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  1. Changing bearing did not help, oddly enough. How much more weight do you suggest? I tried putting exactly one iPhone between the wood and the acrylic and that didn't help.
  2. Welp, after some more poking and disassembling the z-stage a couple more times, I think I can safely discard the leadscrew and nut as the sources of the issue. I checked the leadscrew for straightness and alignment, no issue. I then switched to a new leadscrew and new nut, and the problem remained exactly the same! My only theory now is that there's something wrong with one of the 12mm linear bearings (dislodged balls or something?), causing a slightly bumpy ride in regular intervals. Somehow I have an extra pair laying around. This is the final attempt.
  3. Quick update: no luck. - tried a new PLA, same effect - added weight to the printbed, no difference - cleaned the leadscrew and nut, same thing - disassembled the stage, sanded some of the nut casing to allow some X/Y play, no difference Here's a closer look at the issue. It still happens every ~8mm, doesn't matter which layer height I choose in Cura. Most layers look fine and have the expected thickness (0.2mm in the image). Then every ~8mm I get a bunch of thinner layers followed by a bunch of thicker layers, so that in the end the part has the expected final height. I painted some dark lines with the expected layer height in the image. I even checked the G-code, but the layer heights there are all correct. I find it really odd that it happens at regular intervals that don't seem to be related to the Z screw pitch. The mystery annoys me more than the print quality.
  4. I'll be out of town for a couple of days, but I'll clean and check the Z screw when I get back, since that's reasonably easy to do. If that doesn't work, then I'll try adding some weight to the bed and if none of those work, I guess I'll have to disassemble the stage and work on that brass nut. Thanks again for the feedback!
  5. Okay, so I ran a couple more tests: The top left image is my reference at 0.1mm layers with a single wall (0.4mm), again at 70mm/s and 225C. It's pretty faint, but the irregularity is visible. Then I printed one with 1.2mm walls, effectively using three times as much filament per layer, that's the bottom right picture. Notice the spacing between the bad parts is still about the same, so it's probably not the filament, either. Then two more single wall tests, at 0.15mm layers (top right) and 0.2mm (bottom left). The angle is different to make the irregularities easier to see. Speed was adjusted to keep the same flow rate as the first test. The walls are also pretty wavy, but I'll deal with one issue at a time. So maybe it's the Z-stage. My brass nut doesn't move in the X/Y plane at all. It may take some sanding to make that happen. What's the issue caused by a tight nut? Thanks again, gentlemen!
  6. Some of the oscillation happens when I go too fast, my linear bearings are not as smooth anymore. As for your previous question, each circle on that object has about 100 segments on the larger parts and 40 on the smaller parts on the top. I ran some more tests this morning, a 20x20x40mm hollow brick. These are 5 tests, all at 70mm/s and 0.8mm walls, no infill: 225C 0.1mm (minimum layer time was on, oops, so probably printed at about 30mm/s) 225C 0.1mm 225C 0.1mm manually unwinding the spool, no noticeable change 235C 0.1mm 235C 0.2mm this one definitely underextruded on a couple of layers, but I could be going too fast Here's an earlier piece, with several shades of purple (and some warping on the bottom : And finally some close-ups on the troublesome layers. Some look "bubbly", some look slightly underextruded and some are just not like the others: Dust could definitely be an issue here, I'll try putting some cleaning mechanism on the feeder. Thanks again for taking your time to look at these!
  7. Sander: It's a Chinese unbranded PLA from eBay, not the best quality, apparently. I won't be suprised if the filament is to blame. Illuminati: I'll run some tests giving the spool some turns. Thank you!
  8. Hi everyone, thanks for the replies! Oh, sorry gr5, the white ring on top is a silicone ring, not printed. I used yellow PLA previously, but that was a while ago. I'm halfway through the purple spool and it has looked the same from the beginning. I'll check the number of segments when I get home later. I'll check the spool as well, although it seems to spin reasonably well on the holder. I'll print some hollow cubes or regular parts as well, might be easier to see the problems in detail.
  9. Hello friends, I'm having an issue that got me scratching my head for a several days now, I hope you can help me out. Some layers on my prints look less dense (?) than others. On the first image, you can see some lighter layers. The second one looks more homogeneous, but it's also not perfect. The prints are at 100% infill, 70mm/s, 225C, 0.1mm layers, PLA. I assumed it was an extrusion issue at first, but I think I've gone through pretty much all topics and tips on extrusion, to no avail. It seems very random, some layers are fine, some are bad. The filament is being pulled properly and the extruder teeth marks on the filament look very regular as well. Could it be filament diameter variation? Moisture? I'm waiting for a new roll of PLA to run some tests, but any ideas are very welcome! Thank you!
  10. Would Arduino and a regular RAMPS board work for you? That's what I'm running, but my machine was built around it, so I'm not sure what other UM components could be incompatible with it. Or try these $6 19V cartridges? http://www.dfrobot.com/index.php?route=product/product&filter_name=heater&product_id=865#.UmflwnWkh7s
  11. Hmm, I'm not sure how quiet it is compared to a real Ultimaker. It's quieter than a dot matrix printer, but my wife doesn't agree that it is quiet at all. Maybe MDF is better than plywood at dampening noises? The extrusion problem is now fixed by increasing the flow rate (will probably adjust the E steps in Marlin later). I suspect I need to do that because the diameter of my hobbed bolt's teeth area is smaller than the stock knurled part, thus pushing less material per step? Mine: Stock: I noticed my prints are a tad smaller than they should. Smaller on the Y axis than on X, too. Could be lack of belt tension?
  12. Well, look at that, it works! I had to adjust the Z steps on Marlin thanks to my non-standard lead screw, but other than that, it looks fine. The main issue I have now is some underextrusion, from what I can tell, there's not enough pressure from the spring (it's a spring from the junkyard). I'll try a stronger spring later. http://25.media.tumblr.com/48daac1210a2b9411b3c7df71ef40921/tumblr_mqhy35wN0Q1spn1e9o1_500.jpg
  13. Well, look who's dreaming about printing a calibration cube! After blaming everything on top of the machine for the friction preventing the head from moving, I finally found the true culprit: the 6mm cross bars. Turns out they were 1mm too long, and when they were pushed into place by the C block bolts they got too tight and pushed the 8mm bars outward, bowing them out slightly. Perks of self-sourcing. I filed down those rods, and now everything moves! It's still not butter-smooth, but for the time being I'm quite happy with the motors being able to move the print head. I'll have some filament to do a proper test in a couple of days, but I'm still cautiously optimistic, as the feeder mechanism may have some unexpected problem. Expect an excited post when it works.
  14. Okay, there seem to be a couple of friction sources friction in the machine. One end of a shaft was rubbing a bit against the cap. I've removed all the caps for the time being. The shafts rotate effortlessly without any belts. With the long belts on, there's some friction. The friction also gets worse when the short belt is on and the X/Y motors are pulled down. That's the most significant source, I believe. So the problem seems to be that my bearings don't perform too well under the radial load of the belts pulling the shaft down and to the sides. Or there's still something else I haven't realized yet.
  15. Hi, thanks for the encouragement and help! Hahaha, for sure! But hey, given the terrible quality of plywood I found here, I'm pretty positive I could make better stuff. J/K! Okay, so I made some more tests with the X/Y assembly. Yes, the resistance is pretty much the same in both axis. There was some belt misalignment and that accounted for some of the friction, but it's still not anywhere near acceptable. Loosening the short belt pulleys made little difference, so it's not the motors, either. Without the belts, the sliding blocks slide quite well. I also tried removing the shaft endcaps and that didn't solve the problem. I said it was fine without the head, but it is not! It's only smooth without the long belts. I suspect it may be because of overtensioned long belts. I went with 298MXL instead of 300MXL after reading a lot of belt slack posts (and today I found a couple of posts that said 298 was too tight, haha). They don't seem excessively tight, compared to some tensioning videos, but I can't think of much else. I'll remove one of the long belts and see if that lessens the friction (do I really need two on each axis?)
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