Centering Routed Mortises
Centering routed mortises is post about Joinery bookmarked by jose with ID 13669247941 was uploaded on 12-01-2019 and has been viewed 84,193 times.
John Birchard's door-making article (FWW #49) prompted me to send this mortise-centering idea I've used for quite awhile.Like Birchard, I use a plunge router to cut mortises in the stiles of frames.However, instead of using a fence to center the mortise, I attach two small ball bearings under the router base.
On the Hitachi router I use (and most other routers), the subbase is attached with four screws.I remove two diagonally opposite screws and replace them with the bearing shown in the sketch.The bearing rides on a shopmade press-fit insert that is slightly longer than the bearing's thickness, and that has an inner diameter to fit the bolt.
The fl*ng* at the end of the insert can be machined as part of it, or it can be a separate washer.It need only be thick enough to prevent the bearing from rubbing on the router base...