3Dprinty
Posts: 6
Joined: Sun May 26, 2019 1:53 pm

Accurate hole dimension using polygones

Wed Jun 12, 2019 7:18 am

As described in the article below, polygons with low vertex count seem to not shrink and can replace "round" holes.
http://hydraraptor.blogspot.com/2011_02_01_archive.html

A feature that suggests to replaces holes by polygones automatically would be interesting.

gearsawe
Posts: 141
Joined: Sun Sep 10, 2017 11:06 pm

Re: Accurate hole dimension using polygones

Thu Jun 13, 2019 1:15 pm

You may be reading the graph incorrectly. The greater the vertex count the better. The scale goes from 0.5-1 on the left side where staying closer to 1 is better.
Also this is a function of the CAD software on export. I you want a better print decrease the surface deviation and/or angle which produces finer more accurate model.

Also there is a second problem with making lines to small where some firmware setups will combine multiple lines into one straight segment anywaye if they are to short.

Looking at how the wholes where generated in the article is not how most CAD software works. The polygon wholes circumscribe the circle they represent where CAD deviates from the surface making the polygon inscribe in the circle it represents. There test is not setup correctly is respect to how CAD software actually generate the geometry.

Bellow is a small whole in two different models with 2 different deviations one at 0.001mm and another 0.01mm. (note: your cheap digital calipers don't measure smaller than 0.01). you can see the whole is smaller over all with the larger deviation as it deviates more from the other with much finer detail.
Deviation.png

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