The next step in the birch bench build was to cut the tenons for the leg to top joint, drill holes for drawbores, and glue (most) of the base together

Tenon Time

Disclaimer: Sometimes I get the Tenon terminology switched (shoulders and cheeks).  I think I have a good way to remember them now.  Imagine the tenon is pointing to the ceiling.   Then imagine a person standing up.  Cheeks are up high and shoulders look like someones shoulders.

The  process is much like the other tenons.  The only differences are that I don’t have the mortises cut yet and I need the shoulder to align with the horizontal stretcher.  I want the weight of the top to be supported by more than the leg tenons.

The tenons are 3 1/4″ width (length of bench) by 2 1/2″  deep and 2″ tall (vertical).

1. Dry fit short stretchers to legs and mark top surface of stretcher on leg
2. Layout rest of tenon on leg and carry stretcher mark all around
3. Cut cheeks and faces with bandsaw (and featherboard)
4. Cut shoulders with table saw
5. Clean up shoulders, if needed
   1. Sometimes there is a bit of misalignment between the four different cuts on the table saw
6. Dry fit again and ensure decent alignment with upper stretchers
7. Done for now

Drawbores

I wanted to glue and drawbore the base together for that belt and suspenders feeling.  To get things started, I layed out the holes on the legs for all 6 locations.  4 short stretchers and 2 long stretchers.  I went with 3/8 diameter dowels.  I bought the standard oak ones from Home Depot. The layout was pretty straightforward.

1. My tenons were all roughly 2″ long, so I chose 1 ” as my offset.  This is the dimension from the edge of the leg where the tenon shoulders contact.
2. I also marked the edges of the mortise onto the same surface that I am going to drll into.
3. Roughly split into thirds and mark the two spots for the drill centers.
   1. I wanted three equal pieces of tenon left over on each side of the dowel hole
4. Drill 3/8″  holes at each marked location with the drill press
   1. I used a scrap for backup to avoid blowout on the inside of the mortise and drilled as deep as I could
5. I finished the drilling with a corded drill to a depth of ~4 1/2 inches

The next step was to dry fit the stretchers (again) into the legs and mark the locations of the holes that were just drilled onto the tenon.  Reading Chris Schwarz’s book (Workbench Design and Theory) was very helpful throughout this process, consider buying it. 

One thing to keep in mind is to use a square when transferring holes and use the same drill bit to mark the centers.

Drawbore Magic

Once the centers are transferred onto the tenon, its time to create the magic of drawboring.  Mark a location 1/32 to 1/16 closer to the shoulder than the previously transferred hole.

It is tough to see, but the second mark is a little closer the to the shoulder and then dimpled with a center punch.

Next step is drill a 3/8″ hole at the offset location.  When a dowel is pounded through it tightens up the joint much like a clamp.  It also add some pins on top of the glue for strength.  I drilled these holes with a back up scrap on the drill press for all 10 tenons.

I performed another dry fit.  At this time I am a little concerned with the small tenon behind the criss cross in the long front stretcher.  I am concerned that driving the dowel may crack the  tenon.  So I filed a little bit off the tenon dowel hole, making it an ovalish shape.

Dowels, Glue, and a Hammer

Before I jump into gluing the leg sub assemblies I need some dowels.  I bought 3/8″ oak dowels from HD, cut to ~5″, and tapered one end with a utility knife.

Next I got my glue bottle ready and started to quickly put glue in the mortise and on the tenons.  I inserted the stretcher into the leg.  Then add some glue to the dowel and pound them in (alternating between the two per tenon).  I was a little hesitant to really hit the dowels hard, but that fear was quickly overcome.  For some reason, I also felt the need to add clamps, but I don’t think they were doing much.

I am waiting to glue the long stretchers until the top is finished.  The two sub-assemblies take up a lot less space than the whole base glued together.  They also weigh less and I will have to put the base onto the top to transfer the tenon locations.   Stay tuned.