Sunday, June 3, 2007

Challenge Table: Plug Jig

The original version of the Thorsen House table, and the version published in Popular Woodworking magazine (which was the inspiration for the challenge) both include square plugs on the legs, breadboard ends, and stretchers. I had intended to include plugs on my table but time got the best of me and the plugs did not happen.

I did, however, cut the plugs. (Now I've got a pile of plugs in my shop. I'll have to find another use for them.) To ensure that the plugs were equal in size I made the jig pictured above. This jig isn't perfect, I'll get to that in a minute. First a description of this jig.

The plugs for the table are square. So I needed a way to hold the small (1/4" square) rod while accurately cutting 3/8" long plugs. I decided the safest way to cut them would be with my Nobex miter saw, which is human powered. There are two pieces which support the stock - one on each side of the saw blade, a sliding stop which runs in dadoes in side extensions, and a base.

To ensure that the holes in the support blocks were aligned I used double-sided tape to join them. Then a 1/4" hole was drilled through both. The hole was squared up with a chisel. Then the support blocks were screwed to the base, and the extension wings were screwed to one block.

To use the jig the stock is pushed through the two support blocks with the stop in the closed position (it's in the open position in the picture above). Then the plug is cut. Once the cut is complete the stop is raised and the plug is pushed out.

What I'll do differently next time:
  • the jig is much taller than necessary - the next one will be shorter
  • there isn't enough size in the base to easily clamp it to the saw - the base needs to be longer and deeper side extensions wouldn't hurt either
  • aligning the two support blocks for screwing to the base was tricky - next time I'll make a shorter support block from a single piece of wood and cut it in two after the jig is assembled.
  • chiseling the square hole accurately was difficult - next time I'll cut a 1/4" x 1/4" dado in the bottom of the support block before the support block is attached to the base, and before it's cut in two. This will also provide better support for the plug stock and limit vibration.
The bottom line is that the jig worked but could have been better.

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