Circle not perfect

Discussions about ideaMaker and other printing software.
budi67
Posts: 58
Joined: Sat Oct 15, 2016 5:56 pm

Circle not perfect

Postby budi67 » Sat Dec 17, 2016 12:21 pm

Hello all,

I don't understand why my cricle are not correct.
3 shells

Any idéa ?

Image

Thanks

Zettlinger
Posts: 412
Joined: Mon Mar 21, 2016 11:48 am
Location: Roosendaal, Netherlands

Re: Circle not perfect

Postby Zettlinger » Sat Dec 17, 2016 8:12 pm

you mean the outer line? that its facets?

Your printer doesn't understand the concept of circle or arc so in the stil its basicly a sequence of small straight lines

If you see facets that usually means you set the tolerance too low (i usually try to set it to 1 degree for a nice circle)

btw what temp and flowrate do you use? you might be overextruding a bit ?

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dhylands
Posts: 119
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Re: Circle not perfect

Postby dhylands » Sun Dec 18, 2016 6:29 pm

The issue goes back to the STL files. STL files are basically a collection of triangles, which means that any curved object will get broken down into straight line segments. The resolution of these segments will be determined by the CAD program that you used to generate the STL file with.

You need to re-save the STL file with a higher number of facets and re-slice.

firesped
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Location: Tucson, AZ

Re: Circle not perfect

Postby firesped » Sun Dec 18, 2016 8:01 pm

ultimately, CAD or 3D software can't draw circles either. For instance, in sketchup, I tell it to make a circle. It draws a circle using a bunch of straight lines. The number of straight lines is going to determine how perfect that circle is going to be. A circle has 360 degrees. In order for it to be a perfect circle, you need those 360 point connected by lines. so 361 lines. However, the distance of those lines may be too small, so you might have to go with less resolution to get those lines longer.
RL name: Michael Nolen
printers:
raise3D N2 kickstarter Early Bird
Trinus Deluxe (running smoothieware on Azteeg X5 GT board)
Monoprice Maker Select v2

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dhylands
Posts: 119
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Re: Circle not perfect

Postby dhylands » Sun Dec 18, 2016 8:27 pm

Well. that isn't really true. Most CAD programs have no issues exporting curves (if the exported file format supports it). For my CNC mill, I export DXF with actual curves, and the generated gcode contains curve commands.

Some CAD programs, like Rhino, when converting curves into lines, will have a tolerance, and will allow you to control how far the line deviates from the curve and use that to determine how many line segments to output. I'm not familiar with SketchUp, so I don't know what controls it has for exporting STLs.

I know OnShape has Coarse, Medium, Fine and custom settings for exporting STLs, and the custom setting lets you specify angular deviation, chordal distance, and minimum facet width to control the number of triangles generated.

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walshlg
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Re: Circle not perfect

Postby walshlg » Mon Dec 19, 2016 5:55 pm

Yes and even Onshape, exports stls as triangles, not curves

budi67
Posts: 58
Joined: Sat Oct 15, 2016 5:56 pm

Re: Circle not perfect

Postby budi67 » Mon Dec 19, 2016 7:00 pm

Thank you for all this information
I would make various tests for even

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dhylands
Posts: 119
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Re: Circle not perfect

Postby dhylands » Tue Dec 20, 2016 4:37 am

walshlg wrote:Yes and even Onshape, exports stls as triangles, not curves

Absolutely, and I never claimed otherwise.

OnShape will export curves to file formats that support curves. STL isn't one of those. It's not a deficiency of the CAD program, but rather a deficiency of the file format.

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walshlg
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Re: Circle not perfect

Postby walshlg » Tue Dec 20, 2016 1:37 pm

Interesting, I never knew stl didnt support curves!

budi67
Posts: 58
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Re: Circle not perfect

Postby budi67 » Sat Dec 24, 2016 8:50 am

Thnaks for your answer
I understand better now ;)

caromonster
Posts: 1
Joined: Mon Jun 12, 2017 9:11 pm

Re: Circle not perfect

Postby caromonster » Mon Jun 12, 2017 9:58 pm

Would this be a good solution? Make the object have more than 2 shells, then sand the object smoother. If you over-sand, you can always use wood glue or mod-podge. I'm going to test-print some cylindrical spikes that I drew in SketchUp, exported as .OBJ file then brought into ideaMaker.

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walshlg
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Re: Circle not perfect

Postby walshlg » Tue Jun 13, 2017 12:46 pm

I do tests on critical holes and measure the errors, mostly holes are right on to about .25 mm too small. If doing holes I use LOTS of shells (6) and denser fill

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Brandon
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Joined: Fri May 05, 2017 1:22 pm

Re: Circle not perfect

Postby Brandon » Tue Jun 13, 2017 2:02 pm

I've spent a lot of time trying to understand the intricate relationship of data inside CAD programs like Solidworks and the exported data. I have had the opportunity to speak with one of their developers about differences in Exported files. The point is the issues with exports are not always straight forward especially if you work with different CNC machines. I have a demo I use to test fastener fits when designing cases. It serves a purpose and might be good for some testing. As a test piece this is all negatives so it is only 50% of the equation, someone could make one of these with offset positives about 5 mm tall, it would be more fitting for tests. I'm sure there is probably a better test piece on the net.
small.jpg
Attachments
Holes in MM demo.stl
(143.34 KiB) Downloaded 176 times

Sreevatsa
Posts: 1
Joined: Wed Jul 11, 2018 7:30 am

Re: Circle not perfect

Postby Sreevatsa » Fri Apr 19, 2019 12:43 pm

Hi,

I tried printing circular holes but it was printed as an oval.
Please help.
Attachments
1.jpeg

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Vicky@Raise3D
Posts: 6925
Joined: Fri Mar 25, 2016 3:54 am

Re: Circle not perfect

Postby Vicky@Raise3D » Fri Apr 19, 2019 6:28 pm

Seems that there is something wrong with your couplers. Please check your couplers in both X and Y directions and take video of couplers movement when the extruder is moving around and share videos at http://help.raise3d.com with our technicians to help diagnose your issue.


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