Replies

1. 
   garth | Jul 05, 2003 06:31pm | #1

   I do not like to use a tenon more than about 4" wide, if it were me I would use 2 2" tenons with a stub tenon in the middle, but then again that is just me.

   Scott T.

1. 
   racwood | Jul 06, 2003 05:48pm | #2

   Thanks for the info.  Seems  straight forward and easy but I have a question:  Can anyone tell me WHY two 2 inch tenons separated by a 1 inch gap but connected by a 1 inch stub tenon are prefreable to a simple, single 5 inch tenon.  What's at play here? 

1. 
   imcanadian | Jul 07, 2003 05:12am | #3

   The wood's at play! The wider the tenon, the greater the movement.

2. 
   Elcoholic | Jul 07, 2003 10:56pm | #4

   That's a tough one to figure.  The other rules of thumb for M&T joints (e.g. 1/3 mortised member thickness by 5 x the thickness for the length) are more about the wood strength.  The optimum length of the mortise is effected the wood species, cut, type of glue, pegging, temperature and moisture differential across exterior doors ... and so on.  In my limited experiece I've always used quartersawn white oak or vertical grain doug fir and yellow glue for entry doors and went long, single mortise route without any problems.  I figure that's a good combo stable wood and shock absorbent glue that's stronger than the wood.  Then again I ususally peg door joints so the glue's just insurance anyway.

   Here's one to think about.  If the limits on tenon length and width truely are to limit the surface area of the joint face so that the cross-grain movement in the joint doesn't crack the glue line then why do bridle (open moprtise) and lap joints work?  These would suggest that you can't make a tenon too long or wide as long as you're not using something arcane like hide or fish glue.John O'Connell - JKO Handcrafted Woodworking

   Life is tough.  It's tougher if you're stupid - John Wayne

1. 
   PATHFNDR | Jul 08, 2003 01:24am | #5

   I have found that the quality of the joint as opposed to the size of the tenon is a ruling factor for a lasting joint. I can't remember the last time I used glue in door construction. The joints are tight to the point of standing on their own and pegs are mere insurance. I have doors out there in direct sun and rain, for 15 years, and other than needing oil every once in a while, are as sound as they were the day they rolled out of the shop. If I can make one tenon instead of two, time IS money. I do agree in the 1/3 theory as to thickness. Now width? You have my opinion. And lastly, cut 'em in as deep as they'll go. They WILL last forever. IMHO

1. 
   racwood | Jul 08, 2003 09:47pm | #6

   Thanks for the info.  I've followed the 1/3 width rule by default and the tenons will be 3.5 inches into a 5 inch frame member.  As for the width of the tenon I suppose I'll stick with the 5 inch dimension.  I am curious to know just how you pin these joints.  I plan on using black walnut ending up slightly proud of the door surface on each side with chaffered edges.  Any tips for me?  I love the idea of NOT using glue to put this thing together as it's my very first door and a relatively complex glue up for me.  Thansk again.  Rich Collins

2. 
   PATHFNDR | Jul 08, 2003 11:32pm | #7

   I place pegs diagonally, starting from the outside corner and angling toward the center of the door, as for the middle of the door? Whatever you think looks good. Try to have equal meat around each peg. One hint I would suggest, in Doug fir, is to drill the holes in the tenon about a sixteenth short, maybe a little less, this will bring the tenon home when the peg is driven in, since, I'm assuming the fit of your joint isn't extremely tight. I have to pound mine together, no second chance with these puppies. As for the pegs themselves, a little taper will help them go in without damage and I always, aline the grain patterns. I'm just anal that way. Measure, measure and measure again and try to visualize the project as a whole, with each step. Good Luck