Effect of Bottom of Bore to Ground and Hosel Length on Shaft Flex

SkipperationSkipperation Members Posts: 189 ✭✭
Can anyone explain or point me in the direction of any info on how the bottom of bore to ground length and hosel length will effect the flex of a shaft and potentially how much I should be looking to tip the same shaft going into different clubs to attain the same/similar flex?



If I have two 3 woods, one with a bbtg of 1.25" and a ground to top of hosel length of 2.75". The second with a bbtg of 1.5" and a ground to top of hosel length of 2.5" which is likely to play stiffer?



Is this a thing?



Or is the difference so miniscule that it doesn't have an effect?



If I can detect a 0.25" difference in tipping a shaft, surely these lengths should also have a noticeable effect?



Cheers
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  • Howard JonesHoward Jones Members Posts: 8,483 ✭✭
    edited Jun 6, 2018 #2
    To judge this we dont use hosel lenght, but BBGM and insert dept.



    The 1. Club seems to have a BBGM of 1.25" and a rather deep insert of 1.5"



    The 2. Club a BBGM of 1.5 and a insert of only 1.0?



    Club 1 will play stiffest with the same head wgt and play lenght.



    To make club 2 play equally stiff, that shaft should be tip trimmed 0.75 inch.



    0.25" due to a higher BBGM (to duplicate butt side)and another 0.50" to make the tip OUTSIDE the hosel equal.



    Make sure measurements is correct, so check insert dept and BBGM one more time
  • Stuart_GStuart_G New HampshireMembers Posts: 22,937 ✭✭


    If I can detect a 0.25" difference in tipping a shaft, surely these lengths should also have a noticeable effect?




    If you are really that sensitive, yes. But be careful about how you judge your sensitivity and realize that all increments of the same length are not equal in their effect. The first 1/2" doesn't have the same effect as the second 1/2" which isn't as much as the third 1/2". e.g. most people can not notice the difference in the first 1/2" but most can detect that second 1/2". So in many cases the difference in 1/4" of BBGM isn't going to be noticeable. Can't say for sure (the physics is quite complex) but I think I remember Tom Wishon mentioning it has to do with the amount of parallel tip section left on the shaft - which is typically reinforced and much stiffer than it is above the parallel tip section.
  • Howard JonesHoward Jones Members Posts: 8,483 ✭✭
    Follow me on the math to understand why this is the way to make 2 identical shafts to play equal in heads with different hosel specs.



    Its only the shaft above the hosel top that can bend, so we want this part of the shaft as identical as possible.



    New uncut shafts is often 46.00" long with a 3 inch long .335 tip.



    If we use the OPs hosel specs, and say club 1 was already made with a std tip trim for 3w of 0.5



    On this board the question "tip to graphics" often comes up, and what we wants is to duplicate "hosel top to graphics" from club 1 to club 2.



    Since club 2 had a BBGM of 1.5 vs 1.25, we tip trim the difference. Next is insert. Since club 1 has 0.5 inch deeper insert, we must now tip trim another 0.5



    Now hosel top to grapics will be equal, so tip side will play rhe same.



    The only difference between them will be that club 2 has 0.25" longer butt section than club 1, but that difference is way harder to detect than 0.25 tip side, but even that is something most cant tell the difference between.



    It is correct what Stuart say about the fact that feel of going stiffer is progressive so the first 0.5 inch is not much, but the next is.



    In this case i expect club 1 to be made and feel good, then another 0.75" extra, a total of 1.25" of a 3.0" long tip is no problem and since we duplicated the shaft above the hosel, they will feel as equal as the shafts actually is.



    A good FLO job would make them so equal that no player would feel any difference made by the shaft
  • JCAGJCAG John Curry Members Posts: 2,057 ClubWRX
    Years back some driver shaft manufacturers suggested in order to compensate for shaft insertion depth one insert the untrimmed shaft into the head(s) and measure total length and trim them the same amount to achieve the same total length. Example:



    Head 1 with shaft dry inserted measures total length of 47in. Head two with same type shaft dry fitted measures 47.5in. Trim 1/2in off shaft in head two. Now both total length clubs measure 47in. Epoxy them up and trim to same length. Flex should be identical.
  • SkipperationSkipperation Members Posts: 189 ✭✭
    edited Jun 7, 2018 #6
    Thanks for the replies guys!



    It is kind of what I was expecting regarding the bbtg as I have mainly been going off the old advice about bore-thru/blind bore/standard bore hosels tipping and the way some would tip steel wood shafts based on distance from the ground to the first step rather than just tipping a set amount for every 3 wood for example, though I have had varying success.



    Looking back this is probably down to the fact the hosel depths were different in a few of the clubs I had worked on and probably had an effect. Which leads to what interests me most, the thoughts from Howard about the distance from graphics to hosel. When I first started looking into doing some club work myself but didn't know much my initial instinct was that stiffness would mainly depend up this measurement but I was quickly diverted away from this after some reading and into the standard tip 0.5 for 3 wood etc...instincts are often right in some way shape or form, just need a little tweaking too!



    I'll have abit more of an experiment with a few clubs but hopefully this might mean I will get it abit closer, sooner!



    Cheers
    Post edited by Unknown User on
  • Howard JonesHoward Jones Members Posts: 8,483 ✭✭
    I hope you got to see that its hosel specs alone who makes them different, and club 1 will play stronger than many other clubs if std tip trim is followed, but...since that club had a very deep insert, and we say 1.0 is the minimum, that club can be made with a uncut tip, and we can even shim BBGM up with up to 4/8"...



    So, it all depend on the parts you got at hand, cut or uncut, and where you wants to go with it all.
  • Stuart_GStuart_G New HampshireMembers Posts: 22,937 ✭✭


    Looking back this is probably down to the fact the hosel depths were different in a few of the clubs I had worked on




    What about playing lengths and head weights? Did those vary as well?
  • SkipperationSkipperation Members Posts: 189 ✭✭
    Stuart G. wrote:



    Looking back this is probably down to the fact the hosel depths were different in a few of the clubs I had worked on




    What about playing lengths and head weights? Did those vary as well?




    I try to ensure static and swingweights are as close as possible to each other when I've tried different shafts/tipping. Nothing too scientific but simply based on what I've liked in the past in other clubs, I try to compare apples to apples as much as possible.
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