Author Topic: Pin Knot causing me grief  (Read 2725 times)

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Offline OTDEAN

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Pin Knot causing me grief
« on: December 08, 2014, 02:26:43 pm »
Hi,

Got a pin knot showing on the belly of a bow limb I am floor tillering  The wood is from a tree and heated pretty staight.  The pin knot is full of decayed wood, not very big, I have dug out the crap and will fit it with saw dust and super glue.  The back of the bow has no knots opposite the pin knot, but, the back does rise up ever so slightly where the pin knot is on the belly.  I am using an outside caliper to get my thickness taper right.  When I run my outside caliper over the pin knot its showing the wood is thicker that the wood closer the handle.  Is this because the back is rising up a bit where the pin knot is on the belly?  I have followed the belly so it follows the dips and rises of the back.  Should I keep removing wood from the belly where the callipers are telling me I have a thick spot?  My intuition is telling me I have this wrong and the calipers are lying to me because the back rises?  What do you fellas think, Im stumped with this.  I am guessing I should leave it extra thick at this spot and just make sure the limb after the knot towards the nock is thinner than the wood on the other side of the knot towards the handle and except I will have a stiff spot at this part of the working limb?

Look forward to any suggestions

Dean

Offline bradsmith2010

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Re: Pin Knot causing me grief
« Reply #1 on: December 08, 2014, 02:41:59 pm »
just leave it thick for now, then you have the option to change it later as you tiller the bow,,

Offline JW_Halverson

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Re: Pin Knot causing me grief
« Reply #2 on: December 08, 2014, 03:34:07 pm »
just leave it thick for now, then you have the option to change it later as you tiller the bow,,

+1
Guns have triggers. Bicycles have wheels. Trees and bows have wooden limbs.

Offline okie64

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Re: Pin Knot causing me grief
« Reply #3 on: December 08, 2014, 11:26:54 pm »
Throw those calipers in the trash, they are useless on selfbows. Just kidding, I used to use em until they lied to me one too many times. I know some guys use em religiously but they just never worked out for me. Do what the other guys already said. Remove wood till the bend looks good, some spots will end up thicker than others.

mikekeswick

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Re: Pin Knot causing me grief
« Reply #4 on: December 09, 2014, 03:34:59 am »
I have to disagree there. Sure on real character staves calipers can be more of a hinderance but on anything approaching straight they can be very useful.
Remove wood so you have an even thickness taper. I don't see any point in leaving it stiff on purpose. The only time I wouldn't follow this rule is if I had a localised deflexed spot - these need to be a little thicker to stop them bending too much.
When you have a knot like this the width should swell the same amount that the knot does. This extra width will allow the satve to bend there safely. IF you haven't marked your width out correctly and you have no extra width then maybe you should leave it a little stiff - but personally i'd reduce the rest of the width to leave a wider spot around the knot.
I'm guessing it's an elm stave and i'm guessing that the swell on the back doesn't go full width? More like a high island? If so then average it out don't make the belly follow it precisely just make sure that the area isn't stiff. You can check how much it's bending by holding a straight edge up against the section and flexing the bow.
Show me it at the weekend if you don't get anywhere with it  ;)

Offline PatM

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Re: Pin Knot causing me grief
« Reply #5 on: December 09, 2014, 09:32:56 am »
 I wouldn't call that a pin knot. It's just a grown over broken off branch or twig.

Offline bradsmith2010

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Re: Pin Knot causing me grief
« Reply #6 on: December 09, 2014, 01:42:04 pm »
even a deflexed spot needs to follow the taper of the limb,, it may look like its bending too much, but needs to work the same as the wood around it.. our it will be a stiff spot,, if the bow is over built a bit it will still shoot good,, but that part of the limb will not be working like the rest,,

Offline Springbuck

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Re: Pin Knot causing me grief
« Reply #7 on: December 10, 2014, 05:19:18 pm »
Throw those calipers in the trash, they are useless on selfbows. Just kidding, I used to use em until they lied to me one too many times. I know some guys use em religiously but they just never worked out.

I use them religiously, but only to rough out the bow to an even limb starting thickness, say 3/4"  Once I establish that, I put them aside and listen to the bow....