I was looking for a way to mechanically shake the screen stack rather than shaking by hand as I felt that would do a better job. I found some vibrating tables for sale but most of them were very expensive, as in $300 and up. I thought I could modify the vibrator I used for cleaning brass prior to reloading and as it turned out it was quite simple to do that. The spindle that goes through the tub threaded into the base so by removing that spindle I was able to find a bolt that fit the threads and used that to attach a square of plywood. I then added a piece of non-slip rubber and called it done. It works really well.
Attachment 297317
I got my screens from Amazon and they were expensive, but well made and should last forever. The bottom one is a pan with a flat bottom and came with a lid. The stack is not attached to the table I simply hold my hand on top of it while I run it. This allows me to monitor the progress of the powder through the screens and it only takes a minute or two. I start with the lid on top to keep dust out of the air but then remove it after the initial 15 seconds or so. I can then watch the granules dance around and see when all the pieces small enough to fall through a screen have done so. I then remove the screens one at a time checking each level to make sure the smaller particles have been filtered out. I usually run the vibrator again for a few seconds at each level till I'm sure it's done. This sounds more time consuming than it is, it really doesn't take long at all.
The whole screen stack nests together tightly. Here's a link for them, but as I warned you the price is pretty high!
https://www.amazon.com/dp/B07TP2BHJQ...roduct_details
I was getting more 4f than I'll ever need for priming which is what prompted me to try using the excess 4f as charge powder rather than having to reprocess it. I haven't seen any problems shooting it in my guns and in fact I think it's working better than some of the bigger sizes.