On Monday, April 13, 2015 at 1:10:40 PM UTC-7, Greg Guarino wrote:
On 4/13/2015 7:22 AM, dadiOH wrote:
The thickness of the jig limits the depth of the mortise. Sort of
rethinking and rebuilding, the through mortises (in 1.5" stock) I'll
need will require extra-long bits.

If the cutting diameter = shank diameter, you can cut down a way, remove the
jig and cut the rest by guiding the bit shank on the hole.

That sounds like a pain to do 16 times. I'd probably jsut opt for a
longer bit, or a thinner jig. But I'm curious to know if it's even safe.
Any opinions from the group?

If you can trust the (round) base of your router, you can omit the plate and
guide bushing, guide with the external frame against the router base. A sub-base
can be made round, centered, and in any desired diameter by chucking a
dowel pin in the router, and pivoting the router on that pin - either a
second router, or a router table, can trim the edge of the subbase.

The subbase, of course, can have a 2" hole to clear the router chuck. And
if you make several of different diameters, changing them in will make a single
jig produce multiple mortise sizes.

I hear the wail of gotta-use-multiple-tools, and sympathize. A recent
bookshelf with half-dovetails needed five cuts per shelf end, with two different
router bits (half-dovetail, you know) and the 24 shelves took all weekend,
I've fantasized about multi-shaft circular saws with 1" blades to define the
sliding half-dovetail sidewalls.