more reading on the subject...

Wood joint strength testing

 

It shows that it depends on the application, as the results are different from the previous link.

 

true independent non-sponsored lab results are difficult to find...
more often than not the sponsor comes out looking pretty good...
search for wooden joint strength test and you'll find the results are all over the place...
keep in mind there are a bazillion variables to consider and factor in... doesn't seem possible to cover even half of them...

Fine Woodworking and Wood Magazine did very comprehensive test series - but you have buy the results unless you have the issue of their magazine....

I've always believed that M&T is the strongest of the bunch....
and I see/saw nothing to dissuade me...

"Wood Joint Torture Test" in WOOD magazine issue #173

Wood Joint Torture Test

Wood Joint Torture Test II

 

Dowel joints are foul joints

All the Dowelmax tests show is that dowels have a high shear strength. They tell me nothing about the strength of the glue line between the dowels and the walls of the dowel holes (50% end grain). Nor do they tell me anything about the longevity of the joint when subject to seasonal changes in relative humidity. As a cabinet maker I'm interested in these characteristics. The attached photo makes my point. These two dowels were never subject to shear stress. I will use nothing but mortice and tenon (or slip tenon) joints. If you own a router it is dead easy to cut accurate mortices.

Denis Lock 'Routing with Denis'

 

In my last post I did not make it clear that my photo is of a failed dowel joint (not a joint about to be glued).

Denis Lock 'Routing with Denis'

 

I used to do a lot of doweling but then got a hollow chisel setup and went to mortice and tenons. I think the tenons are a little stronger and I find them easier to fit. Multiple dowel holes were hard to keep aligned compared to a tenon. (I didn't have a dowel max.) With a tenon there are extra steps that can be taken to reinforce the joint such as wedging the end of the tenon or pegging the tenon with a cross dowel.

 

I guess about the link i shared, its more about selling the product than the true story but don't forget they have used like five dowels to make a joint which may be a factor. A two dowel joint might not be as strong as those shown in the link.

I remember a few places where Mortise and tenon are accompanied with dowels to strengthen the joint.

 

if you have ever taken a statistics course, no matter what the data says, with the right presentation/manipulation it can be used to your benefit, to sell your message/product or to play on people's natural tendency to assume to influence/bolster an outcome that would other wise has little chance......

so it pays to pay attention, take notes and don't accept at face value... a little cynicism can go a long ways.....

 

I hate dowel joints. If I had to use them Id give up woodworking. I can honestly say I gave my dowel drilling jig away 30 years ago and haven't drilled a dowel sense.

Not that I don't think they're fine. I just don't like anything about them.

 

Damn! I jumped all over that, Oliver. Went on Amazon.ca, and their system is having a temper tantrum...won't process my order.
$5Cdn plus postage seems fair.

 

I've always wondered what furniture is subjected to the kind of stress that is needed to break a joint apart. I would think dowels, m&t, loose m&t, splines, etc if the joint is made correctly will all be fine especially with today's glues being as strong as they are.
I tend to doubt t that most of us are making furniture that is destined for the Smithsonian.

I don't make chairs, but if I did I might research what joinery is the best for the application.

 

Modern wood glues are rated at a strength of about 2500 lbs per square inch. That's stronger than the wood. I seldom use any type of joint in my projects except glue. If I later recycle any of them I have to take them apart with a short sledge hammer.
:moil:

 

No joints?



Really? You can just butt join chairs and tables together?

Al

 

My take on this is somewhat different. I come from a structural engineering background, but also have a lot of experience in manufacturing. I use numerous types of joints and to me, all of them have their pros and cons...single round dowels are very near worthless in all but rare circumstances, because spinning can occur - but a tenon is also a single dowel - but it is not going to spin. There are many factors of importance in joining wood beyond simply strength - and even if there were not - which strength would one need to consider? A poorly constructed joint of any kind is going to yield unsatisfactory results. My shop uses a lot of dowel joints - none of us have any problem aligning multiple dowels with multiple holes - same situation is true for mortise and tenon joints. I do not build very much furniture, but I do build a tremendous volume of prototypes - and they must fit perfectly! When I have customers that have traveled to meet with me to see how mating parts match-up, you can bet they are going to match-up perfectly! This ain't rocket science, folks - just plan-ahead and develop skill sets for work you will need to produce. It's like hunters doing target practice - practice is the key to developing and honing skill sets.

Otis Guillebeau from Auburn, Georgia

 

My take on this is somewhat different. I come from a structural engineering background, but also have a lot of experience in manufacturing. I use numerous types of joints and to me, all of them have their pros and cons...single round dowels are very near worthless in all but rare circumstances, because spinning can occur - but a tenon is also a single dowel - but it is not going to spin. There are many factors of importance in joining wood beyond simply strength - and even if there were not - which strength would one need to consider? A poorly constructed joint of any kind is going to yield unsatisfactory results. My shop uses a lot of dowel joints - none of us have any problem aligning multiple dowels with multiple holes - same situation is true for mortise and tenon joints. I do not build very much furniture, but I do build a tremendous volume of prototypes - and they must fit perfectly! When I have customers that have traveled to meet with me to see how mating parts match-up, you can bet they are going to match-up perfectly! This ain't rocket science, folks - just plan-ahead and develop skill sets for work you will need to produce. It's like hunters doing target practice - practice is the key to developing and honing skill sets.

Otis Guillebeau from Auburn, Georgia

 

Dowels to me are the gizmo that came before the biscuit joiner. Some use them every day on any board they fit. Some call them the butt of woodworking.

I just don't like drilling holes. I've also seen so many failed dowel joints that are really not easily repairable.

I've got good equipment in my shop and it makes it easier to build with MT joints and dove tails. With 6 routers and a few Japanese saws, I don't have to drill anymore holes and pound the pegs in.

As to glue being stronger than the wood. That is true but the wood can sheer and break at the surface of the glue joint. I only think this idea applies when we mate boards in a glue up. Tables and chairs without sound joints soon produce a view from the floor.

Al

 

Dowels to me are the gizmo that came before the biscuit joiner. Some use them every day on any board they fit. Some call them the butt of woodworking.

I just don't like drilling holes. I've also seen so many failed dowel joints that are really not easily repairable.

I've got good equipment in my shop and it makes it easier to build with MT joints and dove tails. With 6 routers and a few Japanese saws, I don't have to drill anymore holes and pound the pegs in.

As to glue being stronger than the wood. That is true but the wood can sheer and break at the surface of the glue joint. I only think this idea applies when we mate boards in a glue up. Tables and chairs without sound joints soon produce a view from the floor.

Al

I agree... and the biscuits are less fussy. Neither do much of anything for strength.

A good MT joint is hard to beat, as is a good box joint.