tiller method?

[willie]

Hi all
I am new to all this and have recently broken a couple of hickory boards trying to make them into bows. My basic method was I followed instuctions I read about exercising the bow alot to let the changes take affect before scrapping some more, but the boards have broken just before or shortly after reaching 28" draw. I can see that I need to have them closer to finished thickness earlier in the process, but most of what i read is bend a little more here a little less there as you go. But all this is after you floor tiller, and some of the threads say they dont even do that, but some of the guys say that they are just about done with the bow after they tiller it to brace height?
It seems that the art is to get the bow right before you pull it to far, but I dont find much to read about how to know how much it takes to get it bending in the beginning. It's like you have to build it before you can build it. If I want a bow to be say 50# when I am done, is there a forumla to know how much it takes to bend it the first 6 inches?
willie

[artcher1]

Hi Willie, good to have to aboard. Check out this recent thread.

http://www.primitivearcher.com/smf/index.php/topic,43740.0.html

You're going to get good and bad hickory. Mostly depends on how it was stored and processed. Good idea is to do a bend/break test on some scrap before starting your bow. Good hickory will take a great bend without breaking. Mostly it'll collapse without snapping into. Bad stuff breaks clean. Good luck with your future bows..........Art

[Badger]

  Willie, thats the same question almost all of us have when we are getting started. It changes pretty radicaly with the length of the bow you are building and the style to some extent also. There was a similar question yesterday. I went and measured a 50# finished bow on the long string just so I could answer him. The important thing to remember when working with a long string is that the poundage reading you are getting has more to do with how far your string is hanging down than it does the deflection of the limbs. It is very important to try and get it bending as even as possible before ever bracing it. Try not to pull it any further than what you need to pull it to see an area that needs some work. If your long string is hanging down about 6" if you just take your finger and remove the slack it should probably read about 40#@21" and you should be ready for a low brace height. When you are excersizing it just don't pull it over 50#, less if you can see where you need to work it.

[willie]

Badger

yeah, that was me that asked yesterday, and your advice is where i am going to start on the next board.
Aussie came back with a method that was quite different, but since I started aksing about floor tillering in your thread about your spreadsheet, I thought I would move the question to a thread of its own and see what kind of variety people have with their floor tillering.

[Badger]

       That same question has always been lacking in a real solid answer. After you build awhile you will start doing it more by feel. Next long bow I build I plan to take some measurements and write it down.

[Pat B]

Willie, after over 30 years of building wood bows I still floor tiller to about 4" of tip movement. This allows me to be sure both limbs are bending at lease somewhat together and that their weight is in the ballpark with each other. I then go to a long string just longer than the bow. By the time the tips move 8" on the long string and both limbs are bending evenly and together I'm usually ready for a low brace of 3" or so. At this first low brace my main concern is that the string is tracking well. If that is the case I continue on removing wood, exercising the limbs(gradually and not too far for now) and checking tiller. When I get to 14" or so of draw length I start checking my max draw weight and only draw to that weight until tillering is complete.
 Getting everything bending well early on will help you stay on track with the tillering and achieving the draw weight you desire. Ideally you want your tiller to be right on and your last few inches of tillering is only for weight loss.

[Del the cat]

I've been discussing this with someone else and I posted my thoughts on my blog.
http://bowyersdiary.blogspot.co.uk/2013/12/yew-stick-bow-and-draw-weight-to-brace.html
There is plenty of tillering on the blog and if you go back about a month you can follow the tillering of a 130# warbow and all the trials and tribulations on the way.
I make a point on the blog of showing my mistakes too, so you will find some blow ups too... they may make you feel better! This one was a warm up for the 130# bow.
http://bowyersdiary.blogspot.co.uk/2013/07/warbow-explodes.html
I get a bow roughly even taper than get it on the tiller tree. IMO it is a mistake (certainly with a stave) to try and get it finished before you've started! Biggest lesson you can learn is patience... it's not a race... you've got to remove a certain ammount of wood, but there's no time limit on how long it takes you. Only experience will let you rip into it early and get away with it.
Good luck
Del

[bushboy]

If you have a manufactured bow try bending it on the floor to get afeeling of what your after.you could even put it on a tillering stick ,feel the weight and observe the bend.very true what art said about hickory in board form being hit and miss!good luck!

[willie]

Thanks for the replies, guys

Pat,

By the time the tips move 8" on the long string and both limbs are bending evenly and together I'm usually ready for a low brace of 3" or so.

so for say a 50# finish design, do you pull 50# to get that first 8" b4 you brace?
willie

[Badger]

Thanks for the replies, guys

Pat,

By the time the tips move 8" on the long string and both limbs are bending evenly and together I'm usually ready for a low brace of 3" or so.

so for say a 50# finish design, do you pull 50# to get that first 8" b4 you brace?
willie

Willie, if your string is real short and you pull 50# to get it braced you might still be a bit too heavy, If the string is hanging down to about 5" or 6" then you would probably be ok.

[Badger]

  I just did another little experiment. I used a string that was very long and hund down to 13" on a finished 50# bow. It still read 50# @ 27" about the same as it would hve read had I braced the bow and pulled it the same distance. If you put any length loose string on your bow and it pulls about 50#@say 19" then thats about where it would pull if it were braced and not having a loose string.

[Pat B]

If you have the tips moving 4" at floor tiller check it on the tiller tree with the long string and see how it bends. You are stressing the bow very little at this point. Work your way out to 8" slowly, exercising as you go. When you hit 8" be sure both limbs are bending close to each other and both are even in weight. If everything is OK low brace the bow to 3" or so to check how the string tracks. You will also get a true picture of tiller at this point. From now on don't pull the 50# bow past 50# as you tiller and exercise.

 

[willie]

Badger & Pat,

Thanks for taking the time to help me with some real numbers. Just one more question while we are on the subject.
I got one 70" hickory board that I have reduced to about 1/2" thick at midlimb that has since developed a 2" recurve.
Its been set aside until I get a better feel for floor tillering, but I can tell that it wants to take quite a bit to bend it over center to start going the other way, and I read that it is quite easy to be fooled early on when working with reflex or recurve limbs. With a board or stave like this would you tiller it out further with the shortest "longstring" , before trying to brace it?

willie

[George Tsoukalas]

Willie, how long was the stave? Was it straight grained? Did you glue on a piece for the handle?
A big part of the battle is choosing the proper stave. That was what I did not do when I started.
Anyway, consider  making a bend in the handle bow. No glued on pieces.  No narrowing of the handlea rea.You can leave the stave 1.5 in wide for 50-55# or you can rip the stave to 1 3/8 in and get 45-50...at least potentially anyway.
There is a red oak board bow buildalong on my site. Check it out. You can still use hickory.
Jawge
http://georgeandjoni.home.comcast.net/~georgeandjoni/boardbowbuildalong.html

[willie]

George
I assume you are asking about the ones that I broke in the opening post. they were 4/4 boards about 68" x 1-5/8 wide long with stiff glued on handles. I did finally get  a bow out of one, but it was tortured to 28 and shows some set.
As for the board mentioned in the post above your reply, it is a 3/4 board x 2- 1/4" wide with a 1/2 thick glued handle, and might have to become shorter bow, as I roughed the limb a little thin in one spot mid limb. It has developed 2"reflex after roughing the limb to thickness. yes it has nice straight grain hickory. Just trying to get a feel for floor tillering before I pull it too much.
willie