There's really no reason to go with the scale method. They are expensive and unnecessary.
The whole thing about people not wanting to drop a coin because they don't want to damage it is a complete farce. Just what do you think happens to those coins before you get your hands on them? They go through counting machines, bins, hoppers, presses, and you think letting one ding against a table is going to hurt it?
Best method I have ever found...
Use a glass jar or container near the edge of something over carpet. Drop the coin so that it grazes the glass - just kind of slides over it. It will make its sound perfectly known as it falls to the carpet. If it's copper, you will hear it ring all the way to the ground. If it's zinc, it won't make any noise as it falls to the ground. I discovered this method when I was 14 (in 1982) and have used it ever since, and can sort dozens of rolls in an hour.
As a disclaimer, don't let your coins fall six feet to a concrete floor. Put pillows or something around your test drop area so the coins don't get away from you. Just be wise about it and all will go fine.
Problem with using a scale is that it's very slow, expensive, and unnecessary. I can often sort coins at one per second once I get used to doing it. You simply can't go that fast with a scale, no matter what it is.
Edited to add the following::
Back in 1982 when I was 14, I could barely afford the money to save rolls, but I did. I saved every new cent that came in, and when I had a cereal bowl full of them I set up my drop-test and sorted them into envelopes. Once I had enough in an envelope for a roll, I'd paper wrap them.
My drop-test tool was one of those large glass water bottles people often saved change in. I set it in the middle of my carpeted bedroom, sat on the floor, and dropped the coins one by one against the edge of the glass jar. I often caught them before they hit the ground, but even if they did, it was carpet and wouldn't hurt them. I got tired of having to get up and chase the strays around, so I rolled up towels and made a pin out of them so the strays wouldn't go far.
Now...I knew nothing about zinc, copper, resinant tones, science - heck I didn't even know anything at all about coins. We didn't have the internet, I didn't have money for books, so I did whatever came to mind. I had a used 1969 edition of the
Red Book, a few blue penny folders, a few cigar boxes to keep stuff in, and envelopes I took from my mother's secretary desk. That's it...I figured it out way back then with nothing to go on. It should still work without a problem. Amazes me that more people haven't figured it out.