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(10-26-2019, 07:28 PM)jteneyck Wrote: You can pin loose tenons, too, just like you can with integral tenons, if that's something you want to do. With loose tenons, however, you obviously need to pin the tenon in both the stile and rail.
Does pinning significantly strengthen the loose tenon's attachment to the rail?
(I had assumed this was mostly to hold the joint tight as the glue sets and then as a secondary reinforcement to the cross-grain joint in the stile.)
Matt
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(10-27-2019, 03:48 PM)mdhills Wrote: Does pinning significantly strengthen the loose tenon's attachment to the rail?
(I had assumed this was mostly to hold the joint tight as the glue sets and then as a secondary reinforcement to the cross-grain joint in the stile.)
Matt
Your assumptions are correct. Pinning any glued M&T type joint doesn't increase the ultimate breaking strength. The only benefit is if the glue fails the joint won't fall apart.
Before there were exterior glues doors were made with draw bored M&T joints or with wedged thru tenons. In those cases, the pins and wedges were critical to the strength of the joint.
John
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I would use stave construction for stiles. I've built several exterior doors and have had a couple issues with solid wood stiles bowing after a period of time.
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How about dovetail joints?
Center layer will be 1" to hold the glass panel; outsides will be 3/4" or less.
Yes, I've been accused of "over engineering"
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(10-28-2019, 05:43 PM)Wild Turkey Wrote: How about dovetail joints?
Center layer will be 1" to hold the glass panel; outsides will be 3/4" or less.
Yes, I've been accused of "over engineering"
M&T, loose tenons, or dowels. Stick with what has been proven to work.
It's fine to use a 3 layer laminate for the stiles and rails, but the joinery should be buried inside to protect it from the weather.
John
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Yea, no sense in going a different route and have it fail.
Steve
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The Revos apparently are designed to clamp railroad ties and pull together horrifically prepared joints
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Grout was great for info on this type thing
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A 48" wooden door is huge. "Over engineering" may be appropriate. Since John said three layers is okay, I think doing extra long dove tails on the center layer would be stronger (more solid) than pined loose tenons. There's my humble opinion.
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(10-28-2019, 06:14 PM)jteneyck Wrote: the joinery should be buried inside to protect it from the weather.
John
There will be an 8' roof overhang so it will be protected from most weather.
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(10-29-2019, 07:21 AM)Bill Holt Wrote: A 48" wooden door is huge. "Over engineering" may be appropriate. Since John said three layers is okay, I think doing extra long dove tails on the center layer would be stronger (more solid) than pined loose tenons. There's my humble opinion.
I respectfully disagree. Go make a couple of test pieces and you will see that a dovetail doesn't have as much racking resistance in that direction as you might think. Yes, it's strong, but the joint moves a little unless it's cut perfectly. You can't pull a DT joint tight with clamps during glue up either (if you can it wasn't cut very well) and not even a perfectly cut DT joint will ever be as tight as any of the other three when they are clamped up. Glued surface area is what gives a joint strength; again, a DT loses badly to any of the other three. Also, you wouldn't be able to use cope/stick joinery, or any sort of dado and stub tenon for alignment of the stiles/rails because DT's have to go together from 90's. And then how do you glue on the outer two layers and get everything perfectly aligned?
Three layer laminate construction is done before you size the frame members to final dimensions. Laminates sometimes aren't exactly flat after glue up, but being oversized allows you to mill them perfectly flat again and then cut to final dimensions. If you could somehow deal with the alignment problem of the outer laminates only to end up with one or more members of your now glued up door having a bow how would you deal with it?
After what I'm sure were lots of failures the old guys ended up doing things a certain way because those things worked. A 48" wide door is large but nothing compared to any door on a cathedral. Some of those are 6 or 8 ft wide and 15 or more feet high. Go look at how they were put together.
John
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