Monday, March 14, 2016

Project Update: The Roubo Leg Tenons

Once I got the tops of the bench legs evened up, I could start the exacting process of cutting the tenons into them. Tenons are the siblings of mortises - they're the relationship's male half that are inserted into the mortises once they're cut. In fact, the way they're cut is to trace the tenons onto the mortise surface because every tenon has its own set of unique characteristics. Yeah, no two are the same, especially when I'm cutting them.

The first thing I did was divide up the tops into more or less three equal parts with a little notch left over. Once I got the lines drawn and cut to depth, I sawed out the small piece.

This left two tenon parts that ended up being significantly more difficult to complete than I could have ever imagined in my wildest nightmares. Okay, it wasn't that bad, but I'm not accustomed to working tenons or joints of this scale. The next part I tackled was to removed the center piece to create some negative space.

At first, I decided to hog them out using a Forstner bit on the drill press. After a break, I realized I could just bandsaw out this piece using the 14" Laguna with the 1" blade and then finish it up using Little Buddy, the 12" Delta.

This worked well and I was able to cut the space right to the cut line.

The next step was to tackle the dovetail joint at the front of each leg. Now, this might seem like an easy, straight cut. It's not. In fact, it's difficult for a variety of reasons. First, how does one lash the leg to the assembly table for cutting? Answer: 50" clamps and a smaller one at the base for stability. Next, how does one start such a cut? I came up with the hair-brained scheme of using my small, battery-powered Skil saw. Nope - it resulted in what I can only describe as a cut just this side of disaster.

After completing the two in the photo above, I was pretty demoralized, so I went inside and watched Bad Grandpa. It helped. While watching the movie, I decided to text Random Roger Green and he responded with an offer to come for a visit. Thank goodness. When Roger arrived, I think he could see I was about one step away from jumping off the ledge and, frankly, giving up the project. In all honesty, I had been thinking, "What am I doing? I'm in over my head here. I have no business trying to build this thing." You know, helpful self-talk.

Within ten minutes, Rog had talked me back from the ledge with comments such as, "I don't see anything here that really scares me," and, "Remember, it's just a bench." He also reminded me that we had cut the legs to allow sufficient room for major screw-ups; they're all cut at around 36" and the end result needs to be 31" long to reach the bench top. This means I could cut a really nasty tenon 4 1/8" deep and still had room to remove it and cut another. He also reminded me of Chris Schwarz's quote about taking small bites and nibbles and moving slowly, which I'm not really inclined to do.

So, I dove back in and started cutting again. Slowly. I started the first cut carefully using a small saw loaned to me by Random Rog. When I say slowly, I mean drawing one saw tooth at a time into the top. This is difficult because it's end grain and fir is not the easiest wood to work with because it's so soft. I eventually got the cut line started and I switched to a large tenoning saw also loaned to me by Random Rog. The first dovetail came off without a hitch - it was nearly perfect.

The last one, not so much. I think I rushed it too much in celebration of my stunning success with the third leg. Somehow, I was able to get the saw blade off track, resulting in a complete disaster. I sent a photo of the mess to Rog and his response was, "Well, good, you can practice again," So, tonight, I'll cut off the tenon using the Laguna and sled and have a little do-over party. Again, I will proceed slowly and carefully and, hopefully, have all completed so I can start the exacting and terrifying process of cutting the mortises into the bench top.

Until next time...

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