QGL

[cecilx22]

I'm having a very specific issue with the QGL and the inductive probe.

During leveling, the first 1-2 samples are almost always lower than the next 4-5 samples. I see this a bit with bed mesh as well. Same with probe accuracy routine.

I'm sure I could tear the whole machine apart and try and figure out whats up, but I'd really like to try the following first:

1) change the z feed rate during QGL, Mesh and probe accuracy if possible
2) alter the QGL and mesh routines to take and discard 2 samples before paying any attention to them.

Any thoughts on a culprit or other ideas on how to address this? Are (1) and (2) even possible?

 

[NoGuru]

I am not sure I follow. So for question (1) you say feed rate. Do you mean speed at which it probes? If yes, then sure, just change the speed in the config.

For question (2) why would you discard the samples? The machine will remeasure to make sure its sitting flat. If you want it to be more accurate you can change the accuracy value to be a higher tolerance.

 

[cecilx22]

Thanks for the reply!

For (1), what file would I find that in? (related - is there some sort of documentation that I can refrence that would answer these sorts of questions more broadly?)
As far as discarding samples - It appears to me that there is some systematic error in the system as a whole, and that the probing routine needs a 'settling' run or two.

Every time I do QGL or bed mesh, and there is a tolerance error that causes a retry, it's ALWAYS the first data point being too hight. I've watched it a BUNCH and I've never seen a retry caused by anything -other- than the first sample being significantly too high (2x or more beyond tolerance). I'd LOVE to fix the systemic issue, but failing that, I have far more confidence samples 3-5 than samples 1-2. As far as throwing them out, I suspect that on occasion, the system has extra trouble settling, and I'm getting 3 samples in a row that are within tolarance, but might well all be too high. I say this because I sometimes see QGL results get worse after an adjustment.

I've not done any sort of deeper statistical analysis of the errors I'm seeing, this is mostly me going off of gut reaction, and I may well be wrong, I just thought maybe I'd play around with it and see what my results were like.

FWIW, I did tighten one of the Z belts that was the corner where I was seing the most retrys, and it seems to have helped the issue significantly. That said, the first sample I'm reading at a particular point is still almost always the highest reading...

 

[NoGuru]

In your printer config, you can find the speed at which your printer will probe the bed. My computer is acting up or I could find it for you but check the QGL section, or probe section.

Anytime you de-energize the motors you will get some form of sag. Like you mentioned making the belts a little tighter can reduce the sag a bit.