Looking for help on how to make this joint (looks like a mercedes Benz Sign)

I have tried making this joint myself but it isnt strong enough for a coffee table (as someone might sit on it)

Attachment 453471

I was looking to see if anyone had any good ideas of how this has been achieved ? there are no screws visible from the piece I am copying above, however here was my attempt below. I glued also with tightbond 2 and clamped using triangles in the spaces to get pressure. However whilst it worked, it didn't hold up under stress.

Attachment 453472

Attachment 453473

I was also considering dowels, but as the joints intersect twice I would need to dowel, glue 2 pieces (hard to clamp) and then do the remaining one.

The end result I am hoping to achieve looks like this
Attachment 453474

Any help or advice would be very much appreciated

Thanks!!!

The structure itself is weak so it does not matter how you join it together. A 3-way half lap joint will increase the strength but still not strong enough if you want to sit on it.

Attachment 453484

Welcome to the forum. You're using the same joint for the top and bottom of the supporting frame? And it's the top joint you're having trouble with? If that's the case, as Wongo says, the joint is inherently weak. This doesn't matter as much at the bottom where the legs are taking the load, but on the underside of the top you would need much deeper timber (at least 75mm) to have enough material available at the intersection to strengthen the joint. The only way that the light framing could work is if the table top was a structural member integral to the design.

Looking at the last picture (of the table sitting on the carpeted floor) it would appear that the table top support timbers are significantly bigger (deeper) than the floor level braces. It's also possible that these top supports link the legs in a closed triangle and not three open triangles as in the base.

If it is the floor level bracing you're having trouble with the easiest way to strengthen it would be with a metal joiner attached with screws on the underside where it couldn't be seen. Of course you'd have to make the metal joiner.

You'll need access to some pretty advanced machinery and fine woodworking tools, but if you do, I'd suggest you do it like this:

https://youtu.be/7KUHDfi0YbE

It'll hold at least 60kg, give or take a tapeworm or two

Quote:

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Originally Posted by Bernmc

You'll need access to some pretty advanced machinery and fine woodworking tools, but if you do, I'd suggest you do it like this:

https://youtu.be/7KUHDfi0YbE

It'll hold at least 60kg, give or take a tapeworm or two

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Nice. :2tsup:

I doubt it will hold 60kg if the pieces are 3 times longer. Still very nice though. Must give it a go in the future.

The joint on the you tube video is not the same as the one in the original post... There's no load on that joint, so it doesn't have to be very strong.

What about a Y shaped loose tenon? The Y shaped loose tenon could be made of plywood and cut on a band or scroll saw. I would drill out the mortices from square cut timber before cutting the 120 degree angles. Clamping can be done with a rope or one of those bungee hooks..

The three member half lap on the picture would look good too, and clamping would be a breeze

Attachment 453520

There may be no load on the one on the floor, but there is the one under the table top.

Quote:

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Originally Posted by bjennifer19

I have tried making this joint myself but it isn't strong enough for a coffee table (as someone might sit on it)

Attachment 453471

I was looking to see if anyone had any good ideas of how this has been achieved ? there are no screws visible from the piece I am copying above ...

Any help or advice would be very much appreciated

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What I see is a joint that appears to contain a loose plate that has been pinned with what looks to be bamboo pins.

If the plate is made of quality 3 or 5 ply it should be plenty strong enough to hold the joint together -- especially when pinned.

Is the top loose or attached? If it is attached, on each radial, then the top joint is not holding much load at all.


Russ

Thank you so much everyone, the top is attached and screwed to the underside of the table

Quote:

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Originally Posted by ian

What I see is a joint that appears to contain a loose plate that has been pinned with what looks to be bamboo pins.

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Pretty sure it's just wood putty filling the holes left by a brad gun :wink:

If I was to make that table, I'd weld together a steel star with some length to the arms. I's use something like 1"x1/2" (25x12mm) flat solid steel and rebate both of them into the timber. Maybe fixed in with epoxy resin and a couple of horizontal steel pins shorter than the timber is wide, filling their little holes after its all set. The top one rebated from the top and the bottom one from the bottom, so they cannot be seen in the finished table....
Some would consider that cheating - I consider it family safety and longevity for the piece of fine furniture.