Author Topic: Boiling time  (Read 1531 times)

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Offline zoomer

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Boiling time
« on: April 29, 2020, 01:37:29 am »
I have boiled my bow limbs 3 separate times 1 hour each, thinking it doesn't matter if I boil too much. One is to make a sideways kink in the outer limb for string tracking (I put it in the pot), other two are to remove deflex (above the pot covered in foil). The water was boiling pretty hard. I heard Ryan Gill say that more than 30-40 minutes will damage the wood. I noticed that, even when I padded my clamp with leather or even cork, the clamp leaves a noticeable depression. Is my bow now ruined or damaged because it was boiled for so long? Do you boil your water strongly, or just so that steam comes out (steam comes out before boiling), and for how long? Thanks.

Offline Del the cat

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Re: Boiling time
« Reply #1 on: April 29, 2020, 02:01:27 am »
A couple of points:-
1. Steam does NOT come out before boiling. Steam is an invisible gas. You can see clouds of water vapour coming out before boiling, but that's not steam, (I think we all agree that clouds, mist and fog are not hot). Steam is actually V dangerous because it is invisible.
2. Personally I use steam and have found that 30-45 minutes is fine problems are usually caused by not having enough time.
3. Maybe you are clamping and bending too hard... you want to clamp and bend once it's had time to soften the wood, and always clamp and bend against soft gentle curved edges (scraps of old softwood).
Health warning, these posts may contain traces of nut.

Offline Rākau

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Re: Boiling time
« Reply #2 on: April 29, 2020, 04:02:57 am »
Haha Del, I have been called nuts and a fool and been looked at askew :o on many an occasion while trying to explain to people that those great clouds of "steam" pouring out of kettles and geothermal power plants are in fact not steam. People just really struggle to shift long held misinformation. . . especially if it goes allll the way back to primary school!

Offline BowEd

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Re: Boiling time
« Reply #3 on: April 29, 2020, 04:08:07 am »
Zoomer....Those dents  imposed from clamping can be removed by reclamping limb in place so it will not lose any bend induced and reheating with a heat gun lightly but still over 250 to 300 degrees F.Most times it'll suck or expand the compressed wood back to it's original form.With less dense woods this works better.
I've taken dents out with a wet rag and a iron used to press clothes before too on dents on gun stocks.
As long as the dent does'nt cut the fibers any.
Good rule of thumb steam bending is every 1/2"/1 half hour steaming.
« Last Edit: April 29, 2020, 10:00:19 am by BowEd »
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Re: Boiling time
« Reply #4 on: April 29, 2020, 07:32:00 am »
boil 15 minutes for every 1/4 of thickness... is my gauge.. I put bow tip in water and bring to hard boil then start clock... will bend like a wet noodle... you must make the bend quickly however.. within 20 seconds of removal.. IMO... so get everything ready to go as soon as you pull bow from water... when clamping I use a piece of sheet metal strip on belly... protects curve from splinters and belly from indention...  gut

Offline Pat B

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Re: Boiling time
« Reply #5 on: April 29, 2020, 08:12:35 am »
What wood are you steaming/boiling?  If the wood is softened enough to dent I'd think it's hot enough to bend.
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline zoomer

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Re: Boiling time
« Reply #6 on: April 29, 2020, 10:52:12 am »
Thanks everyone for replies. I get it now. I steamed birch.


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Re: Boiling time
« Reply #7 on: April 29, 2020, 12:18:10 pm »
Everybody has covered the steaming thing nicely :)
But for removing deflex in a working limb is best done on a form with dry heat. You can heat treat the belly at the same time with the use of a slightly reflexed 1 inch wide form, shims of scrap wood and some clamps.
Steaming will of course remove deflex but you can be pretty sure it will turn up again when the bow is bending well.
Steaming a piece of birch for 3 hours will leave it in a less than optimal condition and even good birch isn't great to start with.