x y resolution limit?

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    There is one thing I instantly noticed. Cylindrical parts printed by my new SIGMA do not consist of perfect circles. Instead, the circles are flattend tangential to the x und y axis. I have checked the axes. They are perpendicular. For me it looks like an issue of resolution, like a circle drawn on a pixel raster.
    The first picture shows a part of 145 mm diameter. I used a stl-file of very high resolution (according to fusion 360) and sliced it with Cura BCN3D-0.1.4.
    The same stl-file sliced with Cura 15.04.6 and printed on a daycom 3DP-100 does not have such ´resoultion artifacts´. (see second picture)
    Both parts were printed with 0,1 mm layers.

    My question:
    Is this the best possible quality I have to expect from my SIGMA or is there a problem that can be solved?


    Is the second part (Cura 15.04.6 and printed on a daycom 3DP-100) the same quality as on the picture all way round?
    We mostly print cylindrical parts on our Sigma and the surface quality is the same as yours. However part of the circumference is of good quality.
    I think this is slicer issue, it creates toolpath using specific algorithms and the algorithm can be improved,
    But it could also be a problem transforming non-linear paths into step motor movements.
    We’re also concerned about this issue. BCN can give right answer for this, but I’m afraid they’re on holiday.


    The part printed with the 3DP-100 has the same quality all the way around. There are no apparent steps on the circumference.
    Here is another picture of the same part printed on a RepRap NEO (Cura 15.04.4).
    There are steps on the circumference as well. However, in comparison to the Sigma they are much smaller.
    At the moment the printers are busy so I can´t check the steps per mm. I will report later…
    By the way, does anybody know the steps per mm on the Sigma?


    Now I have checked the resolution or better said the steps per mm.
    Sigma and 3DP-100 have both x = y = 80 steps/mm
    NEO has x = 76, y = 89 steps/mm
    That means the ´mechanical resolution´ is the same and there must be an other reason for the different quality. For example the stepper drivers or different path calculation algorithms as mentioned by vlad.
    @BCN: Is there a chance to improve this?


    I have the same problem. Circles are terrible. 0.35 to 0.5mm out of round.


    squares are off too. A 25 mm square is off xy by 0.3mm
    A hexagon measures between flats 30.41, 30.58 and 30.010.

    Seung Beom

    I have same problem on my Sigma when I print rounded shape like cylinder.
    It masses up the quality of printing.
    Hopefully technical support can solve it after holiday.


    I have the same problem.
    Look also here:

    Pixelating the print


    Anyone want me to run some tests based on resolution? Well that’s what I’m doing shortly. Brb!


    I have exactly the same problem. Has anyone a solution?


    Is there any way to correct the steps per mm for the steppers?
    In another forum i have read that with the GCode command M92 you can change the resolution.
    Did anyone have test that?


    I have the same problem. Is this the resolution limitation for the Sigma?


    Hello everyone,
    We are currently developing new drivers that may solve some of this cases.
    However, this can be caused by some other reasons, like wrong belt tension, case misalignement etc.
    in the case of Seung Beo’s printer, the Y stepper belt was a bit too loose, and that was causing all the trouble, but it’s hard to make a precise diagnosis without being able to check the printer.
    If you have any of this issues don’t hesitate to contact us at sat@bcn3dtechnologies.com and we’ll do our best to solve them.

    Seung Beom

    No David,
    tighten up the belt solve the circle problem(printer couldn’t draw even correct circle before A/S),
    but this is different problem which is still existing.
    The problem is pixeling. Always print has a pixeling problem at 4 side of circle.
    I’m sure it is problem on firm ware which control steps of motors. basically the printer shows lack of steps,
    so print always have a strange ridge at same 4 side.
    It really degrades quality of prints, hopefully BCN tech solve this problem.


    @Seung Beom, i totally agree with your post.
    My test prints (rings) look exactly like your print and nothing helped.
    BCN3D, please investigate this problem and give us a hint
    how to solve this or what can cause this.

    roger uceda

    Dear all,
    I am Roger, from BCN3D.
    We are working in some differents ways to improve that issues (drivers, electronics, hotends…) We can not say anything else but all our efforts are in:
    – Noise reduction
    – Better surface finishing (resolution)
    – Better materials compatibility
    We are working on that Sigma evolution for more than 6 months and you will have news before the end of the year.
    All the improvements will be sold as upgrades for the current Sigma.
    Thanks for you understanding!


    Any update on this Roger?
    We are seeing this on our printer also and if there is a firmware update that would sort this I’d be interested to hear.
    Kind regards


    My sigma is printing .5mm out of round…
    Firmware is up to date… stl is good…
    Belts seem tight.
    I need help please. Printer is less than 2 weeks old. I can print a 25mm round and it varies from 24.5 to 25.5mm around the perimeter. Seems off the worst at 11 and 5 o’clock and 1 and 7 o clock.


    I have exactly the same issues.. Been in contact with the support department for 2 weeks now, but the only answers I get is firmware update here, swap nozzle there and that the new steppers should be much better. I don’t buy anything for this, as this printer is not even 2 weeks in my room. My 3 year old printer just kicks the Sigma’s ass which is not what I expected. Circles are impossible to make (smaller diameters are nowhere near round, it’s just an eclipes) and the larger holes are off in size. The ringing looks like shit for a printer of this price. Untill now, I’m absolutly not happy with my sigma, and if the only option to get my 2500€ machine running properly is to invest an other 200+ euro’s is just a joke if you ask me.


    Same problem here since the end of last year. Is this problem addressed in the stepper upgrade?


    Any updates on this problem?
    Do the new driver boards fix this error?
    I had the opportunity to compare some prints from an ultimaker costing the same price and the difference was staggering. I really like the Sigma but this xy problem needs to be fixed.


    And there are people who have both and say their Sigma is better, Every printer is different and not all of the same standard.

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