130lb elm bow

[WillS]

I don't pull it into reflex, no.  You can of course, but exactly as you say it causes problems later if you want to go over the bow again at some point.

Let's say the stave is dead straight, and you've done all the tapering and finishing and nocking etc.  You get it up to the full brace height and you notice straight away that one area is weak, or will end up weak or whatever.  That's the bit you tag with the heat gun - but after just bracing the bow there won't be any set there, so you don't need to induce reflex as well.  All you want to do is add strength to that one small area.

As to other point, yeah I tend to heat treat and leave it until the belly feels completely cold, then just carry on tillering.  There's really no need to add oil, or wait days for the RH to return etc, you can get it bending again almost straight away.  You just have to wait for all the heat to leave, otherwise you risk "heat bending" the area into permanent string follow!

[WillS]

Oh! I forgot to mention, your point about the 1" of set is interesting, because this bow has hardly been shot, it's just been braced, pulled to 30" and drawn a few times.  The set will probably start to creep up as it's shot in, and that's the stage where I decide which limb is upper and lower, and quite possible heat treat the entire bow (sometimes with gentle reflex) to get it nice and punchy again once the bow has settled.

[JNystrom]

Nice, thanks! I like that you have (obviously) experimented heat treating and the wait time on your own, rather than just taking what other people say.

[Marc St Louis]

Oh! I forgot to mention, your point about the 1" of set is interesting, because this bow has hardly been shot, it's just been braced, pulled to 30" and drawn a few times.  The set will probably start to creep up as it's shot in, and that's the stage where I decide which limb is upper and lower, and quite possible heat treat the entire bow (sometimes with gentle reflex) to get it nice and punchy again once the bow has settled.

Very nice indeed.  I've made Elm warbows bows up to 150# before.

I have used this method of heat-treating to touch up the tiller before but find it too unreliable.  It looks good at first but the tiller changes over time

[RBLusthaus]

Very interesting tillering method.  Makes good sense.  I intend to give it a try. 

I have not tillered any horn bows yet, but, is this heat tillering exactly the opposite of how the horn bows are tillered?  What I mean is, when tillering a horn bow with heat, I thought you applied the heat to the stiff spots to lossen them up a little till the tiller evened out.  I realize different materials react differently to heat.   Wood in one case and hide glue in the other.  Just interesting that the same method of tillering (applying heat) is used for opposite purposes on different kinds of bow. 

[RBLusthaus]

BTW - awesome bow!!!!!   I don't think I could even draw it. 

[WillS]

I have used this method of heat-treating to touch up the tiller before but find it too unreliable.  It looks good at first but the tiller changes over time

I've had it happen once, with a yew bow that I "tillered" using mainly heat, and after the bow had settled the tiller began looking worse and worse.  I re-heated the problem areas and it held the second time.  White woods seem to respond superbly however, and I've not noticed any changes happening 100s of shots in with the rest that I've done this way.  That being said, it is a relatively new technique for me, so there's every chance it'll catch up to me at some point! 

[meanewood]

Very interesting technique Will.

I will be keen to try that with my next bow (probably Ash).

I must admit, I have never been too fussy with trying to get a perfect shape from a bow that isn't straight to begin with!
I also start with tapers that experience has shown me to work well with a particular wood type.
The point of tillering is to share the bending strain equally to as much of the bow as you can.
 Obviously if your working a wood to its limits, it's best to include the center area, resulting in a circular shape.

If I try to remove a natural re flexed area in order to achieve a perfect shape, it means that area is bending more (working harder) than the rest of the bow.

What I like about your technique is with a de flexed area, instead of leaving it thicker, you can just stiffen it up a bit rather than have an area that may look like a hinge but is really an area working just as hard as everywhere else!

It's not often I find dead straight staves, so I don't think I have any with a 'Perfect Tiller'!

Anyway, it's always nice to hear people share their knowledge.
I am guilty of repeating mistakes I've made before but overall, I think I'm heading in the right direction being open-minded about things.
 

[WillS]

It does work very well with ash - I think you'll be quite pleased.  My latest heavy ash (150lb) was made almost entirely using the heat method, but I did do a bit of scraping here and there to get some small areas working. 

I've always thought that the quicker you can make a bow the better that bow is.  Hours (or days in some cases!) of torturous bending and checking and bending and checking and tweaking and bending and "exercising" just shoots the bow out before you've even held the thing, and really just isn't necessary.  Also, I can't help thinking that "back then" there wouldn't have been any of that, just good quality staves being tapered by an experienced bowyer, checked at brace height and chucked on the pile.  If you're making 2 or 3 a day, you can't be messing around with all the rest of it.  Whether they used heat we can't know, sadly.  There are a couple of MR bows that show really dark patches of something on the belly which could be scorch marks, but that's just supposition on my part.

[mikekeswick]

Why do deflexed areas act weak and reflexed areas act stiff when you have a perfect taper? What does this mean in terms of strain?

[willie]

This example of differential tempering is an  interesting technique that gets a guy thinking about the meaning of "equal strain".

I suppose that if a tempered area is bent just as much as an untempered area, than the the strains are equal. Presuming of course that the thicknesses of both are the same.

Just for the record, I spend a bit of effort keeping  the tapers on my bows fairly precise, at least up until final touch-ups at near full draw. I usually try to keep plus or minus  .01 inch from a straight line.