Hoping to hear from others who print a lot of ABS on their machine.
My X1C is amazing…but I’ve recently started doing more production ABS printing and I find that holes start coming out as ovals very, very quickly. Much quicker than the 5kg their wiki suggests.
This is occurring almost after 1 or 2 full build plates of small-ish parts (<1kg), and is very annoying - to the point where it’s hit or miss on whether a build plate full of parts will be good or scrap.
Every time, a wiping and cleaning of the rods resolves the issue. I am now resorting to cleaning and wiping the rods before each print, even though the wipes come out perfectly clean.
Has anyone else ran into this problem? If yes, what do you do to prevent or mitigate it? Clean more often? Slow down your printing speeds for ABS?
Thanks in advance 
ABS emits a lot of VOCs and nano-particulate when heated and extruded. Try ASA. It produces parts with equivalent strength over a similar temperature range, the plastic is more UV resistant than ABS, it has less thermal expansion/contraction so it doesn’t warp as readily when you print it, and it doesn’t outgas nearly as much as ABS so it shouldn’t gum up the works as quickly.
That being said, for features in my prints that I need to be fairly precise, I print them with 100% infill and with intentionally “outsized” dimensions and then I take 'em down to the dimensions I want with my CNC. Holes get milled or drilled to ensure they’re round. Mating faces get fly cut so they’re flat. Etc., etc…
But if the holes aren’t round, what about other dimensions/features being right?
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A loose belt or belt slop, can cause lots of issues in 3D printing, such as circles looking like ovals
Belt tensioning procedure | Bambu Lab Wiki
AFAIK, ABS and ASA are very similar in terms of released particulates etc. I can try switching, but this doesn’t necessarily solve my original issue/question, which I’m hoping to shine some light on.
Bambulabs wiki says every 5kg of ABS needs cleaning, which seems alright…but I am encountering the need to clean the rods after 500+g at times.
It’s not this because as soon as I clean the rods without re-doing any tension the next print comes out perfect.
Maybe you’re not getting the rods cleaned effectively enough so they dirty=up again really fast? When you re-clean them after this issue happens, do they look like they needed to be cleaned again already? i.e., If you use a white paper towel does it come away dirty? Even if you just cleaned the rods a couple of prints ago, by wiping them until the paper towel didn’t come away dirty?
Maybe your ABS is “bad”, some organic contaminant that’s cooking off VOCs at a much higher rate than “good” ABS? Try plastic from a different supplier?
I’ve got about 1000 hours on my X1C and maybe half that were ASA prints. I have yet to clean my rods for the first time. Haven’t done it because the machine is still printing fine.
Alas, I’m more of a “rolling” bearing guy. I don’t know much about the characteristics of the sliding bearings used in the printer gantry. But like anything else, they have to have tolerances. I’d assume the bearings are bored to meet inside dimensions. The rods might be more prone to dimensional variation when they’re made. Put a caliper on them and see if they’re meaningfully different sizes?
Another suggestion - do a test print that’s a flat plate with holes evenly distributed across the plate. Are the holes out of round everywhere or just in specific places? Out of round everywhere suggests the problem is the bearings and not the rods. Out of round only in some areas, I’d blame the rods for being too tight in those areas.
Unfortunately, you’re going to have to do some troubleshooting to narrow down the problem area to get BBL to send you parts.
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It’s possible that my previous cleaning jobs weren’t adequate. It’s been emphasized that I need to really get IPA squeezed INTO the bearings and not just wipe the rods. I’ve currently just been doing a thorough clean before each build (skipping re-tensioning & calibration) and it’s been doing alright.
I’ll probably do a deeper dive into this after to see how much ABS actually starts to cause problems and maybe make a youtube video for others.
I would start out with belt tension as others have mentioned. A short term band aid until you find the problem might be to slow the print speed down (100-150mm/sec max speed). Also, just confirming, you didn’t bump up the speeds to “Sport or Ludacris” right?
I think the idea on ABS vs ASA is specific to which is the “better” filament. While I would agree, ASA is “better” than ABS, the different is in price. ASA is roughly 10-15% more expensive for very little tangible benefit. So unless you need the UV resistance, I’m not sure it makes sense to switch for producing something.
It’s not belt tension, it’s particulates deposited from printing materials like ABS with Styrene.
Cleaning is the solution, it was just unfortunately happening more frequently than expected. Possibly just because I didn’t squirt IPA into the bearings and get a real deep clean - I’ll do some further testing to see if this is indeed true, but my suspicion is that has been the issue.
Belt tension issues will result in non-repeatability problems, layers will not be well aligned. But because this is a CoreXY machine, if one axis is more constrained than the other, the less constrained axis will move more than it’s supposed to, in proportion to how much the more constrained axis is not moving.
Holes would be ratty if belt tension was a problem. Holes being oval means one axis is draggier than the other. It’s kind of like the differential on a car. Jam one wheel so it can’t turn, the opposite wheel gets all the power.
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Ok, good luck sorting it all out.
Yup it is 100% a dirty X axis / increased friction X axis issue. The ovals ALWAYS show up in the same orientation, so it’s obvious that the X axis is having issues, while the Y axis is still OK.
Kind of interesting if you think about it. There’s obviously a difference between how the carbon rods and bushings/bearings handle dust/dirty from ABS compared to how the linear bearings and metal rods on the Y axis handle them. Makes total sense because my other printers never have problems like this printing ABS for years.
I made a YouTube video explaining my findings with this and showing how I clean the machine now to prevent these oval holes from happening.
