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John
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Mike, the issue I have with the methods you have pictured is your glue area, I presume you intend them to be glued, is still primarily end grain. Granted, you have substantially increased the area, but not the quality of the joint.
With c-mans pictured approach, the glue area is predominantly long grain which, IMHO, will provide a much stronger glue joint. I, personally, use half lap or scarf joints on lumber you have pictured.
JMHO:smile:
 

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Mike was it you that built the house I had some years ago? When I ripped panelling from the back porch walls all the studs were made up of boards less than 3 feet long, guess a former owner got a deal on shorts.

A couple of the methods you show where long grain is next to long grain may work in a pinch as they are really finger joints spaced wide apart. If I was desperate and did not have the length for proper finger joints or a scarf joint I think I would just do an end to end butt joint with a few dowels added.
 

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Discussion Starter · #8 ·
Scarfs and half laps. Perfect exactly what I needed. Had a make something from pallets and win $ contest at work. i wanna win but don't wanna cheat. Thanks
 

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Half a bubble off.. {Θ¿Θ}
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I try to avoid endgrain joints but sooner or later ya gotta do what ya gotta do.
I have a finger joint knife for a small spindle shaper which makes joints similar to this.



If you look at the brick molding on about any commercially manufactured door you'll see similar joining methods.
Sure.. it ain't perfect but when ya need a board stretcher:blink:

..Jon..
 

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where's my table saw?
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Exzatly

+1 on scarf joints, much depends on the application, if there is side load or not
Wood with a vertical load is in compression, and a joint that has shoulders like a lap or a finger joint will be best, since strength is not relying entirely on the glue bond.

A member that is under shear, or side loading, is more difficult to make secure, but again, a long lap joint or finger joint will be best since the long grain glue bond is stronger in shear.

End grain to end grain joinery has very little strength, if any and that would be from the glue alone, not from the wood structure. So minimize the end grain condition and increase the long grain area for a stronger joint.
 

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Wood with a vertical load is in compression, and a joint that has shoulders like a lap or a finger joint will be best, since strength is not relying entirely on the glue bond.

A member that is under shear, or side loading, is more difficult to make secure, but again, a long lap joint or finger joint will be best since the long grain glue bond is stronger in shear. I disagree, a half lap has only half board thickness in 2 places, and makes a weaker member for side load. we'll just agree to disagree.

End grain to end grain joinery has very little strength, if any and that would be from the glue alone, not from the wood structure. So minimize the end grain condition and increase the long grain area for a stronger joint.
................
 

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where's my table saw?
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A member that is under shear, or side loading, is more difficult to make secure, but again, a long lap joint or finger joint will be best since the long grain glue bond is stronger in shear.
There are 2 ways to orient a half lap under a side load.

One way is so the butted ends face the load, the other is where the long side pieces face the load. I would agree in the first case that there is only a half board thickness to resist the load, but in the second case, there is sufficient long rain surface to be as strong as the board itself. Agreed? :blink:
 

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Old School
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I disagree, a half lap has only half board thickness in 2 places, and makes a weaker member for side load. we'll just agree to disagree.
I would agree in the first case that there is only a half board thickness to resist the load, but in the second case, there is sufficient long rain surface to be as strong as the board itself. Agreed? :blink:
I don't know who to agree or disagree with. IMO, a true half lap is not half a board thickness in two places, constituting its integrity. When the two halves are glued and clamped, that joint is more robust than a single piece of wood. It's the same principle as glued up laminations. The glue joint makes those two parts stronger than if it was just one.

The joint could be further fortified by installing dowels.





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Really underground garage
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Testing,testing,testing.......thats what I say.


Between a scarf and a half-lap,I "think"(and am not willing to research it)it depends on how much,if any....flexure you are shooting for.And then you'd have to assign an X_Y scale to it.

Not to get all engineery but,where a nice super crisp,sharp edge lap joint is the pride of a joiner...and should be,it is going to break/split faster than one where theres a radius at the shoulders.

Anything that bends,flexes,moves around....don't like sharp corners.Start paying attention to concrete design.You'd think concrete is pretty hard,non flexing......like I said,start looking at cracks and where they develop.And if you're real lucky you can go look at some early 20th century buildings.Down in the basements......checking out how far the form guys went to make sure there weren't any stress risers in their finished designs is rather eye opening.
 
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