Tuesday, May 1, 2007

Mortises, Mortises, Mortises

I'm working on cutting the mortises for the challenge table. There are three in each of the breadboard ends, two each in the front legs, and three each in the back legs. For those keeping count that's 16 mortises.

I started cutting these on the dedicated mortiser at class. This is a large free-standing, foot operated machine. Like most of the equipment at the school it has been used and abused for years. (I can't find a picture of anything similar on the web. I'll try to get one on Thursday night.) Even with all of my careful setup, the mortises ended up off center - some worse than others. After careful examination of the mortises I decided that I wasn't happy with them. This left me with two choices - fill the mortises and recut the mortises or recut the legs. Since I'm trying to make this table as perfect as possible I decided to recut the legs, which I did at class on Thursday night. I'd only cut two of the mortises in the breadboards ends and those were acceptable so I didn't cut new breadboards ends.

I decided to finish the mortises on my router table. First up was the purchase of a new 3/8" straight router bit which I did a few weeks ago. I hadn't realized how dull my router bits are until I loaded this one up in my router and made a test cut. So I've added finding a service to sharpen my router bits to my to-do list.

With the new bit in the router, I set the fence. I'm using Norm's method of cutting each twice - running each face of the wood against the fence to ensure that the mortise is centered. This is possible because I haven't yet cut the tenons, so I'll be able to create those based on the thickness of the mortises. Last night I milled the remaining mortises on the breadboard ends. Tonight I finished marking the mortises on the legs, and began the cutting. I decided to start by drilling out most of the waste out with my drill. I chucked a drill bit which is slightly smaller than the final width of the mortise into my drill and started drilling.

I thought I'd carefully measured the depth I needed, but clearly I should have triple-checked it. The drill went completely through the leg! This wouldn't have been that bad except that it chipped out the face which was intended to be left solid. After creating a plug to fill the errant hole, and readjusting which leg is which and which face is the intended outer face I got back to the job at hand. First up - remarking the drill bit, then after cutting a whole lot of holes - one mortise on each leg is 4 1/2" long.

Finally, after checking the router fence using a piece of scrap leg stock, I started working the mortises on the router table. It's going quickly since I've already removed the bulk of the waste. I've got 3 more passes to make on this face of the legs.

On the back legs there are two mortises which intersect - one faces the other back leg, the other faces the front legs. This leaves a very small section of wood on the inner corner of the leg and requires very careful cutting. In preparation for this I've milled a board to fill the mortise that's already been cut and support that small section of wood (come back later for a picture). That wood is a little too thick so I'll need to do some planing/sanding before I start on the other two mortises.

When the router work is done, I'll clean up the corners with chisels. After that I'll be ready to start working on the tenons that will fit into those mortises. 30 days left....

Update 5/3 - Added pictures.

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