Heat treating after tillering

[WillS]

Was thinking about this earlier, Googled it and couldn't find a huge amount of recent information so thought i'd stick it on here.

I've got a yew longbow that's basically fully tillered - I'm very happy with the tiller at this point, and it's drawing around 80#@28 which was my target.  However, I had no idea how seasoned the wood was when I started working it, and despite going slow and being very careful while tillering it's taken about 2" of set. 

As it's now 90% finished on the tiller (just need to bring the tips round a bit at this stage) would clamping it flat and heat treating the deflex out of it make much difference to the tiller?  It's already been heated a fair few times to adjust for twist, lateral bend and deflex but seems to be performing safely.  Don't want to risk having to retiller too much, and 2" of set isn't that much to worry about, but it's not been shot yet, and will obviously take on more natural string follow as it gets used.  Would be nice to start with a straight bow!

[JackCrafty]

Not sure about yew wood, but I don't recommend heating your bow at this point.

You might want to put it up to dry for another month or two to reduce the moisture content but the moisture content might be fine.  You won't know if it's a green stave unless you are actually measuring air temperature and relative humidity and weighing the stave every other day or so.

Someone else probably knows more about this than I do.     Others should chime in shortly.

[WillS]

I'm still not sure if its green or not, as its showing all the signs of green wood (the way its taking set etc) but hasn't lost any weight for weeks, is crisp to work, has been at floor tiller size and less now for about 2 months.  The tillering has been slow and careful, never going over weight while pulling, no hinges or real flat spots to speak of and its no thinner or out of proportion than it should be.

The string follow in the lower limb is right where a big reflex kick was before initial heat straightening at the tip, and in the upper limb the string follow is evenly spread from arrow pass to tip.

[PaleoNinja]

Clamp it into reflex, toast the belly, leave it alone for a month. Retilller it and it'll have no string follow.  Just my 2 cents.

[Del the cat]

I'd say that as it's not had too many arrows throught it or been badly over stressed, you are ok to clamp it flat (or maybe an inch of reflex) but try to get it warmed up a bit first before actually forcing down.
Let you 'feel' tell you if it doesn't want to go.
IMO take great care to keep the heat off the back, you really don't want that going dry/hard/brittle on you.
You can easilly find you've gained 10# draw weight and have to take a hint off the belly to re-tiiler to your target weight.
I'd say plenty of masking tape on back and sides and thin slats of wood too to keep the heat confined to the belly.
Aim for a slight browning, go V slow and don't char it.
Give it several days before exercising it, and take it gently as the draw weight may have come up.
Del

[Gus]

I live by the Heat Treating chapter in TBB IV.

I don't recommend toasting a Green Bow.
But if your bow hasn't lost any weight for weeks...

Once you heat treat you will need to retiller back down to your intended draw weight.
I would recommend cutting yourself a new Toasting Board (form/caul) out of 3/4" plywood or 1x4 .
You don't want to reflect any heat back onto the Back of the bow while toasting so keep it narrow (3/4").

I start at the tips and work my way in.
In most cases the weight of the bow plus light pressure is enough to ease it down to the form as I heat my way up the limb toward the grip.
I wipe Tung Oil onto the Hot belly as soon as I move to the next heating point.

Once the limb is done leave it clamped at least 12 hours, Longer will not hurt.

You can start and stop and restart as you go if needed.
Light to medium brown is my target.
I avoid Dark Brown or Black like the plague.

I'm with Del, 3 days to a week before bending it the first time...

Not saying this is the only way or the right way.
Just my way...

-gus

[WillS]

I'll give it a go then, thanks guys. 

Have to say, I'm not optimistic.  There's so much twist and sideways bend that the tiller is probably going to change completely once it's done. 

I'm sure most of you know what it's like - you get a piece of wood you're not convinced by, and think "this will be an experiment, if it goes wrong, hey ho on to the next one!" and by the time you're 90% done it's taken so much effort and planning and rethinking and baby steps that it's become rather special!

If it goes snap now I'll be pretty bitter I think!  I was stunned that I could get this thing tillered nicely out to 28".

[Del the cat]

...
If it goes snap now I'll be pretty bitter I think!  I was stunned that I could get this thing tillered nicely out to 28".

Well leave the damn thing alone!
Del

[WillS]

Ha! I want to, believe me.  I just know that with this much set BEFORE a single arrow has been through it, within a year's shooting it'll be horrible. 

[richardzane]

I took 3 of my early bows and reflexed them and toasted the belly with mixed results,
all of them developed a lesser degree of set after retillering and shooting.
no BAD results, but with one hackberry ,after retillering the set came back strong.( it was made while it was still too green)
BUT...its still a 50# bow with a dogbane string and shoots fine ...ok, not as snappy as the others, but it's still a good shooter.

[WillS]

Thanks for posting, that gives me confidence! Its been heat treated now, I didn't induce reflex as I've not done this before and didn't want to risk too much.  Its dead straight now, and in a week or so I'll go back to tillering.

[mikekeswick]

I pretty much agree with whats been said so far.
If it didn't/hasn't lost any weight (physical) then it couldn't have been 'green'. Also if a stave has any excess moisture in it and you heat treat it it will check if not you will see the moisture being forced out as you move along the limb.
I reckon the set is likely down to wood that isn't very elastic. Yew is normally great bow wood but like all wood species there is good and bad....and your bow is fairly heavy.
What is the width at the handle and the length?

[WillS]

It's 1 1/2" at the handle, and 72" TTT. 

Interesting that you said some yew is worse than others, as I'd not thought about that.  I've got another longbow from the exact same tree, and that's taken 4" of set within a year of shooting.  It was basically the first bow I ever made (it's posted on here somewhere actually) so whether it's a tillering/design issue (very likely!) or due to being unseasoned/bad quality yew I don't know, but it's food for thought.

[Carson (CMB)]

I agree with what Mike said.  There is quite a bit of variation in yew quality and your building a pretty heavy bow.  I have not heat-treated yew, but I know others say that they will almost always heat treat the low-elevation yew.  I am interested to see what comes of this bow. 

[WillS]

I am interested to see what comes of this bow.

Me too!  I'm just letting it recover for a couple days now, and then I'll retiller and see how it goes.