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Beth has her boards cut for the front and back steps of the stools. As with the others,
the back is 5 3/8" wide and the front is 6" wide. This is not much a difference
but it will require making some change in the dovetailing process.
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No
dovetail jig can be learned without good instructions and the Instruction Booklet for the
Incra System is the very best. It uses a large, tabloid size page which is useful since
usually the instructions for a given joint will fit on the two open pages.
Beth starts by reading the section on centering the bit on the board. Of
course, you can divide the width in half, but the Incra System teaches another way which
will give you a very exact center without working the numbers.
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In the
back of the book, there are pages and pages of template information. They can seem
overwhelming at first, but it is pretty simple to find the right template once you work
through your first joint.
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Beth
first looks through the pages searching for the bit that will handle the 3/4" stock
she will be routing. This one template will handle "through" (dovetail) of
3/4" stock. It also says you could also make a half-blind dovetail in 1" stock.
Every template will tell you the same type of information.
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Beth now
places the 6" board on the template guide and sees that she will have 5 dovetails
over the width and that they will be the "B" cuts (arrow.)
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With the Mast-R-Lift cranked all the way up, she installs the 5/8" dovetail bit that
matches the template she has picked.
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She sets
the bit height to be just at the board's edge.
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Now she
wants to find the exact center of the board. There are a number of ways to do this. The
method I like best will be used here. She first sets the fence so that it is exactly over
the half mark of the bit. These bits often have a small dot in the center that
was a part of their machining and is great for locating the center.
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She can
then move the scale until the cursor is at "0". With that done she can
move the fence until it is 3" on that scale. That should give her a point about
centered on the board. A quick check will fine tune that exactly.
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She
starts the centering check by clamping a test piece in the vertical fixture and making a
cut.
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She turns the test piece around and cuts the piece again. You can see that the opening is
wider.
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Now Beth
can visually center the bit in the widened opening. While there are other centering
methods, including a centering scale, I have always liked this system. Once the fence is
reset, she locks the center position and moves the scales to reflect this precise
point. She will reset the center when she has finished with the 6" wide stock
and starts the 5 3/8" stock. The center will change but the procedure for finding
center stays the same.
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