MOI Matching:great article

This is the best article on this subject I have found so far. Leith Anderson is a partner in THE GOLF LAB, in Palo Alto, California.

http://www.calgolftech.com/whats_new/driver35.html

excerpt:

"Since I’m discussing “standards” that don’t work for most players, if you haven’t checked your length specification recently, buy a copy of Tom’s book and check out his chapter on club length. Manufacturers have been lengthening their standard lengths lately in a quest for more distance. If you are playing irons based on a 38” five iron and you’re not over six feet tall, there’s a good chance your clubs are too long. Confirming club length is simple. All you need to do is hit your irons with impact tape on the face and do the same with irons a bit shorter. Compare the pattern. You’ll probably find that your center strike pattern is better with shorter clubs. We’re finding that a higher percentage of our customers are going with shorter lengths. And you don’t lose distance either. If you’re looking for a breakthrough, you should test shorter length and heavier swingweights."

Quote:

---

Originally Posted by rhh7

This is the best article on this subject I have found so far. Leith Anderson is a partner in THE GOLF LAB, in Palo Alto, California.

http://www.calgolftech.com/whats_new/driver35.html

---

Superb article.

Now, are you going to MOI your next set?

Yes, and I think I will use FST shafts...still trying to decide exactly which one...

Thanks for the link. Just one quick note though. In his article he mentions grinding irons but never mentions cutting the shaft a little shorter which is one of Wishon's method as well.

If you go here, all of his articles back to July, 2002 are archived:

http://www.calgolftech.com/whats_new/index.html

I know, because I spent Sunday afternoon reading everyone of them! In one of them, he goes into detail about trimming 1/4" in both the long irons, and in the short irons, in other words, on either end of the 8 club set.

Quote:

---

Originally Posted by rhh7

In one of them, he goes into detail about trimming 1/4" in both the long irons, and in the short irons, in other words, on either end of the 8 club set.

---

If you have looked at the information sheet I sent you, you will notice that the difference in length between irons is .4" versus the traditional .5", That constant difference is barely perceptible.

You misunderstood my comment. I read the article too. But Tom Wishon knows that most clubmakers do not like to grind clubs nor have the ability to do so. And Tom wishon does not use the swingweight method nor the length method to build a MOI mathed set. He uses a period counter and a software developped by golfmechanics. So when trying to match the period he'll have you add a little weight or shorten the shaft and not necessarily build the set in quarter inch increments.

I just went through a dialogue with Dave Tutelman on the FGI forum about how one could build a "poor man's" MOI apparatus.

Start at about post #9
http://www.freegolfinfo.com/forums/tm.aspx?m=1998988

There are still some out standing issues but I think it was informative.

Charles

Good that you're talking to DaveT. He's the man.

For your MOI pendulum consider the following.

1. Use a caster or wheel with an axel to give you a relatively frictionless swivel.
2. Mount your club holding device on the wheel such that when you put the club in it the top of the grip lines up with the extension of the axel.
3. The club should now swing freely with the top of the pendulum right at the end of the shaft.

For the club holder just put two screws into the side of the wheel/caster.

Quote:

---

Originally Posted by jvincent

Good that you're talking to DaveT. He's the man.

For your MOI pendulum consider the following.

1. Use a caster or wheel with an axel to give you a relatively frictionless swivel.
2. Mount your club holding device on the wheel such that when you put the club in it the top of the grip lines up with the extension of the axel.
3. The club should now swing freely with the top of the pendulum right at the end of the shaft.

For the club holder just put two screws into the side of the wheel/caster.

---

There are many different ways to do it.

The main thing that is still outstanding is finding a relatively cheap way to accurately measure the period of the pendulum.

How about a laser pointer and stop watch?

Just start it swinging and start / stop the stopwatch when you see the beam hit the shaft. Assuming you get enough oscillations, any errors introduced by inaccuracies in the start/stop time should be minimized.

Quote:

---

Originally Posted by jvincent

How about a laser pointer and stop watch?

Just start it swinging and start / stop the stopwatch when you see the beam hit the shaft. Assuming you get enough oscillations, any errors introduced by inaccuracies in the start/stop time should be minimized.

---

I was thinking the same thing, but:
1) have a stop watch with a "lap" option so that you can get several observations on a single test.
2) I was not sure if a stop watch would be accurate enough, is 100ths of a second ok or does this really require 1000ths of a second. I am guessing it would be OK.

Now we just need someone to build one (6wk old at home so it won't be me :grumpy: ) and test the same club against a purchased MOI machine.

A friend of mine built a homebrew MOI period measuring device (not exactly as described above but suitably Frankenstein like) and I believe he measured over 10 periods (~38 sec) and his measured vs calculated results were within a couple of percentage points.

At some point over the winter I might measure my clubs just for the hell of it.

Quote:

---

Originally Posted by jvincent

A friend of mine built a homebrew MOI period measuring device (not exactly as described above but suitably Frankenstein like) and I believe he measured over 10 periods (~38 sec) and his measured vs calculated results were within a couple of percentage points.

At some point over the winter I might measure my clubs just for the hell of it.

---

I was thinking the same thing.

I made a period counter a couple of years ago and just whittled a piece of doweling down until it fit into a couple of skate board bearings that I used when I built my NF2. Then, I drilled two holes slightly smaller than the OD of the bearings in a couple of small pieces of 2x4, braced it so it fit into my vice, and put a screw through the dowell that screwed into the top of the grip.

It's rough, crude, but it seemed to work. I am going to redo it this winter, for something to do.

I've got a half set of irons that I am going to try the MOI matching on. The 6 iron is the "favourite" club, so it will be the foundation. Since I am going to build a frequency tool, I will use the same measuring technology for the period measurement.

I tend to agree with TW that MOI matching is a better method, but I still wonder if it is enough. The MOI is measured from the butt end of the club, but when we swing a golf club the pivot point is more up between the shoulders of the golfer (more or less). Although, I suppose, the release action from un-kocking the wrists is closer to Tom's measuring method. I'm going to have to look at the math and see if that has any effect. Got all winter to fiddle!:(