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three way joint?


Pat Meeuwissen

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looks plenty strong.  and complicated.

 

for my workbenches, i just butted the 2x4s at the corner, and then had a full 4x4 inside of those, all screwed with 3" or 3-1/2" long deck screws, and some wood glue too.  a 3x4" plywood top goes on top.  the 4x4 carries all the weight down to the floor (mine via some casters).  so, yes, the weight on the 2x4s is transferred to the 4x4 via the screws.  but how much weight are we talking about?  i've stood on mine when i was 300+, flipped them on their sides for moving in my truck (and washing), and they still carry on.

 

but that pic is a neater design.  i'm lazy and confident that the screws will carry the load.  i think i have 6 per corner into the 4x4 (3 per 2x4).  

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I got "into" the connection geometry when I was building a gazebo.  I wanted to use a lot of timber joints.  What I found is that 2x4 isn't 12x24.  When you get into smaller thicknesses (probably 4x or smaller), the wood acts differently.  So, I think the second joint (Mortise and Tenon joint has been used for thousands of years by woodworkers around the world to join pieces of wood, mainly when the adjoining pieces connect at an angle of 90°. In its basic form it is both simple and strong. Although there are many joint variations, the basic mortise and tenon comprises two components: the mortise hole and the tenon tongue. The tenon, formed on the end of a member generally referred to as a rail, is inserted into a square or rectangular hole cut into the corresponding member. The tenon is cut to fit the mortise hole exactly and usually has shoulders that seat when the joint fully enters the mortise hole. The joint may be glued, pinned, or wedged to lock it in place">M&T) would be better.  Another thing:  square edges are weaker than rounded ones.  You might consider loose tenons with round edges on tenons and mortises.

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2 hours ago, Pat Meeuwissen said:

Which one are you referencing here Pete? I have a really nice jig I made to do loose tenons which I have just for another large table build and it was very handy.

Sorry, the last one you proposed, Mortise and Tenon joint has been used for thousands of years by woodworkers around the world to join pieces of wood, mainly when the adjoining pieces connect at an angle of 90°. In its basic form it is both simple and strong. Although there are many joint variations, the basic mortise and tenon comprises two components: the mortise hole and the tenon tongue. The tenon, formed on the end of a member generally referred to as a rail, is inserted into a square or rectangular hole cut into the corresponding member. The tenon is cut to fit the mortise hole exactly and usually has shoulders that seat when the joint fully enters the mortise hole. The joint may be glued, pinned, or wedged to lock it in place">M&T, brown and green colors!

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For the Mortise and Tenon joint has been used for thousands of years by woodworkers around the world to join pieces of wood, mainly when the adjoining pieces connect at an angle of 90°. In its basic form it is both simple and strong. Although there are many joint variations, the basic mortise and tenon comprises two components: the mortise hole and the tenon tongue. The tenon, formed on the end of a member generally referred to as a rail, is inserted into a square or rectangular hole cut into the corresponding member. The tenon is cut to fit the mortise hole exactly and usually has shoulders that seat when the joint fully enters the mortise hole. The joint may be glued, pinned, or wedged to lock it in place">M&T proposal please but a ledge on the post that can carry the load of the member putting all the load thru the Tenon in shear is not advised.  Your original idea has plenty of support and the screws should only be holding it together.  They may carry some shear but the wood to wood contact will quickly take over that load.  Go with what your originally concieved.

That said it could be simpler it all depends on the weight you are going to support and where it's center of gravity is.

 

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