Author Topic: Frets, Bad Tillering And other Questions...  (Read 1405 times)

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Offline arachnid

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Frets, Bad Tillering And other Questions...
« on: January 25, 2014, 01:26:51 pm »
Hi Guys!
My name is Dor, I`m from Israel and I`m new to the forum (I`ve been lurking here fr some time but this is my first post).
I`m in the bow building biz for about a year, I`ve built several good bow (and several bad bows.... :( ) and I have some questions
for you guys so I might learn from your experiance:

1. How do I prevent Frets on the belly during the design stage? (I know bad tillering can cause frets, how do I avoid it?)

2. which woods (in board form, not stave) are the most forgiving to bad tillering? beside stright grain, is there anything else I should look
for in a board?

3. After Tillering is done (and looks good) , I shoot the bow about a 100 times and then look at the bow to see if there`s something I missed or something that happend. I this the right way to do?

4. When I look for a board at the lumber yard, and I find a nice straight grain board, BUT it looks like it`s been there for a long time (might been exposed to bad weather) , should I take it or leave it? How can this effect the bow?

5. How does the cross-section shape effects the bow (preformance, durablity, etc...)? how do I know which cross-section fits a given
board?

Well, I think that`s it...... for now... ;)
Thank in advance.
Dor

Offline Badger

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Re: Frets, Bad Tillering And other Questions...
« Reply #1 on: January 25, 2014, 01:51:46 pm »
Hi Guys!
My name is Dor, I`m from Israel and I`m new to the forum (I`ve been lurking here fr some time but this is my first post).
I`m in the bow building biz for about a year, I`ve built several good bow (and several bad bows....  ) and I have some questions
for you guys so I might learn from your experiance:

1. How do I prevent Frets on the belly during the design stage? (I know bad tillering can cause frets, how do I avoid it?)

   Dor, the most important element of design is making sure you have enough wood to execute the design you are trying to build. We use length and width as the design and find the thickness as we tiller. If your bow is too narrow it will still be too thick when it starts bending and more prone to chrysaling. I use something called a mass principle to decide as to whether or not I have enough wood. As a general rule heavier woods make narrower bows than lighter woods. For the most part the wood we make bows from usually ranges from about .60 sg to about .80 sg. So the lighter wood should be about 25 or 30% wider than the heavier wood. The wood you selct is also important as some are more elastic and less prone to chrysal. Let us know what woods and designs you are using and maybe we can make some suggestions ast to starting width and length etc.

2. which woods (in board form, not stave) are the most forgiving to bad tillering? beside stright grain, is there anything else I should look
for in a board?

  Osage orange, Pacific yew, elm, hickory, pecan, white oak are all somewhat forgiving. Maple, ash, black locust, red oak and even cherry all make good bows but are a little less tolerant of design or tillering flaws.

3. After Tillering is done (and looks good) , I shoot the bow about a 100 times and then look at the bow to see if there`s something I missed or something that happend. I this the right way to do?

     I would say yes assuming you did a good inspection of the bend and gave it plenty of pulls on the tiller tree before you started shooting

4. When I look for a board at the lumber yard, and I find a nice straight grain board, BUT it looks like it`s been there for a long time (might been exposed to bad weather) , should I take it or leave it? How can this effect the bow?

     I don't worry about it if I don't see any spalting, checks or mildew.

5. How does the cross-section shape effects the bow (preformance, durablity, etc...)? how do I know which cross-section fits a given
board?

    I feel the flat belly is the most forgiving, trapping the back is a popular treatment as well. Some designs and woods call for rounded bellies such as English long bows, thats why yew is so popular for this bow. I slightly round my bellies on forgiving woods but on less forgiving woods I go as flat as I can.

Well, I think that`s it...... for now...
Thank in advance.
Dor

Offline arachnid

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Re: Frets, Bad Tillering And other Questions...
« Reply #2 on: January 25, 2014, 02:01:03 pm »
Thanks alot Badger, I realy learned alot from your answer.
I have another question, if I may- Does heat-treating the belly helps to prevent frets? if it does, does it work on
all kinds of woods?

thx
Dor

mikekeswick

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Re: Frets, Bad Tillering And other Questions...
« Reply #3 on: January 25, 2014, 02:15:55 pm »
Heat treating tends to be best on tension strong/compression weak woods of density lower than say 0.75 - 0.85sg. Think of it as basically 'hardening' the belly. There are other things going on but....
As for avoiding frets....a bow with a good tiller won't get frets (unless it's pulled too far for it's thickness!).
I think you should stop thinking about what 'tricks' can be used to avoid frets. Heat treating, trapping etc are all things that can be used to increase performance if used correctly BUT a good tiller is still essential.
I suggest making bows of different width profiles to get a better understanding of how a limb should bend. Try making two bows from the same board one a pyramid design and one with parallel width limbs.
What sort of boards can you get?

Offline arachnid

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Re: Frets, Bad Tillering And other Questions...
« Reply #4 on: January 25, 2014, 03:22:36 pm »
Well, I`m not looking for "tricks" or shortcuts, just to better understand this things.
Frets is my major problem in this point and I want to beat this "enemy"!  >:(
(I`m not really mad, it`s all with good spirit  ;D )

anyways....
I can get red and white oak, ash, beech (My first bow is a Beech board. After more the 500 shots I`ve spoted
very little frets in one spot on each limb, so I`m thinking to try and fix it...), maple, black walnut, zebra wood, ipe and cherry (assuming I can find a straight grain board).

I`ve never tried a pyramid bow, so I think I`ll give it a shot.
From what I got so far, I need to make the limbs at the same thickness from the fade to the tips.
So, during tillering, how do I deal with hinges or stiff spots? by removing wood from the sides (not from the belly)?

Offline Badger

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Re: Frets, Bad Tillering And other Questions...
« Reply #5 on: January 25, 2014, 03:33:18 pm »
   Something that is very important is to not pull the bow any further than what it takes to expose a stiff spot or an area not bending enough. Usually only a few inches will expose these area. I would scrape the stiff spots until you get a nice even bend and then excersize the bow watching the tiller as you do this. Just go slow and sneak up on a perfect tiller. Once you have drawn a badly tillered bow too far it is allready too late most of the time.

Offline adb

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Re: Frets, Bad Tillering And other Questions...
« Reply #6 on: January 25, 2014, 03:38:07 pm »
In board form, I think ipe is the toughest and most forgiving of mistakes. It can take a serious amount of abuse.

Offline Danzn Bar

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Re: Frets, Bad Tillering And other Questions...
« Reply #7 on: January 25, 2014, 08:58:05 pm »
arachnid..........some real good info from some very experience guys in the last few posts............ no other comments here other than good advice for those guys....
DBar
Integrity is doing the right thing when no one is looking

Offline Mohawk13

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Re: Frets, Bad Tillering And other Questions...
« Reply #8 on: January 25, 2014, 11:58:03 pm »
Shalom. Great place to learn. Great bunch of people here. Where are you located in Israel? Spent time in the Golan Heights and in the Negev. Hope to return someday soon
He That Raises the sword against us, Shall be cleaved upon seven fold-Talmud.

Offline arachnid

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Re: Frets, Bad Tillering And other Questions...
« Reply #9 on: January 26, 2014, 08:50:15 am »
Shalom. Great place to learn. Great bunch of people here. Where are you located in Israel? Spent time in the Golan Heights and in the Negev. Hope to return someday soon

Hi Mohawk13
I live in a city called Rehovot (which mean- expand. Its a biblical name) its in the lower plains of the center of israel.
I travel to the Golan on holydays and my wife`s familiy lives in the Negev so i`m familiar with it. Nice to "meet" people
who love Israel (hard to find these days.... :-\)

anyways...
I thank from the bottom of my heart to all the great people that took there time to answer. There is`nt a bowyer community
in Israel so it`s great to have people from around the world to share and consulte.
Thank you all!

Dor