Author Topic: Domino Strength Test  (Read 4090 times)

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Offline jaguar36

  • Posts: 182
    • Toolamanjaro.com
Domino Strength Test
« on: July 21, 2017, 07:15 AM »
I'm putting together a full review of the Domino.  One of the things I was curious about was how strong the joints actually were.  So I built a simple test rig to measure the strength of the joint, and compared it to just a plane butt joint and to pocket screws.  The rig is meant to simulate a face frame, as thats one area where I've used Dominos in the past that would be easy to test and where you could use a number of different joinery methods.  I used 5x30mm Dominos in 3/4" cherry for the test.

I was surprised to find that while the Domino did double the strength of the joint compared to just a butt joint, the pocket screws were 50% stronger than the Domino.  One commenter did point out that if strength was a major concern a longer Domino could be used, and that's a good point.   I've got some 6x40mm Dominos laying around so I'll try that out.  Still I was rather disappointed in the Domino as I thought it would be just as strong if not stronger than the pocket screws.

Here's the video I made of the test:
« Last Edit: July 21, 2017, 10:09 AM by jaguar36 »

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Offline Roseland

  • Posts: 530
Re: Domino Strength Test
« Reply #1 on: July 21, 2017, 08:08 AM »
You might be interested in this video, from Paul Marcel:

http://www.youtube.com/watch?v=6LHDdEgDBws&feature=youtu.be

Andrew

TS55, MFT/3, OF1400, OF1010, CT26, RS100, ETS125, CXS, MFS400, DF-500, Zobos.

Offline GarryMartin

  • Posts: 1629
Re: Domino Strength Test
« Reply #2 on: July 21, 2017, 09:10 AM »
If you search for domino strength on YouTube you'll see quite a few different reviews testing different scenarios. It's good that you've added another, but it would equally be interesting to find whether your results match others or are at odds with them.

Have you reviewed other examples?

Offline antss

  • Posts: 1374
Re: Domino Strength Test
« Reply #3 on: July 21, 2017, 09:51 AM »
Few observations / comments:

The domino you used is a bit thin for my tastes. I'd use the next size up which would make for a stronger joint.   If you were using traditional M&T , your tenon would be much thicker.  I can't say your results would measure differently.  It's just how I would construct that joint.

Even when your domino joint broke, it still had some mechanical properties holding it together and stands a reasonable chance of remaining intact.  Once those screws pop , you're really left with an unglued butt joint as not much of the screws bite into the wood anyway.

For me, pocket screws are only advantageous when I'm putting two pieces together without clamps or something that needs to be done fast and won't be subject to much stress.  Not the traditional uses for sure.
« Last Edit: July 21, 2017, 04:00 PM by antss »

Offline jaguar36

  • Posts: 182
    • Toolamanjaro.com
Re: Domino Strength Test
« Reply #4 on: July 21, 2017, 10:08 AM »
The domino you used is a bit thin for my tastes. I'd use the next size up which would make for a stronger joint.   If you were using traditional M&T , your tenon would be much thicker.  I can't saw your results would measure differently.  It's just how I would construct that joint.

Since the Domino didn't break a thicker one wouldn't make much difference as it wouldn't have substantially larger glue surface.  A longer one certainly would have though, and I'm going to give that a shot.

Offline ChuckM

  • Posts: 212
Re: Domino Strength Test
« Reply #5 on: July 21, 2017, 10:17 AM »
FW did a joinery test in 2008, including the dominoes: http://www.finewoodworking.com/2009/02/25/joint-strength-test

Part of the results:

DOWELMAX 759 lb.
¼ -IN. M&T 717 lb.
POCKET SCREW 698 lb.
DOMINO 597 lb.
BISCUIT 545 lb.
« Last Edit: July 21, 2017, 10:26 AM by ChuckM »

Offline HarveyWildes

  • Posts: 580
Re: Domino Strength Test
« Reply #6 on: July 21, 2017, 10:43 AM »
I use Festool Dominos for applications that don't require maximum strength - alignment, etc.  For joints where I want the most strength, recently for bench leg mortise and tenons, I use homemade Dominos that fit the maximum width that the machine will cut, and the maximum depth, minus 1-2 mm for so for glue squeeze.  On my bench project, this nearly doubled the glue surface area of each joint.  Also, I had the room, so I doubled them up.  Even at that, I'm sure they aren't as strong as through mortise and tenon joints, so I still resort to those occasionally.  I'm assuming that the joint glue surface area is one of the main contributors to the strength of a joint.

I don't have enough history with Dominos yet to know what the practical strength limits are.  We'll see if my bench collapses, I guess.
« Last Edit: July 21, 2017, 11:44 AM by HarveyWildes »

Offline ChuckM

  • Posts: 212
Re: Domino Strength Test
« Reply #7 on: July 21, 2017, 11:21 AM »
None of my DJ builds have failed, including the nook table shown here.

The acid-test, to me, is its use in chair-making. I will be making a pair of chairs to match the nook table in 2018 (too many projects, too little time!)

P.S. For the nook table, I deepened the mortises cut by my DF500 and used the longer Dominoes intended for the 700.
« Last Edit: July 21, 2017, 11:30 AM by ChuckM »

Offline antss

  • Posts: 1374
Re: Domino Strength Test
« Reply #8 on: July 21, 2017, 04:08 PM »
Like I said - your test may not be different but a larger tenon would make for a stronger joint . 

You've chose to focus on the glue surface of the butted surfaces.  That in and of itself is not what makes for a strong joint.   I'll stack up  big ol honkin tenon in a tight mortise with two pins and no glue against any glued joint you want.

Chuck _ I agree a chair is a good bellwether for joints.    Nice inlay on that table BTW.   :)

Offline HarveyWildes

  • Posts: 580
Re: Domino Strength Test
« Reply #9 on: July 21, 2017, 04:52 PM »
...
You've chose to focus on the glue surface of the butted surfaces.  That in and of itself is not what makes for a strong joint.   I'll stack up  big ol honkin tenon in a tight mortise with two pins and no glue against any glued joint you want.
...

In my case, I was referring to the glue surface of the larger homemade dominos, not the butted surfaces.  The larger homemade dominos fit as tightly as the Festool ones, and the comparison I was trying to make wasn't between mortise and tenon and dominoes - it was suggesting ways to make a sturdier joint with the Domino tool than you can get with the Festool OTS dominos.  That said, I do agree that mortise and tenons are going to beat Dominos for strength if both are well executed.

Offline Steven Owen

  • Posts: 252
Re: Domino Strength Test
« Reply #10 on: October 18, 2017, 12:10 AM »
None of these tests are measuring the larger dominos from the DF 700.  DowelMax would have a hard time making a video to prove dowels are stronger than a group of 14 mm wide and 70 mm deep domino.

I can’t stand watching the DowelMax videos.  They’re condescending and always focused on bashing other jointing methods without any real understanding of how the equipment was meant to be used.     

After watching the Wood Whisperer it’s hard to watch the DowelMax videos.  You feel you might have to duck down fast to avoid the crazy angry old guy with a dowel fetish who will start throwing dowels at your head if you say anything about domino being better.
« Last Edit: October 18, 2017, 12:45 AM by Steven Owen »