Dominos for outside use

[pntlindsay]

Hi,

I know that Festool sell Sipo domino for external use.
I am wondering why standard beech dominos are not suitable? 
If the joint is tight and the glue used is for external use, then the joint should
be in tact and the domino not subject to external weather?

Am I mssing something?

Thanks, Phillip

 

[Birdhunter]

Theoretically, if your glue seal was perfect and moisture didn't wick into the wood and rot the beech tenons, you would be all right.

I built a bunch of outdoor benches out of Ipe and decided to use Sipo. My decision was based on wanting the benches to be as safe as possible for many years and the value of the wood I was using heavily outweighed any tenon savings resulting from using beech.

I "caulked" the areas around the tenons with two part epoxy to further protect the tenons from moisture.

I did save by buying the Sipo "sticks" and making my own tenons. A jig served to cut the right length. I did have to chamfer the tenons and that was time consuming.

The benches have now survived many years of weather and are still solid.

 

[ear3]

As Birdhunter said, the differences only get revealed years down the road as the elements inevitably start working their magic on the wood.  Sipo is just naturally more rot resistant than beech.  If you only have a specific or a few outdooor pieces you want to make, and don't feel like investing in a stash of tenons that will sit around for years unused, it's actually quite easy to make your own out of your choice of more durable wood.  It helps to have a thickness planer (or drum sander) so you can dial in the exact desired thickness, along with a block plane to chamfer the edges and replicate the rounding on the OEM dominoes -- but you can also do it pretty easily on a table saw as well.

 

[ChuckM]

If I were to use dominoes for an outdoor project (which I don't do) and couldn't justify buying the Sipo, I would use epoxy glue.

 

[Birdhunter]

I have found that water will find a way to wick into the smallest opening. Using two part epoxy will help, but it’s nearly impossible to cover every surface. If every surface isn’t totally covered, moisture will attack it. Moisture inside a mortise doesn’t dry out quickly. It just sits there rotting the wood. If you don’t want to buy Sipo tenons, making your own out of a rot resistant wood might be ok.

 

[w802h]

I like making my own dominoes from mahogany cut-offs or rippings.  The last ones I made were sized to fit tightly with a 14 bit on the 700's wide setting.  I use a roundover bit on a router table to chamfer the edges.

 

[Cheese]

I know that Festool sell Sipo domino for external use.
I am wondering why standard beech dominos are not suitable? 
If the joint is tight and the glue used is for external use, then the joint should
be in tact and the domino not subject to external weather?
Am I mssing something?

Water will breach just about any defense given enough time. Wood also absorbs water because of its basic cell structure. Between these two givens it's not a matter of if, but rather a matter of when. It'd be a shame to spend 40+ hours machining/fabricating/assembling outdoor furniture only to have the tenons give out in 5-10 years.

Sipo is a form of mahogany that's been used in boat building for centuries.

An ounce of prevention is worth a pound of cure.  [big grin]

 

[dibnah]

Quote from: pntlindsay on November 26, 2017, 04:42 AM
I know that Festool sell Sipo domino for external use.
I am wondering why standard beech dominos are not suitable? 
If the joint is tight and the glue used is for external use, then the joint should
be in tact and the domino not subject to external weather?
Am I mssing something?

I thought exactly the same but two years down the road the 14mm beech domino's I had used in a small exterior project had completely rotted through even where i am in sunny Nelson NZ.

 

[Paul G]

I like making my own dominoes from mahogany cut-offs or rippings.  The last ones I made were sized to fit tightly with a 14 bit on the 700's wide setting.  I use a roundover bit on a router table to chamfer the edges.

I wish Festool made wider dominoes, but not too hard to make.