RE: VFA Artifacts on X+Y Straight Edges
Yes, a bearing that will fit over the 8mm silicone tube and still not exceed the original 12mm OD is already quite a low profile, so I didn't see an alternative to running on the bearings (with the silicone tube I have to hand, that is). But that's a good point, and I may thin the printed flange a fraction to make room for a small shoulder.
In fact the central tube (plus flanges) turns quite freely on the spindle, so even if the bearings bind on the flange and force the whole lot to turn, that won't add much friction - but I agree, it would be better not to add any.
RE: VFA Artifacts on X+Y Straight Edges
Oh, and to follow up with my post above on the VFA test tower:
- Prusa assembled Core One
- Belts tightened via new web app to the exact Prusa specifications
- Firmware 6.3.4
Honestly, I think the test tower makes it look a little worse that it appears... there is effectively no VFA on the very top few speeds.
RE:
I just tried the new Belt tuning guide, and for some reason my VFA's are much worse...
Left is with the new guide and right with the old lower frequency.
Printed at 120mm/s (the worst speed for VFA).
RE: VFA Artifacts on X+Y Straight Edges
Printing of Robo, alpaca to test VFA with new belt and firmware…
My apologies if I've missed a post of yours - new belt?
RE: VFA Artifacts on X+Y Straight Edges
Printing of Robo, alpaca to test VFA with new belt and firmware…
My apologies if I've missed a post of yours - new belt?
Nope... new firmware (6.34) and new belt tensioning procedure being tested. The Alpacas were really just a test to see if VFA was horribly noticeable in a real world print job. The two of them were for a Prusa supplied tweaked GCODE vs a normally sliced version to see if there was a function difference. (There does not appear to be...)
Then I printed the VFA test. (Yes, I did it all backwards...)
RE: VFA Artifacts on X+Y Straight Edges
Got it.
Then I printed the VFA test. (Yes, I did it all backwards...)
Haha - ok, so a Benchy next then, and lastly a Prusa keychain. 🙂
RE: VFA Artifacts on X+Y Straight Edges
if you think there is a diagnostically useful reason to do so… Sure
RE: VFA Artifacts on X+Y Straight Edges
I'm paying close attention to this discussion. I did my conversion a few weeks back and have printed a handful of things since then. I had noticed while building that my RH motor pulley was positioned where the belt was up against one of the flanges. I made a mental note to return to it when I had some time, since I have consistent belt ripple on my prints. The other night I loosened the belt, adjusted the pulley location by reaching through the hexagon hole to loosening the set screw and adjust the pulley. I then checked square on the gantry brackets (made a tiny adjustment) and re-tensioned the belts...this time to a slightly higher tension, maybe 89db or so using the old method. Upon starting it back up and re-running the gantry calibrations, I was happy to see that it calibrates even quicker now than before, with fewer bumps. 🙂
However...I almost immediately noticed a tick-tick-tick sound when I moved the extruder along the x axis, as if something is rubbing or not rolling smoothly. I've since printed a couple of items, and the sound remains. Right now I'm running a longer 7 hr print for a new exhaust duct adapter for this printer that I modeled yesterday, and I'm seeing ripples that appear to be even worse than I've seen on previous prints. I can clearly hear the noisy gantry movement over the sound of the printing as well. I've done my best to trace out the belt path and it doesn't appear to be out of place at all, and as the prints (other than the ripple) seem to be accurate. I've heard mention of poor quality idler bearings, and I wonder if it's possible that the noise is coming from one of those?
For those of you who have made changes and had the belts on and off multiple times, have you ever had any kind of rolling noise that showed up like this? Can you think of anywhere specific I should be looking to find some kind of possible contact? I'm really wishing I had one of those long stethoscopes that mechanics use for touching components to find the origin of a noise.
-J
RE: VFA Artifacts on X+Y Straight Edges
I have also noticed a ticking sound. I've read that the linear rail may need lubricating, but in my case I'm fairly sure it's coming from the left-rear corner - the mounting block for the motor and idlers. It doesn't seem to do it if I move the print head around manually. I plan to investigate the next time I have the printer apart.
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I have also noticed a ticking sound. I've read that the linear rail may need lubricating, but in my case I'm fairly sure it's coming from the left-rear corner - the mounting block for the motor and idlers. It doesn't seem to do it if I move the print head around manually. I plan to investigate the next time I have the printer apart.
Interesting. Listening closely, it almost sounds like a quiet knocking sound, like a faint "da-ga-da-ga" during faster movements. I can definitely try lubing the linear rail, but I don't remember hearing it before and I didn't do anything with the rail during my adjustment. I too feel like the sound is coming from one of the rear corners. Too bad we can't easily see into the motor mounts.
I can hear mine when I move it manually. I'll let you know if I figure it out.
-J
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However...I almost immediately noticed a tick-tick-tick sound when I moved the extruder along the x axis
That's normal! I wondered too and took a deep dive into the XL forums. Linear rails apparently do this, when working correctly and the balls are rotating.
It could be the case, that the balls aren't really rolling at first due to too thick grease and are just sliding.
To make the linear rail last for a looooong time, the balls need to rotate and that seems to make a clicking noise. So from what I've read: if a linear rail or the Y-bearings are "silent", then you need to investigate. If they make some "not-loud" clicking or mechanical noises, they are working correctly.
THK and other linear rail manufacturers have very thin, oil like viscosities listed for their own greases. The Prusa-Grease for the Y-bearings might be way too thick, in theory and the grease from the lubrication kit also seems to be very thick for linear rail grease, but I didn't find a video or so for that Klüber grease.
If you enjoy having a jump into rabbit holes:
RE:
However...I almost immediately noticed a tick-tick-tick sound when I moved the extruder along the x axis
That's normal! I wondered too and took a deep dive into the XL forums. Linear rails apparently do this, when working correctly and the balls are rotating.
It could be the case, that the balls aren't really rolling at first due to too thick grease and are just sliding.
To make the linear rail last for a looooong time, the balls need to rotate and that seems to make a clicking noise. So from what I've read: if a linear rail or the Y-bearings are "silent", then you need to investigate. If they make some "not-loud" clicking or mechanical noises, they are working correctly.
THK and other linear rail manufacturers have very thin, oil like viscosities listed for their own greases. The Prusa-Grease for the Y-bearings might be way too thick, in theory and the grease from the lubrication kit also seems to be very thick for linear rail grease, but I didn't find a video or so for that Klüber grease.
If you enjoy having a jump into rabbit holes:
That's even more interesting...they are "supposed to tick"? 🤨 . I have some sewing machine oil that I picked up to lube the rods on my Mk4s before I converted it. It's very clean and fairly thin oil so it has worked well for the rods without getting dirty/gummy. I can try some on the linear guide here.
-J
RE: VFA Artifacts on X+Y Straight Edges
I just tried the new Belt tuning guide, and for some reason my VFA's are much worse...
Left is with the new guide and right with the old lower frequency.
I have found the same putting stock idlers on and testing with the new tensions and firmware. I think there will always be certain combinations of directions and speeds for each tension that cause the system to resonate unless they actively damp it in the motors, which would require an accelerometer, or some mechanical damping. The dream would be active damping but I don't think there's the processing power for that on the xbuddy.
Also @chris-hill if you didn't already consider it, you want to keep some space for your silicone to deform into as if all surfaces are constrained then it's elasticity won't be useful. Perhaps cut it slightly smaller than the bearing along the axis of rotation.
RE: VFA Artifacts on X+Y Straight Edges
Also @chris-hill if you didn't already consider it, you want to keep some space for your silicone to deform into as if all surfaces are constrained then it's elasticity won't be useful. Perhaps cut it slightly smaller than the bearing along the axis of rotation.
Good point.
RE:
I can try some on the linear guide here.
Don't!
Cleaning it thoroughly is an absolute pain, since the balls aren't secured, the print head would need to be taken off, the linear rail taken out of the printer etc.
You really don't want to put some "random" grease/oil into your 1000€+ printer, just to save 20€ on specialized grease.
Do you have a nicely fitting application needle to "pump" it into the service-openings? We really aren't supposed to get any grease/oil onto the rail. The lubricant is supposed to only be inside the carriage to keep particles from sticking to the rail, damaging accurancy and longevity.
If you really want to lubricate it, have a look at my grease-summary at the end of the linked thread, get a set of application needles and fill up the carriage.
But I won't recommend it.
Also, very important:
Prusa states 3-6 months and I've found some interval of 200 km for linear rails.
You can check the distance of your X-axis in the LCD menu.
Mine is slightly beyond 30 km and I'd guess the clicking started at around 25 km. That's 1/8 of the interval and I've researched, that some clicking sound is normal for these linear rails.
So if your X-axis isn't at more than 150 km, I'd really just let it be until it is.
And then we should find out what's currently inside our linear rails.. The Klüber GL-261 from the lubrication kit or some THK grease.
Mixing isn't always a good idea and from my research, the GL-261 isn't really a recommended choice for linear rails, as in our printers.
Either Prusa found some secret sauce or it's similar to using the way too thick "Prusa-Grease" for the Y-bearings with their tiny balls, 2.5 mm belts, a perfectly squared and tuned printer banging its head against the corner for minutes and Z-leadscrews with pitch differences that are visible to the eye.
I love my Core One, but I remain very sceptical about some things...
RE:
I appreciate your input, and haven't had the time today to read through the lubrication post above. I'm holding off of lubricating anyway because now that my current print is further along I can clearly hear the knock-knocking sound with almost pure Y movements, so what I'm hearing isn't related to the X rail afterall.
-J
RE: VFA Artifacts on X+Y Straight Edges
I also have this clicking noise from the linear rails.
At first, I also thought that there wasn't enough grease, so I ordered the lubrication kit from Prusa.
Sometimes less is more, so I only used half the recommended amount.
The clicking disappeared for a short time but quickly returned.
It's actually just the balls that roll. If there is too much grease or the wrong type, the balls slide over the rail.
This results in higher wear and tear.
RE: VFA Artifacts on X+Y Straight Edges
Huh. Mine has clicked since day one. I assumed it was the linear rail making a vacuum as it moved over the holes for the screws and popping as it moved off. Good to know its working properly though.
RE: VFA Artifacts on X+Y Straight Edges
Interestingly, as can be seen in Teaching Tech's review just posted, the H2D isn't immune to the belt ripple problem:
RE: VFA Artifacts on X+Y Straight Edges
I see some people are discussing ticking in the linear rail. Mine developed a louder ticking around 400 hours and using the Prusa lube kit for the rail worked wonders. Operates very smoothly now.