Wow!!! That was my very
first impression when I opened this box. I am used to some fancy boxes storing CMT bit
sets, but this set is astonishing. Part of that astonishment is because somebody thought
it all out, and I don't mean the box but all the cutters. They are shaped "upside
down" — more on that in a minute.
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This very unique cove cutter is the key to the whole set. It is a
7" wheel with 6 carbide cutters and balanced so well that it simply hums. And while
that may be interesting, what really counts is that it gives such a smooth finish to the
infinite number of cove shapes it can do.
The shape drawn on the wood is the bar rail that I cut when I used the
prototype cove cutter. That was a gem [click here to go to that
page.]
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You control the shape of
the cove by setting fence angle and blade tilt angle. Of course, you also control blade
depth. With these variables, the combination of cove shapes is tremendous.
I have developed the chart at the right just to give you an idea what fence
angle and blade tilt angle play in shaping the cove.
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For the cove pictures above, I used a very handy program called "Your Shop Helper -
Cove Cutter". I found this on-line at http://www.woodmagazine.com/software/ysh/.
You can download it for free and if you like the program, you simply send $8.00 to the
author.
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Unfortunately, the "Blade Dia." field accepts 8" to
10" — not the 7" that the CMT Cove Cutter measures. The program is still
useful to give you an approximation of the shape. The illustration at the right shows 8,
9, and 10" blades at 45o at a common depth (1"). You can see that
there is very little difference.
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That said, I went to the
shop to cut out actual, real coves at some different settings — actually, I used the
same fence and blade angle settings as in the composite picture above [45o, 35o,
and 20o fence angle and 0o, 15o, and 30o blade
tilt.]
Now, with these cut I can set out to make any molding I want and without
guessing.
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Before I do that, let me
show you how I have set up the cove cutter. The cove cutter comes with a thick spacer
(arrow). This is mounted on the inboard side of the arbor and moves the cutter away from
it. It is very important to have this spacer in place to keep the cove cutters from
contacting the internal blade guard. It is a good idea to rotate the cutter by hand to
make sure that it has good clearance.
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I had cut
the zero clearance plate for this cutter when I did the bar project. If you are starting
with a brand new plate, simply clamp a piece of wood over the plate and with the saw on,
raise the cutter slowly through the plate. [Note: I am showing the plate in this picture.
When actually cutting the plate, your board should cover the opening and be securely
clamped.]
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This is the setup I used for setting the fence angle for the bar rail project. It
was simple and worked.
For the new cutter, I wanted to set up a fence that would give me all angles.
The Incra Miter Gauge is limiting me to about 45o. Also, the angles we want
will be measured off the blade path rather that perpendicular to it.
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I looked around the shop to
see what I could make a special fence out of — I came across the "vertical
fence" that I used to use on the router table. It had a hole in the center to allow
for the router bit. Since I wanted a smooth surface for the wood to glide along, I used
spray cement on a piece of glossy white hardboard (bathroom shower surround material.) I
am pressing it in position.
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