Sure you can .. it all depends on the delta between the bit and the guide collar, or copy ring as they call it. You will need to take this into account when making the templates.

I like to use 5/8 guide and a 1/2 inch bit whneever possible - all the templates then require an 1/8 inch offset when making them.

So in your case, using the bit/collar mentioned above, the tenon template needs to be 1/8 inch narrower that the tenon size you want, and the mortise template needs to be 1/8 inch wider ...

I use the StewMac system and make my first cuts in about 1/8" increments with the "copy ring" using a 5/8 guide and 1/2" bit. then I go back and finish up with the bearing guided bit for final thickness. The StewMac system gives you a tenon that is a little smaller than the mortise. I think they are assuming a bolt-on neck

The whole reason why you rout after the body is assembled is to get a a perfectly centered mortise...I see no reason to allow a bunch of slop in the joint, so remade my templates for a friction fit.

This informs me that I need to make both the tenon and mortise cut in one pass - not recommended in my view.
John

I use the StewMac system and make my first cuts in about 1/8" increments with the "copy ring" using a 5/8 guide and 1/2" bit. then I go back and finish up with the bearing guided bit for final thickness. The StewMac system gives you a tenon that is a little smaller than the mortise. I think they are assuming a bolt-on neck

Terrence - do use a copy ring for both the tenon and the mortise with the Stewmac jig ?

John

Yes I do for the initial cuts so I can take smaller increments. if you use the bearing guided router bit you have to take a pretty healthy first bite to allow the bearings to contact the template. I switch to the bearing guided bit for the final cut to get the proper size.

I use a 5/8" "copy ring" with a 1/2" bit for the initial cuts followed by the 1/2' StewMac flush cutting template bit with the top bearing for final cuts.