Mortise and Tenon Miter Joint?

 This sample languished forgotten in the bottom of my box of Sample CNC cut joinery.  I was sorting out that box and nearly threw it away as it appears to be a simple miter joint.

Looks Simple

Pulling it apart reveals the inner mortise and tenon that hold it together.

Surprise Inside!

The tenon was cut from what is normally cut off to make a miter joint. Mating mortise cut on the other side face. There is no weak cross grain in the tenon. This tenon also keeps the faces aligned when gluing up the miter. While I cut both sides on my CNC, I'm pretty sure this could be duplicated by a clever craftsman without using a CNC. 

Very much the best of two joint types working together to make a strong connection where there is normally a need for added reinforcement. 

With wider boards, each side can have a tenon and a mortise.  Identical cuts using a CNC.  Tenons on each side slide into the mortises on the other side. 

Comments encouraged!

4D 
 

 

Small Trays Made From Leftover Scraps

I have A CNC. I have a bottle of wood glue, and several clamps. I also have several small odd shaped wood scraps begging to be used for something useful.   

Small scraps glued up can make larger boards. Here are a few shallow wood dishes/trays all made from glued up scraps.  

This first oval dish was cut from three maple scraps glued together. I used my CNC to cut the top recess and rounded edge.  Then used my router table to bevel the side 11.25 degrees, and follow that up with a small 45 degree transition to the bottom.  

Oval Tray

This second tray was the best shape to make from two glued up corners saved from a hexagon table top cutout. 

Diamond Tray

This walnut version was made from several walnut scraps. Add in patching two screw holes with walnut dowels to increase the potential final size. For this one I used the modelling tool in Aspire to create the center recess. It also has a 45° chamfer on the bottom edge.  A rounded rectangle.

4" x 6"

This 4" x 4" Cherry example required several bit changes, and used the VCarve toolpath to make the crisp inside corners of the dish. It used up the left over corners from a round plant stand cutout. Its shape echoes the shape of the glued up corners. 

V-Carved Cherry Dish

Several bit changes were required.  Bits used (in order) were a 3/16" end mill to clear out the center area of the dish, then a 60 degree V-Bit to slope the sides and create the sharp inside corners. A 1/4" end mill cut a clearance path for the final bit and profile out the final shape.  Last bit used on the CNC was a side cutting V-bit to put a groove around the sides as shown below.

VCarved, V-cut, and beveled. 

As with all of these trays some follow up work was needed.  The waste perimeter was roughly cut off using my bandsaw.  A flush trim bit cleaned up the bottom edge on my trim router table.  Lastly a 45 degree chamfer bit beveled the bottom edge. 

Beveled bottom and side groove.

Lastly, an octagon dish. Made from one scrap board nearly 11" long and 2.6" wide.  It had a rough bark side.  I cut it in half and glued the good sides together to make a roughly 5" x 5" block close to 7/8" thick. The inner and outer sloped sides were 3D toolpaths.  The center of the top was a pocket toolpath to bring it down to the bottom of the inner sloped sides.  Hard maple with tight grain cut nicely on the CNC. 

Octa Dish

These are small examples of the value you can find from small scraps of wood left over from previous projects. Glue thin scraps together to make thicker boards that may be more useful. Any scraps with a straight edge can usually be glued up to make a larger board.  A trip across a jointer may be needed to face the edges for the best glue joint. I have a small benchtop jointer that is perfect for this task. Its small expose blade gap between tables make it safer than larger jointers with a larger expose blade gap to slide over. 

So save those odd scraps.  When boredom or inspiration strikes take a few and glue them up to make a larger board that can become something useful.  

Comment encouraged!

4D

Steep Dovetail Corner Joint

 

Face to Face

This is a sample I made to show my Furniture Design students one way to connect wood at a steep corner.   A variation was used to connect the top of A-frame legs on a CNC controller cart the students made. The parts slide together, so technically this is more of a French Dovetail solution. 

Open for Inspection

Careful layout of vectors was require to guide the dovetail bit.  Each half had to be clamped at an angle so the bit could travel level through the ends. My compound angle clamping fixture was used for that task. 

One half slide down into the other

There is a taper to one side of the cuts to compensate for the wide top sliding down to the narrow base of the dovetail shape. This joint only slides together in one direction. 

Tails into Slots

Once together there is no play between the halves,  Snug tight.  This sample has been abused for inspection by students and is a bit worn.  A little glue and the dovetail interlocking would make a very strong steep corner joint. 

Snug Together

I am considering using this joint for the corners of a triangular mantel clock box frame.  With a shallow dovetail corner variation at the top of the triangle. 

All Stood Up

Ends were trimmed so when assembled the end would be flat across. At the top the dovetail pattern is evident and interesting. 

I realize this steep angle is a rare occurrence in projects.  Knowing this joint is possible and how to cut it though keeps it on my menu of options when designing furniture and accessories.  

Comments are encouraged. 

4D