What's my problem?
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What slicer are you using?
I found I got very different quality between the old Cura version (that works immaculately with my old Marlin-based printer) and Prusaslicer, on my Duet-based machines.
With prusaslicer (Bot's version, to be precise) properly set up to match each Duet board / machine parameters, the surface detail is vastly better on the Duets, but it does not support the older machine at all.
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@gnydick looks like you've got some ringing/ghosting on the railcore. You can see it on the circle quite clearly, and that's probably what is causing the pulses on the overhangs.
Have you got input shaping enabled on both? I'd assume that there are default setting for the voron knocking about, but maybe not on your Duet?
There's probably some mechanical impact too. The voron v0.1 is quite small and lightweight so is probably less likely to have ringing issues than the larger railcore with longer rail spans, belt paths etc
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Sorry, yeah, I realize it's ringing, but the settings, speed, etc were all pretty gentle, so I'm not sure why I'm getting it.
It's been happening for a while and I just can't seem to get rid of it unless I print REALLY REALLY slowly.
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@gnydick are you using DAA or input shaping at all? That can help a lot, especially as it seems a very constant natural frequency.
Otherwise, try playing with your jerk and accel settings. Doesn't matter too much how fast your peak speed is on a long straight, if your jerk or accel are too high it will still not go round corners smoothly. If you're controlling this from your print file, you may be accidentally overriding the limits you've set in config depending on how your slicer does it.
It may also partly be a limitation of the railcore? I'm not familiar with the design myself but its definitely one to consider especiallyif trying to do side-by-side comparisons of prints/settings
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Another thought - Are your XY belts tight enough? Any play or "give" could cause problems.
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The ringing on the right side (the much larger printer) is very visible. Did you try to input shaping it?
I am also not sure if RRF's input shaping is as mature yet as Klipper's. I think it's still in beta (?).
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I don't have input shaping on, never have. I've watched the printer in telephoto slow motion and I'm 99% sure there is no wobble, whipping, or other movement. I think it's really the extruder.
But I will definitely check these other things.
Re: input shaping: what am I to do, it's not like the X and Y have the same frequency, so, which do I pick?
I also don't have any input shaping enabled on the voron.
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@gnydick said in What's my problem?:
I don't have input shaping on
Also no input shaping on your Voron V0.1? I assumed you do.
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@zapta nope, I don't have accelerometers, so I can't configure it.
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two remarks:
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you can print the ringing tower and measure the ripple frequency to tune input shaping. Works both for klipper and RepRapFirmware.
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a friend of mine figured some vibrations on their railcore at certain speeds and has to print slower or faster for those to go away. so they either print at 25mm/sec max or at 120mm/sec min. Might be worth investigating.
<>RatRig V-Minion Fly Super5Pro RRF<> V-Core 3.1 IDEX k*****r <> RatRig V-Minion SKR 2 Marlin<>
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as to picking x or y: the vibrations for X and Y should be similar on a corexy setup -- differences point toward uneven tension in the belt system. If the difference isn't too big you will be able to pick either peak frequency and at worst will have to choose an Input Shaping algorithm with a damping factor.
<>RatRig V-Minion Fly Super5Pro RRF<> V-Core 3.1 IDEX k*****r <> RatRig V-Minion SKR 2 Marlin<>
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@gnydick, it's possible that the V0 just has a more stiff and accurate movement system, because of its smaller size.
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Don't take this as me telling you to get help elsewhere, as that's not the case, but there is a Railcore discord server. Perhaps asking at the source might be useful. Maybe it's a common problem or someone has seen it already.
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@oliof Thanks for the info. Yeah, I've noticed that too, but never took the time to find the thresholds.
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@oliof Thanks for the help. Are there any simple ways to determine which algorithm and settings?
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@phaedrux Not at all, thank you. I've been there. Totally forgot about it
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I did some investigation and so far have found that I have some temperamental linear rail blocks. I built an entirely new kinematics that is wider to sit on top of the existing frame and hold the e3d tool changer setup.
I had to buy new longer rails and it turns out that if the screws used to mount into the block are even a hair too long, the blocks actually bind on the rail.
The screws don't even impinge directly on the rail, so it must be deforming something inside the block.
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@gnydick I printed the ringing tower again cycling through the algorithms every 5mm and decided based on that. For the bed slinger I did this on, mvz came out front.
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Again: Check the belts.
"Tune" them, so the equal length long runs give the same note when you pluck them.The long runs on my CoreXY machine (520mm) ring at near the same pitch as the next to lowest string on a bass guitar, around 55Hz.
If they are significantly lower than that for a similar length, or very unequal, it will cause print accuracy problems.
I don't use input shaping, just very low pressure advance.
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Thanks for the input, all. My belt path is quite long and it really needed tensioning. It wasn't tight enough to even resonate. That made a marked improvement.
I've done a bit more fiddling and things are a lot better now. The print head is heavy and the cross beam is just the mgn rail which twists quite easily, so I think I'm at the envelope of what I can expect without input shaping.
