UpDn Diamond Corner Joint

UpDn Diamond Interlock

This is another test corner joint.  It uses a 1/8" end mill rather than a 3/16" end mill to cut both sides. The same initial vector was used for both sides.  For the male side a perimeter line around the end was added so it would pocket out the surrounding wood. On the female side a profile beside the line and clearing profile on the line were used to cut the negative shapes. 

Female Side. Walnut

For contrast the female side was cut on the top end of a walnut board.  The male end was cut on end of an oak board.

Male Side.  Red Oak

Not knowing how exact the dimensions of the bit used were, I made two toolpath versions of the male side.  One with no added allowance, and the second removing an additional 0.003" to allow for some glue room if the first toolpath was too tight. 

The female side was cut first, clamped vertically in my Bridge Vise.  The impractical aspect of such joints done with a 1/8" bit is that it take several passes and considerable time to step down 3/4" around and inside the diamond shapes. 

The male side was cut clamped flat across my bridges with its end hanging over open space.  After it finish I checked the fit and found it too snug to slip together easily.  I made a profile pass with a .003 allowance and recut the end.  Second try the other side slipped on smoothly with no extra force needed.  

Both Sides Cut.

The straight grained oak helps emphasize the contrast.

Nice Contrast

Partly together.

Almost

Fully together.

Fit is perfect with a 0.003" gap for glue.

Once glued together, sanded, and with some finish applied this joint would be a nice surprise to discover on the sides of a kitchen drawer when opened.  It should easily be as strong as a dovetail corner joint. 

With one coat of Tung Oil

The interlocking diamond pattern might be nice for the corners of a jewelry box. With a 1/8" bit as long as your boards are thick many variations can be made for corner joints like this one. Imagination, knowing how to configure a CNC for vertical (and angled) cuts, and some understanding of wood properties are all that is required. 

4D 


 

Square Interlock Corner Joint

Square Interlock Joint

This joint, cut on my CNC, could easily replace half blind dovetail corners for strength.  It can only be assembled in one direction.  It won't pull apart sideways.  As with many of the CNC joints I've come up with it uses the same vector for both sides of the joint.  One side is cut on the end of a board clamped vertically.

Side A. Clamped Vertically

The other side is cut on the end of a board clamped horizontally. 

Side B.  Clamped Flat.

This joint is half blind, showing only on one side of the corner.  

All the corners are rounded to account for the 3/16"diameter end mill used to cut the joint. A sharper cornered version could be cut with a 1/8"diameter bit if the cutting length of the bit was as long as the boards are thick. 

This sample I made from some pine board scraps.  When both sides were cut they slipped together easier than I expected.  This suggests that the bit I used was a little bit larger than .1875" in diameter.  More than enough room for some glue. 

Sample Ready to Assemble

The positive and negative sides together look a bit like a zipper.   

Partly Together

Drawer sides would be a good place to use this joint.  A drawer that holds sewing supplies would be a perfect application for it!

Glue Together and Sanded Flush

As with dovetail joints, the spacing between squares could be varied for a more personal design. Your imagination and the size of router bits available are the only limiting factors. 

4D