What are the reasons to decrown a stave?

[bigcountry]

I read the TBB's and they talk about decrowning a stave.  Why would I want to do that?  Only on small limbs?

Would you ever want to do that on osage, or yew?

[Justin Snyder]

I wouldn't  unless I was backing it.  I know there are some bennifits sometimes. I guess I dont completely understand the logic in violating the back and if the pros outweigh the cons. Justin

[Pat B]

I believe decrowning was done on staves with weak compression and high crowned backs to alleviate the stresses. As long as the grains run the length of the limb and not off of the side or across the back you should be OK. I probably wouldn't do it because I have enough good bow wood so it is not necessary. Some of the ancient bows were made this way and survived.      Pat

[DanaM]

I aslo believe some of the ancient bows were backwards, that is the decrowned back became the belly

[Badger]

     I don't do it often but have found there are some very good bow woods out there that are simply too high crowned because of size. Plum branches are a good example. A 1 1/2" round branch may not hold up if not decrowned. I think it is just another option to keep in your tool bag. Much easier to find and harvest clean 2" branches maybe 3ft long that can be decrowned and spliced. Some woods tolerate this very well and some don't. Steve

[wolfsire]

I believe decrowning was done on staves with weak compression and high crowned backs to alleviate the stresses. As long as the grains run the length of the limb and not off of the side or across the back you should be OK. I probably wouldn't do it because I have enough good bow wood so it is not necessary. Some of the ancient bows were made this way and survived.      Pat

From what I recall reading staves are decrowned when the back is too weak in tensile strenght because with the high crowned back it takes most of the stress in the small top of the crown.  That would be the case small diameter branch or samplings.  Decrowing spreads the tension stress over a broader area of the back.

[bigcountry]

So if one would decrown a straight osage back and go with the grain perfectly, this would be no issues?


So I am not the only one that has trouble with the decrownign idea.  Sounds like it mainly for small saplings? Of some woods.

[Badger]

  Big, decrowning has to be done with some precision, osage is not one of the woods that decrowning works well on either. When you decrown a stave you have to follow the growth ring line all the way to the tips, you may be flattening one growth ring or 4 growth rings but the lines have to run straight to the edge of the bow and cannot crossover midlimb anywhere or it will break. Steve

[JackCrafty]

Historically, as far as I can tell, decrowning was done to increase performance...not necessarily to prevent breaking.  Also, I have NOT seen any decrowned NA bows with a backing unless it was a softwood like cedar or juniper.

It's and advanced technique that requires guts to master.  Personally, I wouldn't try it on anything except hickory.

[Pat B]

Unless we are trying to replicate an original primitive bow there is no reason to decrown a stave unless you plan to back it. The only reason I would back a stave is if that was the only way to make a successful bow from it. If I want a backed bow, I use a board for the belly. A good stave doesn't need backing.       Pat

[snedeker]

In the days of the TBB writing, there seems to have more of a hang-up about a steeply crowned back negatively impacting performance.  It seems to me that many of us make bows from small diameter pieces that work just fine.  Hickory, ash, or elm would be great candidates i think, in a case where you had 3" tree and wanted to maximize perormance.  The engineering argument is that the flat back distributes the tension more widely or something.

I have been meaning to try it on a piece of hickory I have

Dave

[Badger]

Performance aside a too high crown is a good point for a failure, lots of staves are safer to decrown than try to tiller out as is. bendy handle bows are a lot more forgiving naturaly. I have seen many bows where just the crown cracked. Elm branches are excellent candidates for making real nice decrowned bows. Steve

[DCM]

Perhaps it would be easier to think of a decrowned stave as if it were a board.  Because that's what it becomes in effect, a plain sawn board.

[Badger]

Dave, in some ways it might be considered a board I gues but it would still have all the whoop de doos and character of a stave bow and still have to skillfully follow the rings. The belly of the bow would still disply the v's in the grain. I would still class it as a stave bow in the true sense, instead of following one growth ring you may have to follow a couple, one right down the middle and then the ones that lay by it's side. Most guys that have plenty of bow wood might not bother but if you live in the city and find yourself chaseing tree trimmers around it just opens up a new set of options. Steve

[George Tsoukalas]

Badger and I are on the same page on that one. Decrowning is difficult to do. The rings must still be followed in the sense that if the belly dips so must the back maintaining the parallel lateral or vertical grain. I think it is a tall order for a beginner. It is not the same as a plain sawn board, in my view, where the trunk is of the tree is sliced off end to end. I've done one for grins and giggles. I recommend that saplings be left an inch or 2 longer to counteract crown. Decrowning is not needed. IMHO. Jawge