Morris Chair Pinning

[Bill Borchers]

I'm in the process of building my first Morris Chair and the plans I'm following call for pinning the mortises and tenons with 3/8" dowel rod. My question is: Do I really need to do this for structural support, or is just part of the craftsman touch?
I would have thought that a good mortise and tenon with today's good glues (Tite Bond) would not require these pins.
Any insight?

[J. Z. Guest]

Unless your joinery or gluing is lacking, it is just for looks. This actually weakens the joint a tad.

If you have a M&T that isn't glued, the pin obviously helps. (i.e. tusk tenons)

Others feel that glue eventually lets go, no matter how good it is. When it does, it would be nice to have some mechanical reinforcement to the joint. (such as dovetails or a pinned M&T)

[Rich Engelhardt]

Hello,

Do I really need to do this for structural support, or is just part of the craftsman touch?

The latter.

[Scott Vigder]

I have two Morris Chairs purchased from Stickley, and they have dowels. Visually, the dowels add a prestigious appeal to the joint.

My woodworking partner built a Morris and while he altered the appearance of the corbels, he did the dowels (cursing them, as I recall).

[Nate Rogers]

I definately weekens the joint, it is strictly for the look..


Nate

[George Bregar]

Any weakening of the joint is moot, as the large tenons and resulting glue surface is plenty strong with or without pins. I actually used my mortiser and use square pins that stood a little proud and had the A&C bevel look. Maybe not true to original Stickley, but I like the look and made it "mine".

Prefinishing and close up pics

[gary Zimmel]

George

Thanks for the pics of the pinned joints. I was considering doing it on the morris chairs that we are doing in the group build. After seeing how yours looks I will pin mine with square pins that will be proud.

[Clifford Mescher]

Why would joint weaken with pins? Clifford

[George Bregar]

George

Thanks for the pics of the pinned joints. I was considering doing it on the morris chairs that we are doing in the group build. After seeing how yours looks I will pin mine with square pins that will be proud. YW. It's a nice look. The upholster doing my chair didn't want to cover them up on the back :D

[John Townsend]

Don't have the info in front of me just now but I've read test results of joint breaking strength from strongest to weakest: mortise and tenon, (haunched, regular, pinned in that order); followed by loose tenon, lap, dowel, and lastly butt in that order.

[Paul Atkins]

You could build the chair without glue and with pins and the thing would stay together. I have repaired a few chairs that sat outside till the glue was gone and the ones that were pinned were in one piece. Glue helps though.

[John Townsend]

It seems to me that with today's glues (such as Tite Bond III) pinning would be unnecessary. But you could just substitute false pins there instead - has the strength and still has the appearance. There are those that say that the glue will eventually give out so pins would keep it together. It occurred to me that if the glue did finally give out, it wouldn't very likely occur for 60 years perhaps. (assuming the Morris hadn't been kept outside in the weather). If it does give out that far into the future I presume the glues of that future era will be even better, even if it is taken down for repair.

I had this same worry with two bridle joints on the top of a trestle that I was building (glued but unpinned); but I read in FWW recently that breaking strength of a bridle joint utilizing 1 1/4" x 3 1/2" pieces exceeds 1500 lbs! So that would be 1500 lbs at each joint. More than a ton! I can't imagine tons of force being exerted on my table! :eek: I decided there's probably no need to pin it!

Another point to consider
FWW #192 How Strong is Your Glue?
average breaking strength bridle joint -pieces 3/4" thick x 2 wide"; tongue 1/4" thick
PVA type I waterproof (TiteBond III) -----------2024 lbs.
Slow set epoxy -------------------------------1994 lbs.
PVA ----------------------------------------- 1924 lbs.
Liquid hide glue -------------------------------1595 lbs.
Hot hide glue ---------------------------------1531 lbs.
Polyurethane ---------------------------------1164 lbs.