Thread: Please critique my outdoor table design

For the horizontal beam, I’d be inclined to do a shallow mortise and tenon (no glue) and fix with bench bolts.
Given your are joining directly where the lap joint is, you’d likely remove way too much material doing a full floating tennon, and the lap joint would be compromised. Although I may not be understanding what your proposing to do.
You also have the advantage of being able to tighten it up down the track if it gets loose without needing to rebuild anything.


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Looks good to me. The only thing I would maybe add is a couple of vertical rails to connect the X frames to the centre rail under the top for some extra racking resistance.

When I say shallow, you can go like just 5 to 10 mm - it’s only there to locate the beam. The bench bolt keeps it together


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Good old design, there are antique ones going way back that are basically the same. All those triangles make for a strong table but it depends on the joinery . Couple of weak spots I can think of.

The halving joint where the legs cross . The thicker the material the better. At least 45 . You can see some at what looks like 75 though . Which leaves 37.5 per side .

The horizontal piece and how its joined is the most important part . Just floating tenons is a problem just waiting to show up . The slightest movement in time will act right there and pull the joint apart . If you want it to out last you, the two best ways Ive seen that part done is .

1 . The good old tusk tenon sticking through with a tapered wedge through a mortise. Very good but does take away from some of the material in the halved joint weakening that. Its a delicate balancing act with that method.

2. What I think is the best for long lasting strength that Ive seen in Antique designs of this table is threaded rod and a nut basically. It goes way back in time as well and can be a lot more than just threaded rod and a silly nut on the end. The rod goes right through from one end to the other so its the tensile strength of this clamping the ends together. This is done by making the stretcher in two halves with a channel each side to take a rod of say 12.7 mm the two haves are glued together. Most of the rod would be plain with threaded ends welded on or the thread cut . I weld them and hammer the weld out while red hot when I use this clamping method on table columns. On old stuff rather than just a nut on a washer on the outside , A decorative plate can be drilled and threaded , or some of the nicest are large rams horn type nuts forged drilled and threaded . Just like these.
https://www.google.com/search?q=rams...w=1344&bih=687

All this is probably a bit over the top compared to the rest of the design you put up so rather than floating tenons in there, a simple but possibly stronger method may be to screw it with two coach long screws at each end and cap the heads with timber plugs . By long Im thinking at least 250 to 300 long.

Rob

Originally Posted by elanjacobs

Looks good to me. The only thing I would maybe add is a couple of vertical rails to connect the X frames to the centre rail under the top for some extra racking resistance.

Hmm, so basically a vertical post in the dead centre connecting the top to the long horizontal stretcher?

Originally Posted by woodman-79

When I say shallow, you can go like just 5 to 10 mm - it’s only there to locate the beam. The bench bolt keeps it together


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When I say floating tenon, I literally mean a bunch 10mm dominos. is no glue and a really long screw is better? like auscab suggested? I could use the domino to locate it.

Originally Posted by auscab

All this is probably a bit over the top compared to the rest of the design you put up so rather than floating tenons in there, a simple but possibly stronger method may be to screw it with two coach long screws at each end and cap the heads with timber plugs . By long Im thinking at least 250 to 300 long.

Rob

coach screw sounds good too me nice and simple. how does one drill a hole that long though?

Long auger bit. You can get them up to a metre long

Originally Posted by qwertyu

coach screw sounds good too me nice and simple. how does one drill a hole that long though?

I have a few long augers for coach screws that I bought . Don't think Ive noticed them narrow enough for the pilot hole though. I don't even look for them so don't know if they exist long enough.
For more delicate work where I want accurate long pilot hole for special jobs I weld standard drills to rods . You have to pull out to get rid of chips a bit more maybe. I can quickly make up anything I need as long as I need in about the same time it takes to go 2 KM in my car towards the shops. Ive brazed them to brass rod as well but the Mig welder does it fine and stronger . Some of the brazed ones Ive broken .

Rob

Carbitool have 6, 8 and 10mm in 230mm and 400mm lengths

Using bench bolts would be considerably easier in my view, than the hassle of trying to drill 250mm+ holes..
Also, using an actual mortise and tenon would provide a lot more stability than dominos.
Using a MT pulled tight with bench bolts creates incredible structural integrity which can be readily tightened down the track. This method is used on beds and workbenches all the time.
My massive workbench has no other cross bracing and is absolutely rock solid and from one beam attached to the legs in this manner. Having a wide (tall) mating surface is key though so you may be limited there due to the area you have to work with where the lap joint is.

Sure, coach screws and dominoes will work too. I just think it’s more work and I’d wager, not quite as sturdy... but perhaps the difference is negligible.



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I also like Rob’s suggestion of using a threaded rod that goes all the way through. It’s essentially the same concept.
Just route a channel on two mating half beams and glue them together - doesn’t even have to be a round hole/channel - you could do it in your table saw.
Once glued back together, create a MT, bolt it up and bobs your uncle.

One reason I’m against the coach screws is that your relying on the screw biting into the timber for long term integrity on outdoor furniture. I see it as a potential point of failure down the track.
Using either a long threaded rod or bench bolts that issue doesn’t exist - you can tighten it as much as you want basically without issue.


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Can anyone suggest anywhere to get SS or galvanized bench bolts? Both the Timbecon and veritas ones don't say so I assume they're not. Does the length of the bench bolt matter?


Or I could possibly make my own:
https://www.youtube.com/watch?v=dXjL_8jvzD4
but would rather something off the shelf if possible

Athreaded rod the entire length will be difficult for me i think. I have no way of welding SS (can it be done with a MIG with special gas or would one need a TIG?)

You may have a bit of trouble screwing the decking boards down adequately from the bottom as you only have 19mm, so maybe 16 to be safe and with the leading edge of most screws doing little you have very little engagement. I suspect it will be difficult to keep the boards from cupping and maybe even bowing. You might have to screw in from the top?

Also, make sure to allow for some expansion / contraction of the top boards.

Cheers, Dom

I’m not 100% sure but I think the veritas bench bolts are SS (and brass). You could just email them and ask. They are quite expensive though.

There shouldn’t be any need for welding if you go down the threaded rod path. Just get a rod long enough to go all the way through. I think you can get up to 3m lengths from Bunnings. Other suppliers should be able to provide longer lengths if needed.


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Originally Posted by qwertyu

Or I could possibly make my own:

I regularly use 12 mm galvanized rod that I thread at each end. If you are interested PM me.