Heat treating osage gave it string follow??

[michaelschwister]

Been working a real nice osage stave down and have it real close to stringing.  Given all the talk of heat treating I gave it a good heating with the gun, enough to make some brown rings. When I started it had 0 string follow.  As soon as I was done it had 2". What is going on?  I tried this with the last one and it took so much follow when tillering I gave it away. Never have I seen osage do this.  Is this one ruined? or will  re-heat and back setting on a caul fix it??

[4est trekker]

You can certainly reheat a bow.  That said, here's my ideal process:

I like to get a bow tillered to my draw length and then thoroughly heat the belly and induce reflex on a caul, using olive oil to help the heat soak in and to keep the belly from toasting.  However, I'll often toast the belly (temper it) on purpose to hardened the belly fibers. In this case I don't use any oil.  When tempering, I find it most helpful to burnish the belly as I heat it.  It really helps to compress the wood fibers while they're hot and pliable.  

It may be too late to try on your current bow, but I like to finish a bow out about 5-10# under my desired weight and then temper the belly, which adds about that much in additional draw weight depending on the wood, design, etc.  The lower weight helps slightly in minimizing stress that leads to set during the tillering process and gives you more wiggle room when trying to hit a particular weight.  Plus, once you've got the belly nice and temptered, you don't have to go and scrape away the hardened  wood to reduce your weight back down to where you were to begin with.

Sure hope that makes sense!     :confused:

[mwosborn]

This was perfect timing for me.  Just finished tillering a hackberry and one of the limbs took about an inch of string follow.  The other limb is straight.  After roughing out the bow and just getting the limbs to bend a bit, I straightened it and added about 4 of reflex using dry heat.  I wasn't sure if I could reheat and try to gain some reflex back into the one limb.  Sound like i can give it a try.  I might try and curve the tips just a bit too.

[michaelschwister]

I think I will never try to heat a belly on osage again.  I clearly heat shrunk the fibers, and I am afraid it will never hold up properly to the compression load. It was a superb stave and would have made a great bow.

[LittleBen]

Heated dries out the fibers and they will shrink, and the wood will bend towards the heated side (in this case string follow). It's essential to have the bow on a form which either induces reflex or at least holds the straight profile. It needs to stay on the form until completely cool, and then never string for at least a day (my madeup rule) just to make sure the wood inside is cooled off too and its gained a little moisture back.

[fujimo]

hey michaelschwister,
dont give up, these guys know their stuff, sounds like all it would take is some more heatwork with a caul, and you'd be good to go.
i have heated pieces of sage many many times in the straightening / aligning process, and they are still all good shooters.
ya gotta see some of those knarley staves that i see on here, and then when the guy posts the finished pic, it's as straight as a pencil!!!- i know that took a lot of heat work- many , many sessions.
i dont think you have destroyed the stave- by the sounds of it!!

[PEARL DRUMS]

Skip tempering osage all together. Its so strong in compression there is never a need to temper it. Heat shape it, yes.

[John Scifres]

Are you clamping it into reflex as you toast?  This is a critical step.

I have found that heat tempering the belly on osage bows is extremely helpful.  For me it makes good wood great and great wood astounding.

[michaelschwister]

Just clamped it in the vice by the handle.  I have used heat many many times since I started making them from osage in 92.  Never seen this before.  The last ten years I just tiller them the way the tree made them and rub in tung oil. Will get out the old caul if I can find it and give it a try.

[Pat B]

I heat treated lots of osage and never had it pull into deflex. I do clamp it to a caul though. You really don't need to heat treat osage like others said but I do it anyway. Usually I heat and reheat osage just to straighten of bend it while building and that also counts as heat treating IMO.

[2treks]

I have heated and re-heated an osage bow 6-7 times before I finished that particular bow. I did it to work out kinks and twist. Clamp it to a caul and you will be golden. Use a little olive oil.