rowiac

If your hot end is brand new and clear, then the problem could be with the feeder or the bowden tube. If filament slides freely though the bowden tube, then it probably isn't that. Inspect the black plastic roller in the feeder to make sure it isn't damaged. If it is. it can cause inconsistent tension and periodic under-extrusion. If the feeder tension is set too high and still grinds sometimes, this can create burrs on the filament and loose particles that make it difficult for the filament to slide through the bowden tube, exacerbating the problem. When I was having a similar issue, I had found that if I fed fresh filament thought the bowden it would slide easily, but filament that had already been through the feeder once (had marks from the knurled bolt on it) had significant resistance in the bowden.

As @DidierKlein says, get yourself a new teflon coupler if you haven't changed it in a while. Try atomic pulls first to make sure the nozzle and brass tube are clear. In my experience, if the coupler is worn (e.g., no longer seals well against the PEEK isolator, you will get filament jams after printing a while as the heat transfers upward toward the coupler and the filament softens--especially if you are doing a lot of retractions.

I think this is a "feature" of the UMO/+ feeder. The large wheel, being made out of plywood, is not perfectly flat. However, it is not really a problem if you assemble the feeder with enough "slop". Make sure you have two flat washers as spacers on the knurled bolt before installing it through the ball bearings in the feeder. If you already have two washers there, make sure that the knurled bolt is protruding far enough away from the large gear. The assembly instructions provide a guideline, but you may need to adjust it by unscrewing the knurled bolt a bit and re-tightening the acorn nut. It is OK if you have some axial play between the large wheel/gear and the feeder frame. The knurled bolt and gears are wide enough to accommodate quite a bit of misalignment. The important thing is to avoid friction from the large wheel rubbing on the screw heads, which is what I think your problem is.

This sounds suspiciously like what recently happened with my UMO+. Check the black plastic roller in the feeder for roundness. This is the roller with the small ball bearing in it that pushes the filament against the hobbed bolt. In my case the roller had formed a divot on one side so that the tension changed as the roller went around, causing slipping approximately every revolution of the roller. The roller's diameter is 15mm, so its circumference is (15mm)*(pi) = 47.1mm. That's close enough to be the 45mm recurring underextrusion you are experiencing. I replaced the plastic roller with a new one and the problem went away. Since then, based on suggestions from folks on this forum, I replaced the plastic roller with a 8x14x4 ball bearing that should never wear out again.

Hi what do mean with not two fixed nozzles? What would yoy recommend? I'm planning to put the second extruder in my UM2+ extended with a kit. I don't want to buy it if it doesn't work correctly. Thanks. See this thread: https://ultimaker.com/en/community/10657-a-different-multi-extrusion-approach-um-tool-printhead-changer

@gr5: Do you happen to know what is holding the ruby in the brass part? Is there an adhesive that could possibly be damaged by heating it to such a high temperature? Or is it just a press fit?

I still have some Magnalube left over, but if I run out I will most likely use Synco Superlube Synthetic grease, since I have a big tube of that already. We used it at work for lead screws and it appears to be comparable to the Magnalube grease. The Superlube is available at UK eBay.

@amedee: Thanks for that link to the old thread. It looks like I'm about 4 years behind the times. One 8x14x4 ball bearing on order from eBay. I was trying to find a bearing that would replace the small bearing and delrin roller all in one, but that is not an available size.

@gr5: I had a similar thought. Thanks for the link.

The creaking noise seems to occur only when the print head is moving left/right. Is that correct? If so, that could narrow down the areas to look for excessive or loose parts. If you move the print head left/right by hand, do you hear any creaking, or feel any rough spots? If so, I wonder if the "x" linear bearing in the print head has gone bad.

When you get a 1.5mm hex wrench, also get the Loctite threadlocker to apply on the screw threads before inserting it. If you can find the purple threadlocker (Loctite 222), that would be preferable to the more common blue type (Loctite 242) since the screw is less than 6mm in size. If all you can find is the blue type, it should be OK, but the screw will be harder to remove if you ever need to do that. The JB Weld, on the other hand, may make it impossible to remove the knurled wheel at a later date.

@brentwerder: I know this is an old thread, but I'm experiencing a similar extrusion problem with my UMO+ and I'm wondering if you were able to fix it. In my case the feeder roller (the black plastic part with the small ball bearing in it) has a groove worn in one side of it. This seems to be causing uneven feeder tension as it rolls resulting in under-extrusion at regular intervals. I'll need to verify this theory by replacing the roller.

In addition to the suggestions by @gr5, he can install the Solid Inspector plugin for Sketchup which will help identify issues with the model so he can fix them in Sketchup prior to exporting an STL file. Unfortunately Sketchup is not the best modeler for 3D printing for exactly the reason the kid discovered. You usually can, however, correct the issues with some patience and export a usable "watertight" model.

My first reply disappeared after I hit "Post Reply" so here we go again. Hopefully I won't end up with duplicate posts. If I understand your problem correctly, I think the issue is that the STL file is not oriented so that the base is perfectly flat on the build plate. When I opened your file, I saw that there is small angle between the model base and horizontal. To correct this you can try the "Lay Flat" function in Cura, which will rotate the model so that the nearest flat surface lays on the build plate. Or, you can reorient the model in another tool prior to importing it into Cura. Personally I prefer Meshmixer for editing STL files. You can rotate the model by the exact amount for the base to be flat by using the Edit/Align function and playing around with the various options. In this case, the "surface scribble" option will work to select the bottom surface of the base as the surface to orient to. You could also have used Meshmixer to add or remove the base instead of the NetFabb/OpenSCAD combo you used. To add a base I would add a cylinder primitive and adjust it to the proper size for the base, then I would merge the model and base together prior to exporting as a new STL.

Thanks! I just ordered one.

Thanks @neotko @Dim3nsioneer any idea what shipping cost would be to the US? No one else seems to have these and even 3D Solex doesn't have them on their site.

@neotko, I have looked around for TFM couplers for the UMO/UMO+ and the only place I found one was on eBay from a seller in Germany. Maybe it's less necessary on the UMO/+ than on a UM2, but it would still be nice to have a really long lasting coupler.

How does your teflon coupler look? If it gets slightly worn it can cause underextrusion issues. At ~4000 hours of printing, I assume you have changed it several times though.

I still use Cura 15.x for build plate leveling on my UMO+. The Cura 2.x functionality for this purpose is just not as usable. I don't have access to it right now to confirm, but for example, I don't recall the concentric squares pattern to check leveling to be in 2.x. For us folks with UMO/UMO+ can a Cura 15.x style leveling routine be added in future versions of Cura 2.x?

I was having a lot of similar problems on my UMO+ (mainly underextrusion), and aside from one loose pulley, changing the teflon coupler has gotten me back to printing like new. I'm guessing I have about 500 hours on my printer and have done 99% PLA. So I recommend getting yourself a new teflon coupler and maybe buy a spare for future use. My old coupler did not look bad--it wasn't burned or anything--but it no longer had a square edge at the exit end, which was allowing the filament to bulge before it entered the PEEK part, and that caused excessive friction. Another symptom was filament grinding at the feeder periodically, and sometimes a filament jam at the beginning of a print. Also it was getting difficult to remove filament from the bowden tube when I would change spools due to the bulge formed at the tip of the filament.

You may have already seen this, but here's a thread about installing an E3D Titan feeder on a UM2. It seems like a simple adapter could be made to mount the feeder with some hooks to go into slots in the back of the UMO frame, perhaps in a flexible material. https://ultimaker.com/en/community/21029-e3d-titan-extruder-firmware-settings I am also interested in a way to reduce the feeder noise on my UMO+. I installed a flexible damper between the feeder and the frame, but the retraction noise is still pretty loud.

Back your original question of where to buy UM brand filaments in the US, I've bought things from both Dynamism and 3DUniverse. The 3DUniverse brand PLA seems comparable to the Ultimaker brand and is a bit cheaper. I've also had good luck with ProSpec PLA from ProtoParadigm out of Oregon. They don't have a huge selection, but the pricing is great and they have some interesting colors. It prints well for me and does not look cheap at all.

Also make sure that the shaft end caps aren't binding up and preventing the shafts from rotating. I had to put washers under one of them on my UMO+ to provide some clearance.

Did your printer come with the calibration sticks? These are two wood parts with a hook on one end and notches on the other that are used to make sure the x and y axes are square. You can see how to use them in the UMO/UMO+ assembly manual. Once the axes are adjusted, make sure all the pulley setscrews are really tight. Also make sure the pulleys on the x and y motor shafts are tight. You will probably need to remove the motors to access those setscrews. The print head should be able to move smoothly, but with some resistance, diagonally. I don't think I can move mine easily with my pinky, but my index finger could do it.

For DIY coatings, Cerakote C-100 Micro Slick Dry Film Coating looks interesting. This is an air cured low friction ceramic coating used on vehicle engine parts, so it can withstand high temperatures. Might be worth a try. Not sure if it's available outside of the US though.