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Tolliver: an app for dialing in hole tolerances

Posted: Fri Jul 15, 2016 2:54 am
by CastIrony
I'm able to get away with pretty loose tolerances for most of the work I do, but every once in a while I need to cut a hole with a very precise size to achieve a particular fit to some other pice. The easiest way I've found to do this is to cut a bunch of holes at different sizes, test which fit the best, and repeat until I get exactly the fit I want.

Drawing out all of those holes in a CAD program can be pretty slow, though, so I wrote a simple tool to automate the process which I'm calling Tolliver.

Just tell it some basic information (shape name, total width of your material, spacing, size of the center hole, ratio of biggest hole to smallest, etc.) and it will generate a DXF, ready to be imported into a CAM program of your choice and cut. It supports circles, triangles, squares, rectangles, hexagons. The latter three have full support for dogbone corners. The program is easy to run iteratively, just use the best hole from the previous attempt as your center, and the previous delta ratio as your total ratio, and run the script again. After only a few iterations, you'll be approaching the maximum precision of your machine.

Besides a GUI, the main thing missing from this app at the moment is SVG output. Unfortunately, Carbide Create doesn't seem to like the DXF files I'm generating, so for now you'd need something else to convert it.

I hope this will be as useful for other people as it has been for me so far. Feel free to mention any issues, ask for help, or offer feedback!

Re: Tolliver: an app for dialing in hole tolerances

Posted: Fri Jul 15, 2016 9:09 pm
by CastIrony
Here's a set of cuts I did to find the ideal press-fit diameter for a 10 mm bearing. Actually managed to get a good result on the first try!
2016-07-01 17.41.45.jpg
2016-07-01 17.41.45.jpg (59.05 KiB) Viewed 863 times

Re: Tolliver: an app for dialing in hole tolerances

Posted: Sun Jul 17, 2016 12:06 am
by DRobs86
Cool. I will check it out sometime.

While I realize this wasn't the point of your post, I have had good luck with bearings in wood by modeling the hole the exact size of the OD then putting a small radius (a mm or two) on one side then pressing it in.

Thanks for sharing the software.