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Circle not round and other problems

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Posted · Circle not round and other problems

Dear Forum


I have som problems with my Ultimaker Original. After fixing a blocked nozzle a blocked tube and broken filament I was finally able to print a prototype of a plastic bass clarinet neck.

However it is far form perfect yet.


The first problem is that the tube has to be round and it has become oval (see first photo). 

Also on the bottom of the print (the second photo is taken upside down) there is some stringing.

I hoped that the print would be airtight. I selected 100% fill in. But it isn't airtight.



Material: PLA

Layer height 0.2mm

Wall thickness 0.8 mm

Infill Density 100%

Printing Temperature 235

Diameter 2.85

Flow 100%

Traction enabled

Print speed 60mm/s

Travel speed 120mm/s

Cooling - enabled

Support - Touching Buildplate

Adhesion type - Skirt


Does anyone have suggestions to improve this?


Kind regards, Johan Jonker





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    Posted · Circle not round and other problems

    This is a crazy hard print because it has tight tolerances and lots of overhangs.  


    One way to deal with this is to model and print this vertically as a cylinder and after done printing then pour boiling water over the center and bend it to this shape by hand.  That way the tight fit parts will be a food fit.

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    Posted (edited) · Circle not round and other problems

    Hello Gr5 thanks for reacting.

    My english is not so well. What do you mean with a food fit?


    I am afraid when I use boiling water method the section will become oval and an exact total length of the neck is not easy to define.

    Also I wonder why the bottom print is worse than the top print. To honest I am suprised that printing the top went so well without support.


    Edited by JohanJonker
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    Posted (edited) · Circle not round and other problems


    first of all, I think this print is impossible to get in shape without support in the areas that schould fit in tight tolerances.

    Maybe you could define the support to be only in the parts that need to be fitting. As far as I can see, it shouldn't be too hard to remove as these are the areas at the outer sides anyway.

    In general my advise for printing inner diameters with tight tolerances: design them about 0.2 smaller than desired and rework them with a reemer or drill bit. So you can achieve pretty tight tolerances.


    On your problem with getting it airtight without a second extruder for dissolvable support material you could try to design the walls thicker. I'd also recommend the print orentiation in my sketch with the mode support to buildplate. Sou you'll get you fit parts in pretty good tolerance from printing already and the problems with the missing support and not being airtight will only come up in the red marked area. There you could try a thicker wall of the CAD model. If you lower the layer height, your bridging problems will also get smaller, as the horizontal shift per layer into the air is smaller.


    I hope that helps you!


    P.S.: as you can see I'm a god with paint ?

    2018-07-01 04_08_56-Unbenannt - Paint.png

    Edited by Schwobabua
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