Ask the Staff
Question:
In the woodworking plan I am using for a project, the directions call for a 1/2 inch rabbet bit to cut a 1/4 inch rabbet in the middle of each drawer divider. It is a curved edge. How can you tell that your bit is going in 1/4 inch?
Thanks
Craig A. Brewick
Answer:
Craig,
The 2 dimensions of a rabbet are altered by setting the depth of cut and the width of the rabbet. The depth is fairly straightforward, since you can set this depth with your router. The width of some rabbet bits have their width fixed only because the bearing on the bit is one dimension and the bearing cannot be replaced or switched for another bearing diameter (which would alter the width of the rabbet).
There are many rabbeting bit sets that come with multiple bearings with different outside diameters. You can select the bearing to install on the cutting bit and this will alter the final width of the rabbet.
Click these links to take a look at the
CMT Grand Rabbet Bit set
and the
Super Rabbet Bit Set
.
Rabbeting curved edges with a bearing rabbet bit is fairly easy for most situations. The tricky parts are beginning the cut and leaving the cut; when you are doing curved work and are not using a fence to guide the material into the bit. The chances of kickback go up as the wood is first being cut, but before the edge of the wood has contacted the bearing on the bit. As you end the cut of a freehand piece, without a fence to guide the stock as the cut is finished, you need to visualize keeping the stock running in a line along the line it was running as the stock was in contact with the bearing. When the wood comes off the bearing at the end of the cut, the cutters could still cut inappropriately if the operator is pushing the stock too firmly towards the bit as you come to the end of the piece.
However, if you cannot do the cut on your project with a bearing rabbet bit, you would need to provide more detail about the orientation of the drawer divider's curve for me to possibly help you.
For profiles or rabbet widths to be cut well using any bearing bit on curved work, you need to orient yourself to a single target tangent point on the circumference of the bit and try to keep the contact of the stock at this point through the curve(s). This is the only way to achieve consistency for the cut. (And a safety issue when cutting.) Wavering away from this point could alter the look of the finished profile or the width of the rabbet along the curve.
Regards,
Ed Scent
Highland Woodworking
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