Hello, I would like to ask for some (unrelated to MoI) math help.

I don't know how to word it best, I can try to lay out what I have and see if i make sense to get help. I am helping my brother with a "Lead Mold"

The goal is a "X".oz result
Using a volume to weight calculator We create our volume which in "Lead material" should weight "X.oz"

Due to variable in lead type and pouring conditions, the resulting weight is off. But this is a repeatable difference as using the same material and conditions will produce predictable results (Not all lead weighs the same)

I have some real numbers for the difference, but need to be able to generate the numbers for a formula to express the difference at different weights.

Let me explain.

Looking to get a 2.0 oz result. Calculated volume should be 0.3051 Cubic inches
Generate actual part and result returns 2.2 oz

For this one part, we can just do a weight to volume calc and enter in "1.8" as the conversion and get a new volume of 0.2746 cubic inches and get a result of 2.0 oz

(This close is OK. We aren't going to mars!)

Here is the calculation i need help with.

the .2 difference as will be applied to future weights.

Since .2 diff was created by a .3 cubic volume, I will need to figure out the "ratio-percentage???" difference and method to apply to future numbers.

So the mathematically challenged just thought "remove .2 from ALL NUMBERS to achieve results. At some point they realized .2 was generated by a fraction of 1 whole of a cubic inch.

So the result needed is when a particular weight is desired, what is the deduction to perform that reproduces the lower difference. Or, calculating the overage at different weights, to remove from those weight to volume calculations. Like what would the number be on "7 oz?"

Does that make any sense written down?

Really appreciate any input.