Weight scale for high speed assembly line?

[nfl2k2]

I have an assembly line that I run a variety of parts down. It's easy to mix the parts as there are a variety of small design differences between them - these "small" differences are critical to the customer and I have no good way to poka yoke a machine with sensors or a vision system due to the nature of the parts (difficult to fixture). One key difference is the weight. I envision a small scale on the side of the machine, operator places the part on the scale, analog value is sent to the PLC, if it falls within my control limits the part is released and the operator then assembles. Does a small scale exist for this application? parts are between .2 - 1.5 lbs, about 3" x 5".

[Crossbow]

Look at a machine called a checkweigher. It weighs parts as they pass by on a conveyor system. I've seen them used to weigh boxes after product filling (like cereal). Most have a controller which can give you a pass/fail based on the weight limits you set in the control, and I bet they can give you an analog output you can use. That way the operator doesn't need to do it manually. Might be overkill depending on your application. There are several types of load cells available which give analog outputs.