[JIMMIEM]

I need to make a mortise 3/4" wide by 3/4" deep on 4 ends of a frame. Frame is already assembled so mortising options are limited. I made a mortising jig from 3/4" ply and needed a 1" slot to accept a 1" guide bushing which will accept a 3/4" router bit. I don't have a 1" diameter router bit so I made a 3/4" slot on the router table and then was going to use a rabbeting bit and flush trim bit to widen the slot to 1". But my 1" slot turned out a tad wide. I suppose I could just run the bushing against one side of the jig slot? I put some tape around the bushing to get a tighter fit but not sure if something might go wrong and mess up the mortise.
Any thoughts or suggestions or just redo the jig?

 

[harrysin]

A few photographs will bring forth more suggestions Jim.

 

[DesertRatTom]

Are you talking a square or round mortise? if round, use a drill press and Forstner bit. If square, then I'm not quite sure what you're talking about. My guess is that you could use the Forstner to clear most of it and then carefully chisel it square. If you're not comfortable using a chisel, do a trial run on some scrap of the same material. Sharpen your chisels before you start--razor sharp. This may not work well if the corners have complex beads and coves. Picture please.

 

[TWheels]

While I agree with @harrysin that a photograph or drawing would be very helpful, a 1 inch PC type guide bushing is available from Lee Valley. I am not aware of any other source for the 1 inch; sets are available but none
that I have seen have the 1 inch. 1-3/16" Brass Template Guides - Lee Valley Tools

Lee Valley is also the sole source for the Oak Park style guide bushings. 1-3/4" Brass Template Guides - Lee Valley Tools

Lee Valley is doing fee shipping on orders over $40