Roubo Is Coming… Part 5

After several months of work, this is the moment when the various components of the workbench start to come together and look like something. There’s a great deal of distance left to go, but I now have the makings of a workbench undercarriage.

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Marking the tenon shoulder with the Vesper 4″ square and Hamilton marking knife

Cutting the mortises for the short stretchers was enjoyable but slow work, so I was looking forward to swapping my chisels for a tenon saw and cutting the second half of the joint. This is much faster work, even accounting for fine tuning the joint. When I laid out the mortises I had locked my marking gauge in position, and it will stay at that setting until the undercarriage is completed. I laid out the bare faced tenons with the marking gauge, and then scribed the shoulders with a square and marking knife, before shading in all of the waste with a pencil.

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The Roubo Beastmaster is the definition of controlled aggression – it ploughed through this 3″ oak tenon like the Apprentice ploughs through chocolate brownies

To cut the tenons I reached for my Bad Axe Roubo Beastmaster tenon saw. This build was one of the reasons I originally ordered this saw, and at 18″ long with 5″ depth saw plate it is a substantial tool. The key to cutting any joint is to establish a saw kerf to guide the saw through the entire joint, and cutting the tenon cheeks takes three cuts. First I set the stretcher at an angle so I can work to the layout lines on the end of the stretcher as well as one side. This keeps me cutting straight on both vertical and horizontal planes. I start at the corner nearest me, and keep sawing until I hit the far corner of the tenon end and the baseline on the side facing me. I then flip the tenon over and work down to the baseline on the newly exposed face, using the saw kerf along the end of the tenon to guide me. Once I hit that baseline, I place the stretcher vertical in the vise and cut out the triangle of waste that remains above the baseline.

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After making the first cut, turn the stretcher over and cut the second side, using the existing saw kerf to guide you.

Once the cheeks are cut, I cut the shoulders (this time with a Bad Axe Bayonet saw, filed hybrid – this is my “do everything” utility saw, as I’ve written before). The tenon shoulders are a “first class cut” and so I keepen the knife line with a wide chisel and pare out a small trench to guide the saw. Placing a finger gently on the toe of the saw prevents it from jumping out of the cut, and I saw down to the layout line until the waste pops out.

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Cutting the shoulders with the Bad Axe Bayonet

Placing the tenon in the corresponding mortise helps to identify if there is any tuning or further material to be removed. A broad chisel helps to remove any small humps from the tenon cheek, but to be honest if you have cut the tenon carefully you shouldn’t need too much tuning. Gently chamfering the corners of the tenon helps it to slide in smoothly without any junk in the corner of the mortise (often the hardest parts to clean out) fouling the fit.

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Chris Vesper says this is square, which is good enough for me

Once I had a pair of tenons cut I did a test fit with a pair of legs, checking for square with my Vesper 10″ square (the final arbiter of square in my workshop). I now have two subassemblies of legs connected by short stretchers, and next will be to cut the mortises and tenons for the long stretchers.

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One of the two completed sub-assemblies. Now to cut the joinery on the long stretchers and connect them all up.

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