The new Milo just happens to have a good article on different objects around the house that can be used to test grip strength.
Crushing an apple: approx to #1 CoC
Crushing a bulb of garlic: approx to #2 CoC
Crushing a raw potato: harder than #3 CoC, takes 25 sec to do
Crushing a walnut in the palm: as hard or harder than #3 CoC
Raquet ball - touching the side walls: a little harder than #2 CoC
Tennis ball - touching the side walls: quite harder than #3 CoC
Note: the above feats are done without using the fingers to "stab" into the objects; finger crushing strength only.
Crushing an apple: approx to #1 CoC
Crushing a bulb of garlic: approx to #2 CoC
Crushing a raw potato: harder than #3 CoC, takes 25 sec to do
Crushing a walnut in the palm: as hard or harder than #3 CoC
Raquet ball - touching the side walls: a little harder than #2 CoC
Tennis ball - touching the side walls: quite harder than #3 CoC
Note: the above feats are done without using the fingers to "stab" into the objects; finger crushing strength only.