Strain Gage for Measuring Load on Shaft

Hello everybody,

I'm new here, have visited on several occasions and lurked in an effort to learn - but this is my first time posting.

I'm an engineering student working on a project and am working with strain gages for the first time. The project consists of a rotating aluminum shaft (3 mm in diameter, 10 mm in length), with a motor on one end and a variable load at the other (load varies between 0 to 8kg). I'd like to mount a strain gage onto this shaft to be able to measure the load.

The shaft does not rotate continuously, only back and forth within a range of approximately 120 degrees. My thought is to model this problem as a bending load at the end of a shaft and determine the deflection in the aluminum shaft. Doing this, I might be able to spec out a strain gage. My problem is I'm not sure how to use these deflection / stress calculations to determine an appropriate strain gage - I've been looking through the Omega and Vishay catologues. I'm also not sure if it's even reasonable to expect to find a strain gage that is small enough to fit on a 3mm shaft, that has a resolution capable of measuring such small deflections.

Would anyone familiar with Strain Gages be able to provide a little insight / help for a lost student? 😀 Thanks!