Chairmaking question


I have been thinking about making some dining room chairs. In all likelyhood I will stay in the thinking stage for another year, but I have been making alot of mental notes in chair design.
The most common failure for chairs (cheap ones that I have seen anyway) is the pulling apart of M&T joints on the rungs below the seat. I have only found *one* chair (design) which used pins to lock the M&T. And in that case I'n not sure that it was not a decorative addendum.
Why are pins not a standard joinery technique for chairs? Or nor imnportantly, is there a reason why I shouldn't?
-Steve
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Stephen M wrote:

Get some books on chair design -- they're cheap these days. :-)

Across the grain expands quickly. Long grain expands slowly. (relative to each other.)
A Pin _may_ pull the joint apart more quickly that letting it "slide" -- at least till the glue loses all flexibility.
At least that was the argument I saw in a Fine Woodworking book.
M&T is the best joint I think. A Pinned M&T is a debate.
If you choose your wood so that it expands slowly in both directions it should be stable for many years. Is there such a wood? :-)

-- Will R. Jewel Boxes and Wood Art http://woodwork.pmccl.com The power of accurate observation is commonly called cynicism by those who have not got it. George Bernard Shaw
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Sady the one FWW reccomends is out of print (beats me why a Taunton publication reccomneds and OOP taunton publication)

I don't follow you Could you clarify that a bit?
-Steve
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Stephen M wrote:

Steve:
See page 54 -- (Article) Coping with Failing Joints, (Book) Traditional Woodworking ISBN 0-942391-94-2
Available from Lee Valley - Maybe...
Quote " In very old furniture, pin can split leg by preventing shrinkage across grain." Pg 54...
"...Often keeps joint together when glue fails, but it will eventually split the leg..."
Failure mode given is when the the grain shrinks from side to side around the pin -- and then splits.
You will not be there to see it probably. :-)
I thought book was a "throw away" -- but for $8.95 cdn -- what the heck. It is actually quite useful.
I remembered the article because I had been debating the same joint for similar applications.
Trust that helps.
-- Will R. Jewel Boxes and Wood Art http://woodwork.pmccl.com The power of accurate observation is commonly called cynicism by those who have not got it. George Bernard Shaw
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Quote " In very old furniture, pin can split leg by preventing shrinkage across grain." Pg 54...
"...Often keeps joint together when glue fails, but it will eventually split the leg..."
Failure mode given is when the the grain shrinks from side to side around the pin -- and then splits.
You will not be there to see it probably. :-)
I remembered the article because I had been debating the same joint for similar applications.
Trust that helps.
Thanks Will. It does. I am still skeptical (not of you, you are exceptionally well cited, it's the source that I question)
I have an 1860 vintage home. It still has two original "storm windows" I have broken up and discarded a couple of the other ones which were replaced by modernstorm windows and they dis not come apart without a fight. The wood was in pretty bad shape from 100+ years of exterior exposure. The joinery on those windows is pinned M&T. Some of the pins started to wiggle their way out; otherwise, the joint was solid after all that time in a tough environment.
Needless to say I was impressed with the longevity of this joinery technique.
-Steve
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C & S wrote:

Steve:
Appreciate the information. I have refurbished windows of this type as well. Old, old old... :-) Had forgotten till you mentioned it. Cleaned them, repainted and probably still in use today...
The same book has articles that mention using Hide Glue. Not because of longevity - but because it can be heated, disassembled and repaired. If you are making fine furniture -- assume it will be repaired -- rather than discarded.
One note on windows. I do not believe that the stresses are the same as chairs. Consider that when you proceed.
Have fun. :-)
-- Will R. Jewel Boxes and Wood Art http://woodwork.pmccl.com The power of accurate observation is commonly called cynicism by those who have not got it. George Bernard Shaw
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I have never messed with hide glue. Yes it is does have the benefit of being more repairable. But then again, if they had modern glues 200 years ago they may well have used them.

Good point.
As I see it a chair is probably has the most abused joinery of any common wooden object. It makes sense to make the joinery as solid as possible. My goal would be to not ever have to repair them in my lifetime. Chairs are a b*tch to fix because you have to competely dissasemble (or mostly) them to fix a single joint. 200 years ago there were alot more people around with the skills or inclination to fix a chair. I think I'm better off making it as unbreakable as possible rather than repairable.
Realistically, if someone had the skills to repair a chair with hide glue, then they would probably no it be too imtimidated by drilling out a pin and replacing it.
Regards,
Steve
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<snipped>

A club member (Arnold Champagne) in San Francisco, trained at the College of the Redwoods, makes (and teaches) high-end chairs. Arnie holds and voices a strong opinion on a lot of topics. He uses a doubled mortise & tenon joint as a primary feature of his chair joinery. I don't recall seeing him use a pinned joint. He cuts these by machine, using primarily a Multirouter type of system.
In a recently re-aired WoodWorks episode, David Marks showed an oak bar stool, using M&T joints, pinned with 1/4" brass rod.
I think that you could strengthen the joint either way, however:
Both the Jeff Miller book (Taunton's out-of-print title on chairs) and Norm's recent NYW show emphasised the importance of glue blocks to the structure of chairs. Unless you are building a solid seat, you will want to plan on using these. Or so say those with more experience.
There have been several good articles in the last year in Woodwork Magazine on chairmaking. Unfortunately, these were not available on- line, the last I looked. Maybe in your library's collection? And PopWood had a good article on Welsh/Windsor/Shaker chairmaking 'cheats' in the current issue.
Keep us posted on your learning, please.
Patriarch
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Patriarch wrote:

Patriarch:
Appreciated the info as well.
http://www.canadianwoodworking.com /
Had an article on page 7 this month. Not shown on Web site yet.
Dining room chairs...
It was with bandsawn back -- each side one piece. Simple Slats - M&T joints to top and bottom back rails. H stretcher on legs,M&T on all joints - single. Corner blocks on the seat frame. Glued and screwed...
Not quite as nice a design as the one you depicted. Probably reasonably stable though.
-- Will R. Jewel Boxes and Wood Art http://woodwork.pmccl.com The power of accurate observation is commonly called cynicism by those who have not got it. George Bernard Shaw
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<snip>

Arnie isn't known for half-measures. And he is 'fairly proud of his work', if you get my drift.
What you described is likely entirely sufficient; just not for a multi- thousand dollar chair.
Patriarch
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Patriarch says...

Those pins were in the cross braces at the bottom of the stool. Those cross braces weren't joined at all IIRC. I believe he epoxied them in without joinery, thus the brass pins. The M&T joints were where the legs met the seat.
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wrote in

What's a "doubled" M&T joint? I can't picture it.
Dan
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http://www.technologystudent.com/joints/joints4.htm
This should help.
Patriarch
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the legs green. Or the spoon bit days when you ended up with, essentially, a ball and socket, by swinging the bit to hollow a bit of inside, and shanking the tenon a touch or fox wedging.
I've seen designs where the front and rear rungs locked the sides by intersecting. It's normal for folks to lean back in chairs, so it makes sense to lock those tenons. Seems the Shakers even made some with ball and socket feet in the rear as well.
Anyway, makes sense to me to lock 'em, and I've seen some which were "Normed" with staples or brads. Nice brass pin would be decorative _and_ functional.
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For a change of view - take a look at a few Maloof style chairs which use the joinery of the legs to the seat as the only stabilization of the chair. This eliminates chair rungs and the seemingly inevitable problems of cross grain joinery that's under a lot of stress (like in a chair). I've made a few such chairs (and rockers) and the joint is easy to do - incredibly strong and a great attractive piece of woodworking in my opinion.
Just my 2 cents - I'm a big Maloof design fan.
Gary in KC

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Stephen M says...

The plans for a shelf I'm building call for through M&T's reinforced with dowels. Talk about an over-built shelf. 7/8 cherry, reinforced M&T's and even the stiffening cross brackets have M&T joints. I'm going to simplify it a little and go with poplar and dowels. In reality, butt joints would probably be enough, since anything heavy enough to stress the joints would just tear it out of the wall, but I do have standards.
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I guess you are not making Windsor chairs. They have that one figured out.
I know a fella who runs a small windsor chair factory (5,000) chairs per year. All the chair spindles are through-tenoned, with the ends wedged (like hammer heads). In many years of sales, he has never had anybody return a chair with a spindle (tenon) pulled out. Of course, a brawney college kid can still break the spindles by picking up a delicate chair carelessly.
As a note, the stretchers are not wedged. My friend says the since the legs are wedged and can't come out, the stretchers don't need wedges.
If you don't visualize, here is a pic of a chair, with wedges not yet cut flush and sanded. http://www.duckloe.com/const/45d.htm
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Yup, wedged tenons are an excellent solution that also leave an opportunity to tighten the joint in the future.
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On Thu, 24 Mar 2005 14:47:58 -0500, "Stephen M"

Because even bad chairs don't break before you've got them home.
Because good chairs last for years before this joint fails.
Because an un-pinned joint comes loose and can easily be re-glued. A pinned joint that breaks will break the tenon, which is almost unrepairable.
Because a pinned joint is weaked than an unpinned joint (you've drilled a hole through the tenon). Make sure your timber isadequately strong enough to allow it. I'd do it in oak (and AFAIR, so did Stickley), but not in beech.
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Andy Dingley wrote:

Andy:
I thank you for the tips as well.
Speaking of oak and strong timber....
One book recommends choosing flat sawn boards -- then-- using the edges of the board where the grain is diagonal. This produces 4 faces of quarter sawn -- and by Jove it works. :-)
Stool I just posted pics of used this technique for legs -- the legs look nice anyway. http://woodwork.pmccl.com/Business/productsbusiness/productsfurniture.html
Side view shows them best. I compromised a little bit on the cut -- not much. This was intended to be a Low quality shop stool that would be kicked around.
-- Will R. Jewel Boxes and Wood Art http://woodwork.pmccl.com The power of accurate observation is commonly called cynicism by those who have not got it. George Bernard Shaw
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