Which type of joint is strongest in 2…
user-1119429039
| Posted in General Discussion on
Which type of joint is strongest in 2-1/2 x3/4 in. stock?
- Mortise and tenon
- Pocket screws
- Bridle joint
- Miter
- Half-lap
- Floating tenon
- Other (post in Knots)
You will not be able to change your vote.
Replies
Uh, in what application? Without context, this seems a rather arbitrary question.
Application?.... Haven't we all read thousands of wooodworking articles. There are essentiallty two main types of load, seismatic and vertical (whether pulling or pushing). But time and time again the half lap has been proven the strongest. Sometimes, fancy is only a feel good method, where as in most cases simple is the strongest. Don't get me wrong, mortise and tenon are very strong, but only about half as strong as half lap joint. Half laps are as strong as the glue and wood you use, where as m/t joint are only as strong the wood you use.
Yeah, how silly of me to wonder if we were joining them at right angles; at ends; or in the middle; or edge to edge, or face to face, or ...
And I didn't argue for M&T, by the way.
And despite all those thousands of woodworking articles showing that half-lap is the right answer in every single application, only 10 of those voting seemed to know it?
I almost voted for the half lap, till I saw the bridle joint. I had to go with the greatest surface area. Using a pinned bridle joint with today's adhesives seems to make the most sense to me.
I hope that FW now puts us all out of our misery by actually testing all these joints in one article.
P.S. I won't even use a miter joint on a picture frame without a spline, making it a derivation of a bridle joint.
There was a recent article in one of the woodworking magazines where they tested the different typs of joints. If I remember correctly the mortice and tenon joint tested stronger.
I responded with the M&T for strenght, but I would think the pocket would be much quicker.
If it moves, tax it. If it keeps moving, regulate it.
And if it stops moving, subsidize it.
I also responded with the mortise and tenon; however, I would agree that the pocket joint would be much quicker, but it has its limitations as far as applications. The M/T joint has been proven for literally hundreds of years in many different applications from home and barn building to fine furniture. Its my pick hands down; however I need to check out a couple of the joints that I did not recognize.
All,
This poll needs a few words of explanation before I get buzz-sawed for coming up with a question that's too vague and answers that aren't sufficiently detailed.
Here goes:
We want to know which of the joints listed ought to be strongest against racking forces--side-to-side stresses, in other words. The question gives the size of the members forming the joint, so you don't have to puzzle over whether we meant joints in table aprons or Windsor chair legs. And we're assuming that the joints are well-made, neither too loose nor too tight, and that they have been properly glued.
Feel free to base your answer on your own experiences, or on your knowledge of engineering and physics, or anything else that seems relevant.
Finally, a few words about these polls in general. Several forum participants have complained that the questions we devise are too vague, or that the choices for answers aren't well defined or that the list is incomplete. I'll plead guilty with an explanation to all those complaints.
The explanation is simple: We aren't using the polls for rigorous market research. (We couldn't do proper market research with these polls if we tried. The Knots software and the design of the FWW home page limit our ability to ask in-depth, carefully worded questions.) Rather, we want the polls to be entertaining, a brief diversion from your normal day. And if you read the posts that accompany many of the previous polls, you'll see that participants with a good sense of humor come up with answers that are far more entertaining than our questions. That's as it should be.
So I invite you to put your tongue firmly in your cheek, take a grain of salt, suspend disbelief, and vote in the poll.
David Heim
Managing Editor
FineWoodworking.com
"Feel free to base your answer on your own experiences, or on your knowledge of engineering and physics, or anything else that seems relevant."
Would the recently-published (not in FWW) results of a test of such joints be deemed relevant?
-Steve
sure
What's the point of a question like this? Everyone (most woodworkers) knows M+T is the strongest. Might be more interesting to know which joint is perferred in particular application, with all real world factors accounted. Also, how does skill/experience level play in chosing a method of joinery? Brian
Brian,
See http://forums.taunton.com/fw-knots/messages?msg=39561.4 in this discussion.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Given the ambiguous nature of this question and the relative impossibility of answering it without substantially more information, I have a great question for your next poll:How long is a stick?A) six inchesB) from twelve to eighteen inchesC) somewhere around two feet, more or less, but less than six feetD) exactly 39.370079 inchesE) depends on the weather and relative humidity
Dear mjshep,
If this woodworking thing doesn't pan out, you may have a future as a question-writer. But I understand you gripe about the nature of the question. Take a look at my previous post, where I tried to add some information that would make the question less dopey.
Best,David HeimManaging EditorFineWoodworking.com
As material is variable, so are questions and so are answers. Just as there is no one answer, there is seldom only one way to get to it.
I'm learning a lot reading the 'answers.'
well here's my cheeky answer. It did not say about dovetails joint, & second it has been a long time I'm out of my carpentry trade like close to 35 yrs. As a student I had worked on lots of joints in those day, & the teach had a simlar guestion on this then too. The mortise and tenon is the right answer. Plus I was reading about joints in a magazine recently & explained several joints on this matter. By the way I had an average of 90-95% in my class at my exams when I graduated. We all must look at this as a game & a challenge for yourself + learnig experience....
David, your ambiguous question is great. Nice to have something legitimate to whine about. However, my immediate thought was the dimension sounds like a cabinet door frame. That is a 2 1/2" wide frame that is 3/4" thick. Out of desperation sitting at the airport in a snow storm, I read an article in Better Home and Gardens Wood Magazine, issue 181 about joints. Both door and drawer joints were tested. They used 2" by 3/4" red oak.
Results were interesting, using a pull apart and shear test. The shear test is a test of racking. The vertical stile is held in place and weight applied on the horizontal rail until failure. They tested Half Lap, Mortis and Haunched tenon, Stub Tenon and Groove, and Cope and stick joints (the commercial door joint made on shaper).
Joint Pull apart strength Sheer Strength
Half Lap 1918 lbs 1073 lbs
Mortis 1533 lbs 482 lbs
Stub Tenon 727 lbs 226 lbs
Cope 677 lbs 262 lbs
Conclusion of the article is the strongest joints are those that have the most face-grain to face-grain glue surface. The photo of the lap joint shows wood failure halfway across the joint and glue failure at the outer part of the joint with a note that dado score marks did not glue well. A bridal joint, could be stronger but maybe the thinner material will be a factor? The Mortis and tenon failed at the bottom of the the mortise, and they did not test a through tenon, which may be stronger, but taken to the logical point, a bridal joint is a through tenon with more face to face glue surface?
Just for grins, here is the test on the drawers..
In drawer joints they tested Box Joints, Locked Miter, Locked Rabbet, Through Dovetail, Sliding Dovetail, Rabbet with nails (ok it is Better Homes...), Shouldered dado, and Half blind Dovetail. Without going into the specifics and from the test results above the right answer is the joint with the most face grain to face grain glue surface, ie the box joint. The relative strengths are in the order listed above, I was surprised that the through dove tail was weaker, but the test showed even though the dovetail broke at the glue joint it still held together mechanically, rather deformed though. The box joint failed completely but at higher strength, 2019 lbs vs 1457 lbs for the dovetail.
Also mentioned in the article is the need for smooth faces, and thin glue joints. Rough joints have non structural fibers that fail easily.
So, the purpose of Knots polls is humor, now I get it. It was hard to understand what they were about from a woodworking perspective. Woodworkers tend to be a serious lot when it comes to their work, we need to lighten up. I still think it would be fun to try to break things, scientifically or not. How about tying joints up to Bigfoot and the Gravedigger or letting some of the WWE divas have at them, maybe put a piece of furniture in a teenage party. This video is kind of humorous but we should be able to come up with something more meaningful and funny. A little clink on the machine leaves us wanting some more. Total annihilation would be much funnier, smoke, flames, scantily clad ladies. If it's only about having fun, let the good times roll.http://www.youtube.com/watch?v=DhLfb7m9Fug&feature=relatedBeat it to fit / Paint it to match
Actually, I'd go with a Drawbored M&T. I was this close to voting for the miter just because.
Chris @ flairwoodworks
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
I voted for the bridle joint since it has the largest gluing surfaces. Mechanical joint locking is just for decoration and sentiment with modern glues.
Why didn't you include dowels and biscuits?
ne sutor ultra crepidam
Ditto on maximum glue surface area. Can't quite go with the rest though because modern adhesives do fail. A pegged bridle therefore may be the strongest. John O'Connell - JKO Handcrafted Woodworking
The more things change ...
We trained hard, but it seemed that every time we were beginning to form up into teams, we would be reorganized. I was to learn later in life that we tend to meet any new situation by reorganizing; and a wonderful method it can be for creating the illusion of progress while producing confusion, inefficiency, and demoralization.
Petronious Arbiter, 210 BC
Is this a trick question?
"Strongest" in what? shear?tension?compression?
This sounds like a newbie question on the forum...
Expert since 10 am.
Take a look at my earlier post in this thread, where I try to provide some detail about the question. It's not a trick.
David HeimManaging EditorFine Woodworking.Com
When a piece breax, it almost never breaks on the glue line. Which suggests to me that the glued lumber is stronger where it's glued, than where it is glue-free.
For that reason I go for the floating mortise - you can put as long a tenon as you want, thereby making more of the piece less breakable.
I enjoyed David's treatise on joints and agree with all his points - especially the one concerning the fact that there are appropriate and inappropriate joints depending on the purpose of the project.
For example - what would be the purpose of building a mega-strong joint for a picture frame? A butt joint with a line of glue is sufficient for something that's just going to hang on a wall, IMHO. Now ... consider a structural beam - there we need the strength of lots of interlocking faces in the joints, glued.
Interesting discussion. My preference would be M&T. However I have a question that a woodworking buddy of mine and I disagree.
Eons ago when I took Woodworking 101, the instructors said that the strongest M&T would be where all surfaces, both mortice and tenon, we as smooth as a babys behind, and at tight as "Dicks Hatband", (never did quite understand that one). My buddy said, not so fast, if you leave them rough, and not quite so tight, as in doing the mortise with a radial arm saw you end up with a better (more?) glueing surface.
Anyone have any thoughts on this?
Phillip,
I would say smoother is better. It would seem to provide a better gluing surface to surface whereas the rougher surface would allow pockets of glue where the bond wouldn't be as strong.
Just my 2¢.
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Thanks, my thoughs exactly. It seems to me tight and rough would leave pockets where there would be no glue.
Phil
Philip,
Like you, probably, I read all them FWW articles (and others) comparing the various M&T styles and variances. They do tests where, typically, they try to part or snap the joint. However....
My impression, looking at many older M&Ts, is that cycles of dry/moist are what damage M&Ts that are initially tight-fitting and glued. The grain is typically at right angles, mortise-face to tenon-face. In addition, grain orientation probably varies in the two (eg one may be plain-sawn and the other quarter-sawn). Therefore, significant dry/wet changes will (especially in larger section M&Ts) eventually make something give - if not the glueline then some part of the wood within the M&T.
If this is so, then the best M&T will be a dry-fit one that is mechanically pinned with a dowel or wedges. No glue to fail and the pin/wedges will mechanically keep the joint sound even if the wood in the joint differentially shrinks and expands a little.
Certainly this is the approach in many outdoor M&Ts. In the English Lake District, where I do a lot of walking, there are thousands of wooden field gates, typically oak but modern ones are treated softwood. They are bar and post gates - the bars tenoned into the posts with through tenons. This allows water migrating into the joint to easily evaporate out again when it ceases to rain. It rains a lot there (between the lovely sunny spells).
The M&Ts are pinned and, although older gates do begin to sag a little as the M&Ts go a bit slack over the years, these gates last for anything up to 50 years in a very demanding climate.
The conclusions I draw (which anyone may argue agin') are:
* Glue/tight-fit is best for small M&Ts where the wet/dry cycles are not great.
* Biscuits may be the best version of a small "M&T" for a lot of indoor cabinets that are not subject to great racking forces, as their tight mechanical grab, small area and thin section makes them more immune to moist/dry cycle destruction.
* M&T may be better if the furniture is going to be stressed - e.g. a chair.
* M&Ts that are larger and/or subject to significant wet/dry cycles might be glued and tight-fitting but should have a mechanical backup (pin or wedge).
* In extreme cases (eg outdoor furniture) dry fitting M&Ts with mechanical pinning would be the best option by far.
But only part of this is from experience, with a good dose of guesswork.....
Lataxe
Great info, Thanks.
Hi All, So, I notice in this question that they also put pocket hole screws joints in the mix. How strong are they, really? I have used them for face frames and putting boxes together, and they seem strong. However, I have never seen them in any study that I am aware of, and so I am curious. BTW, in my limited experience, M + T seems to be real strong, and this is what I voted for. But I am curious about the pocket holes as there seems to be a lot of hype about them, kind of a lot of sizzle, but where is the steak, the data that proves how strong they are. And so I ask with all due respect for all as I am simply curious.Kind regards.
I'd say the strongest would have quartersawn stock and glue the 2.5" sides together for the length of the boards. Of course, you may be wanting to make a box corner, rail and stile, T, cross, or some other type of joint configuration.
Pardon the sarcasm, but each piece has three sides: end, face, edge. So you can join two pieces in 9 different ways (three choices for the first piece * three choices for the second piece). Then one piece can be rotated, so that would be 18 ways. And you can join in the center of each piece or the end (head hurting, head hurting), so that would be 72 ways (or is it 36???). Then worry about the type of stress you expect -- tension, compression, racking, shear, twisting (rotation). Factor in that some joints need to be cosmetically pleasing for an application, you would probably not use a dovetail on a rail & stile application (head still hurting).
Edited 1/16/2008 6:25 pm ET by byhammerandhand
Another brilliantly thought out poll question.......
ha ha ha
Half lap, titebond II, hydraulically clamped, pinned with carriage bolts and fender washers and reinforced with angle iron, wrapped in kevlar saturated with epoxy resin and kept in a cool dark place.------------------------------------
It would indeed be a tragedy if the history of the human race proved to be nothing more than the story of an ape playing with a box of matches on a petrol dump. ~David Ormsby Gore
Now THAT's funny.
If I could, I would change my vote to half-lap joint because I did not read that the stock was 2-1/2 by 3/4.
David,
I voted other as nails weren't offered as a choice. Actually I would use just one nail. This will allow the joint to flop all over the place so the wood won't get broken. This type of joint also affords the look of rustic I don't have a clue what I'm doing funiture.
A single nail also enjoys the advantage of allowing wood movement!
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
This is just a general responce, but as much as we have advanced. what I miss most is just being able to sit around and actually talk to each other and not have to depend on this writing all the time.
God Bless you all
Was there any serious doubt?
Probably the horizontally laminated fingers if there are enough of them.
This forum post is now archived. Commenting has been disabled