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Main Boards => The Bowyer's Bench => Topic started by: Robyn Hode on March 06, 2016, 07:27:00 PM
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I am trying to toast the belly on a hickory board bow but I am not sure I am doing it right. The bow is 57 inches nock to nock, 1.5 inches wide at the fades out to about 6 inches, then straight tapered to 1/2 inch at tips. I have trapped the back to reduce set and have tillered the bow to 45 pounds at 24 inches. I am shooting for 50 pounds at 26 inches. I have clamped the bow to a 2X4 with slightly re-flexed tips to toast the belly (pictures below).
Since I have not toasted/heat treated a bow's belly before I have a few questions about the process.
1. How dark should the belly get? I read that the belly should turn a chocolate color but not black? Do I need to heat treat more?
2. If it is not dark enough do I just go over it again?
3. Should the brown color be even and consistent down the limb or is spots in the brown color OK?
4. How long should the bow re-hydrate before I finish tillering it?
Any help would be appreciated.
(http://i.imgur.com/tNwS2W5.jpg)
(http://i.imgur.com/LW5K0SR.jpg)
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You need to read this
Bowyer's bible volume four
Marc St Louis Heat treating bows
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Reading Marc's chapter on heat treating is a good idea...but in the mean time...you can go a lot darker. Here's how I do it.
start at the fade and move the heat gun back and forth on a 6" area. I hold the heat gun about 1" above the belly and keep it moving constantly. When that area get the color you want move out another 6" and do the same, going back over earlier part some too. At the end I go over the whole limb belly one last time then let it sit for a few days, depending on the humidity. You want the wood to rehydrate some after heat treating.
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Thanks for the suggestions.
I am re-toasting the belly now using a combination of Marc St Louis's method (with the heat gun jig holding the gun 4 inches about the limb) and Pat's. Marc's method seems to darken the wood quicker but Pat's method seems to heat deeper and more even along the limb. I will post pictures when I finish.
Thanks again.
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Are you adding any pitch or resin like Marc describes?
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No. I didn't add any pitch, resin, or anything to the belly like Mark did in TBB4.
Here's what the belly of the bow looks like now. One side looks darker than the other because of the lighting but they are about the same.
(http://i.imgur.com/31nIETN.jpg)
(http://i.imgur.com/qmPdnE1.jpg)
Here's my heat gun set up:
(http://i.imgur.com/nl7XeeN.jpg)b
Do the limbs look dark enough now?
Thanks for your advice.
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4" is to close
you want to heat slow and deep
osage at 6" was to fast, so I moved it up higher
Ash
about 6" on this one, and I brushed shellac on as soon as the heat gun stand was out of the way.
the back of the bow was already sealed.
my 2 cents
(http://i1293.photobucket.com/albums/b593/osagemark/68snakeash/100_0720.jpg) (http://s1293.photobucket.com/user/osagemark/media/68snakeash/100_0720.jpg.html)
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Well, I am still not sure if I got the limbs dark enough or as Mark suggested I heated the limbs too close and did not get a slow deep heat. I waited a week and braced the bow:
(http://i.imgur.com/UC0Eb7a.jpg)
Then I drew the bow several times at different draws until I got to 25 inches:
(http://i.imgur.com/DuRWdxd.jpg)
I am wanting this bow to be around 50 lbs at 26 inches. It currently is about 53 lbs at 25 inches. I was hoping to have zero set or a little reflex in the tips but right now I have about 1 inch of set.
I am trying to decide if I should be happy with what I have and make another bow, or toast the belly some more, or maybe even steam a little reflex in the tips.
Any suggestions?
Also please critique the tiller I am trying to improve my bow making skills and any suggestions will be appreciated.
Thank you.
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She looks stiff right off both fades and at the outer limbs. I leave the last 6" stiff but looks like you have 8" to 10" stiff there.
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Yes also when you unbrace your bow look closely at where the set is. This will tell you with 100% certainty where your limb was strained.
the 'rule of thumb' with set is that you want none inner limb a little midlimb and most of it mid to outer limb (but not at the very tips).
All wood bows take set and you can't get away from it but I use the set to tell me how well I've tillered the bow. If the set is how I described it above then I'm good. If however it is concentrated in one spot then that's the bow telling you that you haven't done the best job.
On your bow it will be concentrated in mid limb because as Pat says that's where all your bending is happening.
You should really concentrate on getting the tiller dead right on this bow or else you will lose weight later on as it is shot more. So get the tips working more and finesse the bend back in towards the handle.
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Well I finally got back to working on my bow and it broke when I tried to string it.
I did try to fix the tiller by getting the area outside the fade and the tips moving more but I think the belly toasting did me in.
The bow ended up breaking about 6 to 8 inches from the tip and the wood was toasted almost completely through the limb. I'm guessing the heat treating and bad tiller weakened the limb. I probably should have ask for help sooner.
This bow was the third hickory bow I have had break about 6 to 8 inches from the tip.
So, time to start a new bow. This time I will watch my tillering more closely and try not to burn my limb.
I would like to thank everyone for your comments and advice. If you have anymore belly toasting tips I would appreciate the help. I am going to keep trying as long as I can find good hickory boards or until I get it right.
Thanks again.
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Also when you heat treat you must make certain that the 'form' you use is narrower than the bows limbs. What happens when the form is wider is that the heat gets bounced onto the sides and the back of the bow.....not good! I suspect this is what happened to yours.
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I heat treat the same as Pat no form. Also I heat treat to induce set back only once, at the floor tiller stage. After that I am a sceptic of inducing set back on a tillered bow. The compression has already begun on the belley especially at the tillering stage you were at. To me that is although minimal the same as bracing the bow backwards. You compressed the belly then stretched and heated the belley several times just not what I would do. Tiller, hit you weight then toast but I wouldnt try to force set back at that point just me.
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Mike you are right on that one let me tell you. Heck I almost lost a bow by heating on a form. It reflected back off and under the bow.
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were all the bows from the same board?
could be the board had a hidden flaw in it- which presented on every bow- seems too much of a coincidence for them all to break in the same place.
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I've never heat treated a kiln dried board. Haven't they already been heated enough?
Anyway, I believe Marc counsels against burning the wood and some of the above staves look burnt.
Jawge
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fujimo - The bows were not from the same board. I have a tendency to get the tips bending to much and I think I just got the limbs to thin that's why the limbs on this bow were not bending very much. When I tried to correct the tiller and get the limb tips bending more the bow broke.
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When you put a finish on the heat treat it gets much darker.
Black is burned, brown is toasted