[Ed Law]

Originally Posted by NickE

For something not super-accurate, I've seen scales intended for weighing airplane luggage. They typically have a handle with a digital display in it and a hook to attach to the luggage. This would probably work fine, depending on the application, and would be fairly affordable.

EDIT: Here's some for under $20.

Originally Posted by Dick Linn

For pulling up to 75 pounds, a $10 luggage scale might work:

http://www.amazon.com/Travelon-Stop-...ref=pd_sbs_a_1

Otherwise make something with a spring.

Originally Posted by jtkellertx

A digital fish scale might do what you need.

Originally Posted by Collin Fultz

I'll second this if all you need to do is measure force in a pulling direction. They key is mounting it in a situation that allows the robot to keep full contact with the floor (i.e. don't have the scale "pulling" the robot "up").

Thank you to all for the ideas. I really like the fish scale and luggage scale idea, and I don't have to spend a fortune. I will look at amazon.com and other places.