>>Just used one today in Home Depot and guess what - they work only for a certain range of weights. You can't buy a door and get it through that, too big. In our case, eight little bags of seeds didn't weigh enough to be detected. We ended up in a procedure longer than a simple register scan would be.
>
>Yep. I didn't see anything about weight though. Ours have barcode scanners, so only things that will scan can be bought. That also becomes a problem for a 25 cent bolt - no barcode.

The weight comes to play the moment the machine says "put the thing into the bag". It then tries to sense when did you do it, i.e. it expects the plate where the bags are to have an increase in weight, and it can't sense 0.5g bag of seeds. I tried nudging it, but it expects the weight to remain constant and rise by each item, until you pay. Then it expects a decrease.