what’s wrong with Domino joinery

[Ollie McDottie]

Hello Everybody.

I apologize if this is a repeated thread or query, I did do a search to see if it’s been addressed elsewhere and didn’t find apt answers.

I’m a big fan of my domino. I use it as much as I can and it has never failed me. Joining boards for table tops, rails, stiles, aprons, legs. If I can get the machine in there, I’ll use it.

However, I’ve heard more than once that it’s not structurally sound. That really it’s more of an alignment tool than a joining one, like a biscuit joiner. And frankly I’m totally confused by this. How is a tightly/well fitted loose tenon glued on both sides not performing a structural capacity? What am I missing here?

Say for example, I’m making a table base with an apron — How is a fat 14mm domino glued a good inch or more into both sides of the joint not as strong as a tenon cut out of the apron going into a mortise cut out of the leg or a sliding dovetail/bridle joint/etc.?

As always, great gratitude for all of the fantastic insights you all share so generously here. And if I’ve missed the thread that addresses this, please redirect me.

[Stewart Lang]

Nothing's wrong with it. Some people just *think* there's something wrong with it

[Keegan Shields]

Like everything in woodworking, I think there are tons of ways to accomplish most tasks.

I like to have options when it comes to joinery, but its important to understand the strengths and weaknesses for each method in a given application.

I like my Domino, but I also use a router, a swing chisel mortiser, dowels, dovetails, splines, half laps, box joints, mechanical fasteners, tongue and grooves and so on....

As a general rule, if all things are equal, the joinery method with more long grain to long grain glue surface is stronger.

You also have to consider the type of force you think will be applied to a joint. M&T joints are really strong in shear but much weaker when being pulled apart.

For pulling forces (tension I think?) a wedged through mortise and tenon joint is much stronger. Or you can add dowels to pin M&T joint.

And then there are all of the cool joints that aren't in common practice...

So many fun things to learn in woodworking!

-Keegan

[Brian Holcombe]

I’d rather just size out and cut something closer to ideal with free standing machinery. Nothing ‘wrong’ with domino joints other than that. They can be accurate or sloppy depending on the user and the prep.

[Andrew Hughes]

I did some testing with domino loose tenons. The results very good !

[Richard Coers]

Make a few samples and then destroy them. I picked up some cutoffs from a friends shop that had been joined with dominoes. There was no wood transferred between the domino and the walnut mating piece. That has me concerned and I want to do some samples myself. Personally I think the dominos are too tight and makes for a slightly dry joint, or the striations on the domino make for a thick glue line. But I want to see wood fibers on both sides when the joint fails.

[Patrick Kane]

I think some of those critiques leveled against the DF500 are fair. It can only plunge 25-28mm, which isnt tremendously deep. I also think 10mm is pretty weak for most furniture joinery. Thats my opinion, i do think there are structural concerns with the DF500's joinery in typical furniture joinery. However, i have the 700 now, and i cant level much critique towards its joinery capacity. It can plunge almost 3" of depth, and 14mm has some substance in numbers. Ive used it on king size bed frames, a 13' dining room table, and a bunch of chairs and smaller end tables. On really big projects, i think the 700 is slightly outgunned. For example, on the 13-14' dining room table the long aprons are connected into the legs via a very hefty dovetail. I used the 14mm dominos for the short apron connection to the legs. I didnt feel comfortable with the 14mm dominos being strong enough for that 9' span, and the majority of the stresses in that table are on the long apron joint.

Its a fantastic tool and suitable for 80% of joinery needs, but i dont think its a panacea. I also think half the fun of woodworking is exposed joinery, or complex joinery. That is how i use the domino. If it wont be seen, and its up to the task then i use it every time. If it can be seen, or the domino is undersized for the potential forces at play, then i do it "by hand". And by hand, i mean a table saw/shaper for the tenon, and a router and chisels for the mortise.

[Matt Day]

Ignore those people. It’s simply a floating tenon. Very good strength when used and sized appropriately.

[Alan Schwabacher]

I suspect the statement began as something like "For edge joining, dominos provide only alignment". In this case, as a glued edge butt joint is as strong as the wood in that weak direction, it's true.

In other uses, they are the same strength as a similarly sized standard mortise and tenon. If you replace a large tenon with multiple smaller dominos, it gets more complicated.

[Mike Henderson]

The Domino has worked very well for me in a lot of situations. No complaints or problems.

Mike

[Albert Lee]

its floating joinery... been around for a long time... long before the Domino were invented.
for domino made by the 500, yes, its probably not strong enough as its only 25-28mm deep. but the 700 is different story. I have 700, 500, and Mafell Zeta P2. different horse for different course.

[Jeff Roltgen]

I've built and sold close to 100 bar stools, all joinery done with a DF500 and 10mm dominos. None have been reported as coming apart over ~6 year span of production.
This includes a couple in the shop that get abused regularly.
I will continue to build this way with confidence.

[Mike Cutler]

Ignore those people. It’s simply a floating tenon. Very good strength when used and sized appropriately.

Bingo!!!

I don't own a Domino, I don't need one. I can cut M&T's all day long, a dozen other ways, cheaper. Blah, blah, blah.
If someone ever gave me one though, you better believe I'd use the beejeezus out of it !!!
Most folks, myself included, have a problem with the initial investment in the tool, and try to argue it away. It doesn't detract one iota from the actual value of the tool though.
They're nice. They really are. Keep using it within it's capabilities and you'll be fine.
Sometimes I wish I didn't know a dozen other ways to cut M&T's.

[Eric Arnsdorff]

The biggest problem with it is I don't own one!

I've had other tools I wanted/needed (ok wanted) more and can make do without one just like everyone did before the tool was available.

Strength statements are so very often subjective and I rarely see proper testing that would hold up to any scientific rigor. I used some dowels in a skinny face frame recently. A domino would have been "stronger". But so would a carbon fiber face frame, etc. But I don't need stronger for something that already has a safety factor in the triple digits. I also wouldn't use a wood domino to join a structural steel weldment. As stated here many times - it's about the application and not what is "stronger".

So if you'd like to fix my problem with Dominos ... I'll PM you my address for shipment ;-).

[glenn bradley]

It is just a speedier way to do a lot of sizes of floating tenon joinery. When my requirement is too large or too small or otherwise not suitable for the Domino I use mortise chisels, a router or whatever I used to use for everything before I got a Domino. I have never used the factory domino biscuits but, assume they are as good as the ones I make myself out of whatever stock I am using for the piece. I think a couple of the responses got it right; what's wrong is that you don't have one or that you want to convince yourself that something is wrong with them. I don't see the benefit of a radial arm saw. That doesn't mean that there's anything wrong with them. A gazillion RAS lovers can't be wrong