# How strong are dowel joints?



## Woodchips2 (16 Dec 2014)

I’ve been using a Joint Genie dowelling jig for a while making shelving units, stud partitions, cupboard doors and the like and have been very pleased with the results. I use a shooting board to ensure I get accurate matching surfaces for the glued joint. However I wondered how strong a dowelled joint is compared with a traditional mortice and tenon. Also I’ve thought about buying a biscuit jointer. 

I had a search on the internet and found this site http://www.dowelmax.com/jointstrength.html where hydraulic tests had been carried out and you can view the videos of the tests. The test was done by Dowelmax which looks a lovely bit of kit but does the same job as a Joint Genie.

The test results were:
20 Biscuit 285 lbs. per square inch
Pocket hole (5 screws)	420 lbs. per square inch
Double Domino 560 lbs. per square inch
Routed mortice & tenon	640 lbs. per square inch
Multiple dowel 890 lbs. per square inch

They only used a 1” depth of penetration so I presume a through mortice and tenon would be stronger than the test results.

Think I’ll stick with my Joint Genie and not bother with the biscuit jointer.

Regards Keith


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## RogerP (16 Dec 2014)

I use dowels quite a bit but the only snag, unlike other joining methods, there's no "wriggle room" total accuracy is required.


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## Tetsuaiga (16 Dec 2014)

I imagine it might depend on the size of the dowels and how many you use also if they are hardwood.

The only doweling i've done is where you secure the two pieces together and drill through both pieces in one motion to give guaranteed accuracy.


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## RogerP (16 Dec 2014)

Tetsuaiga":3iy4k9pe said:


> I imagine it might depend on the size of the dowels and how many you use also if they are hardwood.
> 
> The only doweling i've done is where you secure the two pieces together and drill through both pieces in one motion to give guaranteed accuracy.


... yes, that's okay but when they're blind holes things get a little trickier 

Of all the gadgetry that's available I still find the old "dowel points" do a good job.


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## Random Orbital Bob (16 Dec 2014)

I must say one of the only glue joints I've ever had fail was a dowel joint on a piano stool I made near 20 years ago. Maybe I did something wrong but it started to come adrift about 2 years ago. I'm yet to have either pocket screws, dominos or biscuits fail. There again they haven't been out there being sat on etc as long as my dowel joints have!


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## RogerP (16 Dec 2014)

The modern fluted (straight or spiral) dowels stay put much better that the old plain ones.


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## Tetsuaiga (16 Dec 2014)

18 years sounds good enough for me.


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## finish_that (16 Dec 2014)

Not sure that was entirely fair test - in that - from what I could understand one biscuit was up against the others in multiples apart from the M&T - what would be the result with one dowel or one pocket hole ? Not knocking them , but I would also want to look into the speed and ease of accurate work . 
It is more about how you like to work and the size of the joints biscuits cannot be used for tiny joints like dowels , but
are faster and more flexible for others .


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## dzj (17 Dec 2014)

I use dowels. They're OK. But for serious stuff, I go for mortise and tenons.

Problems that might arise with them is that their moisture content might not be the same as the pieces they are connecting. Also, with time, the glue sometimes fails.
Time is what is missing in the 'Joint Strength Test Comparison Videos'. 
It's not a longitudinal study.


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## timber (17 Dec 2014)

RogerP":363z0soa said:


> I use dowels quite a bit but the only snag, unlike other joining methods, there's no "wriggle room" total accuracy is required.


 Quite right Roger !!!!!! I have to start my chair seat all over again (hammer) Also today I am going to look into the quality of some dowels ,they look more like compressed paper, I left one in a glass of water overnight a few days ago and it looks a bit strange well dry now
Richard


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## Jacob (17 Dec 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 a weak joint.


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## RobinBHM (17 Dec 2014)

I think dowels and biscuits have different applications.

Dowels have been used a lot in manufacture, as they can be drilled accurately on a point to point or through feed boring machine. Also dowels can be inserted automatically. Glue can be applied by a capsule or jet. 

The disadvantage of dowels is they require exact centre to centre spacing and they require the right amount of glue. Dowels often fail due to either glue starvation, too much glue or drilling depth wrong (its easy to drill too deep to be sure the joint pulls up, but only to find the dowel then sits down too far when inserted in the first side). I have looked at the joint genie website -it certainly looks a good tool.

Biscuits have significant tolerance in one direction, just requiring a rough pencil mark for positioning. They are very good for bespoke carcase making generally much quicker than dowels.

I havent used a domino machine, but judging by the number of people on here raving about them, perhaps I should try one! Ive managed to avoid Festool so far -Im worried it may the start of an expensive collection.....


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## Baldhead (17 Dec 2014)

Random Orbital Bob":cim67026 said:


> I must say one of the only glue joints I've ever had fail was a dowel joint



+1



Jacob":cim67026 said:


> Dowels are glue only, with a small glued surface area- basically a weak joint.



Totally agree.

Baldhead


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## Paul Chapman (17 Dec 2014)

In my experience, dowels are always the worst option. M&Ts, loose tenons, dominos and biscuits are all far better. Dowels just don't stand the test of time.

Cheers :wink: 

Paul


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## John15 (17 Dec 2014)

I think dowel joints are OK where there is little stress to the joint, for instance I used them recently to fix a bookcase facia.

John


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## rafezetter (17 Dec 2014)

Matthias Wandel did tests of his own for dowels vs other joints, be sure to read the additional links at the bottom where he revisits the tests after a dowel jig company complained about his results..

https://woodgears.ca/mortise/strong.html


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## Chris152 (1 Jun 2018)

I found this is interesting - dowels vs mortice and tenon. Obviously they had an axe to grind with Fine Woodworking, but still interesting.
https://www.youtube.com/watch?v=WoOEwEuB1ag
I'm sure real world context changes things, but has anyone tested that?

edit - I came to this question after considering box/ dovetail joints for box-making, and wondered if the reason people use them is appearance/ a romantic attachment to the past rather than efficiency? Not that joints need to be terribly strong for your average box, I guess.


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## dzj (1 Jun 2018)

Longitudinal studies are missing. 
When the glue fails over the course of time, M&Ts will do better. 
Dowels, like loose tenon joinery, have their place, but for moving elements, M&Ts is the way to go.


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## Chris152 (1 Jun 2018)

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?


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## custard (1 Jun 2018)

Personally I'm a fan of dowels, I use them regularly and regret that they've fallen from favour.

The first argument I'd put in favour of dowels is their affordability for the hobbyist. Yes you can spend a lot of money on some dowel jigs, but traditional dowelling jigs like the Record 148 work very well and are as cheap as chips compared with a Festool Domino or a Lamello Biscuit Jointer. If they have a problem for the hobbyist working with solid wood (rather than sheet goods) then it's the same problem as Dominos and Biscuit Jointers, they all reference directly from the workpiece, so if the workpiece isn't dead square and true then the joint will be gappy. That's just a fact of life.

The second argument is that sometimes nothing else will do the job quite as well as a dowel, so even if you prefer other jointing solutions dowels should still be in your armoury. I could give dozens of examples but I'll just use two. 

You'll regularly encounter in cabinetry a rail beneath a drawer secured at either end with twin tusk tenons, but in order to accommodate a traditional drawer stop this rail needs to be deeper, so needs another jointing element. I've tried lots of options but keep coming back to a single dowel. You can just see the arrangement in this photo,






What's even better is that I locate the position for the dowel with the simplest and cheapest device imaginable, the traditional pointed dowel marker shown here. It works for me, and with care it'll work for you too,





A second invaluable application for dowels is with chair making. The most highly stressed joint in a chair is where the side seat rail attaches to the back leg, so you give the majority of the available "meat" in the leg thickness over to this joint. But that leaves a problem, how do you then attach the back seat rail? The solution is a very large, but very shallow stub tenon only about 10mm deep. However to "pin" that tenon securely in place it needs reinforcing with two or three dowels. You can see a typical back rail chair joint here,





Once again the added beauty is it requires a little bit of skill rather than a great deal of money, because for chairs I always make my own dowel jig. Simply a block of hardwood with a mortice on one side and a tenon on the other, shaped to perfectly mate with the corresponding stub mortice and tenon joint, through this I drill three holes and that's the jig made. It won't last forever, but you don't need it to, you only need it to get you through the eight or ten chairs in a set.





Final point. I think debates, about if dowels are stronger than dominos or M&T's, are missing the point. I don't care which is the absolute strongest joint because by and large they're all strong enough for domestic furniture. What matters to me is their practical application within the context of making a piece of furniture. If I was looking for ultimate strength I'd forget about wood and weld the thing up from angle iron.


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## Jacob (1 Jun 2018)

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.


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## dzj (1 Jun 2018)

Chris152":2tjntpg0 said:


> 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.


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## custard (1 Jun 2018)

Jacob":2cyp18r9 said:


> 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.


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## ColeyS1 (1 Jun 2018)

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


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## screwpainting (1 Jun 2018)

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)


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## Phil Pascoe (1 Jun 2018)

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.


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## Jacob (1 Jun 2018)

custard":36wyxvyn said:


> Jacob":36wyxvyn said:
> 
> 
> > The most common (90%?) furniture failure brought in for repair is a failed dowel joint.
> ...


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.


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## Phil Pascoe (1 Jun 2018)

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


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## Jacob (1 Jun 2018)

ColeyS1":3q0oxuqu said:


> 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.


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## Jacob (1 Jun 2018)

custard":39kqt63f said:


> .........
> 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?


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## MatthewRedStars (1 Jun 2018)

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


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## custard (1 Jun 2018)

Jacob":3rzebc6w said:


> 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?


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## Chris152 (2 Jun 2018)

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. 



Jacob":32fd1auo said:


> 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.


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## Jacob (2 Jun 2018)

Chris152":3u16svue said:


> .....
> 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.


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## ED65 (2 Jun 2018)

Jacob":12xm408o said:


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





Jacob":12xm408o said:


> ...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. 



Jacob":12xm408o said:


> 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.


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## Jacob (2 Jun 2018)

ED65":23jp95kn said:


> Jacob":23jp95kn said:
> 
> 
> > 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) ..."
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.


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## Lons (2 Jun 2018)

Jacob":1ezucouj said:


> 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


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## Phil Pascoe (2 Jun 2018)

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.


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## Jacob (2 Jun 2018)

Lons":b0tjkh2a said:


> Jacob":b0tjkh2a said:
> 
> 
> > I've also had to repair one I made - not enough glue in the dowel joint!
> ...


Yeah well nobody's perfect!


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## Lons (2 Jun 2018)

Jacob":3a7px6f7 said:


> Yeah well nobody's perfect!



*What!* 

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


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