MOI matching formula / link

[chima]

been looking for that old posting, can anyone re-post or link it? thanx!!!!!!!!!!!!!!!!

[We B Clubbin]

Tom Wishon says:

 

"To common sense MOI match your irons. Start with the swingweight of the your 6-iron, then you increase the lenght and decrease the swingweight of all the clubs with have lower numbers than the 6-iron by increments of .04"/1/2 swingweight poiont...The 7 through wedges go the odther direction in lenght and swingweight progression." - Common Sense Clubfitting: The Wishon Method

 

May the course be with you!

[Dyno]

Courtesy of Jeff Waller from the TWGT forum:

 

I have found that a modified form of the original MOI equation:

 

MOI = Mh x CL^2 + (Ms/3) x CSL^2

 

approximates the actual period measured MOI value usually within 1 gram of head weight (10 Wishon units). It also matches the set within enough accuracy that humans cannot tell the difference.

 

CL=clublength, CSL=cut shaft length (which is less than clublength by the bore to ground and grip cap dimensions). Mh=Head Mass, Ms=Shaft Mass, just make sure to use consistent units.

 

The point being that the shaft mass has about 1/3 the effect of head mass (actually a little less because CSL is used versus CL) on the final MOI. So, if you change shaft mass by 10 grams, the head mass needs to change by about 2-3 grams to yield the same total MOI.

[acgolf]

[quote name='Dyno' timestamp='1176610091' post='527399']
[b]Courtesy of Jeff Waller from the TWGT forum:[/b]

[i] I have found that a modified form of the original MOI equation:

MOI = Mh x CL^2 + (Ms/3) x CSL^2

approximates the actual period measured MOI value usually within 1 gram of head weight (10 Wishon units). It also matches the set within enough accuracy that humans cannot tell the difference.

CL=clublength, CSL=cut shaft length (which is less than clublength by the bore to ground and grip cap dimensions). Mh=Head Mass, Ms=Shaft Mass, just make sure to use consistent units.

The point being that the shaft mass has about 1/3 the effect of head mass (actually a little less because CSL is used versus CL) on the final MOI. So, if you change shaft mass by 10 grams, the head mass needs to change by about 2-3 grams to yield the same total MOI.[/i]
[/quote]


I think i'll put that formula in a spread sheet and post it for everyone. That way we can enter variables and seewhat adjustments best create the moi matched set (head mass, shaft length etc).

[dogsbe]

In all honesty, I am not really happy with just taking an MOI measurement off the 6 iron. What I do is take the 3, 6, and 9 iron to the range with loads of lead tape and impact tape. I swing the clubs until I am convinced that the swingweight is producing the best center hit pattern on the face. Once done, I put them on the swingweight scale and see if there is an MOI pattern. The last time I did it, it worked out 0.5 sw per 0.5 inches. This really convinced me of the value of MOI.

I do this again this week, but I am just going to do with all my clubs and see what I get.

[TomWishon]

[quote name='We B Clubbin' timestamp='1176537645' post='526295']
Tom Wishon says:

"To common sense MOI match your irons. Start with the swingweight of the your 6-iron, then you increase the lenght and decrease the swingweight of all the clubs with have lower numbers than the 6-iron by increments of .04"/1/2 swingweight poiont...The 7 through wedges go the odther direction in lenght and swingweight progression." - Common Sense Clubfitting: The Wishon Method

May the course be with you!
[/quote]

Need a correction in your transcribing of my comment.

Length increment change is 3/8" or close to 0.4" and not 0.04.

Tom

[mxtitleistgolfer]

[quote name='Dyno' timestamp='1176610091' post='527399']
[b]Courtesy of Jeff Waller from the TWGT forum:[/b]

[i] I have found that a modified form of the original MOI equation:

MOI = Mh x CL^2 + (Ms/3) x CSL^2

approximates the actual period measured MOI value usually within 1 gram of head weight (10 Wishon units). It also matches the set within enough accuracy that humans cannot tell the difference.

CL=clublength, CSL=cut shaft length (which is less than clublength by the bore to ground and grip cap dimensions). Mh=Head Mass, Ms=Shaft Mass, just make sure to use consistent units.

The point being that the shaft mass has about 1/3 the effect of head mass (actually a little less because CSL is used versus CL) on the final MOI. So, if you change shaft mass by 10 grams, the head mass needs to change by about 2-3 grams to yield the same total MOI.[/i]
[/quote]

I know this is being dug out of the depths, but in this equation the variable "mass" is used. Does anyone know if it is actually mass, or is it supposed to be weight?

[webber]

What kind of lie angle progression would be normal at 3/8" length increments?