broke a bow...why?

[mitchman]

ok so i made my first bow today. well almost.    this is how i did it.

drew it out.       62" ,  .75 - .5" taper.    cut it out. and i used a hand planner to do tapering. i thought it was pretty good lookin tiller. it was perfect. it was not all the way tillered yet, (it didnt bend enough) but i but a short string on it<not enough to brace it> and pulled it back. it went all the way to full draw, twice. easy and smooth. i put it on the tiller rack and pulled it to 20 inches.                                                                                               SNAP!!!!!     man did that hurt.  i dont get it.

  please help.

[George Tsoukalas]

Was it made from a board? jawge

[Justin Snyder]

what width?  Pictures would really help.

[Pat B]

How can you tiller a bow without pulling it first? Sounds like you went too fast and overstressed the bow.   What kind of wood is it?      Pat

[Justin Snyder]

ok so i made my first bow today. well almost.    this is how i did it.

it was not all the way tillered yet, (it didnt bend enough) but i but a short string on it<not enough to brace it> and pulled it back. it went all the way to full draw, twice.

If it wasn't tillered all the way yet and you pulled to full draw twice, you probably drew it to 150#.  Never draw beyond the final draw weight.  Justin

[mitchman]

its a red oak board and i did tiller it i just wasnt all the way done tillering it and getting it down to the right width. it looked like a done bow. i did not brace it. i used a string that i could just barley get strung and pulled it back. then i put it back on the tillering stick to scrape some more wood away. i was just checking the weight and the bend and everything before i finished tillering it. it broke half way up one side of the bottom limb in two places. ill try to illistrate it

       ----------------------------/------/-------
nock           handle       brake brake nock


the dashes illustrate the bow and the brakes are the slashes

[Eric Garza]

Wow, you went fast if you did all this in one day.  My first few bows took several days to shape and then another several days to tiller.  Remove a little wood, study it for awhile, remove a little more... 

I'd cut the bow to shape first, then use a tillering string just a bit longer than the nock-to-nock length of the bow to draw it further and further an inch or so at a time.  That is to say, draw it to one inch, remove wood until it sits at your desired draw weight, then draw it several times to this length before drawing it another inch and re-tillering. 

Repeat until you can brace the bow without it exceeding your desired draw weight, then from that point on use a string sized to give you your desired brace height while drawing and tillering the bow an inch at a time until your done.  As before, at each tillering stage taking enough wood off to get it to your desired draw weight at that length.  Once I get to where I'm using an actual length string on the tillering board, I only use a scraper to take wood off so that I don't end up with too light a bow after going back to clean off file marks with a scraper.

Obviously my method takes a long time (it's not uncommon for me to invest 10-20 hours tillering a bow over the course of a week or two).  But then I've never had a bow break at any stage of the building process, so there's something to be said for taking one's time.  And I'm not a for-profit bowyer either, so I can afford to invest 20-40 hours on a single bow, and routinely do. 

Hope you have better luck on your next project!

-Eric

[mitchman]

thanks eric

i did not do that. thats a great  idea. ill do that on my next one. that i have all shaped and roughly tillered. i glued the handle tonight and the nock tips so they are taking up the time tonight. but tomorrow i will do exactly what you said. thats a great idea.

thanks again,
   mitch

[RT]

Mitch,

I must admit i learn from my mistake very late, approximately after building 20 bow then i learn................."better late then never"

What i mean is i never "long string tiller" my bows before,  tapered my core then after glue up , I floor tillered it..........and when i thought it was bending already, straight away pulled it on to brace height with a short string.........if your bow is not evenly tillered, putting it onto short can cause HUGE damage to the bow, causing the limbs to break or crystallize.........

Go slow and slower again, always start with the long string 1st. cheers!

[david w.]

my first bow was a board bow and it took 3 months of SLOW work. just remember to go slow and it will turn out fine

[Hillbilly]

What did the grain of the board look like where it broke? Runouts?

[George Tsoukalas]

Hillbilly, that was my thought too. The 3 important things in board choice are grain, grain, and grain. I think that is 3. LOL. mitchman, check my site for more on board choice. Jawge
http://mysite.verizon.net/georgeandjoni/archer.html

[Ryano]

Glue some kind of backing on the next one for insurance. Silk, linen, or  rawhide.

[Postman]

Im a novice, but ya might need to back it and / or add a riser.Here's an easy board bow showing cheap way to do it.
http://www.geocities.com/salampsio/oak8.htm
Good luck
postman

[Slivershooter]

I agree with the others, you are rushing the tillering process.  Slow it down a little and teach the limbs to bend in small stages, no more then a ¼”– ½” at a time and at least thirty times at each stage.  Also, as stated by others, never pull your bow beyond your final draw weight until you reach the final draw length. I prefer to never pull the draw weight beyond 80% of the final weight until the last three or four inches of draw length. 

That being said, a smooth grained board bow shouldn't take very long to tiller properly.  My first board bow went from a 2”x ¾” slat with a ¾” handle section glued on it, to a well tillered, shooting, bow in one 10 hour day (that included making a string).  I took twice that amount of time to prep it for finish, re-finess the tiller, apply the finish, and install the handle wrap.  For those interested, the bow is still shooting eleven years later