Diy Club Build. BBGM and Insert Depth for MOI Matching.

[golfnut1300]

Evening Guys.

 

OK over the last few years i have tinkered with DIY MOI Matched iron builds.

It that time of year where i start on my next project.

I have a few question that i would like some answers to.

1. What effect does the BBGM and insert depth have on shaft Flex. I have got some cobra F8 iron which have different BBGM throughout the set.

2. I managed to get a great deal on a set of new TT AMT Red r300 0.355.  Does anyone have the FCM for theses shafts. Please note Tip length to the 1st step decrease 1/4 inch between shafts ( 4 iron 12.5inch 5inch 12.25 etc)

3. Are these shafts built with a standard BBGM and Insert depth in mind if so what are the measurements.

4 .These shafts will be install into 0.370 hosel with shims. However i have read that it is possible to tip trims taper tip shaft a maximum  of 1/4 inch is this true.

5. If trimming is possible how do i work out much to trim taking into account BBGM and Insert depth.

6. Does any one what swing speed bracket these are for.  ( my 6 iron ss is 75-80 mph) i ordered these after doing the online shaft fit

Any info will be appreciated.

Cheers phil.

 

 

[Stuart_G]

12 hours ago, golfnut1300 said:

Evening Guys.

 

OK over the last few years i have tinkered with DIY MOI Matched iron builds.

It that time of year where i start on my next project.

I have a few question that i would like some answers to.

1. What effect does the BBGM and insert depth have on shaft Flex. I have got some cobra F8 iron which have different BBGM throughout the set.

2. I managed to get a great deal on a set of new TT AMT Red r300 0.355.  Does anyone have the FCM for theses shafts. Please note Tip length to the 1st step decrease 1/4 inch between shafts ( 4 iron 12.5inch 5inch 12.25 etc)

3. Are these shafts built with a standard BBGM and Insert depth in mind if so what are the measurements.

4 .These shafts will be install into 0.370 hosel with shims. However i have read that it is possible to tip trims taper tip shaft a maximum  of 1/4 inch is this true.

5. If trimming is possible how do i work out much to trim taking into account BBGM and Insert depth.

6. Does any one what swing speed bracket these are for.  ( my 6 iron ss is 75-80 mph) i ordered these after doing the online shaft fit

Any info will be appreciated.

Cheers phil.

 

 

 

1.   BBGM effects the shaft performance similar to tip trimming.  Longer BBGM stiffness - like a bit extra tip trim,  shorter BBGM softens it up a little.   Insertion depth is similer as it changes how much of the shaft is active during the swing.  Longer insertion depth is similar to more tip trim, shorter insertion depth, less tip trim.   The amount of tip trim adjustment would be equal to the difference in BBGM or insertion depth.

 

3 (and 6). As I understand it, historically 1.5" was a 'standard' BBGM but irons seemed to have gotten shorter over the years.  Whether the shaft designers have adjusted or not is hard to say.  Standard insertion depths are about 1.25". 

But fortunately it's not really that important a question since it's really not a very meaningful baseline if you have no history with that particular shaft so you have no idea how good (or bad) a fit the baseline stiffness is for you.    And since you apparently have no history with the shaft, the baseline is meaningless. And no swing speed is not any kind of accurate indicator.  It only helps (minimally) in starting the fitting process, not finalizing it.   Same can be said for FCM.

 

Best approach is to build one club with no adjustments for those and test it out to see how it feels.  Cut to a length that's 1/2" longer than desired and test choking up.  That will give you room to go back and tip trim if the feel comes up a bit soft for you and your swing during the test.

 

4.  The normal rule of thumb with taper tip shafts in a tapered hosel is one might be able to get away with up to 3/8" BUT that depends on the manufacturing tolerances for the hosel bore and shaft tip diameter.  The tighter the fit, the less one would be able to tip.  Well you can tip more but there is a point where it will no longer effect the insertion depth of the shaft.

 

With  taper tip shafts going into a .370 parallel hosel, the only limit to how much you can tip is the length that the tip section of the shaft stays at .370.   So with the AMT's (or any DG's) you have a lot of room to work with.  If you do any tip trimming (less than 1/2")  it may mean having to jury rig a shim since the standard taper to parallel shims may not work any more. 

 

 

 

For all these questions, just realize that 1/2" of tip trim is equivalent to one hard step and that is still only a very subtle change in performance for the shaft.  Many might not even be able to notice the difference.   So when we are talking about playing around with smaller tip trim amounts - such 1/4" or 1/8" - we are really talking about amounts that really wont make any difference for the majority of players.    What you might do to the head weights (For MOI matching) will likely be much more important.   

 

Speaking of which, are you planing on using an MOI machine to do the MOI matching?   For some people the poor man's version of MOI matching (using swing weight increments) has been found not to work very well with the AMT shafts.

 

[golfnut1300]

thanks for you feedback. I do not use a moi machine I have used a program found of the web. that takes into account all components ie weights. bp's etc and have been very happy with the results. 

 

What I'm working on this time is moi matching and matching the balance index.

 

what I found out through my previous projects That to match the balance index the shafts got heavier. very unsightly when  lead tape is used to achieve this. 

 

hence why the Amt,s caught my eye.

 

Thanks again for you feedback.

[Golfrnut]

Can't speak for the reds, only the whites, but for both sets I have done with a MOI scale and swingweight matching AMTs (at 1/2" increments), they have ended up with a 20 point spread +- from the 4-PW.  That is using loose tolerance shafts that were not all that great in terms of being on spec to the charted weights.