Vectorious

Ok I am slowly getting where I want and I think I found the source of the error. First I loosens all the sliding blocks and pulleys and tried to check for friction but found that everything worked quite well. In the end I reassembled everything double checking belt tension and pulley positions. I again adjusted the short belt tension and test printed again. (bottom one is the latest print) Now at least the gaps around the circle are closed! But unfortunately it is still not perfectly circular. Anyway. While printing I sometimes could hear a light crack (like wood tension cracking) at certain positions and tried to find its source. Well, it turns out that, as you already said, the pulleys are super eccentricity and the light cracking occurred when the tension on the short belt was slightly increased by this. I will now decrease the tension again to not stress the parts too much but I already ordered the GT2 ... Thank you for your help and your advice!

Short belt tension was the first thing I checked and adjusted before I posted here. I will disassemble the printer a bit and will test the sliding of the sliding blocks individually now. I already saw another post (of you I think) talking about the gt2 pulleys and I will definitly do that! I just thought that the original ones are not so bad that they cause the uncircular circles. I also planned to uprgade the sliding blocks but since I have to print them and they have round structures in them I am afraid I have to fix my problem before. My last hope is that lubrication will solve the problem.. Anyway, thank you for your help!

Hey, First of all thank you for the advice! I checked the alignment and ajusted it (was not too bad though). I also checked the belt tension and printed belt tensioners and installed them. Z-Stage is lubed quite well and I am waintig for the sewing maschine oil to arrive so I can oil the shafts. I checked if x/y is perfectly square and so far it seems like it is. But well.. As you can see in the picture the sitution did not improve (left is before right is after adjustments). What I did not really understand was the wooden clamp thing with the uneven pressure. You mean the one in the sliding blocks holding the belts? And how should the belt tension adjust itself?

I already followed this guide before I posted here and was not successful (although I didn't lubricate the rods). I also tried printing very slow (20 mm/s) but the print maybe slightly improved.

Hey guys, I recently got my UMO+ and finished Assembly this week. I had some minor problems finding the perfect settings to get nice prints and was quite successful with the help of this Forum! But there is still something which bothers me alot and I cant find a solution. If I I print circular structures I always end up with something slightly not circular (see pictures). With the 3DBenchy chimey it was the worst and I started looking for solutions. I already checked belt tension/improved belt tension for the long and short belts. I rechecked the pulley positions, played around with print speed, extrusion speed and so on and it seems like I couldnt get rid of the error. The Euro coin calibration pieces are the last things I printed and you can see that the circles are still not round. I dont know any further and I cant find more things I could do online. Do I have to change the x/y travel distance to solve this? Everything else seems perfectly fine (rectangles are rectangular and so on)! Thank you in advance for your help and ideas!