Designing, Laying out, and Cutting Double Tenons to Attach the Workbench Top – Part 1

These legs seem to be taking a long time to make.  I have the mortises cut and the tenons fitted.  Now I need to cut the legs to length and cut the double tenons on the top of them that will attach the benchtop.

I spent a lot of time reading and researching about workbenches before I began this build.  Much of my inspiration came from Christopher Schwarz’ books on benches, but I also did many an image search on Google for other ideas.

When I came to the stage in my planing process, if my jumble of ideas could be called a process, where it was time to decide how to attach the top to the base, I was most impressed by the double tenon joint shown on Roubo’s Plate 11.

A close up of a portion of the Plate 11 workbench.

A close up of a portion of the Plate 11 workbench.

I had some reservations about my ability to execute this joint, and I mentioned them to Chris Schwarz when I met him at the Port Townsend Wooden Boat Festival a year ago. He told me, “just lay them out and cut them.”  Fair advice I’d say.

Here’s a closer view of the leg detail:

A close up of the leg tenons.

A close-up of the leg tenons.

That said,  I don’t want to make mine exactly as they are depicted in plate 11.  I just spent all that time and effort wrapping my benchtop in sapele, so that the bench would have a hard and durable exterior.  I don’t want to cut into that sapele and have the douglas fir leg showing through the benchtop edge.  I really like the double tenons, so I will cut two tenons that will pierce the benchtop, but behind the sapele edge.  I can also widen the mortises in the benchtop a little on the top side and wedge the tenons for a stronger mechanical attachment.

Let’s be honest here, through tenons are not needed.  I could cut hidden/stub tenons that go 1/2 to 2/3 into the benchtop and peg them through the edge.  The benchtop must weigh nearly 250 pounds, it’s not as though it’s going anywhere.   However, dovetailed breadboard ends weren’t “needed” on this bench either, but I’m game for the challenge. There’s nothing wrong with a little bench bling is there?

Before I can cut the tenons, I need to cut the legs to length.

1st leg ready to be cut to length.

1st leg ready to be cut to length.

I marked the leg at 35″ and began.

I made a mark at 35 inches.

I made a mark at 35 inches.

After reading Paul Sellers rave about his Stanley fold out knife on his fantastic blog, I ordered one from Amazon.  I like it.  It excels at marking a deep layout line and can handle being pressed with a fair amount of force.

Square a line across from the mark.

Square a line across from the mark.

I squared a line all the way around the leg.

Square the line all the way around the leg.

Square the line all the way around the leg.

I started the cut with a backsaw and cut diagonally in from each of the four corners.

Start in the corners and follow the lines on two faces at once.

Start in the corners and follow the lines on two faces at once.

Cut the other corner until it intersects with the first.

Cut the other corner until it intersects with the first.

Completed with the panel saw.

With all four corners started, I finished the cut with my panel saw.

With all four corners started, I finished the cut with my panel saw.

The end is a little rough, so I’ll clean it up with a block plane.

Leg cut to length.

Leg cut to length.

To immobilize the leg for planing, I clamped it to the edge of my benchtop.

I clamped the leg to the edge of the workbench.

I clamped the leg to the edge of the workbench.

I cleaned up the end-grain.  This part will be trimmed away later, so this is not being done for any cosmetic purposes, but I want to have a clean and relatively smooth surface on which to lay out the tenon lines.

I used a block plane to clean up the saw cut.

I used a block plane to clean up the saw cut.

Ready for the tenon layout lines.

Ready for the tenon layout lines.

I got to this point and froze.  I had been putting off this decision for ever and ever, but… How high was I going to make the bench?  I hummed and hawed for a while and measured every other counter-top and tool table top in sight.  It was paralysis by analysis for sure.  In the end, I said to myself, screw it, I’m marking the tenon shoulders at 30 inches.  With a benchtop thickness of 4 ½”, this will give me a workbench that stands 34 ½” tall.  That’s about 1″ lower than my grizzly table saw and 1″ higher than the benchtop is right now sitting on saw horses.  It’ll work.

I marked the leg at 30″ and proceeded to square a deep line all the way around.

I marked a line 30" from the bottom of the leg.

I marked a line 30″ from the bottom of the leg.

Marking tools.

Marking tools.

I then used a chisel to remove a little wood and create a sharp knife wall.  This will serve and the base line for the tenons and guide the saw in later steps.

I used a wide chisel to remove some wood on the waste side of the knife line.

I used a wide chisel to remove some wood on the waste side of the knife line.

To make the knife wall more pronounced, I deepened the line with the chisel and removed a little more wood on the waste side.

Use light taps to deepen the knife line.

Use light taps to deepen the knife line.

I created a fairly deep "knife wall" all the way around the leg.

I created a fairly deep “knife wall” all the way around the leg.

I deepened this line on all four sides of the leg.

This line will serve as the baseline for the tenons.

This line will serve as the baseline for the tenons.

And then I repeated the process on the other three legs.

The process is repeated on all four legs.

The process is repeated on all four legs.

I had intended in this post to show the complete layout and cutting of the leg double tenons.  However, I’m up to about 20 images all ready and have at least another 25 to go. Since I didn’t open with the words “Call me Ishmael”, I suppose I should break this into two posts to stop it becoming an epic.  I’ll post the rest tomorrow.

More soon

 

– Jonathan White

 

About Jonathan

I am a woodworker and hand tool restorer / collector. I buy too many tools and don't build enough - I need help!
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