i have a great set of scales i got for 25 dollars on ebay...they are the size of a set of bathroom scales..they weigh up to 345 pounds...they are great...i use them for large ebay packages..when i started buying escrap items from locals i found the scales needed to be bigger... i just cut a good size square platform from a piece of plywood and i set it on top of them...they are very accurate..ive never had them more than an ounce off, and an ounce is no big deal when dealing with steel and aluminum....
you may want to browse ebay and see about high capacity portable scales...just make sure the model you get has a detachable screen..if it doesnt it is sometimes hard to read your scales when you have large or bulky items on them
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