Author Topic: Plum shortie, need some help!  (Read 1169 times)

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Offline MM2

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Plum shortie, need some help!
« on: May 08, 2020, 02:06:23 am »
Hi, everyone!

Iím Michael, 48 years old, from Budapest, Hungary. I have been lurker for a long time, and I have learned many-many things and tricks from You. Thousand thanks, guys!  :D
Over the past two years I built some not-so-good but useable bow and many-many nice tomato stake for my motherís garden.
And now I need some help. Iím working on a plum sapling Ė 43Ē ntn, my aim is 35 pounds at 18 or 19 -, and I found two small cracks on the belly, each starts from a small knot.
What can I do with them? The bow is almost done, right now itís 38 pounds at 18.  My idea: simply rasp out or fill them with super glue. (I canít  buy raw hide or sinew right now.)

Thankís in advance!


Offline Del the cat

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Re: Plum shortie, need some help!
« Reply #1 on: May 08, 2020, 06:21:22 am »
They look like "pinches", compression fractures (aka chrysals).
IMO there are only two viable courses of action.
1. Ignore them.
2. Rasp them out (they go surprisingly deep) forming a fairly long scoop and glue on a patch of the same wood blended to match in nicely. A patch will cover the pin knot which is the weak point that allowed the chrysals to form in the first place.
There are loads of posts about patching the belly on my blog... here is one:-
« Last Edit: May 08, 2020, 06:24:37 am by Del the cat »
Health warning, these posts may contain traces of nut.

Offline GlisGlis

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Re: Plum shortie, need some help!
« Reply #2 on: May 08, 2020, 10:42:45 am »
if you folllow 1 you may also give a little more bend on the tips to relieve some strain from that area

usually rawhide and sinew are to reinforce the back of the bow.

Offline JW_Halverson

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Re: Plum shortie, need some help!
« Reply #3 on: May 08, 2020, 12:04:10 pm »
Either way, get the outer third of each limb bending a slight bit more. Good luck!
Guns have triggers. Bicycles have wheels. Trees and bows have wooden limbs.

Offline Hamish

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Re: Plum shortie, need some help!
« Reply #4 on: May 08, 2020, 07:13:49 pm »
The one in the photo is due to the pin knot. You  need to leave a little wart at that spot on the belly, ie leave that area alone. Like the other guys mentioned you need to distribute the bend more evenly along the limbs.

You won't get rid of them(unless you patch it) but they won't get any worse if you can get the rest of the limb doing more work.

Offline bownarra

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Re: Plum shortie, need some help!
« Reply #5 on: May 08, 2020, 11:53:53 pm »
No it is the tiller that caused them. The knot simply gave the chrysal a place to start. It isn't bending anywhere near enough from mid limb to the tips. The inner limbs are well overstrained.
They may well get worse even if you sorted the tiller out because the wood is already damaged there. The fibers have literally slipped past each other and ruptured. This can't be fixed satisfactorily. The best 'fix' is to learn the lesson and start a new one :)

Offline Hawkdancer

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Re: Plum shortie, need some help!
« Reply #6 on: May 09, 2020, 12:24:24 am »
Amidst the advise of the folks who know more than I do, Welcome aboard!  Be sure to ask any question that you have, and hopefully your mother has to buy this season's tomato stakes! (lol)!
Life is far too serious to be taken that way!

Offline MM2

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Re: Plum shortie, need some help!
« Reply #7 on: May 09, 2020, 12:02:28 pm »
Hi guys!

I knew that you are soooo helpful! Thanks a lot!  :D

I realize I miscalculated. Because the plum is very strong and tough, my plan was: first to shape the grip and
the inner limbs then adjust the outer limbs. (I never built a bow with bending grip and I was afraid of it.)
This proceeding was a great mistake.

But, I don't start to patch it with wood - Del, you are a great magician, I'm not  :D !!!! - and I'm reluctant to give the stick for my mother
because the plum is a rare treasure hereabouts.

I think I'll adjust the tiller, and hope for the best.

If it turns out well, I'll proudly show it to the world. And if not, I'll cry for some hour then start a new bow.

Thanks for your advice!


Offline Hamish

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Re: Plum shortie, need some help!
« Reply #8 on: May 09, 2020, 06:59:34 pm »
Bowanarra, Some woods will chrysal at a pin knot despite other wise perfect tiller, if it is not compensated for in the layout. Some woods chrysal even with apparent perfect tillering and never been overstrained past the intended draw weight. You might get away with it with yew, osage, or some other recognised bow wood, and never even realise it might be a potential problem in other lesser used woods.

You won't really know for sure either way. It was definitely strained due to bending too much in the inner limb, no ones disagreeing with that.  If the pin was compensated for in the original layout it is possible that even with poor tiller it might not have chrysalled.

A knot, even a pin knot is a weakness in the grain in both tension and compression, and has the potential for trouble even with what would in other circumstances be seen as decent tiller. If you compensate for it you stack the chances of success in your favour, but of course there are no absolute guarantees.