First of all I’m trying to figure out how to go about trouble shooting this problem, as it’s a bit odd. Rather than hoping for some sort of magical fix.
Printing the part in the video…
Attempt 1.
It gets to a point and then the head moves of to some random position where it’s not supposed to be. I think maybe the accelerations are too high and turn them down a bit from 7,000 for travels to 3,000 per the rest of the settings.
Attempt 2.
Reslice the model, re-run the print and the exact same fail in the print.
Use Repetier Host to look at the G code layer by layer and see no issues.
Attempt 3.
Check setting in printer.cfg, remove a bunch of garbage, and have another go.
Same result, same fail at the same point.
The video shows what’s happening:
Either somethings going on with one of the XY motors or the G code is bad or what? I’m guessing as it’s happening every time in the same part of the print so I assume something in the code has to cause it, but I can’t see it.
There’s no G90 or G991 commands in the G code.
Next, I’ll try re-orienting the part and moving it to a different part of the bed, then re-slicing, even if that works it doesn’t explain why it did it in the first place though, so I’d like to get to the bottom of it.
FYI I’ve printed taller things and bigger things previously with no issue, but the printer still is in it commissioning stage.
I’ve just backed up my current Pi setup and I’ll set about cleaning everything up so it’s as clean as I can get. I’m not sure due to using the MKS Pi how clean that is but we’ll see.
Also the Red Back (Black widow) spider living in the control box gave me a bit of a jump, running across my hand.
First of the X Y limits of this machine are 635mm x 620mm.
I cleaned up the Klipper install and updated everything to the latest version which was probably overdue anyway.
The problem in testing persisted, I had the idea to try and reproduce the issue by attempting similar moves as the failed one from a similar area of the bed. By this method I could see that the issue was still there.
I suspected my max acceleration and / or speed settings were too high. So, by dropping them I was able to get the issue to stop.
At the moment I’m re-running the print to see if I truly have fixed the issue.
What I’d like to figure out is, is there a methodical method to establish the kinematic performance of a machine? I’ll have to go look for that.
So changing a couple of parts got out of hand, but it’s mostly done now.
Attached is the latest klippy.log klippy.log (181.3 KB)
After doing some math and testing the machine is now set to do a max of 10,000mm/s2 acceleration and a max speed of 400mm/s.
Input shaper thinks its good below 13,000 acceleration, so we’ll see.
The 400mm/s top speed is limited by the nema 23 motors I have not being able to spin any faster, I should have paid more attention to the datasheet, but this is more than good enough for the moment.