Heating In Reflex & Exercising a New Unbent Bow

[mmattockx]

First question:
I am going to put some reflex in a new bow (maple pyramid) but I don't want to use so much heat that I get to the point of heat treating it much, if at all. My concern with the heat is that the limbs are quite thin (finished thickness will be less than 0.400") and I don't want to damage the back fibres or backing material with heat. How much heat or how hot do I need to get in order for the maple to take the reflex but not get cooked significantly? The heating will be done using a heat gun with the bow clamped to a caul.


Second question:
Back in 2008 or so David Dewey (Woodbear here, and elsewhere) did a red oak board bow for a challenge put out by Badger. The bow was designed using his spreadsheet calculator, made to match the finished dimensions from the spreadsheet and only pulled to 10" (to confirm the basic tiller, I think) by David before he shipped it to Badger. Badger then worked the bow in to full draw length and shot it. It was never tillered as such or exercised significantly before Badger got it.

My current bow is an experiment where I am doing basically the same thing, making the bow to the calculated dimensions from the spread sheet before ever putting it on the tillering tree. I am leaving a touch of extra thickness on the limbs to allow some weight adjustment, but only ~0.010". Since I will have a basically finished bow to start with, what is an appropriate schedule to work the bow in to full draw? I was thinking of a low brace and pull it to maybe 10"-12" to confirm the tiller is ok, then full brace followed by Badger's no set tillering procedure, pulling it an inch at a time with 30-40 draw cycles at each length. Is that reasonable or should I do more exercising, less or what?


Thanks,
Mark

[Hamish]

re the heating into reflex, use a heat gun and a form  rather than a reverse brace over the hot coals method. Avoid caramelising the colour of the maple, or light scorching it, like many guys do for a deep tempering of the belly. That should give you the results you are after.
 Give it a week or so to rehydrate before stressing the limbs.

[Pat B]

I use veg oil where I heat correct, adding reflex, recurves and straightening. The oil helps prevent scorching and I think helps to distribute the heat evenly and hold the heat longer.

[willie]

when i have heated with the gun in the past, I have noticed a point where you can smell something aromatic coming off the wood a bit before seeing a color change in the wood.

Does anyone use their nose as much as their eyes for judging heat? or maybe one of those laser pointer temp gauges?

[Pat B]

...that and my thumb. If I can hold my thumb on the wood for 2 to 3 seconds, it's not hot enough.

[willie]

Back in 2008 or so David Dewey (Woodbear here, and elsewhere) did a red oak board bow for a challenge put out by Badger. The bow was designed using his spreadsheet calculator, made to match the finished dimensions from the spreadsheet and only pulled to 10" (to confirm the basic tiller, I think) by David before he shipped it to Badger. Badger then worked the bow in to full draw length and shot it. It was never tillered as such or exercised significantly before Badger got it.

My current bow is an experiment where I am doing basically the same thing, making the bow to the calculated dimensions from the spread sheet before ever putting it on the tillering tree. I am leaving a touch of extra thickness on the limbs to allow some weight adjustment, but only ~0.010". Since I will have a basically finished bow to start with, what is an appropriate schedule to work the bow in to full draw? I was thinking of a low brace and pull it to maybe 10"-12" to confirm the tiller is ok, then full brace followed by Badger's no set tillering procedure, pulling it an inch at a time with 30-40 draw cycles at each length. Is that reasonable or should I do more exercising, less or what?


Thanks,
Mark

Only ten thousands? wow, you like to cut it close.  I would think that just having early and late wood in the limb would make the wood vary enough to prevent that much precision. What kind of wood are you making the bow from?

[mmattockx]

Only ten thousands? wow, you like to cut it close.  I would think that just having early and late wood in the limb would make the wood vary enough to prevent that much precision. What kind of wood are you making the bow from?

Well, David didn't leave any margin at all so I figure I am leaving a couple pounds there, maybe a bit more. If I end up at 38lb instead of 40lb that wouldn't be the end of the world, plus I am adding some reflex once it is worked out to full draw so that will likely add a bit more weight that I have to take back off. While I was working the limbs down to thickness I found that I could easily catch variations of 0.002" in thickness with a set of vernier calipers so 0.010" isn't as crazy at it seems.

The wood is a pretty dense (50lb/ft^3), stiff maple board that seems to be an above average example of the species. I'm just hoping I don't screw it up somehow now that I'm close to having it worked to size.


Mark

[Selfbowman]

I put my reflex in before I start the tiller On my Osage selfbows. Maybe I misunderstood the post. Arvin

[Del the cat]

If you use steam, you can't overheat the wood.
100C will allow it to flex. 200C is needed to heat treat.
Del

[mmattockx]

I put my reflex in before I start the tiller On my Osage selfbows. Maybe I misunderstood the post. Arvin

Some guys do it at the end as well. It doesn't seem to matter too much when it is put in.

If you use steam, you can't overheat the wood.
100C will allow it to flex. 200C is needed to heat treat.
Del

Thanks for those numbers, guidelines are very helpful. I would need to make a steam box to do the whole bow at once on a caul and I'm not there yet but i will keep that in mind for future upgrades.


Mark