 failed to detect the stall.. I then unplugged the spindle and on the first attempt got to the end of the toolpath without error ( It had failed 100% of previous attempts, within 13:20, 12:00, 9:00 and 17:00 minutes on the recorded occasions - including 2 of those where the spindle was spinning in the air, with and without a tool in, and not cutting anything during the test run but with stalls both occasions. )

Based on the above evidence, that the stalls are not occurring in the same place, or even at the same time, and I can't find any mechanical issue with the machine, It has to be an electrical problem.
It is not effecting the Y axis, and the Y axis cabling does not run anywhere near the spindle cabling, but the X and Z axis runs right next to it the entire wire length.

So, I have ordered some heavy duty VFD cabling ( siemens Protoflex EMV ) and I am also going to re-wire the Z and X stepper motor cables, with some different Foil + wire shielded, and move them to either sides of my cable tracks, with the water lines in the center.

After re-doing the cabling, that is almost the entire electronics replaced, except the ETH400, and stepper motors themselves.

My toolpath is being tested by the UC400ETH retailer, to confirm they do not see any issues from it during the parallel operation, to try rule that out also.

Should be able to test in a few weeks when new cabling arrives, Let you know how it goes.


M_C, the stalls are loud high pitched, and without any movement at all from the jammed axis while the high pitched noise is active, which is normally for the 3 - 4 seconds, or the duration of the attempted move for that axis, until commanded to hold or reverse and it unstalls at that point. I tried straight after it stalled to force it, and it was futile, I would have needed a serious tyre lever to have any chance of making a mechanically forced stall happen with these low speed / accel settings.