VC4 400: Second peak not appearing
Hey, first time tuning belts on a coreXY. Not sure why the second peak is not appearing. @miklschmidt suggested before that my belt tension is too high, but I matched both belts on the one peak I have and reached low end of 1e6. Is it still too high, or can there be another explanation for this issue? There might be some noise due to the fact I didn't finish cable management on the toolhead yet, but I reckon it doesn't influence the general look of the graph. Thanks!
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this is my graph if I loosen both belts by about quarter rotation of hex key
this was the best second peak I had. from that point I was baby stepping by lowering tension by quarter rotations on both belts and that peak slowly disappeared
improved by making sure that my X gantry is square. the official docs may be lacking nuance or be wrong: https://ratrig.dozuki.com/Guide/09_Gantry+Alignment/249?lang=en in my case, those instructions did not fix the issue
Rat Rig
09_Gantry Alignment
this should be aligned with belt tensioning imo, same process, you're just using the belts to make sure there's no gap in either side (push the joiners against the frame individually, if you hear it clacking, it's too tight in that side compared to the other).
After that you should re align your Y rails, ie, loosen the screws on one side, then tighten the screws from front to back while moving the gantry towards the back, the gantry will align the Y rail.
Then do you think the guide should mention re-aligning the rails?
in the edge-case of rabbit-hole trouble shooting, yes probably. For what's currently described in that guide, no.
What do your belt tension graphs look like now after following these steps and aligning your Y rails?
I actually am redoing the measurement now to see, I'll post it in 4-5 minutes. I'm still not happy with the graph, to be honest. On all other graphs the two peaks are way closer in amplitude than mine are. I don't know what's the fundamental cause of them being so far apart and I can't find it anywhere online
it's looking like this right now
@miklschmidt could you share your thoughts? The X gantry is aligned now
That's looking slightly better.
it's definitely better, but 1. upper has higher amplitude on the left peak and lower has higher amplitude on the right peak 2. the amplitude difference between them is still higher than what I saw with other people's printers
I'm going to try get a granite slab this week to see if a bit better base would help with that. right now that printer sits on a regular desk
Y peak is plit in two. Looks like your belts do not have the same tooth count from grabber to grabber. This one https://discord.com/channels/582187371529764864/1258022079148855389/1258085145878073365 looked better. It does not seem that your realignment fixed anything, but at least it made it more obvious that your belts aren't the same length.
Try releasing a tooth on the upper belt, and equalize tension again.
Get it off of there
Put it on the floor
Level the feet too
I just did!
good 👍
that'll help
you can always put it back once you've made sure the machine itself is good
this one is with printer on tiled floor
I guess I'll try to lower the tension? I hope the teeth count issue was a fluke because I really don't want to reroute those belts 😅
That's looking slightly better again. What are your input shaper graphs looking like?
this one is after sitting overnight, I think I'm losing belt tension
I'll try to tighten belt clamps and set screw on tensioners
this one is after I tightened the back clamps and one of tensioner set screws. I also made sure that the front clamps are grabbing the belt fully, but there wasn't any problem
and those are my resonances. somehow they are getting worse 😐 yesterday I had a bit better results
For future reference: during last days I tried a few things, but nothing fully solved my problems. I removed belts and made sure they are exactly the same length (turns out they were off by about 5 teeth). It did not make a significant change, though. At this point I decided to just cable manage the printer and I'm working on getting it in a ready-to-print state
Have you checked that the inserts in the front part where the grabbers screw in are properly seated?
Yeah, and all of them are engaged. There’s always a chance that the belts aren’t equal length because the locking method on the back is non-discrete and it’s easy to grab a tiny bit more on either side
When I’ll have time to work on the printer again I’ll try @chicken‘s live resonance method to see if I could spin the key just the right amount