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Well,
I was lucky to be able to get such good joints with the locking miter bit in my shop
cabinet project. Since then, I have been doing a lot of corners and trying to find a
simple way to set the bit height and the fence so that perfect joints are easy to
get...and not just luck.
After quite some experimenting, I have found what I think is the fool proof way to
setup the locking miter bit and fence.
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What I wanted to do is to use this
strong, attractive joint on small decorative boxes. I cut sides of maple and ends of
walnut—mainly to give contrast for the sake of this demonstration.
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Rather than tell you of all the
earlier attempts, I will jump right to the final method—one that, in fact, will allow
you to set your bit height and fence depth for any thickness stock you wish to use.
I have taken two pieces of 1/2" birch for this demonstration and have
marked one "A" and one "B".
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I mark the center on the end of
"A".
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This is the next step: adjusting the
router bit height so that the center point of the bit is at the center of the stock (see
inset).
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Next, I adjust the fence so that it
holds the work piece at the 1/2 mark. This is hard to set since the mid-point of the bit
isn't marked (see inset). Since this is a test setup only, you need only get close.
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I make the first test cut with BOTH
pieces flat on the table. The "A" piece I route with the "A" mark up
and the "B" piece, I route with the "B" mark down, flat on the table.
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Now I dry-fit the two pieces to see how
great a discrepancy there is. If the "A" piece is high, as in this case, the
router bit should be raised by 1/2 the discrepancy error.
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Two tests later, I have the perfect
fit. You can see that My "A" and "B" markings are getting chopped.
That is simply a matter of me cutting off the earlier tests and trying again with the same
pieces.
In practice, when cutting actual box components, it would make sense to make
one piece of each dimension 3" longer. Use these longer pieces to make the test
cut(s), and when satisfied with the settings, cut each piece to exact final dimensions.
[Note: I save these marked tests so that I will do it right the next
time. I store them with the push blocks.]
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