Z axis randomly diving

[Parkgrr]

I've been using UCCNC for about a year now and I love it. It has its little gremlins sometimes but usually they are my fault.

One issue I've been ignoring since the beginning is an intermittent, random, and completely unprompted movement on the Z axis. When it first began occurring (when I first installed UCCNC and the UC300ETH on my machine) I was new enough to the software and to machining generally that I couldn't be 100% sure it wasn't my fault. However I am now 100% positive it is not. Z will do random movements completely unprompted and at random intervals. Usually the movements are rapid but short and downward, between an inch and 1/8 inch. However once in a while they are huge movements and always rapid, often sending the tool diving into the spoilboard or whatever else is beneath the spindle. My machine is 6x12 feet and the spindle is 2 feet tall and weighs about 300 pounds. Today Z took randomly took a rapid dive and broke my ATC while I was calibrating tools. For obvious reasons I really need to see what in the world is going on.

Because of the intermittent and random nature of the issue I can't say for sure what is happening. I've gone weeks with 0 issues, and days where it's happened twice in a day. Here's everything I've gathered:

I use the UCR201 wireless pendant with the UC300ETH and an alienware PC. I use the UCR201 pendant every time I use the machine, so it's difficult to say whether it's involved, however the issues occur exclusively when the machine is not running code, and rather during times around when I have been jogging the machine, but at moments when the machine is idle.
Today I was jogging Z to a specific height, then left it in position to do some positioning with the ATC. I can't remember if Z was selected on the pendant or not when it malfunctioned. My sense is that it was. I'm also not sure whether the pendant was 'asleep' or not at that moment. When the issue happened the first few times I changed the RF channel to C-1, if I recall it may have stemmed the issue somewhat. UCR 201 plugin is v1.4. The only reason I mention the pendant is because it is the only component on the machine that runs on USB, and likely the most prone to interference, everything else is ethernet. I'm clueless otherwise.

Because the issue is totally intermittent I can't re-create or induce this malfunction.

[Parkgrr]

I'm happy to try troubleshooting ideas and any ideas are very welcome, however due to the extremely intermittent but consequential nature of the issue I'm first curious to know if others have experienced or reported issues like this and if there are fixes that are directly related to this issue. At the moment I'd prefer to avoid blanket fixes or things to try, as troubleshooting that way could take months and leaves the machine open to erroring out further because of how seldom this error occurs.

[eabrust]

you should make note if you witness the z-axis position DRO value change when your Zaxis makes a sudden uncommanded move. If the Z DRO does not change, you can pretty quickly rule out UCCNC and the pendant sending commands to jog z down. ie, the z axis is moving uncommanded, and could be due to electrical noise to the 'step input' or other issue causing the motor driver to 'go'.

You don't describe if your machine is servo or stepper driven. Given your description of the size of your machine and weight of z axis, is it servo driven? If so, do you have a flakey encoder on Z?

regards,
Eric

[Parkgrr]

Good thoughts Eric I appreciate it. All servos. The software reflects the erroneous moves in the DRO which indicates to me that UCCNC is making the commands. That rules out a bad encoder IMO.

[eabrust]

That should narrow it down to anything that can send a move command to UCCNC then.

Do you have a touchscreen, or wireless keyboard that may be misbehaving?

Or if you unplug and go without the wireless pendant for a bit can you confirm it no longer happens?

Do you have any plugins that can command movements enabled that aren't in use (ie, an xbox plugin, or other similar plugins) which can initiate jogs or moves? If so, disable them.

You'll have to do some level of trouble shooting, as randomly moving axes are not a common problem anyone else has.

regards,
Eric

[Parkgrr]

Thanks for the thoughts. As I mentioned it's not something I can test as it's completely random and it's possible to go months without an error. I did happen to have another episode this week, I can now confirm this is a UCR201 issue. It occurs when the pendant is on and Z is selected. It doesn't matter the pendant's distance from the receiver. It doesn't matter what jog % is selected. In my case MPG mode is on. The error does not occur when E-Stop is on from the pendant.

Balazs/Dezsoe? Should I shoot you guys an email instead? I always try to post on the forum to help those coming after me.

[dezsoe]

It's OK to write here. In UCCNC version 1.2114 there is a new version (1.8) of the UCR201 plugin.

There is something strange at a few users that causes some unwanted operations like yours, but we cannot find the problem. A user even sent us his known malfunctioning PC, but with my UCR201 I could never reproduce his problem. However, the most of the users never meet this behavior.

[mickecarlsson]

I am one of those that have problem with Z when using the UCR201. My problem is when I do Auto Zero (using Screenset 2010), when the bit reaches the plate it will just continue, it does this 9 out of 10 times.
If I disable the UCR201 it will do AutoZero 10 out of 10 without problems.
From what I gathered when I was troubleshooting this is that the trigger when the bit touches the plate is blocked somehow.
And sometime I had the bit crashing down in high speed.
I have downloaded the new version but when I used it with Screenset 2010 all “ticks” on the settings screen are missing.
And I have not had the time to test it with the default screenset but will probably do this in a week or two.
My computer is an Intel NUC running Windows 10 LTSC with UC300ETH-5LPT.

Is it possible to copy the DLL for the UCR201 from 1.2114 to 1.2113?

[dezsoe]

Yes, you can copy the new plugin to 1.2113. (Note that 1.2115 was just released, but there's no change in the UCR201 plugin.)

If you mean that the settings on the probe screen do not work then you have to enable the probing plugin.

[Parkgrr]

Thanks for the information Dezsoe and sorry you're having the same issue Micke, for me it's proven to be quite dangerous and very expensive.

Dezsoe, I am glad not many users encounter this, but it sounds like at least in some cases it's a pretty serious issue. In my case I'm faced with hundreds of dollars in repairs, broken tools, and about 3 weeks of shop down-time as well as I could have faced some pretty bad mortal consequences had I not been as over the top careful as I was. In the last episode the spindle crashed into my ATC carousel at full speed, bending an 15 inch 8-tool carousel and a the 1 inch steel output shaft that connects it to the ATC stepper/planetary gearbox. Like many I use a thin piece of paper to find Z0 on new projects. That involves placing my hands around and under the spindle. This error causes the spindle to PLUNGE into the spoilboard and whatever else is below it as fast as it can, which in my case is extremely fast. It's possible to E-stop the machine when working around it, however in some cases like zeroing Z having hands around the spindle while it's enabled is a necessary day to day operation. I don't need to explain why this is really really a dangerous bug.

I'm confident the issue is caused by some specific signal interference which would be why the other gentleman's issue couldn't be reproduced at your shop and also why the issue only occurs to some users. I only use the Velocity Speed MPG mode and I know the error always overrides the velocity speed. Every time this error has happened I've had 1% or 10% velocity selected on the UCR201 but the spindle plunges at what would have to be 100% velocity. It may override the velocity speed percentage but also equally likely is that it gives UCCNC a big step command rather than a velocity/direction command even if MPG Mode: Velocity Speed is selected on the pendant. Is there some sort of logging software I can run to track what is happening? Would you be open to working with me to implement a safeguard for this issue? One solution would be to place a checkbox on the UCR201 plugin that limits the commands that are passed through to UCCNC to only velocity speed commands as well as limit them to only the sort of commands that are actually humanly possible to be generated with the jog wheel by hand.