MOI of a golf club, where did it go?

[HSTNGolfer]

What have your experiences been when MOI/MBI matching with ascending mass shafts? For example when using the True Temper AMT White or TT AMT Black with 3g increments between shafts. Did you use 1/2 inch length increments or 3/8 inch or something in-between?

Also, have you tried it with Ping/Nippon AWT2.0 or Recoil 95/110 where the the weight increments are smaller than 3g?

I have an Auditor MOI machine and have built many MOI matched sets with constant weight and descending weight shafts. Best results were when using the 9 iron as the baseline and 3/8" increments. I have 37" wrist to floor, so +0.5" on the 9i (36.5") provides a comfortable length on the shorter clubs. I also like having a 5i that is 38" long.

At a recent fitting I had very good numbers with the True Temper AMT Black S300 shaft. I am keen to try these shafts with an MOI/MBI build using some new forged heads that I recently acquired. Some have posted that they did not have good results with AMT shafts with 3/8" length increments. Interested to hear your feedback.

 

[joostin]

You're correct on the nuances of axis alignment. Luckily the head's MOI about its own CG is very small compared to the MOI to the butt. Monte's driver example shows the head's "self MOI" as 5 kg-cm^2. That would come from OEM info when they're advertising forgiveness of off-center hits (5000 g-cm^2), but i think you're right in that it's not the correct axis orientation to what we really want - vertical axis through CG with toe pointing up and hosel horizontal. That can only really come from the design team's CAD model of the clubhead or physical testing. We don't have that info. But that 5 kg-cm^2 is probably a good enough estimate because in relation to his 2511 kg-cm^2 MOI (point mass equation) to the butt it's tiny. Also the direction the clubhead is rotated would slightly move the distance between the parallel axes. Like if you lie the club horizontally on a table with the head hanging off, the head CG will be vertically in line with the shaft, and that would be the shortest distance between the vertical axis through the head CG and the axis at the butt.

[Howard_Jones]

@joostin
Since you seems to the the one who can do the math, see what you can make out of this shafts, they are IMO the most advanced steel shafts on the marked. I cant offer you more specs for it than TT own step pattern drawing with step diameter and step length, plus uncut weight and that shafts balance point like you see it below in the PDF.
Most shafts on the marked today uses variable wall thickness, thats needed both to get flex strength right and to get a useful balance point. Its a piece of art what we see here where weight and balance point has to be right to make it work, still with a bend profile as they want it, so i can only scratch my head when we think about DYNAMIC (later Dynamic GOLD by sorting, then Tour issue), since that design is from 1942, and STILL kicks a...on the tour. The #9 iron in AMT white is the classic Dynamic from 1942.
Even if my numbers for this shaft is wrong, the simplified numbers ive made for it say this shafts is MOI matched or silly close shaft by shaft in the set. It would be really interesting to see if you get to the same, since nobody here has bothered to put the shafts them-self on the Auditor and shared those numbers

AMT_White_Drawing1.pdf
For shaft weight progression, ive concluded that for shafts with a neutral Balance point, we will see a uncut weight progression of 3-4 grams pr inch in woods(46 long ), about 5 grams in hybrids (42 long), and 5-6 grams in irons. (variable from 41 to 36). That seems to give about the same feel of shaft weight all the way, so it have to be MOI of the shafts that ends in the same area is my thinking, but without my Auditor to measure that i simply dont know why.

[Noodler]

Great timing on your part as this is exactly what I've been working on over the past month or so.

When it comes to MBI matching, the best matching for the MOI balance index will be achieved for 3/8" length increments when using a 3g shaft weight increment. For 1/2" length increment it is 4g weight increment. There will be a required slope in the progression of the head weights (achieved using tip weights or lead tape, etc.), but I will leave it to you to experiment for yourself now that everyone has Monte's spreadsheet. The head weight progression is not linear and it is optimized if you strive for starting with a 6g increment when using the 3/8" length increments or 7g increment when using 1/2" increments.

I arrived at all of this "poor man's" guidance through a ton of testing and building. This is all general guidance as Monte's spreadsheet will provide the specific values to achieve the final MOI and MBI matching. These are just "starting" values for the shafts and heads that make matching much, much easier.

So then I spent time investigating ways to modify head weights and shaft weights. I experimented with Liquid Nails impregnated with tungsten and poured into the back of club head cavities. Also, tungsten putty; just looking for some alternatives to lead tape because it sometimes takes a TON of lead tape to achieve a 6g head weight increment progression when you get into the lower lofted heads.

For the shafts, I have come to the conclusion that there is no acceptable way to modify shaft weight for my needs. Applying lead tape to the outside of the shaft is problematic due to the way we use golf clubs (shoving them in and out of a bag). It also looks bad and impacts the balance of the shaft in unpredictable ways across multiple axes. So for the shafts I'm sticking to using weight sorting. My latest testing has been with AWT 2.0 shafts (made by Nippon). I purchased many sets and used weight sorting to achieve as close to a 3g increment progression as possible. So far this is working out well. If you want to use a 1/2" length increment, then stick to the AMT shafts with their larger stock weight increments and then weight sort multiple sets to get close to the 4g progression.

What I have provided in this post really could be the "keys to the castle" as they say. What I'm seeing in my builds are clubs that are MOI matched, MBI matched, and the swingweight only varies 1.0 to 1.5 points from #4 to PW. So these are effectively matched across whatever method you "believe" in; whether you pray at the altar of MOI matching or swingweight matching.

[Noodler]

I decided to put this next "epiphany" in a separate post because it really needs its own focus. I have found that I am much more "sensitive" to the MBI being matched than the MOI alone for my swing (my strength, skills, flexibility, etc.). What I mean by this is that I was incorrectly attributing MOI alone as a primary fitting element because I hadn't begun experimenting with MBI. I went back through all of my iron sets and testing clubs and calculated the MBI for all of them. What I was trying to do was account for why I was feeling "matched" to different MOI values over the past 3 seasons. Every season it seemed that I would find different MOI values that I was swinging well with. What I didn't understand was that it wasn't the MOI alone that I was really matching, but rather the MBI.

What I've found is that I'm actually quite comfortable with any MOI from 2650 to 2700. I call the low value the "sufficient" MOI needed and the high value the "excessive" MOI amount. For those who have worked with MOI matched clubs for a while, you know that 50 units of MOI change is fairly significant. You can really feel the difference in needed effort over a space of 50 units. What I've found is that anything below 2650 results in insufficient feel of club weight for me to track the club well. Values higher than 2700 result in clubs that really start feeling way too heavy to swing well when it gets late in a round of golf. So as long as the iron set is matched to an MOI value that is somewhere in that 50 point range I can probably play them just fine - AS LONG AS THE MBI IS MATCHED to the golfer. The iron sets are still matched to a single MOI value across the set; please don't misunderstand that the range means that the clubs within a set can vary in MOI. That's not what I'm stating. It's that a club set can be matched to any MOI value in that 50 point range.

With the MBI calculations in hand, I was able to look back through all of my notes over the years and immediately realized that although the MOI values I preferred varied over that time period, the MBI did not. In fact, the MBI requires a much tighter range to be truly "fit" for me. I think the range is at least 10 points on the MBI 0-100 scale, but it may be even as tight as 5 points for the clubs to feel close enough to the best fit for your club delivery. I have found that I am much more sensitive to the distribution of weight across the club components than to the final overall MOI of the built clubs. Using MBI matching I have found that I much prefer having the balance of the club skewed toward the head than the shaft+grip. This means I need lighter (but still sufficiently stiff) shafts paired with heavy heads. Unfortunately this is tough to do these days as manufacturers keep lightening the heads because they keep lengthening the clubs over the years (and they still what to achieve the "false" D2 swingweight goal).

So the epiphany is that it's really all about the weight distribution, not just the MOI alone. And the beauty of MBI is that it works across all of the clubs in your bag and also supports the notion of why it makes sense that we use different MOI values for different club types. It's not about using a single MOI value, but it is about trying to achieve a single MBI value across your entire bag.

BTW - My index has dropped 6 points over the period as I put MBI matched clubs into my bag. I really think I could pop an even par scratch round in the next month or so (my best has been +6 so far).

[HSTNGolfer]

Thanks, that is just what I have been looking for.

My recent sets all had MOI in the 2710-2720 range with MBI between 35 and 45, lowest in the longer irons and going up as the clubs get shorter. Those were all +0.5" starting from 9i (36.5") with 3/8" increments. In recent years I seem to play best with iron shafts in the 105 - 115g range. In the last three MOI matched sets that I built for myself, I used KBS Tour R+ constant weight, then Wishon Stepless S descending weight (but weight sorted) on an old set that I rebuilt last year and now Nippon NS Pro 1050 GH constant weight on the latest set. The uncut Nippon shafts had amazingly tight tolerances across the set, all within +/-0.5g of the 109.5g nominal weight.

It will be interesting to see if ascending weight shafts make a significant improvement for me across a set.

 

 

[kam39]

Noodler,

Mondher did answer my email a few days ago (22 Jul) but I'll have to summarize his response until I get his release to post his reply here. Basically he stated they'd originally looked at a variable fulcrum for the axis of rotation but found it to be impractical for several reasons. He suggested the most cost effective solution would be to use the parallel axis theorem in a spreadsheet after first finding a clubs MOI about the butt end using the Auditor MSM. He also let me know it would be impractical to modify my MSM as it would require a new beam design and backstop.

I no longer have a working version of Microsoft Excel on my personal computer (when Apple updated their OS last year my version of Excel became incompatible), so I'll need to figure out the nuances of Apple's Numbers program for implementation. I plan on leveraging Dave Tutelman's "MOI Matching -- But Which Axis" page (https://www.tutelman.com/golf/clubs/MOImatchAxis.php) transforming the axis section formula for the computations..."Ia = Ib - M A (2G-A)".

It will take me a little while to catch up on the last few days of posts as I've been wading through local school board issues, state high school athletic issues and some other rapidly evolving topics due to the current pandemic. Trying to remember the intricacies of Monty's spreadsheet will be a welcome respite but will require some uninterrupted mental focus that I can't currently commit to.

[joostin]

Here are the MOI calcs for the AMT Tour White shafts - right side column, using Monte D's formula. S300 and X100 had the same exact weights and balance points. It would be nice to compare with regular DG shafts, but I couldn't find balance point info, just overall weight and step patterns.
[img]https://s3.amazonaws.com/golfwrxforums/uploads/6X7OH5YP0S3C/moi-of-amt-white-shafts-png.png[/img]I'm attaching my updated Excel sheet below if you'd like to enter any other shaft or any club for that matter. I might eventually add columns for the other MOI components.
I didn't know the history of Dynamic other than the Gold weight sorting. Amazing it's the same since 1942.
Swingweight_Torque_Calculator_20200724.xlsx

[BREWMASTER95060]

1 of 2 ways I do it.

head weight 7 gram spacing.

Adding weight with lead tape to shafts @14 inches from butt that so it does change swing weight.

I do a 5 grams per shaft Ascending weight.

I build all clubs to match 5 iron.

example:

5 iron 105 Grams club length 38

6 iron 110 Grams club length 37.5

7 iron 115 Grams club length 37

8 iron 120 Grams club length 36.5

9 iron 125 Grams club length 36

W 130 Grans club length 35.5

doing this I get SW match and MOI match and MOI index is super close.https://forums.golfwrx.com/discussion/comment/19387728/#Comment_19387728

[BREWMASTER95060]

2 of 2 ways I do it. (this may not work for you.)

7 gram spacing on head weights.

weight sorting shafts. ideal 5 grams per shaft per 7 gram head increase.

weight sorting shafts less than ideal unless you are lucky.

if weight is less then ideal it is length of club is what suffers.

ideal example: sw C9

club wt head wt shaft wt grip wt club bp

5 iron 440 255 105 80 27.7

6 iron 452 262 110 80 27.3

7 iron 464 269 115 80 27.0

8 iron 476 276 120 80 26.7

9 iron 488 283 125 80 26.3

PW 500 290 130 80 26.0

less than Ideal:

5 iron 440 255 105 80 27.7

PW 485 290 *115* 80 26.4

((440*27.7*27.7)/485)^(1/2)=26.3836719265

may or may not feel ok.

weight sort to find lower then 290 head weight

5 iron 440 255 105 80 27.7

6 iron 450 262 108 80 BP=?

((440*27.7*27.7)/450)^(1/2)=27.39049307901

7 iron=470 272 118 80 BP=?

(((440 * 27.7) * 27.7) / 470) ^ (1 / 2)

26.80138135532

[Howard_Jones]

@joostin
#9 shaft in AMT is the regular DG shaft, BP is 18.30" for the #9 (18.30 / 37.00") = 49.45% from the butt, and its the same for all irons in the set.

[Howard_Jones]

Just a short input, 50 MOI points is what im using from Irons to my driver, and its about the same from #9 to #3 in a-classic flat SW matched set.

I have never build sets using MBI, but have a extra Iron set set here thats MOI matched but without grips (3/8" set), so i will try to adjust MBI on that set using the grip side to compensate.

Earlier you said there was no way for you to get the weight progression on shafts you wanted, so il chime in with a tips for that, even if it want get you all the way. When we soft or hard step a constant weight set, weight moves equal to 0.5" inch of shaft weight, so as example, a set classic DG who is average 3.42 grams pr inch (#6 iron), moves half of it for each step in a classic 4/8" set. (1.7 grams pr club).

if we combine weight sorting with soft stepping 1x and 2 x , tip trim up to 3/8" plus going 3/8" between clubs (on taper constant weight), we can manipulate a set Classic Dynamic Gold into Ascending weight Flighted with average 1 grams shaft weight progression. Its not much, but a contribution in the right direction.

Here is how that set up looks like, and ive limited tip trim to 3/8" so we dont run into hosel insert issues, and to get tip length progression and flex slope to become FLIGHTED. All shafts used is regular GOLD sorting and within GOLD tolerances. The set up gives 6.6 grams Ascending wgt from #3 to PW. Comparable wgt after mods, before butt cut goes from 124.4 to 131 grams

The same concept, now mixing S200-S300 and S400 looks like this: Here we can get to about 10 grams Ascending wgt from #3 to PW

We have a few examples here on this forum where users have tried AMT white as 3/8" MOI matched but was not happy for it. If its this players starting point, the shafts progressive BP or Total weight thats off in this cases, i cant tell, but AMT dont seem like a good starting point for 3/8" set ups.

[JCAG]

Golf chats are like the Preacher, preaching to the choir while the church is going broke.

[rx7mark]

Hi guys,

Great thread and discussion!

I am just an amateur golfer and club builder, but a structural engineer by trade. I started trying to find a better way to build a set of irons because constant swing weight does not work for me, especially in the longer irons. Fast forward 12 years and a lot of reading on line and experimentation and club building trials and I found that Monte's MBI spreadsheet built irons are for me the perfect solution. I have built 4 sets so far, some went to friends who wanted the consistent feel this offered, after trying my irons. I have also found that I am not very sensitive to the balance index, within reason, (46-52) as long as they are the same thru the set (+/- 0.5) I adjust with a little play. I am much more sensitive to the MOI value and try to match this to +/-5, but that is hard to achieve sometimes without compromising length. My best set used the Steel Fiber Players Spec ascending weight shafts, but even these are not accurate enough in the weight increments and I start with the heaviest shaft relative to the desired progression and fix light shafts with a little spiral wound lead tape under the grip right under my hands. Pure grips help as I can take them on and off several times to make minor adjustments as required. The amazing part to me, is in the end the irons are MOI matched, MBI matched and relatively closely SW matched as Noodler mentioned. And they all feel exactly the same when you swing them. Of course the end results all depends on how well the fit was to start. This is the hardest part for me, and took me the longest to find my best fit for total weight, minimum length, and length progression. Once everything is right on I can hit long irons again and was able to retire my hybrids, though I do use the new Maltby FDI driving irons in my long irons.

I have aslo had fellow golfers zone out on me when I mention that I not only build my own clubs but build them different than what they would be able to buy, except at a few very good club builders. Actually I am not sure what most pro builders would say if I walked in and told them I wanted a MOI and MBI matched set? It takes a lot of effort and I suspect I wouldn't like the price, if I could even find anyone who knew what I was talking about and would do it. And most would not want to do a one or two club fitting, so that I could build the rest, so that is why I went to the effort to do it myself.

Happy to hear from others who have tried this type of build with success!

Mark

[Noodler]

MOI matching for the actual build isn't much more difficult than swingweight matched builds and could be just as easy if the equipment was produced with MOI/MBI matching in mind. Of course that will never be the case, but you have to wonder what the shaft manufacturers are trying to do in producing ascending weight shafts. I still haven't figured out their motive since swingweight matching rules the roost. For those of us who prefer MOI/MBI matching, ascending weight shaft sets have been very welcome. Maybe the manufacturers are just trying another approach to produce a "flighted" shaft set that doesn't descend in weight, but still produces higher ball flight in the long irons and more trajectory control in the short irons and wedges.@rx7mark - in reading your comment it actually looks like you are quite sensitive to MBI. The range you specify is tight. And don't confuse MOI matched sets (being in a +/- 5 unit range) vs. a fully matched set at 2650 vs. a matched set at 2700. I think you would be surprised just as I was when I figured out that there really is a range of different MOI values that can work (as long as all of the irons are matched to a specific value within that set of irons). I have irons sets at fairly different MOI values (2650 and 2690) that have almost the same MBI and they both play fairly well for me. And in reverse, I have different sets that are basically set to the same MOI values, but have vastly different weight distributions (different MBI) that play nothing alike. There really is something to this. We need more anecdotal observations from testing and possibly a more scientific validation (if we can come up with a testing protocol).

[rx7mark]

Noodler,

You are of probably correct, and I guess I am sensitive to changes in both the MOI and MBI from club to club in a set. The tighter I can make everything the better I like the set, to a point. My first set using the spreadsheet was built to a tolerance of MBI +/- 2. and MOI +/- 20, and that set was good, but not great for me, and I eventually sold them. Built to the tighter tolerances I mentioned in my latest set took more effort, but every club feels like my favorite club. No club stands out as better or worse.

[BREWMASTER95060]

For rx7mark

if you have measurements( length, weigh, balance point swing weight) for the “Steel Fiber Players Spec ascending weight shafts” or any other set of shafts and head weights could you please post them.

thank you

 

 

[BREWMASTER95060]

For noodler

”So as long as the iron set is matched to an MOI value that is somewhere in that 50 point range I can probably play them just fine - AS LONG AS THE MBI IS MATCHED to the golfer.”

yes I think that also.

For me it was all the short clubs eight, nine and wedges always in the past would FEEL too head heavy

BUT NOW with heaver shafts they feel great.

[Noodler]

That's great to hear. I truly believe that there is something "there" with the MBI build approach. I shot +5 and a +7 rounds last week and the set I used isn't yet perfectly MBI matched because of variances in the weight increment progression in the ascending weight shaft set. I am now starting to experiment with using lead counterweights in the butt end of the shaft to achieve the ideal shaft weight increment progression. This is done using Monte's spreadsheet since it provides the calculations for the counterweight addition to each club. The lead weights are really cheap and easy to grind to the exact weights I need. I had experimented with counterbalancing in the past using TourLock and Opti-Vibe units, but they do not provide the weight granularity needed for this purpose. The point of this exercise this time is NOT for the counterbalancing aspect, but just for the MBI matching. I want to see if weight added to the butt end of the shaft to achieve an MBI match will actually result in the same matched feel as if the shafts themselves have a perfect weight increment progression.

[rx7mark]

Yes I can post the data, I need to get it off of a different computer, but I will put it together for you.

Mark

[rx7mark]

Here is an example of one of my earlier MBI builds for a buddy of mine who is much younger, in his early 30's and much longer than me, and needed a shaft upgrade anyway. So we upgraded the shafts to the DG AMT X100 Tour ascending weight shafts. The shaft set we got were supposed to be +/-1 g and more expensive, the non-tour are +/- 3 g, and would have been a much harder build. The shaft weight shown are after trimming to final length. Also notice that this set does not meet the MOI tolerancing I mentioned above, and at the very least I would have reworked the 4i, 7i, and 9i if the set was mine, to correct the MOI. But after letting him try the set as is, he would not give them back, and still says he loves the balance thru the set. Notice the variation in total length required to get the MOI's correct. That is because I am not willing to lighten any of the heads, I only add weight with hosel weights. He also did not want to see any lead tape. If I were to have reworked the 4i and 7i, they would have needed 1.5g and 2g added to the hosel to bring them into tighter alignment with the rest of the set. And the 9i I could not have improved without either cutting down the hosel or trying to drill out the hosel to lighten the head, or I could have shortened the length to get the MOI down to the target.

Lengths are in inches, weights are in grams. The largest amount of hosel weight I had to add was to the 4i, 8.5g, and remember it really needed 10g to get it into better toerlance. The most I had to add to a shaft under the grips was 6g to the AW.

Mark

P.S. I will try to add my Player Spec build summary in the near future.

[JCAG]

AS said:

It takes a lot of effort and I suspect I wouldn't like the price, if I could even find anyone who knew what I was talking about and would do it. And most would not want to do a one or two club fitting, so that I could build the rest, so that is why I went to the effort to do it myself.

Nothing personal but some have to learn that some customers are not worth having. Also there are few willing to pay for experimenting are few and far between and this is the reason I avoided thsoe wanting to try for long drive contests.

[rx7mark]

OK, here is my Steelfiber AMi99 Players Spec MBI build. Note that these were pulls that I bought off Ebay, and had all ready been cut to lengths and are taper tips, so no substituting or moving the shafts around within the set. These were stiff, and steel fibers are pretty stiff to flex, so for me, I decided to soft step twice. I always build one test club, usually a 7i or 8i to confirm specs. I bought 3i thru 9i shafts, but the 9i arrived damaged by the mail carrier, so I had to substitute a SF i110 for the 9i shaft, which actually did not work out great in weight, but the i125 would have been too heavy. In reality I do not even notice in play. I actually built a 5i also, but do not use it, so I did not include it in the list. I now use Maltby FDI driving irons for the 5i - 3i. The Apex 6i is 27 degrees, then I go to an FDI 4i bent to 24 degrees to fit my gaping. I was actually very disappointed in the weight progression in the SF ascending weight Players Spec's, I expected better from SF! I would have liked a better total weight progression, but this was not the top priority, and mostly caused by the shaft weight variation.

Notice the tight calculated MOI & MBI matching, as I had mentioned in a prior thread. The most hosel weight I had to add was 9g to the 9i, the most I had to add to the shaft was 16g to the AW, but this was because of the shaft substitution. It would be great to have access to hand select shafts and heads to get a perfect weight progression, as well as MOI & MBI matching, but that is not for us mere mortals.

Let me know if you have any questions on either build.

Mark

[rx7mark]

JCG, yes I agree totally, and no offense taken. I can't imagine how hard it is to make it in the custom club building business. Best of luck.

[Noodler]

Thanks for sharing. Nice to see confirmation of what I have seen in MBI matched builds; the MOI is matched and the swingweight is also pretty well matched for all intents and purposes.

[kam39]

Brewmater95060,

Missing swing weight but you can calculate that based on listed weights & balance points.https://www.golfshaftreviews.info/aerotech-steelfiber-players-spec-iron-golf-shaft-review/

[rx7mark]

Swing weights are the last column at the far right on each chart. This is the swing weight predicted by Monte's spreadsheet. I measure them also and they match pretty close but not perfect.

[BREWMASTER95060]

rx7mark thank you!!!!

question:

lead tape under grips does Monte's SS let you include the weight addition ??

what is the most weight you have added under the grip?

thanks again!!!

[Noodler]

The spreadsheet will account for both "aux weight" and "backweight", but it only provides a place to enter the weight and the CG. To determine the CG of the weight alone you need to use the same method as is used for the determination of the Head CG. Take a shaft with a known balance point, add the weight, and then remeasure the BP. This will determine the impact of the weight and the weight's CG. Monte notes that a CG of 0 is for a weight added at the very end of the shaft, but in reality any weight added is going to impact the MOI (although much less so than weight added at the head end). So a CG of 0 doesn't really make sense unless you want to completely ignore the impact of the weight on the MOI.

...

Just a quick follow-up after checking some of my most recent data. The impact of a back weight on the MOI is so incredibly inconsequential (even up to 32g which I've used), that using 0 as the CG is probably just fine.

[BREWMASTER95060]

for Noodler

" Take a shaft with a known balance point, add the weight, and then remeasure the BP."

yes that is what I have found also.

"Just a quick follow-up after checking some of my most recent data. The impact of a back weight on the MOI is so incredibly inconsequential (even up to 32g which I've used), that using 0 as the CG is probably just fine."

Yes but i was hoping otherwise.

"So a CG of 0 doesn't really make sense unless you want to completely ignore the impact of the weight on the MOI."

yes

so this is what I will try:https://www.valuegolf.com/sting-stopper-vibration-dampening-shaft-inserts

somehow add lead to these and get it off the outside of the shaft.

I currently put lead tape on the outside of the shaft.

I have never used and /or touched these ever.