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When I was reassembling the whole XY part, because I wanted to change all the pullies, I was playing with the brass bushings by moving it over the rod by hand. First I cleaned it with a dry cloth and they bushing slided very easilly over the rod. Then I applied some machine oil and.. it felt like it behaved like a Newtonian liquid. The faster I moved the bushing over the rod, the more friction it gave. Imagine with print speeds up to 200 mm/sec (travel) this generates a lot of friction. Then I cleaned the rod and applied some WD40. The effect was still present but much less. And the best lubrication that I got was by spraying some WD40 on a cloth and swiped the rods slightly with it. So.. yeah, you could do some test for yourself, maybe I'm wrong. But because of the effect that I noticed, I'm hardly using any lubricant than just a superthin film of WD40 (actually it's Silicone72 from Kontact Chemie but it's almost the same stuff).

Be carefull that you don't tighten too much heck out of it! The standard UM pullies tend to deform in an oval shape if you tighten them too much. I had that issue.. so I bought new pullies.

Hi Aum, I think you should try lower a temperature. 210°C is already 'fairly hot' for most PLA so try 205 or even 200 with a lower print speed and high fan speed. You can choose a different speed for outlines and infill. Let's say 30 mm/sec for outlines and 60 mm/sec for infill (at 0.1 mm layer hight). So you keep the speed but increase surface quality. Hope this solves your issue! Groet, Bas

Ok, here it is No improvement at all I think the only way then is to use matching gradient/transition colors.

You're right Peggy, I meant the Colorfabb vase. And cool that they use a transition filament! I've have 0 infill for that bear model but it does have 0.8 walls. I think I'm going to switch to 0.4 walls with the 'spiralize the outer contour' function enabled. And now from blue to red so maybe I'll put some purple inbetween. I'll post a photo of the result.

Haha, thanks guys, but I wan't to emphasize that I DO want a graduated color change. I've done serverel prints with the 'pauze at height' option, and with good clean separated colors. But I had hoped that with welding two colors directly to eachother, the change would be as graduated as possible. I think it has something to do with the printsettings that the blending is relatively short. I printed this bear at 0.07 heigh, so the filament is moving very slowly into the nozzle. Therefore there isn't much mixing going on in comparrison with a faster moving filament. I was also thinking about cutting diagonally but this is very hard to do. Not only to cut it (PLA is quite hard) but then also to weld it back together... Has anyone some more ideas?

Hi guys, I'm trying to print a dual colored bear. I wanted the changing of color to take place at about 50% of the print. Cura showed that this print would use 3.2 meters of filament so I took 1,6 meter blue and 'welded' it to yellow filament with a lighter. But the problem is... I wan't the color change to be more graduate and not so fast like I got now: I saw some more dual colored prints on this forum which looked much more graduate. Is there a trick to do something like this?

The 180 was just an example And your explanation is good, and I think you also might be right with that. But there is a limit of how much heat the heater can generate versus the heat that is taken away by the cooling air. If you look underneath the UM when heating, you see a red LED lighting up constantly and it starts flashing when it has reached the set temperature (so turning on and off the heater to maintain the desired temp). Try to heat up to your printing temperature and then turn on the fans. They probably start cooling the nozzle. Then check if at any moment the red LED starts flashing or that it stays on continuesly. If it stays on continuesly, it means the heater is fully on and cannot keep up with the dissipated heat by the fans. Also, a picture of you ducts would be helpfull

Hey LePaul, you asked about this problem also in respons to my post in 'Fixing Pulley Accuracy' and by chance I just saw the picture of your printhead in this topic. I told you that I never had any problems with the bowden popping out but now I see that you have this black plastic thing screwed on the head. My UM came without this black thing so my white insert is just directly inserted in the wood. I guess this black part is an 'upgrade' on later UM's to prevent the bowden from comming out but maybe you should try remove it. Then insert the white insert in the wood and try printing. Hope this helps!

En ik kom uit Den Bosch. Tijd voor een Ulimaker 3D party

Wild guess.. That the fans are blowing to much on the nozzle. I think I've noticed that there is an optimum fan speed for a particular fan duct. For example, from speed 0 to 180 the airspeed coming out the fan duct is increasing but when you go higher then that optimum (180), the airspeed actually decreases because of pressure buildup in the fan duct. So although you feel like the fan speed is lower, the air output should be lower, the opposite might be true. And so cooling the nozzle. But again, it's just a guess! I also use two fans in parallel and never had any problems with it. That's why I think the problem could lie in the actual cooling of the nozzle.

# LePaul The printhead is here: http://www.thingiverse.com/thing:154845 It uses the same white insert as the original head to prevent the bowden from popping out. And the blue horseshoe holds this white insert in place. I never had problems with the bowden comming out. If I pull hard on the bowden tube it's very hard to pull it out and I have to push down on the white insert. I think you should check this white thing if it is tight enough arround the tube. # jhertzberg I did not test this other than printing a simple iphone casing. And I didn't see any changes in the layers on that print. It needs a bigger, or at least, higher print to evaluate that. But even if it's flexing/compressing, this effect should be the same at each layerchange and I think only visible at the Z-seam. A couple of UM users on this forum use the same couplers for direct drive on the XY-motors and as far as I know they have not reported any problems. I'll let you know when I've printed some more

On Ebay from a guy from China. It only costed 11,80 euros for three couplers including shipment. If you search for 5 to 8 mm flexible coupler, you can find many more suppliers on Ebay.

Here some photo's of the things that really helped me improving XY and Z accuracy. The new pullies from foehnsturm make a huge difference like I said in two post above. After one print, however, I noticed that the Z-wobble was way more visible because it stands out in comparison with the very accurate XY. The Reptar XY Blocks are nice. They don't give you any accuracy improvements but removing the 6mm rods and printhead is super easy with these blocks. They don't have a belt-tension option so I used some clothespin springs for that. The smaller printhead is lighter so theoretically you can print faster but I don't expect much quality improvements other than I think this head just looks nice. Fortunately, today, three flexible couplers came in which I had ordered earlier. Just by replacing the UM coupler with the flexible one, the wobble completely disappeared immediately! So for only a few bucks and no tinkering, one of the best upgrades :grin: Two other upgrades/tools are these XY belt-tensioners and endcaps. I think everybody knows these endcaps by now, and be sure to print the ones where you can put some set-screws in them. The belt-tensioners are just perfect and really easy to set to the right tension. Good luck with improving your machine!

I'm sorry for those who hadn't had a chance to buy a set, I don't want to poke you an eye out but... Man, what a difference! I was very sceptic at first but with all those enthusiastic replies.. I had to get a set for myself. Because the whole XY part had to be disassembled, I took this opportunity to also upgrade the slider blocks. I printed the reptar blocks (newest version). Also printed some external tensioners for the X and Y motors and used clothespin-springs to tension the long belts. Will post some pictures later. It runs so smooth now, very little resistance when manually moving the head. And because of the more accurate positioning and smooth movements, even with high travel speeds, it will travel back to the exact same spot every time, which greatly increases the XY surface quality! Somehow it's also much quieter (almost as quiet as an UM2). One (important) thing I noticed when I was sliding the brass bushings over the XY rods was that, if you use machine oil as lubricant, it was much less smooth then with a silicon lubricant. The machine oil felt like it was behaving as a newtonian liquid! The faster I moved the bushing, the harder it became! So especially with the high speeds of 3D-printing, I'm going to use a silicon spray lubricant.

I found another very nice and easy way to level the bed. I think this is not very difficult to implement on UM.

Thanks Ian. The files are on Thingiverse. The space shuttle: http://www.thingiverse.com/thing:10228 The launch cloud: http://www.thingiverse.com/thing:150212 Have fun!

Well, I had the same thing with a few of my vases. The most important thing (ofcourse) is that the extruded lines are touching each other. If that is not the case, then it doesn't matter how much your bottom height is, it will always be leaking. But if the lines touch, 1 mm bottom height is more then enough. I think it's just a case of increasing the flow a little bit so the bottom lines are nicely squeezed next to eachother. You can try to do it manually, so when printing 110% flow for the bottom and then set it back to 100%.

A multi-part print of a space shuttle launching. The stripes I put on later with a black and red marker. Especially I like the launch-cloud which looks kinda realistic.

I'll give a shot to a possible improvement. I would suggest to increase the temperature. The flexible PLA probably has a longer melting-traject and will be more sticky at the transitiontemperature. Therefore it will stick more to the nozzle and will be dragged along with it. So it could create the rounded corners. Compare it to dragging a stretchy rubber hose over the floor while walking the same path of the nozzle. It will bend at the corners because its more connected to the part which you are still holding. I hope you get my idea haha. With a higher temperature it will be more fluid and wont stick to the nozzle so much. Just try and share the results please!

Ai, are you planning on making some more sets foehnsturm? I'd also like a full set... :mrgreen:

Totally agree. Typing filename would be good. Specially for multiple (test) settings of the same object.

I think that's the 'travel speed'. The speed at which it moves when not extruding but moving from one place to the other. You can find this setting on the second tab (I think the default setting is 150 mm/sec). But for best print results you should not lower this value because traveling with a low speed alows more time for oozing.

Zulu's don't wear sunglasses

I 'modeled' it on Tinkercad (steal a mouth and nose from other objects ). It's only half a cone, the back has some kind of rectangle holder to hold the legs of the glasses. I'll try to upload the .stl if you're interested (and only if you wear glasses B) )