Sometimes it’s necessary to increase the depth of a Dado or a Groove very slightly. This is usually done by just adjusting whatever method you used to create the joinery, but often that is no longer possible without a lot of fussing since you may have set the device to new settings for other tasks.
Enter the Router Plane. This is an indispensable tool (that my wife bought me!) which allows for in situ adjustments of depth-vital joinery.
Here’s what you do…
This process basically works by setting up the router plane while there is some sort of shim between it and the work. When you remove the shim, the plane will be protruding in to the work by the thickness of the shim.
Here I’m using 3m ScotchBlue Painter’s Tape which has a thickness of 0.004”/0.01mm.
The first step is to cleanly apply tape to the bottom of the plane. This will act as our shim.
Notice that in the picture there is a small crease on the right piece of tape. This is no good. I noticed it after I took the picture, removed the tape and re-applied a new piece cleanly.
Now carefully set the depth of the blade with your shimmed router plane. The tip of the blade should barely touch, but not engage the work.
Remove the tape and use the tool. Some router plane’s have fancy adjustment systems that allow you to increase the protrusion of the blade easily…. supposedly. I don’t trust these mechanisms for anything other than setting the blade to depth while in place.
Different tapes can be used, or you can use multiple layers of tape. Shim stock or feeler gauges can also be used if you have them.