Domino Joint verses Mortice and Tenon

drchristian

New User
David
Got a Festool domino jointer. When do you use a domino verses a tradition mortice and tenon. I have used mortice and tenon for years. What is your opinion of the strength and advantages of each type joint?
 

Henry W

HenryW
Senior User
David - congrats on the new toy/tool. (May I officially state that I am jealous?)

A domino is a standardized form factor loose (mortise and) tenon joint, with pre-made tenons - so they really are the same thing.
Two mortises are cut and a loose tenon is inserted - this form of joinery has been around a long time (before Festool produced Dominos).

'All' the Domino does is make the process faster and more convenient, as long as the standardized tenon sizes are suited to your project.

I wish I spoke from experience; all I speak from is wishful thinking. I have read of a few folks reporting the strength/failures of Domino joints, but my read on these is that these were cases where traditional M&T joints may likely have failed as well (i.e. joints in 'Z' base chairs with thin stock).

Hope that helps
 

zapdafish

Steve
Senior User
I use the 500 more for panel glueup alignment, case alignment, and where beefy mortise and tenons are not needed/possible like a coffee table. Beefier ones IMO should be done with the 700, like for a bed or dining table where I think the tenon should be longer than 25mm.
 

Rwe2156

DrBob
Senior User
I think they are just as strong as a M/T. I mostly use it for face frame construction and panel glue ups, although lately for ff's I've been going with pocket screws because no clamp time.

I built several drawers using and it works well for that, too. Just have to remember to reset the depth if they are 1/2".
 

zapdafish

Steve
Senior User
I recently got the big foot, it's a great accessory for case work and drawers. I used to have issues with getting accurate 90 plunges with certain setups.



I think they are just as strong as a M/T. I mostly use it for face frame construction and panel glue ups, although lately for ff's I've been going with pocket screws because no clamp time.

I built several drawers using and it works well for that, too. Just have to remember to reset the depth if they are 1/2".
 

Graywolf

Richard
Corporate Member
I can't totally recall who did the test between the two but the mortise and tenon won on the strength tests. With that said the difference between the two were not that far apart. So I'd say the real advantages are where and when you want to use each joint. I'd have to say the domino would have a speed advantage over the M&T.
 

JimD

Jim
Senior User
I have a 700 with the Seneca adapter and all sizes of bits except a 4mm. I'll get one of those if I need it. But the only pre made tenons I have are some 12mm that came with the tool (I bought it used).

If the tenons are the same size and glued properly, there is no difference in the strength of a domino joint. But if you use little 1 inch wide tenons, you cannot expect the same strength as a 4 inch tenon.

I used my 700 recently to make 14mm by 40mm mortises for a crib. The tenons were made of 18 mm maple plywood by making a thin cheek cut in each face, removing a little from the ends and then using a rasp to round the tenon over on the ends. The plans called for the rails to be of plywood but recommended laminating the legs with enough space in the inner layer to use the plywood as the tenon without the cheek cut. I think my way is better and plenty strong. Some of the rails are 6 inches wide. I made a long mortise by repeated plunging. It took very little time.

I am working on a bed right now for me. It is from the Woodsmith "Classic Cherry Bed" plans. I think I will use some of the pre-made tenons on this one and use about 3 per joint. That isn't exactly the same size as the one tenon in the plans but is close and I think it will be plenty strong. But I might just make 1 longer mortise and then cut some scrap for the tenon.

Using the premade tenons makes it very easy to get a tight fitting joint. But It also means little tenons but often you can use multiples to make up for that. Using a domino 500 also limits you to about 1 inch mortise depth. That can also be a strength limitation. But the 700 will make 2 3/4 deep mortises which should be plenty for most projects.

It isn't how you make the mortises that determines the strength. It is the size of the joint and whether it is cut and glued correctly. The domino helps a lot with the fit if you use the pre-made tenons but they can result in a smaller weaker joint. But if you make your own tenons, you can have the same size and strength as a conventional mortise and tenon. The tests I've seen compared a smaller domino joint to a conventional M&T. Not surprisingly it was weaker. Not much of a test.
 

Gofor

Mark
Corporate Member
I would say that a nicely fitted domino would be just as strong or stronger than a poorly fitted M&T. As for those non-standard sized applications, there is nothing that says you have to use it for all joints. Have fun with the new tool.!!
 

Tarhead

Mark
Corporate Member
I got one when they first came out in ~2005. For Domino'd joints I am concerned about strengthwise...for example the base of a large cabinet, I add 2 pocket screws in the inside of the joint out of sight. This eliminates the need for clamps. Adding lots of floating tenons close to each other quickly hits a point of diminishing returns unless you're dealing with thick stock where lots of meat is left to support the tenons.
 

ashley_phil

Phil Ashley
Corporate Member
when i made my sons crib we mortise and tenoned it.

a couple years later when i did the footboard to make it a bed, Tarhead, came over with his domino and we knocked it out in an afternoon

several more years later, only way i know which is which is luckily i have enough memory left to recall having done it.
 

JimD

Jim
Senior User
I have my mortises cut in all the legs and with the rails of the headboard (there are 3). Due to my placement mistake, I ended up using long home made tenons for the top two rails but will use 3 pre-made tenons for the lowest stretcher. It took maybe 15 minutes to make the 4 wider tenons from scrap cherry. The are 4 inches wide and long. The plans call for 1.5 inch deep mortises but the legs are 3 inches square - so plenty of meat for 2 inch deep mortises which the 700 does easily.

My three pre-made dominos have the same 6 square inches of area as the recommended 4 inch wide by 1.5 inches deep mortises in the plans. With the same area, they would have essentially if not exactly the same strength. My home made tenons have 8 square inches so they will be stronger. But almost certainly overkill too.

The domino is easy to use and quick. But planning the location for multiple little tenons is a new thing and led to a mistake - that will make no difference in the end result. Still learning a new tool. A great thing for my little shop is the fact that it so much smaller than even my benchtop hollow chisel mortiser (need to sell it).
 

Tarhead

Mark
Corporate Member
The domino is easy to use and quick. But planning the location for multiple little tenons is a new thing and led to a mistake - that will make no difference in the end result. Still learning a new tool.
Yep...thank goodness the Dominos are made from wood. I had to saw off lots of them and re-mortise when first starting out. I now cut one side on the tight setting (+.5mm slop side to side) and the matching mortise with the tight setting and then again~1-2mms on either side of the line. This gives me more flexibility with getting things dead on.
I also don't fret too much with trying to get the joint exactly centered top to bottom as long as it's close. You just have to use the same side as a reference on both pieces. A few mm's too high or too low won't make any difference as long as you select the proper width Domino. (~1/3 of the width of the workpiece)
Another Pearl I've picked up is to wait for the wood to dry from the glue used in the joint before sanding. If you don't you can get a telegraph of the joint when the swelling goes away.
 

JimD

Jim
Senior User
My mistake was in the reference point for the mortises. On the bed posts, I put them 1 inch, 2.25 inches and 3.5 inches down (centers). On the rails I started out putting one in the center and then the others 1.25 inches up and down from that. I made the outside mortises on the posts with the wide setting and all the center mortises, and all the mortises on the rails with the narrower setting. But my centering of the mortises on the rails meant the top edge of the rail was well above the top of the post. I could have ripped the rails down but I think it was better just to widen the mortises into one that is 4 inches wide and deep. I had to make my own tenons for these mortises but that was pretty easy and just used up a little small scrap.

In the end, it took me a little more time but the only effect on the project is the mortise and tenon joints will be stronger than called for in the plans. Not really a bad thing. Hardest part was fiddling with the fence centering to recut the mortises to the wider configuration. The scale is pretty hard to read. I can see why they have the stops and people use special plates.
 

Matt Furjanic

Matt
Senior User
I made 5 solid walnut chairs for my daughter In 2009 using dominoes. Then I made 4 birch chairs for my dining room a year later. All 9 chairs are SOLID. Also used dominoes on numerous other projects, and have no joint failures. I think that if you put lots of stress on the domino joint, the wood would fail before the joint. The domino seems to be as strong as necessary. Possibly, a mortise and tenon joint is stronger, but I believe the domino joint is strong enough, and way way faster and easier. It’s basically a big time saver.
 

cyclopentadiene

Update your profile with your name
User
It depends on the stress applied to the joint. I have used Domino's for conventional joints i.e. standard tables etc. and had no issues. Typically the stress on a "normal table is equally distributed across all 4 legs.

However, I made a Maloof inspired desk for my daughter (the photos of the desk is blow). The rear legs were angled and curved so all of the stress was on the two back legs. I used two Dominoes in the joint for these two rear legs as it was much easier based on the design of the desk. It was partly poor design as all of the weight of the entire desk was shifted to these two legs. However, my daughter works from home and upgraded her computer monitor to a 36" monitor which is very heavy. the result was a failed joint over about a year. I was able to make a repair by removing the legs, reattaching the Dominoes and inlaid butterflies on each side of the joint on both legs. It has not been a couple of years and I have seen no problems.
 

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