Increase head light, how much lead to add and where?

[GasquetGOAT]

Stick 1:

Head Size:
100 sq. in.
Length: 27.5 inches
Strung Weight: 10.8oz / 306g
Balance: 4pts Head Light
Swingweight: 326

Stick 2:

Head Size:
100 sq. in.
Length: 28 inches
Strung Weight: 11.6oz / 329g
Balance: 13pts Head Light
Swingweight: 321


Stick 2 is my primary racquet, stick 1 is my spare. I want make the spare feel similar to my primary. As it is now its too head heavy. They feel too different.

How much lead (and where?) do I need to add to stick 1 in order to make it feel closer to stick 2? Balance, swingweight and etc..

 

[loubapache]

Unfortunately, it is not possible.

1) has a higher swing weight than 2). You cannot decrease swing weight without removing materials from a racket.

The closest you can do is to add about 23 grams to the handle (near the butt cap or inside the handle) to stick one so it will be 12 - 13 pts headlight, with a total mass of 329 grams but a swing weight of 328.

 

[elephas]

in order to figure out center of mass of multiple parts all you do is multiply the mass and distance from a reference point, sum the total, divide by the total mass and you have your center of mass from the reference point.

so if you wanted to make your first racquet 13 pts headlight by adding only weight down in the handle area (however you want, i've seen adding lead fishing weights in the handle) you'd do this:

(taken from center of racquet 27.5/2=13.75 in from either end.)
(4/8)*10.8+d*m=(13/8)*(10.8+m).

pick where/how you want to put the weight, put in the mass of the added weight (m) and you can get the distance from the center you'd need to put it. obviously it can't be more than 13.75 inches or else you have to put in more weight.

or you can pick the distance, and it will tell you the weight you need to add.

example: let's say you wanted to put lead fishing weights in the handle, and you put them 3 inches from the end of the handle.

that means you are 13.75 - 3=10.75 from the center of the racquet.


(4/8)*10.8+13.75*m=(13/8)*(10.8+m)
5.4 + 13.75*m=17.55 + 1.625*m
12.125*m = 12.15
m=1.002 oz

so you'd add roughly 1 oz at 3 inchs from the end of the handle and you'd have a racquet which was 13 pts head light and 10.8oz+1oz=11.8oz total.

 

[elephas]

post did not work so i'm repeating the formulas, but as loubapache said, you cannot decrease the swingweight to make it similar.

(4/*10.8+d*m=(13/*(10.8+m).

(4/*10.8+13.75*m=(13/*(10.8+m)
5.4 + 13.75*m=17.55 + 1.625*m
12.125*m = 12.15
m=1.002 oz

 

[loubapache]

elephas:

I think the 13.75 you plugged into the calculation should be 10.75. That will give a result of 1.3 oz added to make it 13 pts headlight.

Although you are correct in your calculation, it could be greatly simplified. Just pick the new balance point as the axis to do the calculation. You will have

md = (10.8 oz) * (13 - 4)/8, where m is the mass added and d is the distance from the added mass to the new balance point (13 pts headlight means 12.125" fro the butt cap).

So if the mass is added at the butt end, d = 12.125", then m = 1 oz.

If the mass is added at 3" above the the butt end, d = 9.125", then m = 1.3 oz.

 

[elephas]

you are right on both counts. it was just easier to think about it from the geometric center for some reason. but yea, the center of mass is probably a better reference point. good catches on both counts.

 

[GasquetGOAT]

Thanks loubapache and elephas. Another question if you don't mind.

If I add 1 oz of lead to the butt end of the following racquet (resulting 11.3 oz strung) to make it more stable. How much change would I get in the balance and swing weight?

Head Size:
110 sq. in. / 710 sq. cm.
Length: 27.5 inches / 70 cm
Strung Weight: 10.3oz / 292g
Balance: 2pts Head Light
Swingweight: 325
Stiffness: 69

 

[loubapache]

Thanks loubapache and elephas. Another question if you don't mind.

If I add 1 oz of lead to the butt end of the following racquet (resulting 11.3 oz strung) to make it more stable. How much change would I get in the balance and swing weight?

Head Size:
110 sq. in. / 710 sq. cm.
Length: 27.5 inches / 70 cm
Strung Weight: 10.3oz / 292g
Balance: 2pts Head Light
Swingweight: 325
Stiffness: 69

Your racket will be 11.5 pts headlight and has a new swing weight of 328.