# Domino 500 strong enough for settle/bench rails?



## KevinBlair (Jan 13, 2012)

I am in the process of making a mission style settle/bench for outdoor use. The sides will have the traditional through mortise and tenon joinery, but I am thinking about using dominos for the rails that would join the sides together to form the supports for the seat and back.

I have the domino 500, so the maximum domino would be the 10mm x 50mm. I'll need to order the outdoor dominos (Sipo ones) if I go this route.

The rails will be 5 1/2" wide by 75" long and 1 1/2" thick. Given the width and thickness, I can probably get 4-6 dominos (depending on which side dominos I ultimately use) instead of a traditional mortise.

If I have 3 adult males weighing 200 lbs plus sitting on the bench (enjoying a beverage or two) at the same time, that would be a maximum weight of maybe 650-700 lbs…can the dominos handle that much weight?

Thanks,
Kevin


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## BroncoBrian (Jan 14, 2013)

Kevin - good question. You might try asking Festool about this. They would be happy to answer.

I have the same joiner, and my understanding is that the domino is more about joining and less about strength. Obviously it does have solid material and will add strength, but the glue should be the bond.

Will the wood handle that weight if you were to use pocket screws and glue? If so, then I would expect the dominoes to be just as useful.

Curious if anyone has relied on them like this.

Also, check out Festool Owners Group and ask there. You would get an answer in minutes.

I would not imaging the XL with the next size up for the domino would be the difference maker. If so, something is wrong.


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## KevinBlair (Jan 13, 2012)

Surprisingly with 120 views your's is the only comment! I thought this would be a common enough question and that I'd get a lot of responses. A web search doesn't provide any real answer. Most of the strength testing seems to be along the lines used by Matthias Wandel; using force to see when the joint stresses and breaks. Those tests would seem to indicate that the dominos should be strong enough, but I'd like to make sure.

I am going to try the festool owners group and see what I get. If it's useful I'll post it here.

Given how the rails would join to the end post (end grain glued to long grain), a mortise & tenon or some other strong joinery is needed. I can certainly use mortise and tenons on these rails, but the domino would be much faster and reduce the number of mortise and tenons I need to make by a lot. I am actually making two of these benches that will face each other creating seating on a patio for 6


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## zmann (Jan 1, 2014)

Kevin,
if I understand you right you will have 150 lb on every corner joint. Most of the force is shearing force on the Domino, some of it is pulling on it or the glue respectively. if you can fit two Dominos that should easily hold the weight, if you are not sure and you want to improve the joint you can insert the apron 5 mm into the leg that really should do it because the weight will go straight into the leg and there is only pull force on the Domino.


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## KevinBlair (Jan 13, 2012)

Thanks Jorg! I believe your analysis of the weight distribution and force on each joint is correct. The 150 lbs per corner would occur if 3 adults are sitting and if they each weigh roughly 200 lbs. So, most of the time the weight and resulting stress would be much less.

It seems to me like 4 dominos (maybe 6 if I feel paranoid) should be more than enough. I'm also thinking I can add a center support at 35" across (essentially adding center legs to take all of the weight in the middle).

A shallow mortise reinforced by the dominos is an interesting idea. In the end though, it may be easier to "bite the bullet" and make everything with traditional M&T joinery….we'll see…

BTW, I did post this to the festool owners group; roughly 40 views and thus far no replies. Seems to suggest this is not a typical question.


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## zmann (Jan 1, 2014)

Kevin,
I don't think you need to worry if you put in 4 Dominos and a center leg you can park your car on that bench.


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## KevinBlair (Jan 13, 2012)

Thanks Jorg! The Festool Owners Group also came through with some nice answers. Essentially, the consensus is that #10 50mm dominos (2-4 of them) should be more than strong enough for my needs.

I'll post pictures when I have them built; hopefully in a few weeks to a month.


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