If you mean the yield is less by weight, it’s because of the weight of the seeds.
If you want to learn seed removal, the zig zag pictured above is a good final step to remove the last plant material. The steps prior to that are dry, crush, sift, and then toss up and down in an angled box. The seeds roll to the bottom. Gravity separation works by density. The entry level seed separator machine is the clipper office tester and it goes for about $3k last I looked, but you can do it by hand with patience.