UGS or Longboard losing zero position or not taking new zero position

When I did my initial cuts I thought I had a situation where the machine wasn’t taking a new set zero position. I set it repeatedly and there were no errors UGS, but the machine insisted on changing to a new location and height. Given other teething problems I had I assumed it was something I had done or not configured and let it go. But I just had it happen again so I wanted to raise it and see if anyone else has seen it.

I make a marker holder so I could do some large scale plotting of images for the kids. Machine was working fine. I brought it to the approximate corner of the paper and slowly lowered it until I got a dab of ink on the surface and I reset my zeros. I then lifted the Z up about 5mm and started my gcode (a trace function from Fusion 360 of an SVG). The marker plunged HARD in to the paper (probably 3-4mm or more) and dragged along the paper.

I immediately stopped it and lifted the Z and brought it back to where I wanted the zero to be. I reset zero again, about 2mm above the surface of the paper to see what would happen. I re-ran my gcode and it again dove HARD in to the paper and dragged along. No bueno. I tried a third time. Same thing. The Z position was just not taking in the software.

I exited UGS and power cycled the Longboard and then restarted UGS. I loaded the same gcode file of the artwork and set the Z and this time it was fine. I made no other adjustments to the machine or software.

Has anyone else seen this where the Z zero is not updating correctly? If that had been an expensive cutting bit, I would have potentially ruined it and a workpiece, so definitely something I’m concerned about.


Jeff: From time to time, I have what is likely the same issue in UGS. I set xyz0, but when I look on the UGS controller state screen, it registers .2. It’s always .2 when it’s not zero. I need to zero it again to get it to show zero.

When you’re clicking to reset the zero point, is the yellow cone graphic re-locating in the visualization window in UGS?

I will pay more attention to that @chrismakesstuff. I don’t know the answer for sure. Also, I was mostly looking from above in the visualizer view, I’ll need to tilt it to see if the height is updating. MIght not have noticed if the X,Y didn’t change.

Is there a way to get the visualizer to show you zero without sending the machine there?

Good to know. When you zero it a second time, does it take? I wasn’t having any luck without restarting. I am on August 2019 build if that matters.

Yeah, I always get it to take without a restart. I am on the same build as you. Judging from the discussions on the UGS group, it seems that there have been several new nightly builds since then. I’m thinking of tempting fate and trying one soon.

Since it doesn’t install and just runs from a directory, I think you could just have both versions on your PC and switch between them in the event the new one caused issues. Is that correct?

Correct. (The rest of this is just to meet the 20 character minimum.)

Yes, the three coloured lines should indicated the zero position

Jeff, when I’m using the zero block I almost always have to do it twice because UGS ignores the first time. After that it’s fine and I can re-zero each axis individually without a problem. I’ve seen accounts on other forums of the same issue, and the assumption is that UGS can get screwed up when it first starts up, then settles down.

If you are compiling with F360, make sure there ist no G28-Command in the Code.

@jwoody18 Jeff. I had the same issue again today. Twice, I set zo manually, by bringing the bit down to the surface of the material, and hitting Z0 in ugs. Both times, when I looked at the controller state, it read z .1. I was able to fix it, by clicking on soft reset, then hitting Z0 again.

Hmm so I wonder if this is a UGS bug or something in the Longboard?

@jwoody18 I posted about this issue quite a while ago on the UGS forum, but did not get any replies. I don’t know if that points to this being a controller issue rather than an UGS issue, though. I’ve never gotten a reply to other issue that are definitely UGS, either. It’s a good thing that I’m used to being ignored.

Based only on general software/hardware experience, it sounds like it could be a timing issue around when the Longboard reports to UGS. Just a hunch, based on the fact no one on the UGS forums corroborated your experience but we have multiple issues of it here.

It’s definitely something to be investigated. @chrismakesstuff any ideas?

This is an odd issue, I’ve never experienced it myself. I’ll have to see when I can go over to the office next to take a look and try to replicate the issue you guys are talking about. What build of UGS are you running @jwoody18? And for you, @gwilki?

@chrismakesstuff I’m still running the august 19 build. I know that there have been several since this one, but since this one is running fine (apart from the zeroing issue), I’m reluctant to move to a newer one.

As an side, today, I did two lidded boxes, requiring 3 bits changes each. Each time, when I hit the key to zero all, x and y went to zero, z went to .1. Hitting soft reset, then Z0 corrected it. This was before actually setting the Z0 with the probe.

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I am also running August 19 build. I also was doing some work today on my machine, trying out the PPE face mask head piece. I had multiple instances of the zeroing not taking. I believe it affected more than one axis, but was this wasn’t my primary focus I’m afraid I didn’t take good trouble shooting notes. I’ll try and be more diligent in the future, but I definitely had multiple issues with it today.


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@jwoody18 I’ve only ever had it happen with Z, FWIW.

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Has anybody figured this issue out? I’ve destroyed an increasing number of projects and cant seem to figure out when this thing is going to destroy my parts and when its going to run fine. Just as gwili, Ive only had it happen on the z axis zero. Id say about 70% of the time the first moves (That do not appear in the code) end up diving deep all the way through the material, in different directions. Sometimes in line with the part, some times a squiggly line. It doesnt seem to matter how many times i soft reset or manually reset the zero.