Negative Space Tolerances

I was able to pass all of the Make 2015 test pieces with the exception of the negative space tolerances. See pictures and settings for test below:

[www.thingiverse.com]

Does anyone have and advice on how to achieve a higher accuracy on negative spaces?

Cheers,

Hi Ryan,

I am not sure what this test represents. They talk about radial tolerance and, I assume, you are saying you cannot remove the peg marked 0.2?

Are they saying here that the peg exhibits a 0.2mm clearance from the hole all round? What about the squashing of the extruded filament and the convex edge it creates? If the slicer does not compensate for that you would probably get a tighter fit.

You are already using Skeinforge so I would imagine the application of nophead's W/H modification for perimeter flowrate is important. Perhaps modifying that parameter is the solution.

It is nice to see that the Mendel90 can achieve top scores. Well done!

Regards,
Neil Darlow

Edited 1 time(s). Last edit at 11/19/2014 06:16AM by neildarlow.

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

Skeinforge with the correct settings should get polygonal holes the right size but round holes and round pegs will be too small. Possibly you can fix that with the stretch module and some trial an error but I always use polyholes to avoid the problem.

The circular error depends on many things, such as the viscosity of the plastic, so it isn't straight forward for a slicer to correct.

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[www.hydraraptor.blogspot.com]

@neildarlow

The test represents how much clearance (Or negative space) your printer needs for parts to not stick together. In my case I was able to remove all of the pegs except the one with a 0.2mm radial clearance. I am using Skeinforge with slightly modified settings from Nopheads original settings they can be found here [forums.reprap.org]

I tried modifying the perimeter flow rate to 0.5 and still wan't able to get the 0.2mm peg out of the hole. I will maybe try my 0.1mm profile which has a Width equal to the nozzle size 0.4mm but I don't think it will work.

@Nophead

You are too smart, the stretch module seems like it will do the trick.

Cheers,

Quote
RyanMark
@Nophead

You are too smart, the stretch module seems like it will do the trick.

Cheers,

Is that in the spirit of the test? Will you be cheating?

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

What is it supposed to be a test of? The dimensions of the results have little to do with the printer, only the slicer, its settings and the calibration.

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[www.hydraraptor.blogspot.com]

The test was used to "rank" a bunch of 3D printers and their slicer settings printed out of the box. Make magazine does a "ranking" every year. Doing the tests let you compare to other printers and their slicer settings. Most of the test have to do with slicer settings (First 5 tests) but a few have to do with the actually printer (# 6 & 7 are resonance tests xy and z).

I don't think it would be cheating as the negative space test as Nophead said is mostly to do with the slicer settings.

Here's how to rank each of the 7 prints [makezine.com]

You can get a copy of how the top 10 ranked here [makezine.com]