Hello first time poster here. Ok here it goes. I’m in the design stage for making an exterior door. Plan on using full M&T joinery. Heres my prob. It has to do with coping the detail on the inside edges. I don’t plan on using a standard coping bit, instead I just want to put a 3/8″ rabbit on the inside edges. I should also note that it will be a 2 1/4″ door, leaving 3/4″ for the panel thickness. Should I rabbit the entire edge of the stile and then “cope” the rails into it, or should I cut back the detail and just square off the edge for a better glue surface. Here is a partial dwg of what I’m talking about. As far as the second option, that is the way Joseph Beals did it in an old issue I found here while browsing. It’s the Sept./Oct. 1996 issue. Again I’m just worried about glue surface and strength. Thanks.
Digger
Replies
Digger,
This is not a direct answer to your question. But I assume, since you are asking about the strength of glue joints in such a project that you have little or no experience making a door, especially an exterior door. Am I right? What wood are you planning to use?
Even wood workers who have ample experience with M&T construction are not usually familiar with 2 important construction techniques that are really important in a successful large door, and especially when building an external door.
First, while M&T joinery is a must, with the width of the rails and stiles, a haunched mortise and tenon is required or the joint will self-destruct due to wood movement. An exterior door is subject is very large humidity gradients and severe racking forces. Are you familiar with the haunched mortise and tenon?
Second, are you familiar with "stave core construction?" The rails and stiles of an exterior door should not be made from solid wood. There is just too much wood movement. Normally frame and panel construction should accommodate this, but not with the width of the members of a house door. They could be made entirely from quarter-sawn stock and that would solve the problem, but quarter sawn lumber in the dimensions you need, of quality hard wood with appropriate figure will be frightfully expensive, if available at all.
Stave core construction solves these problems and has been used for centuries in successful door making. The rails and stiles are built up as a kind of "engineered" product or a plywood type of construction. The inner core of the members is made from quarter sawn lumber that has low value for appearance. Poplar or even soft woods can be used. Then "skins" of high-quality, figured hardwood are glued to the core. The outer skin is generally about 1/4-1/2" thick. Wood movement mostly occurs in the direction of the thickness of the door, which is much less a problem then if the door width were affected.
Stave core can be purchased, or made, depending on your work shop capabilities.
I've attached a diagram of stave core construction.
Rich
Edited 12/6/2008 10:52 am ET by Rich14
Hmm . . .It didn't attach. Try again
Yeah actually plan on using quarter sawn white oak. I live in St. Louis and know a guy who mills lumber and has alot already dried. As far as my knowlege is concerned, I am a general contractor with mostly finish expierience so I know I can do this. And I I thought I should haunch those. I look into the stave core thing as well. Thanks alot.
Diggs
Rich is right. Making doors is a lot more complicated and nuanced than many people think. And once you've got it glued up there's no way to make it right if it warps. It's a very risky business actually.
I just ordered from a door company and hung two doors very similar to what you're talking about - quartersawn white oak, 3-0 exterior units with one top lite and a carsiding type design (also of white oak) for the lower panel. The door company made the door with stave core construction, exactly as Rich pointed out. I think I might have gotten a hernia trying to lug these things around. They must have weighed north of a hundred pounds each.
I paid $845 each for the doors, and wouldn't have been able to build them myself for anything close to that. Whittling out the hinge gains and lockset holes was no picnic. That white oak is tremendously hard and abrasive stuff.
ZoltonIf you see a possum running around in here, kill it. It's not a pet. - Jackie Moon
digger,
The glue surface and strength issues are dealt with in the mortise and tenon. The end grain of the tenons shoulders will not make a strong glue bond with the mating surface on the stiles edge. As long as the two surfaces are well mated, it really won't matter what their contour is.
Ray
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