Thanks for replying, using 1/2" length increments, that would be:
6 iron- D1 7 iron- D1.5 8 iron- D2 9 iron- D2.5 ????
That would give an MOI match. The THE MOI match but AN MOI match. Just as you could match swingweight at several levels (e.g.- a set matched at C8 or a set matched at D2), you can MOI match at any level of MOI.
I'm real curious as to what the Wishon software model would bring back as suggested headweights to get an MOI match. Is the formula they use calculated or adjusted by actual experience? Or is final MOI matching only acheivable by a period counter and lead tape?
As far as I know the Wishon software just computes the actual MOI from the period and a few direct club measurements. (Distance from balance point to butt, and total weight in grams.) Basically, it's an electronic "swingweight scale" that measures MOI instead of swingweight. Just as with swingweight matching, you have to get busy with the tip weights in response to what you actually measure.
It does have an additional function -- which is similar to the spreadsheet you're already using. It will tell you how much head weight to add or subtract to change the MOI enough to get it where you want it. You can use that, or you can develop your own rules of thumb. For instance, you already have rules of thumb for how much head weight (or shaft weight, or length) to add or subtract to achieve a certain gain or loss of swingweight. If you're MOI-matching by matching a sloped swingweight, you can use the swingweighting rules you already know.
Just to clarify a bit... MOI is not the same thing as the pendulum period. You can calculate the MOI from the period and the other two measurements I mentioned above. This is an exact calculation, not an approximation like the formulas you cited that you were using. Or anyway, it's as exact as the measurements themselves. If you have a standard gram scale and can measure length to about 1/16", then the Wishon software will give you about as good an MOI match as you're going to get with the sloped swingweight approach. Measuring the period to a microsecond (one part in a million) is probably overkill, because you'll be measuring length one part coarser than one part in a thousand, and mass about one part in two or three hundred. So you could be 100 times sloppier in the pendulum period, and still not have the period counter be the thing that controls the precision.
Anyway, suppose you swingweight-match a club with the steps:
(1) Measure the swingweight on the scale.
(2) Add or remove head weight (with tip weights or lead tape).
The change is from your swingweight rules of thumb.
(3) Measure the swingweight on the scale.
If not on target, go back to step 2.Then Wishon's product (hardware + software) will have you MOI-match with the corresponding steps:
(1) Measure the MOI. This involves:
- Measure balance point
- Measure total weight
- Measure period
- Crank them into the software and get out MOI
(2) Add or remove head weight (with tip weights or lead tape).
The change is recommended by the software.
(3) Measure the MOI. This involves:
- Measure balance point
- Measure total weight
- Measure period
- Crank them into the software and get out MOI
If not on target, go back to step 2.
That is my understanding of what Wishon's offering is. If someone who has used it can verify or correct this, I'd appreciate it.
Cheers! DaveT
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