my sinew came off !

[bradsmith2010]

I was adjusting the weight of this bow, I have been shooting it for months,,
wanted to go to below 50
it was about 55@26 inches and would shoot a 500grain arrow about 180 fps,, I was pleased,,
i wanted to see if I could keep the same ratio of draw weight to arrow speed at a lower draw weight,,
was getting close today and heard a tick,, hmmmm
looked at the bow and it was lifting,, i pulled the whole thing off in a few seconds,,
I have never had this happen before,, been making sinew bows for 20 plus years,,
obviously I did something wrong,, am I getting old,,
it does not look like the back is roughed up as much as I usually do,, well
at least the bow did not break, and if I get a good even sinew job on it,, should not have to tiller much,,
her are the pics,, just when you think you are getting the hang of it,,

[bradsmith2010]

ok one interesting thing I forgot to mention,, the bow was holding reflex with the sinew on, and the unstrung profile was nice,, you can see the bow is not holding any reflex now,, and looks like it is taking some set,, so the belly was being compressed even though it did not show with the sinew in place,,

[Stick Bender]

Wow that sucks  Brad I'm just curious could it have been the glue ?  I know you prep the back carefully , a lot of things are running threw my head  right now could happen to me around the corner but my check list of suspects would be glue,sizing coats, cure time & curing conditions etc but I'm sure those are running threw your mind also ,  at least the core is intact but that doesent save the art work & time sorry to here that !

[Danzn Bar]

Hate to see that happen.....did you have many shots through it?
DBar

[BowEd]

Yea I can see why your surprised.Something new.Good observations too.Great the core wood is in good shape yet.I'd reconstitute the sinew into glue and reuse it.Ought to be a easy job to resinew it.I'd rough it up better the next time.I've used 36 grit paper or old drum sander belts.Maybe even use an oven cleaner like simson has used on the wood before sinewing.

[sleek]

I have reused sinew before. Just wet it and resize the back, then lay it down as one large piece.  Why tjrow that backing away?

[willie]

I have been using  hide glue for wrapping sinew etc. It does not bond well if the wood is the least bit waxy or oily.

[BowEd]

Scratching the back with an old hacksaw has worked great.If you glue the intact layer of sinew back onto the bow make darn sure there are 0 air pockets under there is all I gotta say.

[Marc St Louis]

I would also try to re-apply that sinew, done it before. 

I don't much care for sinew and Osage

[PatM]

 If nothing else it shows what's really happening with a reflexed sinewed bow. The sinew pulls it back, the belly actually is compressing. We just rarely get the chance to prove that.

[osage outlaw]

Did you use oil while doing any heat bending on the bow?  My first sinew attempt came loose in one big layer like that.  I used oil while heat bending the bow and I didn't clean it off good enough. 

[mikekeswick]

If nothing else it shows what's really happening with a reflexed sinewed bow. The sinew pulls it back, the belly actually is compressing. We just rarely get the chance to prove that.

Yes indeed and It happens on any tension strong bow wood. I've pulled ash bow too far to induce set then cut them along the neutral plane on the bandsaw and this same thing happens. The back springs back to straight and the belly 'relaxes' into more set.

[bradsmith2010]

thanks guys for all the input,, got me to thinking,,
I usually use lye or draino or dishwashing powder soap,,,to clean back, on this one I think i just used soap,, I did rinse with boiling water,
and I did use oil to heat bend,
the way the backing came off I feel I did not degrease well enough, ,
maybe that and a combo of how I had the glue mixed ,,,,,
and the back could have been roughed up more as suggested,,

I had about 900 grains of sinew on the bow,, and it seemed a good middle of the road between holding reflex and not adding too much mass,, the bow was not extremely reflexed maybe holding a couple of inches,, but had nice cast,,

I have made so many bows now, if one fails,, and i learn something I am not too dissapointed,, I have learned I need to be more careful and not skip any detail on a sinew bow,, or it wont be sinewed for long,,

Danzn Bar,, yes I had shot this bow a bunch,,

I am looking forward to seeing what I can do when I re apply sinew to this one, I am going to put a little more reflex into it to start with and see how it does,, I had shot it through the chrono before it came apart,, so can compare performance with the new backing,,,

thanks again for all the suggestions and input,,:)

[loefflerchuck]

Yup. Clean up the back of the bow and sinew side it was attached to.  Put wet towels on the sinew side stuck to the bow for a few hours. Heat it all up and re-glue the whole backing. Then wrap it tight to dry. I tried this with a hornbow not expecting it to work and it held. So should for sure work with wood bow.

[BowEd]

Sounds like a good way.I'll have to remember that.