I'm THinking of a project where I need to route a nearly square recess

[LCHIEN]

The recess will be about 3" x 3" square and 3/16" deep.

I'm thinking about a oversized template and using a hand router and a 1/2" spiral straight bit.
That will leave corners that are 1/4" R round. I'd like to get some 1/16" radius round corners and not have to chop the corners with a corner chisel and chisel out the rest.
If I use a smaller bit of 1/8" diameter it will take forever ( at least 16x as long since it has 1/16th the area) and probably not be so smooth on the bottom.

So I'm thinking make the template 1/8" oversize (1/4" overall) using a 3/4" OD bushing and 1/2" dia bit , to do the bulk of the removal
Then switch to a 3/8" bushing and a 1/8" bit. To do the corners, without moving the template. Just have to clean up a little in each corner.
Since the difference in Bushing OD to Bit OD is .125" in both cases the small diameter bit should fit the corner and finish it with a nice small radius.


My template would need to be 3-1/4" square to make a 3" square recess with 1/16" radius corners.

See Anything wrong with this approach?

[capncarl]

Not quite sure the purpose of the recess, but the corners could easily be cut with an oscillating saw and cleaned up with chisels. I’ve even had surprising success sanding corners with the dorky looking oscillating saw triangle sanding attachment. It might be just the trick for cleaning up the bottom or your recess.

[LCHIEN]

Oscillating tools have a large radius, can't get into corners without leaving a lot of collateral damage.

[LCHIEN]

I just wanted squarish corners with a small but nice looking small radius.
Reason is complex and immaterial.

Using a half inch router bit will leave corners like the left . Much bigger than I wanted. 1/8" router bit on the right.