Limb Alignment????

[buzz lite beer]

Want to find out the consensus is when adjusting limb pockets to square up (centre) limbs, a few people use the long rod, I can't believe that even with the best of CNC machining facilities that this can be guaranteed as 100% true 90 degrees to limb pockets as in most bows this is just a push fit, glued in bushing. I personally place masking tape down the centre of each limb, put the loop of my bowstring on the nocks and wrap the string through the limb pocket notch, then draw a line on either side of the string on the masking tape (don't have beiter limb gauges), then make adjustments accordingly, I even check for limb twist with two spirit levels. Any other procedures people have and trust in will be gladly received.

[geoffretired]

I would never trust the long rod either. Your idea with the string and masking tape is much the same as the one I use. For limb twist, I use two straight arrows. With the bow strung, wedge an arrow under the string near each limb tip. Make sure the arrows are parallel to each other when viewed looking at the string with the riser beyond. If you then look along the string from one limb tip to the other, the arrows should line up. Very small twists can be detected.
This has one drawback, it only compares one limb against the other, but it is a good starting point. With two more arrows held at the pocket ends of each limb(rubber bands work well) each limb can be tested separately too.

[buzz lite beer]

I have seen arrows under string twist checking, My concern with that is how do you ensure they are parallel, Do you simply measure them with a tape? If they aren't spot on then you get limbs appearing to be way out when you look across them. Plus using ACE and X10 with these being a barrelled arrow will add discrepancies

[geoffretired]

I think the thing with the arrows is that they become magnifiers of any twist.
It is a well tried method for testing for flatness on narrow surfaces. Because they magnify, when placed under the string, any "out of parallel" is magnified and the eye picks that up and you adjust the arrows accordingly. Also, the arrows make 90 degrees with the string and judging right angles is something people seem to be good at. If in doubt about the 90 degrees, a square can be used. Barrelled arrows would create problems I suppose.

[GreenSteve]

This method was suggested to me also but substitute rulers for arrows

[buzz lite beer]

Originally Posted by geoffretired

I think the thing with the arrows is that they become magnifiers of any twist.
It is a well tried method for testing for flatness on narrow surfaces. Because they magnify, when placed under the string, any "out of parallel" is magnified and the eye picks that up and you adjust the arrows accordingly. Also, the arrows make 90 degrees with the string and judging right angles is something people seem to be good at. If in doubt about the 90 degrees, a square can be used. Barrelled arrows would create problems I suppose.

Thanks for clarifying my cloudiness.

[SimonW]

Simon Needhams new book deals with this subject very well.

In fact it covers almost every subject you could think of in more detail than any other book by either a top archer or coach.

Another *must* for the bookshelf and at less than £17 a bargain.

Simon

[buzz lite beer]

I'm not lining that man's pockets, (old adversary, not jealous of his abilities at all) £17 that's a weeks wages where I come from.

[Stretch]

The problem with the masking tape and the Beiter limb guages is that you're also measuring the profile of the limb as well - so it is not guaranteed. Although I do use this test with Beiter guages it is worth double checking with an alternate method.

The best method for me is the Hoyt recommended technique. Look along the string limb, tip to tip. Then look at where the tip of your limb sits relatively to the face of the limb and repeat at the other end. If it sits in the middle both ends, fine and dandy. Otherwise time to start twiddling. The string should sit somewhere close to the line of your longrod - but with machining tolerances, how straight is your long rod, extender, washers under compression etc it can be out a bit

For anyone who owns an Avalon you can also use a 23xx aluminium arrow and an 18 strand fastflight string - as those dimensions exactly matched the centreshot of that riser - no use with other bows though

Stretch

[Timid Toad]

Yup, I like the masking tape trick, plus the eye is, as has already been said here, very good at picking up right angles. My long rod is definitely off a little too. My impression is that modern, good quality limbs and risers are much much straighter than a few years ago.