Pyramid instead of a come

[andrey_filippov 1]

We just purchased Ultimaker2. Nice machine, but instead of the cone it printed a 32-faced pyramid. Is it a firmware problem of the Ultimaker (it does not have an arc primitive) or the Cura software can not generate them? Or both?

Generation of arcs for stepper motors is trivial - it even does need multiplication (to say nothing about square roots or division).

I found May 2013 topic - https://ultimaker.com/en/community/view/3025-arc-support, and now it is 2015. Any updates on the issue?

We planned to use this printer for mechanical parts, not pieces of art, so true arcs area a must, not a just desirable feature - 64 or even 128 faces is still not enough.

Andrey

Elphel, Inc.

[gr5 2,194]

The STL format doesn't support arcs - that's the most common standard that all the slicers accept. I don't know any slicers that support arcs either. marlin I think does support arcs maybe? I think you can enable it in a compiler setting maybe? Maybe not. I'm sure some of the newer "cell phone cpu" based printer controllers like beagle bone and tinyG have the cpu power to support arcs.

How about 1000 sides? Is that enough? At some point the printer is adding more error than the error of converting a circle to edges. A million polygon part to be printed is not unusual.

[andrey_filippov 1]

Yes, I agree about STL - I'm new in 3d printing, and so far always used old STEP format (all our camera parts, such as for Eyesis4pi have the STEP files posted). Noticing that 3d printers use STL format (never used it before myself) I just got a wrong idea that this format is newer and more advanced than STEP.

Then the question is - why Ultimaker does not support STEP? We send our files to machine shops here in the US, and to China - all CNC shops understand that format.

As for million-faced design - I'm new in 3d printing, but I designed many PCBs. And the software that "thinks" in terms of straight line approximations of arcs is just not good enough (not going into details). It still could be OK if Cura can do this conversion as a last step, but how can I import a real cone to Cura? For 3d design we use proprietary software (running on GNU/Linux), and there are no configurable options for STL format. Are there other good STEP -> STL converters that support "1000 sides"?

[tinkergnome 927]

Then the question is - why Ultimaker does not support STEP? We send our files to machine shops here in the US, and to China - all CNC shops understand that format.

 

It seems to me that supporting STEP files is on the wishlist for a long time. Perhaps it's worth to reopen this old discussion about Stepfiles and G02/G03 arc gcodes?

[ultiarjan 1,223]

Are there other good STEP -> STL converters that support "1000 sides"?

 

have a look at 'design spark mechanical' (= free version of space claim) to export stl from step. You can even use it to modify the step by using a trick to unlock the step file (search this forum for how-too) let me know if you can't find it then I'll have a look for the link...

[andrey_filippov 1]

have a look at 'design spark mechanical'...

 

It seems it only works on Windows - I haven't use one since W2K - did not like idea of online activation that started from XP. And I'm not too good in making programs run on Wine on my computers - all of them have Ububtu/Kubuntu installed.

[neotko 1,417]

I export step with rhinoceros it let's you define the resolution of the stl to export. Once tested 0.001 and the file it's huge and full of smooth curves. I think it let's you go even higher

Edit. Other important think it's to use a slicer that doesn't 'scale down' the resolution when processing it. On simplify you can choose the level of detail to process. This it's really usefull when using a 0.25 nozzle to work simulating a 0.17. The level of detail it's amazing but it takes ages to print.

Edited August 2, 2015 by Guest

[neotko 1,417]

 

Then the question is - why Ultimaker does not support STEP? We send our files to machine shops here in the US, and to China - all CNC shops understand that format.

 

It seems to me that supporting STEP files is on the wishlist for a long time. Perhaps it's worth to reopen this old discussion about Stepfiles and G02/G03 arc gcodes?

 

Yes please! I wonder how much processing this needs and if the board of umo could handle it. Isn't atmega a bit old? I mean I suppose that even when 'it's ok' a bigger cpu should open new possibilities

[andrey_filippov 1]

Yes please! I wonder how much processing this needs and if the board of umo could handle it. Isn't atmega a bit old? I mean I suppose that even when 'it's ok' a bigger cpu should open new possibilities

 

Neotko, I believe it is not about atmega - it is about Cura being able to import STEP files (STEP has arc support, STL - does not). And about Ultimaker - I did not get reply if it supports arc primitives (it both reduces file size and makes it easier to maintain constant speed of the extruder). Actually you do not need to have any CPU power to draw an arc (even elliptical) - you can do it with a 40-years old 8-bit microprocessor easily. If you have a rasterized grid (like motor steps) you can generate a sequence of 1 of 8 (using diagonals) or 1 of 4 (only orthogonal steps) using just integer addition, subtraction and comparison. You will need to use multiplication only at arc set up, not for each step. And no square roots, of course :-) .

[andrey_filippov 1]

Maybe this project can help to add STEP support to Cura?

It is LGPLv3: http://www.pythonocc.org/features_overview/data-exchange/