mcgyver wrote:
Building an old growth fir front door. 2 Rails and 2 stiles(42"x80") which
will have a 30"x60" double pane of glass in the middle. I'm going back and
forth on traditional M&T joints or a floating tenon joint done with my
plunge router (I've done lots of these joints before) I'm concerned about
the strength and particularly whether this joint will support the racking
forces once the door is hung. I'm thinking 1/2" think tenons by 5" wide and
2 1/2" deep mortices. Any suggestions on the sizes needed to keep this
together?


I have built numerous doors, all using floating tenons. I just delivered
a pair of 30" doors with tempered glass similar to what you've
described. Mine were made from Vertical Grain Doug Fir. My doors were
1 1/2" thick and I used 1/2" tenon stock.

I have never had a problem with doors sagging or racking, but the oldest
door is only 6 years old, so I guess it's possible that a problem could
develop in the future. If you have any qualms about the strength, I
would suggest that you drill for a metal screw in each tenon at the 4
corners, and plug the holes with face grain doug fir plugs. However
inelegant, the screws add a lot of strength. Also, make sure your tenon
stock really matches with width of your mortises without any additional
space in the mortises. The tenons can't really rack if there isn't a
void to rack into . . .

Rick
http://www.thunderworksinc.com