Autopsy (**Updated - pics added to first post)

[akila]

I think sulphur is right....the problem wass  the cut in shelf, and specialy the fades...it looks to me that the fades are to abrupt, and to short.... and  i think it wass happenng a leverage efect there......and the  cut in  shlef  broke.... the tiller lok verry nice...but the problem wass the fades area  and that cut in shelf....i think that this type of handle should be made a little longer.... specialy the fades area...and also the bow should not bend at the fades......sorry for my english....

[George Tsoukalas]

LOL, radius, are you stepping on some bow making toes? It's not that those 3 rules of mine only apply to red oak. Rather, they apply to all boards for bows no matter what the wood is. I allow 2 run ups or outs per limbo for a 50-55# board self bow. I look at the face and end grain.
I actually think one of the better wood species in board form is red oak. I've made at least 50 red oak board bows and I've had only one break. But I'm picky with the grain. Once a bowyer learns to read grain its bow maker's heaven. Jawge

[Innocente]

thanks guys
red oak because it's available.  hard to find good stuff.  i'm in Yew land, but it's tough huntin so far. dreaming of the day when i make a nonboard bow!
a short backing strip like you put on looks like a GREAT idea medicine, as does sulphur's recommendation to not exceed a 1/4" cut. 
i think the diagonal break i showed was a demonstration of Jawge's 3 principles of the board bow.  i thought it looked like a good piece!

and hey jawge: it sounds like YOU need more experience watching red oak board bows explode, i'm gonna need you to come over to my garage for a seminar.  it's titled "Watching a grown man cry", and you MUST bring your own first aid kit. i'll supply all the BOOM clatter clatter sound effects.

[sulphur]

hang in there man.  when you get that first shooter its gonna be worth the effort.

[Pat B]

I believe George had 14 BOOM clatter clatters before he got a shooter. What George says is definitely from experience.   We've all been there and as long as you are learning something from each mishap it isn't a failure. It just means you happened to take a longer road to success. Study the break and determine what went wrong. I still have the first osage selfbow I made(20 years ago) that was over drawn and went Ka Blooy! I study the break on occasion just to reassure myself that it broke right where it should have broke.
  On your next bow consider that the fade area of a bow is where most of the stress is. Design your handles to withstand these stresses. Elongate the fades so it is a gradual taper from handle to limb.
 

[Innocente]

luckily i saved all my failures.  listening to you guys dissect my fracture has given me good insight into troubleshooting wood (at least retrospectively!). planning on autopsying my breaks on them to see if i can find their fail points.

right on with that break and learn suggestion, by the way.

just started my next, and i went for longer more gentle tapering fades this time.

[medicinewheel]

...
a short backing strip like you put on looks like a GREAT idea medicine, as does sulphur's recommendation to not exceed a 1/4" cut. 
...

The painted one is the the only full shelf I ever cut; my friend told me to have an overlay or it would be a risky spot there on the backing, no matter how good the grain is! I've used these overlay stripes on backed boardbows a lot!




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[Innocente]

hey medicine when you do a short backing strip like that, do you just apply your cloth backing where the backing strip ends or what?
lemme ask that more clearly: if you were to run linen backing over that bow in the pic, would you cover the backing strip with it or start the linen where the backing strip meets the back of the bow?

[medicinewheel]

I have never done that, but I guess i would run the cloth over the overlay, and even wrap it some so it wouldn't lift.
Has anyone done this before??
(The bows in the pics all had wooden backings.)

[Gordon]

Dang Frank, you put out some nice work!

[radius]

medicine wheel, you are very understated but a very good craftsman

[otis.drum]

innocente,
i had a lam bow break from the sight window, and thats what i put it down to. it was bending too much through the handle and i didn't have it backed in that area. i made another identical bow without the window, and she still shoots  

if you've kept your failures its time to put a couple together and make a sleeved takedown. how you'll do that primitively i'm not sure  

[medicinewheel]

Thanks guys!
Sorry innocente, didn't mean to hijack your thread!

[denny]

Hey I'm a little late in posting my idea, but bear with me. I have build many board bows and have sure broken my share. But what always amazes me, Is when you think you gota beautiful design, the dang thing blows. Anyway, Stay with wider handle if your are going to build a cut in handle. If you build a fiberglass bow they say never cut in near the center line. However we are talking wooden lam bows. No more than an 1/2 an inch or add a shelve, there are many designs. You are never going to center shoot the bow anyway. Now more importantly, extend the top fade out next time , cut you window 1 1/2 inc above the centerline and you should be okay. Most all bows want to bend in the handle , common physics tells me it is going to give at the weekest link. Hope this helps , good luck. Denny check out my web page for examples. jerbowden.net Denny

[radius]

denny i'm gonna check that site right now

while i'm at it, feel free to check out nomadarchery.ca

Scott