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Thread: WNS Carbon/Foam Limbs

  1. #1
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    WNS Carbon/Foam Limbs

    Yesterday I fitted a pair of the new WNS Carbon/Foam limbs I have purchased. They were fitted on my Fiberbow 6.9 riser.

    To set-up the bow I checked the limbs 'natural tiller' in the following manner.

    Using a feeler gauge I wound the limb bolts in until the underside of the lower collar contacted the feeler gauge. I did this because the tiller bolt does not have a 'bottoming' stop.

    I fitted both limbs and braced the bow. There was a variation in the measurements between string and limbs at the limb exit points from the riser. So I adjusted the lower limb bolt to get a '0' tiller.

    I unbraced the bow and reversed the limbs (top in lower - lower in top). When I re-braced the bow and checked the tiller I got the following measurements. Top distance 204mm. Lower measurement 190mm. A difference of 14 mm. Which if I am correct is a natural tiller of 7mm.

    When I have done this with previous limbs I only got variations of 3 - 4 mm. Is this 7mm acceptable or should I return the limbs as faulty. I have read that over 6mm is not acceptable.

    What do you suggest as it appears to me that the top limb is much stiffer than the lower limb.

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    So you set tiller to zero, reversed the limbs and got a tiller of 14?
    2*limb-tiller = 0 - 14 = -14
    The limbs are tillered to -7?

    I'm not sure the amount is important, 7mm doesn't sound all that excessive to me, but I'm willing to take direction from any bowyers who chip in.
    It is reversed. Could be the limbs are labelled wrongly. Is there a visible difference between top and bottom on these limbs - decals, printing on the back? If not, I'd probably just correct the labels, so long as there don't appear to be any other problems...
    Ever tried? Ever failed?
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    Quote Originally Posted by Rik View Post
    So you set tiller to zero, reversed the limbs and got a tiller of 14?
    2*limb-tiller = 0 - 14 = -14
    The limbs are tillered to -7?

    I'm not sure the amount is important, 7mm doesn't sound all that excessive to me, but I'm willing to take direction from any bowyers who chip in.
    It is reversed. Could be the limbs are labelled wrongly. Is there a visible difference between top and bottom on these limbs - decals, printing on the back? If not, I'd probably just correct the labels, so long as there don't appear to be any other problems...
    Hello Rik
    I checked the labels to see if they had the same serial number - they have. One limb has a slightly thicker butt than the other, but I discounted that as it would be within the pocket of the riser. I was under the impression that limbs were now manufactured to be equal tiller - much easier for the manufacturing process, so it should not make any difference which was labelled which. I should say that when I set-up my bow I set the initial tiller between '0' and the natural tiller (in this case 7mm). So I would probably set it to 4mm positive. But my concern is the amount of 'natural tiller'.

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    Quote Originally Posted by albatross View Post
    Hello Rik
    I checked the labels to see if they had the same serial number - they have. One limb has a slightly thicker butt than the other, but I discounted that as it would be within the pocket of the riser. I was under the impression that limbs were now manufactured to be equal tiller - much easier for the manufacturing process, so it should not make any difference which was labelled which. I should say that when I set-up my bow I set the initial tiller between '0' and the natural tiller (in this case 7mm). So I would probably set it to 4mm positive. But my concern is the amount of 'natural tiller'.
    My understanding is that mass produced limbs are produced in singles then paired up before being labelled. So all it takes is for a pair to get swapped, to produce this. They won't be trying to get an exact match, just within a certain tolerance.

    But reversed limbs can happen even with a made to order kind of situation - I saw a thread about a pair of Border limbs which were supplied reversed. They apologised, re-labelled and re-finished them.
    Ever tried? Ever failed?
    Try again. Fail again. Fail better! - Beckett

    The marksman who hesitates is lost. Just take it for granted that you are going to hit and fire away before you have time to doubt the certainty of success. - Annie Oakley, 1894.

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    I am going to contact the supplier and see what they suggest. Another option is to redo the same exercise with the limbs reversed and see what the result is.

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    Update. I shot the limbs for about an hour at my club. It was noticed by myself and several other members that the string was out of its groove by about 6mm, that is no longer central to the limb. I thought it was just an alignment issue but it was not. I checked everything. I put my original limbs back in - perfect. So I sent the limbs back to the suppliers saying I thought they were twisted. They replied that they had tested them and they were not twisted. I fitted them again - shot them for about 6 ends (6 arrow ends) - result = string again out of central position. To cut a very long story short I did a very close examination of the top limb. I found that the string groove had been cut unequally. One side was wider than normal and it had a shoulder in it. The other side was correct width but it had been cut more into the centre of the limb. These minor defects were causing the limb to twist and the effect was to pull the string out of alignment.

    I contacted the supplier again and sent the limbs back (this is costing me money). They agreed that the grooves were as I stated BUT they said they were within tolerance. BUT they also said I was being too critical and I had to expect that as these were only 'Intermediate' limbs and not 'professional' limbs to find such defects and accept them! I copied their comments to WinWin Europe along with photographs of the defects asking for their comments. I said I would wait a week for their reply. The week passed today, no reply. I got the limbs back and I got some 2 part epoxy resin filled the defective grooves and re-cut the grooves correctly. I setup the bow. Checked the 'natural tiller' = 2m not 7mm as previously! When I shoot them again I expect that after my repair of the defects that they will shoot correctly.

    The part that really annoyed me was "I had to accept these defects as they were not more expensive limbs". I have always brought and shot SF brand limbs and up to this point never had an issue with them. I accept there will be differences based on price but not an identified manufacturing defect.

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