Printed circles are not circles...

Hello,

I recently bought and assembled the Ormerod printer. The first test run of the machine (after calibration) was the ormaxis file from the SD card. This printout came out well, so I tried to print some of my own models.
I created two test objects in SolidWorks - one of them is a rectangular box, the other is a solid circular disc, 40mm in diameter and 10mm high. Both of them were exported to .stl files, and ran throught the slic3r software to generate gcodes.

The box was printed almost flawless, but the disc doesn't look like a disc at all - the walls are composed of short straight lines and the printout looks more like a fancy cookie...
I noticed, that any model featuring arcs, is not printed properly.
I tried to enable native arcs support in slic3r ( --gcode-arcs) but this doesn't help.

I am sure that the machine can print smooth circles because it did that when printing the ormaxis file, so what am I doing wrong?

I use the newest release of slic3r (1.0.0RC3) and pronterface.

PS.
I read on the web, that the Marlin firmware (the one in the Duet board) does support G2 and G3 codes, but slic3r does not generate them for any models. Why? I found some other slicer software like skeinforge, but I don't have time to play around - I just want to print, having as much knowledge as needed to do that quickly, but not more...

Slicing is probably the weakest link in 3D printing at this time. There is no perfect slicer and you must work around shortfalls.

I found this about arcs [blog.freesideatlanta.org]

I use a modeling software designed for the graphics industry and it uses triangle polygons and you can set the number or resolution. Doing so I can achieve perfect circles with no visible facets. So you can either try to figure out how to get arcs to work, or you can make higher resolution objects from scratch with high poly counts.

Example attached. Note this example is not as high res as some other round objects I print, I just don't have photos of anything better right now.

Edited 2 time(s). Last edit at 03/09/2014 06:30PM by tmorris9.

I think it i not the slicer that makes the circles smooth. It is the design language that determines the geometrics.

For instance
In OpenScad, you use the variable $fa to define the smallest straight line that makes the arc and thus the circle.
The smaller the variable, the smoother the result.

So you have to go back to the design fase to fix this.

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www.3daybreaker.blogspot.com

Orca V4.4 rebuild to Ramps with Mk8 and E3D, as well as a Rostock Delta Mini and an OLO in backorder :-)

Hi

Im having some issues with holes within objects, and its not printing perfect ones. On my makerbot i got good results. Ive thought i narrowed it down to the slicing of the object, as you can see in the following photos, it doesn't matter if I'm printing a curve within an object i.e. a hole, or if the actual object has a curve in it, the quality is pore at the top.

After reading this thread, could this be a resolution problem?