Monday, August 25, 2014

The Broken Chisel and the Shameless Birdhouse

The day started with laying out the mortises for the harvest table. This is somewhat finicky work, since if done with care, all other layout will cascade from the mortises, which themselves depend upon the mortise chisel's dimensions. If the outside edges of the mortises are consistent, the slop can fall to the inside where nobody will see it, but a consistent reveal will be visually apparent from the outside.

The kid came into the shop during this procedure, and I tried showing her what I was doing. Then it was time to do the chopping, which I knew she would not enjoy. Still, she insisted... so I gave her some earmuffs, and it was all going ok, until...

The tip of the mortise chisel suddenly snapped. Ah well, it's just metal. At this point, I did have to get the kid out of the shop since 1) I don't want her breathing metal filings and 2) I don't want my leg grabbed while using the grinder.

Good as new, or maybe better, since I put a new bevel angle on it. I do microbevel my mortise chisels, although there is some debate about it. It provides a steeper angle for one thing, and sharpness really does help in my experience, especially during the early, defining cuts. It does need to be touched up often, sometimes even within a single mortise, but with a good sharpening setup it takes so little time that it is well worth it. I always appreciate myself when I take the time to touch up an edge but can't really think of a time I have ever said "wow, glad I did not take the 45 seconds to sharpen up!"

The width of the mortise is defined by marks made by the chisel itself (seen at either end). Marking gauge is then set to that edge, and the inside mark is made. Good habit to mark waste since I are dumb and have chopped in the wrong area more than once.

Using a technique Robert Wearing discusses in The Essential Woodworker, I like to make a series of shallow scores with the chisel, and then drag the side of the chisel along the mortise. This pops out all the little chips and leaves a well-defined shallow mortise in which to start the chopping in earnest.

You know the rest of the drill. If not, its a lot of hitting with a heavy mallet and prying out chips. Repeat. Repeat more, until complete. Then do the other 7 (2 per each of 4 legs).

Today, I started to lay out the tenons while explaining the process to same kid as above. She was not really feelin' it, so instead we made a birdhouse. Yes, I went there; don't judge. We often use an old-fashioned eggbeater to make pancakes or crepes, so it was pretty cool for her to point out that the drill we used for pilot holes "looks and sounds like an eggbeater".

1 comment:

  1. Normally I've hit a nail when that happens to one of my chisels but being a site chippy it's par for the course. I always micro bevel mine but as I'm on site I can only sharpen them with my oil stone and that's the best method for getting an edge quickly. nice mortise chisels by the way.


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