CNC Dove Tail Joint

For this project I was assigned to make a dove tail joint using CNC and modeling it using rhino. The point of this joint is to show the advantage of the CNC in that it can cut out joint which would be too hard to do by hand.

(Edit Sep12: this kind of Joint is designed to make a corner with 3 pieces and leaving as little seam as possible while making the corner durable against the force inwards.)

First I made the sketches.

I used a filleted triangle shape as the dove tail, and a filleted rectangle as the groove/trail(?) in the middle.

Then I mirrored the piece and connected what was necessary. And then using "offset" I was able to make the outline for making "pockets" in the CNC.

Here in the picture, the helping lines and the pocket outlines are in red, while the outline of the actual piece is in black.

Then I edited the model in Carbite to get CNC ready.

I edited the tool path and set the pocket depth to 9mm per side, and for the grove and rail, it was 5mm and 13mm.

I added the tabs and saved it as .nc.

Then CNC!

(Edit Sep12: for the board I used 18 mm jointed () wood. Since there are two pockets overlapping inside the same piece (the one to the right), I had to select both the outlines and exclude in area inside for the first pocket, and then re-select it to make a pocket of it's own, otherwise it would remove the groove in the middle by cutting a deeper pocket over it.)

The pieces came out having a bit larger curve on the end of the groove than expected. So I took some chisels and removed the extra part so that they fit.

(Edit Sep.12: I later fixed the file so that there won't be any extra bit left)

I also did a bit of sanding to make sure the pieces fit together, also got rid of the tabs left.