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Tiller for Recurves

5540 Views 9 Replies 7 Participants Last post by  tpoof
I'm a little confused, exactly what is meant by tiller for recurves and long bows. I realize that with most take down bows, that limbs can be adjusted, but how is it done on one piece bows and what is the result of such adjustments?

Wagoosh
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tiller

tiller on a recurve or longbow is done when making the bow to make sure that the limbs are bending properly that there are no hinges or flat spots proper tiller can be the difference between a good shooting bow or a bad shooting bow hope this helps
 

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Wagoosh -

On one piece bows tiller is built-in to the bow design and actually has two different but related meanings. In general, tiller is the relative strength of one limb to the other. In most, but not all cases, it's handled by the relative amount of reflex built in to the fade-out, but may be handled by actual limb strength (by slightly varying limb width and/or thickness.) In the case of relative reflex, most bows are set to approximately 1/8" lower limb strong, as measured at the end of the fade-out. The typical variance is neutral (0/0) to 1/4" lower limb strong. That works quite well with most bows in most applications.

The other meaning, typically discussed with selfbow is the relative flex along the lenght of the limb, meaning the the limbs bend evenly.

Viper1 out.
 

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Bows are generally tillered with a stiffer lower limb because the shelf is made 2" high of center so the lower limb is effectively longer and thus needs to be stiffer to have about the same flex characteristics as the upper limb. The cams on some of the newer compounds are engineered such that this difference is compensated for by the cams so upper and lower limbs have identical flex and can even be switched.
 

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I was looking at an old classic target recurve (1970, 64", one-piece wooden bow) and discovered that the tiller was 3/4" positive at the top limb.

I find it hard to believe that the bow was designed that way. There is no limb twist and no outwardly sign of limb damage. Maybe the bow was stored standing up and the limb could've taken some set? How would this tiller affect the bow's tuning/shooting characteristics?
 

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Piney -

Just to be clear, the term positive has different meanings depending on who you talk to. Is the brace longer at the upper or lower fade out?

Some older, usually entry level, bows had the UPPER limb brace much longer than the lower. (in my terms, a very POSITIVE lower limb). These (sometimes called "chested") configurations were to help increase cast on lower weight bows. A 3/4" variation should be clearly visiable to the naked eye.

If lower limb is weak (taller brace) compare to the upper, then something is amiss and the bow should be horendous to shoot.

Yes, it's also possible that some manufactureing defect caused that to happen with time - unless you have a catalog pic of the bow, no way of telling.

As far as tuning, I have no idea, as I've never tried to tune one of those. Also. not sure I'd be too comphy with it.

Aside, yumi (Japanese bows) are designed with their lower limbs much shorter than their upper limbs and the bow is STRONGLY lower limb positive. I've shoot yumis, but never tried tuning one. Different animal.

Viper1 out.
 

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The brace is longer at the upper limb. The bow was top-of-line target bow in it's day. I've had a bow or two that have had as much as 1/4 longer brace at upper limb with no apparent shooting problems, but 3/4 seems a bit extreme.
 
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