Miter-fold joints on the CNC

Anyone have any experience with this process? I’m trying to build an open top, nesting box (top slides over bottom, for a game board)

I’ve found a couple of references, (Design into 3D miter box - #7 by WillAdams - Tutorials - Carbide 3D Community Site) but cannot seem to duplicate the effect.

Stock is 9mm baltic birch.
Vbit selected is the 301 (.5"diameter, flute length .25")

As I understand it, I need to program a vcarve tool path 2x the thickness (in order to allow for a full v) and just shy of the full depth of the material thickness. When I run the simulation, I still get a shoulder on the cut- this shoulder reamians even if I increase the width of the v. (see attached pic). is this a simulation error or are the shoulders going to show up? Do I just need a larger vbit?


My first response is to model it in 3D(Fusion360, FreeCAD, etc) and then toolpath generation in Kiri:moto but I think since already deep in 2D V-Carve why not just tell it your stock is another 1/8" or so thick?

Thanks for reading and responding.

My apologies for not understanding the remark about the depth- the bit DOES appear to go to the required depth, it just appears (in the simulation) that the v bit ‘trenches’ and doesn’t form a full v. This COULD be a Carbide Create preview issue. I could go into the shop and run a test, but i ideally like to have my design issues resolved (to the extent possible) before i go in as shop slots are precious.

3D modeling is a whole 'nother dimension (inadvertent pun) past where I am now in terms of digital design.

Thanks again!


The way I’d go about making that cut is V-carving a pocket equal to twice the thickness of the material with a 90 degree bit. To form a 90 degree corner you’ll need two 45s and the lovely thing about a 90 degree bit is the math. For every X" down, you’ll cut X" out on either side. Below is a material 0.25" thick.

Using Carbide Create I made a rectangle 0.5" wide, defined an Advanced VCarve tool path using a 301 (90n degree, 0.5" wide) which went down the thickness of the material. Voila! With a little blue tape as a hinge go hold it together as you fold and glue it, you’re set!

Capto_Capture 2021-06-16_07-52-39_PM

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Ken, what I was getting at was the fact that if your stock was actually shorter by the depth of those shoulders then there would be no shoulder on the final work.

Maybe Travis has the better solution, ie use a 90 deg bit.

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