How strong are dowel joints?

[Jacob]

Old thread! I posted on 2014;
"The most common (90%?) furniture failure brought in for repair is a failed dowel joint.
M&Ts are belt and braces - glue and wedges and/or pegs. Dowels are glue only, with a small glued surface area- basically an inherently weak joint."
The most common failure is chair back to seat joint.
Often found in cheap machine made furniture but never used in trad joinery as a joint except for holding unstressed items (decorative bits etc), because they make a weak joint.
On the other hand they are/were widely used to pin through a M&T joint, sometimes draw-bored, where they are effective.
Would be stronger as a joint if made bigger i.e. with more glued surface area. The famous Reitveld red & blue chair has fat 16mm dia dowels, which seem to work OK.
If you must use them they must be well filled with glue. A 1mm weep hole for blind holes helps, and is invisible once the glue has gone off.

 

[dzj]

Yep, hadn't thought of that. Do you know how long it takes before the average glue fails? Again, I'm sure it depends how the joint is used?

Can't say. Sometimes they don't fail.
Sure, it depends how the joint is used. Who uses it is also a factor.
Adolescents and joinery don't get along well.

 

[custard]

The most common (90%?) furniture failure brought in for repair is a failed dowel joint.

Is there a source for this statistic, or did you just make it up?

It's also wrong to say a dowel isn't a "traditional joint", there are plenty of examples out there in top end work, for example it's difficult to make a first quality chair any other way than how I laid out. It wouldn't have been hard for a workshop to have a metal plate drilled, and then the craftsman could hammer cleft pegs through it to produce their own dowels.

The main source of failure in chairs is the side rail to back leg joint, despite having a massive M&T this is almost always the one that weakens first, and once that's loose the glue bond in every other joint in a chair will progressively give way.

But hey, you've long proven yourself deaf to facts and incapable of rational discussion, so you make your furniture your way and I'll make mine my way.

 

[ColeyS1]

I'm still trying to figure out how this could have happened

Here's how the other side looks
.

If I try repairing it I'll think I'll add two dowels where the arm joins the back. One really isn't very much is it !?

Sent from my SM-G900F using Tapatalk

 

[screwpainting]

Never a truer saying...

It ain't what you do, it's the way that you do it!

If, you know how to make things using dowels, and how to properly use them and what out of, but most importantly, when not to, then you my son will be a man! (Woodyard Kipperling)

Every jointing method exists because it has a particular application...

Comprehensively understanding the limits of what a joint needs to be and how to achieve it is a wonderful skill to have and very hard learnt knowledge, but so difficult to pass on in a short, forum post.

For my part, I will listen to Custard, who I think should be his own stinky =D>

Sorry, I meant sticky 8)

 

[Phil Pascoe]

Virtually every dowel joint I came across that had failed failed because the glue was useless - I daresay a m&t glued with the same rubbish would have failed as well. I've assembled cheap and flat pack furniture using decent glue having thrown away the "glue" that came with it and the stuff has lasted for decades.

And /or the joints were dry.

 

[Jacob]

The most common (90%?) furniture failure brought in for repair is a failed dowel joint.

Is there a source for this statistic, or did you just make it up?

Just a guess - hence the question mark.
What I do know is that easily 90% of furniture I've ever repaired has been due to failed dowels.
Not so with failed joinery - because dowels as joint in place of M&T is never used (except in modern rubbish - cheap hardwood doors etc), though dowel as peg is common.

 

[Phil Pascoe]

And out of curiosity - what % had chewing gum stuck under it?

 

[Jacob]

I'm still trying to figure out how this could have happened .....

It happened because of tiny, spindly, inadequate, dowels as joints. Very typical, especially of decorative stuff where more substantial joints are not easy to fit in. Or cheaply made stuff.

 

[Jacob]

.........
But hey, you've long proven yourself deaf to facts and incapable of rational discussion, so you make your furniture your way and I'll make mine my way.

I'm sure your twin tenon plus dowel works OK but if dowels are good why not use three and make it even easier?

 

[MatthewRedStars]

The Mafell double dowel jointer is a joy (a very expensive joy) if anyone has cash to burn.

 

[custard]

I'm sure your twin tenon plus dowel works OK but if dowels are good why not use three and make it even easier?

I guess a square tenon is marginally stronger than a similarly sized round dowel, and with a mortice machine I can make the twin tusk tenons pretty quickly and efficiently. But if I didn't have a mortice machine, or I was desperate to shave a couple of minutes off the build time, then I'd probably use three dowels.

Confession time, on those shaker style side tables, with first quality drawers I can just make a pair in a week, which is critical to make it profitable. But to do that I domino in the side and back rails to the legs instead haunched M&T's, I'm not entirely happy about that decision so maybe I try and compensate with a little gesture like traditional twin tusk tenons?

 

[Chris152]

Thanks all for the replies.

Totally reassured by your comments and use of dowels, custard - and I now know what a tusk tenon looks like (after googling it). Til now I've been using a set of locating pins for the dowel alignment, very cheap and can be accurate - though I recently made a picture frame with them and while it was perfectly square, the faces were off and needed lots of work to correct. User error, but that could have been in the drilling rather than the marking up. I'll keep an eye out for a decent price Record 148, tho looking at the pics online it's not so clear (to me) how it's used!

And I know exactly what you mean by adolescents and joinery, dzj - I have a 60s Scandinavian dining set on which, at any one time, one of the upper back supports is always broken as a result of leaning back too hard.

On the other hand they are/were widely used to pin through a M&T joint, sometimes draw-bored, where they are effective.
Would be stronger as a joint if made bigger i.e. with more glued surface area. The famous Reitveld red & blue chair has fat 16mm dia dowels, which seem to work OK.

Funnily enough, the original Fine Woodworking video/ article (that the Dowelmax video is responding to) says that pinning through a M&T joint weakens the overall joint, if I understand what they say correctly. And one of the reasons that the Rietveld chairs stand up so well is that nobody ever chooses to sit in them! I have a repro one that lives in a shed, given the design it's not soooo uncomfortable, but I never found myself collapsing into it at the end of a working day.

 

[Jacob]

.....
Funnily enough, the original Fine Woodworking video/ article (that the Dowelmax video is responding to) says that pinning through a M&T joint weakens the overall joint,

Well they are utterly wrong. Nothing new there!

if I understand what they say correctly. And one of the reasons that the Rietveld chairs stand up so well is that nobody ever chooses to sit in them! I have a repro one that lives in a shed, given the design it's not soooo uncomfortable, but I never found myself collapsing into it at the end of a working day.

Surprisingly they aren't uncomfortable at all - I've had one for years and have sold a few copies. Not that I'd particular recommend them as a seating solution but they are a picturesque item for those interested in design history - and a brilliant demonstration of ergonomics; geometry as the biggest component of comfort .
I've also had to repair one I made - not enough glue in the dowel joint!
PS I've got 3 to do at the moment - all planed up and ready to go, some recycled hardwood from a demolished conservatory. They are really boring to make - very little woodwork skill required at all, just precision positioning of the dowel holes.

 

[ED65]

Often found in cheap machine made furniture but never used in trad joinery as a joint except for holding unstressed items (decorative bits etc)...

...dowels as joint in place of M&T is never used (except in modern rubbish - cheap hardwood doors etc)...

The above are simply not true.

I'm not going to argue the point with Jacob for reasons well established by now, but for those interested a review of old guides (and old furniture where possible) will show this is the case.

If you must use them they must be well filled with glue. A 1mm weep hole for blind holes helps, and is invisible once the glue has gone off.

Can't argue with this however. Just like with a plain M&T (no wedges or peg/drawbore) it's best to coat both hole and dowel before tapping the dowel home.

Not applying enough glue initially is the primary cause of starved joints when the joint is very tight or bags of clamp pressure is applied, not from the tightness directly but because the surfaces weren't wetted to begin with.

 

[Jacob]

Often found in cheap machine made furniture but never used in trad joinery as a joint except for holding unstressed items (decorative bits etc)...

...dowels as joint in place of M&T is never used (except in modern rubbish - cheap hardwood doors etc)...

The above are simply not true.

I'm not going to argue the point with Jacob for reasons well established by now, but for those interested a review of old guides (and old furniture where possible) will show this is the case. .....

"....dowels as joint in place of M&T is never used (except in modern rubbish - cheap hardwood doors etc) ..."
I meant in joinery i.e. doors, windows, utilitarian furniture/fittings. Basically not a good hand tool joint and only came in with machines and cheap production methods, excepting the aforementioned occasional use for fitting decorative bits n bobs.

 

[Lons]

I've also had to repair one I made - not enough glue in the dowel joint!

The single most common reason why they fail. You should have done it properly first time Jacob. :wink: :lol:

Dowelled joints have there place just as do most other methods, choice depends on a number of reasons not just preference so it's horses for courses.
One of my customers asked me why the garden seat he'd made fell apart. Poor dowel fixings with the odd screw and he confessed to using interior grade Poundland pva. :roll:

I use them occasionally and have a simple set of dowel points in 3 sizes which I bought 30 years ago for that purpose along with decent glue, usually titebond or Cascamite. Can't remember any failures that weren't the result of abuse.

Bob

 

[Phil Pascoe]

Irritating - yet another post disappeared into the ether.
I never saw a dowel joint fail for any other reason than dry joints and/or cheap glue. When I was about twelve my father (who was no craftsman by a mile) told me to drown any joints as it was impossible to get more glue in afterwards - this always seemed reasonable to me. However virtually every glue I've ever used has the explicit instruction - apply glue to one side only. No one has ever explained properly why. I certainly wouldn't coat only one side of a dowel joint.

 

[Jacob]

I've also had to repair one I made - not enough glue in the dowel joint!

The single most common reason why they fail. You should have done it properly first time Jacob. :wink: :lol: ....

Yeah well nobody's perfect!

 

[Lons]

Yeah well nobody's perfect!

What!

I had to read that twice Jacob. You must be mellowing with age. :wink: