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Main Boards => The Bowyer's Bench => Topic started by: flyonline on December 13, 2019, 06:44:26 PM

Title: Crack in selfbow - Toast?
Post by: flyonline on December 13, 2019, 06:44:26 PM: Unstrung my osage selfbow a while back and noticed this small crack running across the grain on the back of the bow. It's a bit past 50% along the bottom limb.

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Can it be fixed? My thought was a bamboo patch over the crack and bound with something (thread etc.).

Thanks

Steve
Title: Re: Crack in selfbow - Toast?
Post by: Pat B on December 13, 2019, 07:17:29 PM: Tension failure is pretty uncommon in an osage selfbow but that crack is connected to a pin knot it looks like.
You could fill it with super glue and add a sinew wrap around the limb over the crack and a little on either side. Adding a placebo wrap on the other limb will add balance to the bow's appearance.
Title: Re: Crack in selfbow - Toast?
Post by: Forwardhandle on December 13, 2019, 08:28:26 PM: I did this bow a few years back that had a similar issue around a pin, I did a tapering flax patch and then raw hide on the working limbs and no retiller was needed flax is very tuff stuff probably could have got by with it alone but put the raw hide on for insurance !
Title: Re: Crack in selfbow - Toast?
Post by: OkKeith on December 14, 2019, 11:03:30 AM: Maybe superglue and then rawhide back the bow?

I think rawhide takes a little "snap" out of a bow but it certainly adds a near bullet-proof backing. Sinew would add some draw weight and be a fair choice as well but involves a greater amount of effort.

I have built a few sinew backed bows but no real success for me. I have built several rawhide backed bows (deer rawhide and cow rawhide) and all of them have been shooters. That is no reflection on how well sinew bows shoot, just a comment on my lack of skill.

OkKeith
Title: Re: Crack in selfbow - Toast?
Post by: Pat B on December 14, 2019, 11:49:57 AM: I wouldn't waste the effort or the sinew to sinew back this bow. A sinew patch or wrap, a flax patch or a silk thread or other thin, strong thread wrap would be a better choice. IMO.
Title: Re: Crack in selfbow - Toast?
Post by: flyonline on December 14, 2019, 09:41:21 PM: Thanks all.

Sinew ain't really an option as it's not available readily unless I make my own. Rawhide might be (dog chew etc.) though. I'm not worried on how it looks, a bit of patina is fine :thumbsup:

Forwardhandle can you give me more details on the flax? Where do you get it, original intended use etc. so I can have a search around here.

Cheers

Steve
Title: Re: Crack in selfbow - Toast?
Post by: Forwardhandle on December 14, 2019, 09:54:43 PM: Flax or flax toe is carried by weaving or spinig shops its like long white grey cat hair but can be applied with TB 2 or 3 I exstend the patch about 3" each side of the crack and sand a taper with the apex being centered over the bad area but if your going to use it on osage you will want to sand & use dish soap & really hot water to clean the area if done like that usauly no retiller is required flax is brutally strong but if its a bow that is going to be keeped for a long time I add the raw hide too , another simple fix is just wrap the area with serving just like you would a string on a larger scale and soak with really thin CA ,I have done that on hickory bows that pulled a splinter & are still shooting years later !
Title: Re: Crack in selfbow - Toast?
Post by: Eric Krewson on December 15, 2019, 09:46:34 AM: I superglue first then string wrap these types of cracks. I use braided serving thread, put it on with a string server out to 1/2" on either side of the crack then soak the wrap in superglue until it won't hold anymore. You caught your crack early and a wrap like I suggest will hold up for years. I fixed a friends bow this way, he heard a "tink", it took a group of us a long time to find the crack (we were at a tournament) but once found the serving fix held the bow together for years. Actually the bow is still together but after over 100K arrows after the fix he decided to retire it. He finished second in the IBO worlds with his patched bow.

Here is a thread wrap repair, in this case bamboo that raised a splinter;
Title: Re: Crack in selfbow - Toast?
Post by: OkKeith on December 16, 2019, 12:10:03 PM: Steve-

I have ordered deer rawhide from 3 Rivers Archery and it works very well. I have also bought cow rawhide from places like Tandy Leather. It always comes out "clearer" than the dog chew rawhide and is more consistent in thickness and quality. Sometimes you can get good cow rawhide strips at Farm and Home supplies. They are used to wrap saddle-horns on roping saddles. They are generally pretty cheap.

OkKeith
Title: Re: Crack in selfbow - Toast?
Post by: George Tsoukalas on December 16, 2019, 01:00:53 PM: I've fixed many a problem with a serving thread set in epoxy.
It is always a good idea to tiller knotted areas to not bend as much in relation to the rest of the limb.
If they are large enough leave a little bit of extra width.
Jawge
Title: Re: Crack in selfbow - Toast?
Post by: flyonline on December 16, 2019, 09:14:52 PM: There you go, thank you all.

I had assumed that a thread wrap wouldn't hold up for a latitude crack as it's just the glue holding it all together, rather than lengthways fibres helping carry the load like a splint over the top be it flax, sinew, rawhide etc.

Keith

ordering stuff from the US is killer for me, so I will search locally for something. My dad did a lot of leather-work in the past, so he may be able to point me in a good direction.

I like the simplicity of thread and CA, so that will probably be my solution this time around.

Thanks again

Steve
Title: Re: Crack in selfbow - Toast?
Post by: Pat B on December 16, 2019, 10:14:23 PM: Steve, silk thread set in super glue or epoxy works well. Silk thread is thin and strong.
Title: Re: Crack in selfbow - Toast?
Post by: OkKeith on December 17, 2019, 05:10:29 PM: Sorry Steve... I didn't think about that!

Looking forward to your fix and seeing you shoot that bow some more.

OkKeith
Title: Re: Crack in selfbow - Toast?
Post by: flyonline on December 18, 2019, 12:54:23 AM: Quote from: OkKeith on December 17, 2019, 05:10:29 PM
Sorry Steve... I didn't think about that!

Looking forward to your fix and seeing you shoot that bow some more.

OkKeith

All good, you can't know where everyone is :thumbsup:

Will post up some pics when done.

Quote from: Pat B on December 16, 2019, 10:14:23 PM
Steve, silk thread set in super glue or epoxy works well. Silk thread is thin and strong.

Think I've still got some wide silk thread in my fly tying box, otherwise kevlar thread is always an option :laughing:
Title: Re: Crack in selfbow - Toast?
Post by: Pat B on December 18, 2019, 09:40:08 AM: Kevlar would be a good option if the Kevlar thread will absorb and stick to the glue. By using a thread wrap you prevent the limb fibers from lifting from either side of the crack when the back is in tension.
Title: Re: Crack in selfbow - Toast?
Post by: flyonline on December 23, 2019, 12:04:44 AM: Wrapped up the crack last night with 3x layers of kevlar thread and then rubbed in with as much Loctite 406 as I could stand. Strung it up today and put it on the tillering tree to make sure it wouldn't give me a good whack on first pull. When it survived a few dozen pulls to full draw after gingerly working up to full draw, I flung a couple of dozen arrows through it and so far all good :thumbsup:

Still need to do a bit more on grip to get it sitting right, but very glad to get it back to shooting condition, so thanks again for all suggestions and advice :notworthy:

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Title: Re: Crack in selfbow - Toast?
Post by: Pat B on December 23, 2019, 10:39:33 AM: Nice save. :thumbsup: Just be sure it doesn't happen somewhere else. A cotton ball will tell you if there are any splinters or cracks starting again.