Bend the bow too fast?

[Mgydas]

Okay, I am new to building bows and after doing plenty of research I finally started to create my own.

I purchased a few ash staves and wanted to undertake an english style longbow at 68" long, 1 1/4" x 1" at the handle and tapered it to 1/2" x 1/4" at the nocks.  The first broke mid limb in between rings due to a bug infestation (I identified the tunnels).  My second, after chasing the ring, checking the tiller first on the floor and second on the tree, and ensuring there were no hinges still snapped about mid limb.

Now, what I did (I think the mistake) was to string it and check once again the brace of the bow was to start drawing it at further intervals, and upon full draw it snapped.

So did I happen to try and draw it too fast or could it been perhaps my dimensions were off for the ash I am using?

[John Scifres]

How much weight were you pulling?  You should really get it bending pretty good before bending much.

I like to get it thin enough that it will be about my target weight at 20" before really going at it.  Never pull a bow more than it's designed draw weight.

[Mgydas]

I was shooting for 45 at 30, however at about 25 I was pulling 30 so I assumed it would fall short.  I do wonder however, I'm keeping the wood in a shop that is kept pretty dry.  Could that also be a factor?

Any and all help is very appreciated.

Thank you

[fujimo]

if Montana is anything like alberta- where I used to stay- my hickory would be 4% in my shop!!
each time you take a little wood off, you need to exercise it on the tiller tree, I like to do anything between 30 and 50 pulls per time- and like john said, only pulling it as far as the maximum draw weight- even if it only gained a 1/4" of draw length-NEVER EXCEEEDING THE INTENDED FINISHED DRAW WEIGHT!!
unless you are developing a problem area- (hinge or flat spot)- then fix it before continuing
cheers
wayne

[Mgydas]

Okay, I had not been exercising it at all.  Thanks for the tip.  Montana is extremely dry, particularly this year.  I may have to store the last few staves in the garage.  

Appereciate it guys.

[Roy from Pa]

X-2 on exercising 30 times after each wood removal.

[John Scifres]

I suspect it is the moisture content.  It may be best if you store your wood in a location with relative humidity in the 40-50% range.  Do you have a hygrometer?

I definitely recommend you exercise the bow as you tiller but failing to do that alone should not cause the breakage you describe.

You design specs should do what you ask of the wood and it should not have been a problem with the bows being drawn to far too fast as you were pretty light already.  Are you sure there wasn't some problem with the back on the second bow?

[fujimo]

if the staves where sister staves- maybe they both had problems in the same area- ?
1.where they sister staves?
2.when laid side by side, are the breaks in the same area?
3. but I know from southern alberta- things get super dry!!!

[Mgydas]

Fujimo: Yes the first two were sister staves, one broke more towards the center due to the bug tunnels. The other broke more towards the nock, roughly three inches from them.  So it's hard for me to tell.

John: I did put my third stave in an unheated garage that tends to be more humid for whatever reason. But I will be keeping it out there for a few weeks, and exercising the bow properly. I wish I had a hygrometer, but all the ones I have found are 300 plus.
 And as far as the back, it was all one solid ring with no islands or breaking of the ring. None of the rings separated, it was a pretty even break through, well as clean as wood can break that is.

But after all I'm just treating these as learning experiences.

[John Scifres]

You can buy cheap hygrometers at hardware or cigar stores.  It's best if you can look at several of them on the store shelf and choose the one that is reading in the middle.  They tend to vary widely in their readings even when sitting in the same spot.

I would not expect a bow to break that close to the tip unless there was a problem with the wood.  It does not bend there on a properly laid out and tillered bow.  Was it especially thin or narrow in that spot?

[Mgydas]

I had nicked one side of it but it was only about 1/16 of an inch.  I tried to compensate with more thickness.
Tjanks for the info on tbe hygrometer!

[Mgydas]

As a side note, I had it on my tiller tree and the tips didn't bend and I was just examining the break, and put it up on the tree again just to see the other limbs bend. It snapped just before where the intact limb stopped bending. It may have been inexperience, butI have a tendency to be overly meticulous with the micrometer. So I'm not sure.

All I can do is take what I know now and try again.

[John Scifres]

Sometimes stuff happens.  I have broken a lot of bows and many of them have been mysteries to me.

[Mgydas]

Either way I appreciate the help, it's just too much fun to give up.

[George Tsoukalas]

Way too short for an ELB made from ash drawn 30". I would have gone to 72". Jawge

[Mgydas]

Originally it was going to be 72" but met an unfortunate accident with the bansaw and had to reconfigure.

[mikkekeswick]

Too short and narrow for ash. Ash will make an elb but it needs to have a crowned back and flat belly.
Ash is nigh on unbreakable due to it's extreme tension strength.
The wood was your problem eg. bug damage. If there are bug holes in a whitewood cut it into little pieces and put it on the fire! Remember a bow is a tortured piece of wood start only with the best.

[Mgydas]

Okay, good to know. It was a slightly crowned on the back due to the shape of the ring. But I had also crowned the belly.  How much of a crown would I have to put on the back?

I chose ash because it is one of the most readily available trees I can harvest in my area.  I plan to do so once the leaves start growing again.

[fujimo]

choose a smaller diameter tree 6 to 8" that should give you all the crown you need- just strip the bark off, carefully- there is your 'unviolated' back of the bow.
make sure your belly is FLAT!
this will all have the same kinda effect as trapping any tension strong wood- like hickory etc!
the old saying was that longbows were as long as the man- now that would also have had something to do with the heavy draw weights, and longer draw lengths etc