joining billets

[nsherve]

I was just reading a little about this. My question is, has anyone tried joining them with mortise and tenon? Houses, furniture, etc. have been built with this and they withstand a lot of pressure and movement. I've built a table or two, and plan to build us another new dinner table with that. None of them have fallen apart, so it's not too new to me.
 I've never done a bow out of billets before (bows ARE fairly new to me), and I don't have a plan to do one for now... All of my staves are at least 70-75" long, and I have plenty of them. It's just a curious question, which come to my mind pretty often.
   Any thoughts or experience? 

[Del the cat]

Bad idea.
Furniture joints are not under bending strain. Any sharp corners are going to be the start of splits and cracks.
There is an exception to this where a continuous backing runs over joint, this would work because the belly is under compression and even a simple butt joint would work! It's still a bad idea tho' as any slight force flexing the bow the wrong way would open up the join.
It is no more work to make a well fitted V or Z splice than it is to cut a well fitting mortice and tennon.... the key is the "well fitting"
Del

[DC]

+1

[bradsmith2010]

9 times out of ten,, if you think of a new or different way splice a bow,, its a bad idea,, its like trying to re invent the wheel,,I am sure there are exceptions,,, just saying,,

[DC]

If someone would make a $100 finger joint machine I'd buy one in a minute

[Dances with squirrels]

What's the big deal? I can whip out an accurate Z-splice in a couple minutes. I've done a pile of them, in heavy weight bows too, and never had one fail, not once.

[bradsmith2010]

thats the point, the tried and proven methods to splice work pretty good,,

[stuckinthemud]

Gotta say I tried finding a different way to join billets and all I found out was how truly enormous the forces exerted by two 3 foot long levers working in opposition really are! 

[bradsmith2010]

yes,, one of the first spliced bows I made,, not fitted real well,, I gave it to a friend,, well the first time he pulled it was in front of a bunch of people and it exploded,, hmmmm,, that was embarssing,,  I was much more careful after that,, to say the least,,

[nsherve]

haha...like i said, it was a thought. the m&t would both be pretty thin, also. but, one of these days, i may try it out anyway.

[stuckinthemud]

As you say, the size of the joint is part of the issue, but the biggest problem is that the shoulders of the joint - any joint- become pivot points (fulcrums) for the limbs to rotate around.  This is the same principle as bolt-cutters or nail-pullers - a really long arm (lever) rotating around a fulcrum exerts multiplied force on a really short arm - the m+t is maybe 2 inches long?  You would need a very heavily built joint to withstand those forces and there is not enough material available in a bow-handle; even modern glues can only do so much. To avoid this you need to design a m+t that avoids shoulders, leaving you with a socketed wedge, as even champfering the shoulders of the m+t is not sufficient slope to avoid the fulcrum effect. Ultimately what this leaves you with is splice.

[mikekeswick]

haha...like i said, it was a thought. the m&t would both be pretty thin, also. but, one of these days, i may try it out anyway.

Don't bother it won't work. Simple

[loon]

I'm not even sure if Z is worth it over the V splices. Maybe the V splices are just better with a lamination on top of them, like in the horn bows

[stuckinthemud]

Personally I've never liked a Z, V-splices are so easy to cut by hand, look good, and are really strong when done right. As Loon said, if it withstands all the stresses in a horn-bow, it'll work anywhere.  The biggest secret to a V-splice is to cut a little saw-kerf straight down the limb for 1/4 inch from the point of the V which makes gluing and clamping up the joint much easier as it allows the joint to wriggle into place when clamped.

[Del the cat]

...The biggest secret to a V-splice is to cut a little saw-kerf straight down the limb for 1/4 inch from the point of the V which makes gluing and clamping up the joint much easier as it allows the joint to wriggle into place when clamped.

Cool tip...
Del