Squaring rabbeted corners for glass

Don’t know if this title really says what I want to talk about….

A few weeks ago, I got a job to remove the 1/4″ wood panels from a bunch of cabinet doors and cut a rabbit in the door frames for glass.

Removing the panels was straight forward. the doors are what’s called a “Back Panel” door; meaning the center panel is attached (glued & nailed) to the back of the frame rather than set into a groove cut in the frame. First I drill a hole near one corner of the panel. Then using a flush trim bit and the inside of the door frame as my guide, I rout away the panel from the frame.

Stack of doors after routing out the center panel

(actually, this picture shows the rabbet too. I forgot to take earlier photos of before & after.)

The next step as a little harder. I needed to cut a rabbet that was 3/8″ wide by 3/8″ deep. Normally, this would be easy too using a rabbeting bit of which I have several. Problem is, I don’t seem to have one that will cut a 3/8″ wide rabbet. Everything else, up to 1/2″ wide, but not 3/8″. So I had to jury-rig a bit & bearing to do the job. (the bearing didn’t quite fit the rabbeting bit’s shaft.)

Rabbeting bit

Once I got things to work (the bearing wouldn’t fall off or run out of round) cutting the rabbet was easy too.

But after routing the rabbet, I needed to square the corners as the bit left them with a 5/8″ radius.

door frame showing the rabbet cut for glass and round corner I need to square

Now, normally, I would use a chisel to square the corners. But I have 17 x 4 = 68 corners to do so chiseling by hand will be a little too slow & costly.

So I made a jig to speed things up.

Computer generated drawing of corner squaring template

Using a computer to lay out the template helps in determining just how deep the template’s corner notch needs to be so the 3/16″ bit doesn’t cut too deep or too shallow into the rabbet.

Now, this set up will also leave a radiused corner but it has gone from 5/8″ to 3/32″. So the glass should fit fine if it’s cut with a little wiggle room.

The corner routing jig clamped in place

corner after routing with 3/16" bit

The end result is a pretty good looking corner, IMHO.