Hello, For an academic paper i am writing : I am trying to calculate gear bending stresses on the MS Excel, without using printed tables or graphs. I use the following formulas : http://up353.siz.co.il/up1/gzomnjjezjw5.jpg From AGMA 908 B89 My questions are : 1. Do these work with SI units ? if not where should i look for something that does? 2. Is there a formula to get SF (thickness) just using the module ? 3. My results are not even close to Yj values i see in tables, what could be wrong? 4. If anyone has an example of these calculations I would be glad to have a look... Thank you.