I need to cut a 1/8 by 3/8 ledge into the end of 1/2″ plywood, but I don’t know how to phrase my question clearly. It’s about how to approach the cut, and what kind of bit to use.
Do I use use a 3/8″ plunge bit on the face of the board, sinking it 1/8″ deep? Or use a bit that cuts into the edge of the board?
Janet
Replies
methods
The table saw/dado set method that Roc describes in his respose is one method:
http://forums.finewoodworking.com/fine-woodworking-knots/general-discussion/jyang-rabbet
If you don't have a TS or a dado set, it can be done with your router using either an edge guide accessory, or by clamping a guide strip farther in from the edge. Just set the bit depth to 1/8". You can use a rabbet bit with the proper bearing to give a 3/8" width, or a straight bit larger than 3/8", setting the edge guide or the guide strip to give you a 3/8" wide cut. The method you choose depends on what you have, tool-wise.
Janet, The approach depends
Janet,
The approach depends on which dimension is critical. If the depth of the rabbet is critical, using a router, all you need is a 3/8" bearing piloted rabbet bit set 1/8" deep. If the thickness of the remaining tongue is critical you need a bit with the bearing on the shank that runs between the base of the router and the bits cutter head. With a shaper this is easier using rub collars either above or below the cutter head. With hand tools, use a plane like a moving fillister to rough out inside gauge lines then finish to the lines with a rabbet plane; a sash fillister will leave a specific dimension in the remaining tongue if that's what's needed.
Another after-thought
If you haven't done edge routing before, one issue is keeping the base firmly against the material on the inside of the cut, particularly if the edge guide adds a lot of weight on the outboard side. Any wavering has obvious effects on the regularity of the cut. It helps to have an offset base on the router, like this one from Pat Warner:
http://patwarner.com/offset_subbase.html
I bought an offset base, and a couple of his precision bases a few months back for my PC 690-series routers. Solid products and good service..
You know, I had wondered if the balancing act would be a problem. Thanks for the link. Looks sturdy.
Janet
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