I assume this is related to your previous drill press topic:

Yes, you're correct. This wasn't meant to deviate towards repeating the drill press thread. This is what I've done that led me up to this thread. I measured speeds on every belt combination (on both the idler and chuck pulley along with the motor) using a meter and the majority are extremely different than the tag on the press (the high speed should be 2800 and I"m getting around 3900 - I don't have the numbers with me at the moment). Now, I went ahead and measured the circumference of each pulley by tightly wrapping a string around the base of each one and then measuring the length of string on a tape measure. This is the circumference, and, from that, I could also (obviously) get the diameter if I cared to use this or have a need to use it.

Trying to find the "pitch diameter" and/or measuring error factor, I entered all the measurements into Excel and created a "fudge" number cell that will allow me to enter a number that adds a larger (or smaller) circumference and all the cells will update accordingly. This will allow me to see if I can get all the calculated numbers equal to the numbers I measured.

As an example: if one pulley is 3" circumference, and I have all the cells calculating the ratios from the motor, speeds, pulley ratios, etc... Then in my "fudge" number cell I may enter 0.3" and see if that makes the drill press speed what I measured.

What led me to post on this thread is that my Excel formula wasn't working and I thought it was an Excel formatting issue caused by me. What I learned is that one of the ratios was canceling, and it wasn't a formatting issue in Excel that I caused, so the ideal mathematical way of calculating is still eluding me.

I don't have the numbers handy, but I can post them to the original drill press thread I began and cease this thread as it's pertained to Excel - which has been resolved - and confirmed it was something I was clearly doing wrong.