Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on February 25, 2020, 11:47:06 am
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Has anyone noticed negative results when tillering dry wood. I'm just talking about evenness and difficulty, I guess. I realise the DW will go up and there will be a greater danger of explosions but it's just the "getting it to bend nicely" that I'm thinking about.
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Lately this winter the humidity has been 40-50 percent and it’s allowed me to make some pretty good shooting bows. I know in the summer when it gets 80-90 percent humid all summer long it was a struggle with all the set the bows were taking. I need to build a hot/dry box for the upcoming summer.
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That sounds like it would work in my favour. Drier= less set.
I'm looking for a reason other than incompetence why my tillering has taken a down turn in the last 6 months to a year. It occurred to me that I haven't gotten any new staves in a year or so, so everything is much drier/more seasoned. It's probably my skills or lack of, combined with fairly extreme designs that's doing it. Or maybe I'm just getting old :D
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What is going on with your tillering that you think it is taking a down turn? Could it be a lack of patience? Are you getting more set than you used to?
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Just one limb bent more than the other or a weak spot. Fixable stuff but would bring it in under weight. Like this one, my last bow, weak bottom(left) limb. It's not to FD in the pic. It still shot 197fps@10gpp but I can't help but think that if the limbs were balanced it would have been the one. I'll weaken the top limb to match and see what I get. The one before this was the same and when I sorted it out it lost about 4 lbs but gained 3 fps@10gpp.
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I have fixed similar problem with heat treating. I turned heat gun on max, pulled the limb straight and worked from very close distance so the air flow won't reach to the back of the limb. It was backed bow too.
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Jeez 197fps. Yeah that’s way out of my league....for now 😁
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I have to ask you the question that I have asked you before. What draw length,and what poundage are you shooting to get 197 fps with a 10gpp arrow? That is some real speed.
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So I worked it a bit. It was 40#, now it's 37# and speed is down to 190. It hasn't taken much if any set still 3 1/4" reflex. Not sure where 7 fps went. I did scrape off the upside down DC so that's a +. It's still not perfect but I'm not sure how the shadows affect it.
Maitus- were you trying to get rid of set when you heated it? I've often wondered about heat and backed(epoxy) bows. Interesting
I have to ask you the question that I have asked you before. What draw length,and what poundage are you shooting to get 197 fps with a 10gpp arrow? That is some real speed.
It's the same bow that you asked about last time and it was 40@28 when it shot 197. It's not anymore
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Do you drop the arrow weight to reflect the lost poundage?
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Maitus- were you trying to get rid of set when you heated it? I've often wondered about heat and backed(epoxy) bows. Interesting
Yes. I didn't heat too long. I just used high heat for a short time to harden the outer side of the belly. Heat didn't reach to the glue line. Then I put it aside until to the next day leaving it in clamps. And it worked.
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Do you drop the arrow weight to reflect the lost poundage?
Yes, I have two carbon arrows I use for my machine. I put a weight inside one and I have an assortment of tips to screw on so I can get from 320 to 450 grains in 10 gr increments. It needs some fine tuning but the DW of a bow is never an even pound so I just pick the closest. I go to the next heaviest to keep me honest ;D(unless it's really close ;))
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Maitus- were you trying to get rid of set when you heated it? I've often wondered about heat and backed(epoxy) bows. Interesting
Yes. I didn't heat too long. I just used high heat for a short time to harden the outer side of the belly. Heat didn't reach to the glue line. Then I put it aside until to the next day leaving it in clamps. And it worked.
Did you use epoxy? I'm wondering if the heat allowed the glue to creep and as a result you ended up with a little more reflex. Can't think of any way to test that. :)
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DC, if you got a little bit more limb working that could possibly count for a speed loss due to vibration. The more working limb you have the more opportunity for vibration. Thats why very few glass bows are hitting 190. Really more like distortion than vibration I think.
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this is my take on it,, as you get better at tillering, you get pickier about the tiller,, you just see more and expect more,,
your tillering skill has not taken a down turn,, you are just more critial of the results and are expecting more consistant results,, dont worry,, your skill with catch up to what your eye sees and your expectatioins,, :)
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Did you use epoxy? I'm wondering if the heat allowed the glue to creep and as a result you ended up with a little more reflex. Can't think of any way to test that. :)
Make one experimental limb from some scraps. It won't take much time :).
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Got one sitting on my bench :D
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DC, if you got a little bit more limb working that could possibly count for a speed loss due to vibration. The more working limb you have the more opportunity for vibration. Thats why very few glass bows are hitting 190. Really more like distortion than vibration I think.
This opens up a whole bag of thought. I remember Alan commenting on this but I'd forgotten. So now we're leaning toward Molles or whip tillered maybe. Is there a chance that uneven tiller could help cancel out vibrations?
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DC, not sure if you've followed some of my posts but dryness is a huge PITA for me.
I've found that when I get to the short string, I have to exercise the limbs a bit, string the bow, exercise a bit more, and let it sit under tension for about a half hour to a full hour, to let things kind of settle and relax. If I skip this, I'll tiller what I think is a stiff spot, and it will end up being a weak spot when next I string the bow.
It's frustrating and time consuming, and maybe it's just coincidence and it forces me to slow down and take more time, but whichever it is, it helps.
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DC, not sure if you've followed some of my posts but dryness is a huge PITA for me.
I've found that when I get to the short string, I have to exercise the limbs a bit, string the bow, exercise a bit more, and let it sit under tension for about a half hour to a full hour, to let things kind of settle and relax. If I skip this, I'll tiller what I think is a stiff spot, and it will end up being a weak spot when next I string the bow.
It's frustrating and time consuming, and maybe it's just coincidence and it forces me to slow down and take more time, but whichever it is, it helps.
Interesting. There's no way that my MC should be as low as yours as I live 100yds from the ocean but the heated shop does get dry. Sometimes 20-25%RH.
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What is the best humidity range to tiller a bow?
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It's not so much the RH that you're tillering in, it's the moisture content of the wood. It should be around 10%. If you store your wood in 45-50%RH it will equalise at about 10% MC. As long as the wood spends most of it's time at 45-50%RH you're fine. These numbers are ballpark, there's quite a bit of leeway. My shop goes from around 50%RH at night to 25-50% during the day so it should average out OK. All this assumes the wood is already dry.