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oval rendering of circles


aag
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Posted · oval rendering of circles

I am printing a bunch of plates with 3.7mm holes. The holes are round in Fusion360, they are round in Cura, and they come out as ovals in the physical 3D print. I am using an Ultimaker 5S with AA0.4/BB0.4 cores with Tough PLA and PVA, respectively. What might be the issue?

 

20190512_114341.jpg

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    Posted (edited) · oval rendering of circles

    Without doubt that will be the short belts need tightening, check the manual of how to do it. It's easy. 

     

    I am assuming you are printing this part flat rather than vertical. 

    Edited by Link
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    Posted · oval rendering of circles

    Wow.

     

    First check that the gantry is square.  It just takes a few seconds.  Push the head around with your hands and put it in the center and look down to see if the rods passing through the head are as visibly crooked as these circles.  Then push the head to the 4 sides and make sure the side blocks reach the same end position and at the same time.  For example if you push the head to the center rear position as far as it goes - the left and right slider blocks should both be all the way back.  Sometimes one block is clearly not as far back because one belt or the other slipped a tooth.

     

    This kind of thing is usually caused by belt pulleys that are not drilled in the center but if so the pattern would be good for a few cm and then bad for a few cm and I don't see that.

     

    A large amount of head play might cause this.  Gently push the head around without enough force to move the steppers.  How far does the nozzle move n X and Y without the head/steppers moving?

     

    Printing slower might fix this.  I'd try printing very slow - say 25mm/sec - just to see if that fixes the problem.  Then you can gradually increase the speed on each layer in the TUNE menu until the problem returns.

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    Posted · oval rendering of circles

    I checked the gantry using the alignment tools. The precision of the tools is limited, I do not believe that any deviation by <1mm would be detectable. Within this limitation, the bars are orthogonal. Also, there is no detectable head play.

     

    What I noticed instead, is that there may be a problem with the left hind stop. When pushed against the side block, the head bounces back a few millimeters. This does not happen with the other three side blocks. I suspect that this is caused by some kind of uneven tension of the belt. What do you think?

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    Posted · oval rendering of circles
    On 5/12/2019 at 2:34 PM, Link said:

    Without doubt that will be the short belts need tightening, check the manual of how to do it. It's easy. 

     

    I am assuming you are printing this part flat rather than vertical. 

     

    You, sir, are a genius! The left short belt was totally loose, I mean so loose that it was a wonder that anything would work! After tightening the short belts, circles are now perfectly round! 🙂 This community is a blessing, seriously!!! 🙂

     

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    Posted · oval rendering of circles
    6 minutes ago, aag said:

     

    You, sir, are a genius! The left short belt was totally loose, I mean so loose that it was a wonder that anything would work! After tightening the short belts, circles are now perfectly round! 🙂 This community is a blessing, seriously!!! 🙂

     

     

    no problem, glad you got it sorted 🙂 

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