Neither the top nor the bottom, your finger "should" end at the middle hole where the heavies would drop through into a catch cup

Bill

My understanding was that the Knudsen Bowl was a deep cone not a flat spiral wheel. Fed by a pipe down the center to close to the bottom. The axis is vertical, not tilted. It was spun fairly fast, not slow like a wheel. Lots of water circulated till done, then a plug removed in the bottom and everything left was flushed out.

Sorry, thought it was a wheel
Learn something new today LOL

Jump over to golddredgerdotcom, ask the question there
A member used to own a prospecting store in socal, Im sure he would know
The fellow is HoserJohn, if he dont know, no one will

Bill

Thanks,

That's a new forum on me, I thought I had researched for all of them.
I'll check it out.

This will explain how the Knudsen Bowl works, newer versions also have an automated extraction of heavy materials without shutting down. here is a video of the workings explained:  https://www.youtube.com/watch?v=h1NEG0xQI-g&feature=youtu.be

Thanks Walter,

That link didn't take me to any particular video. There was a list of totally unrelated vids after just one about a Knelson concentrator.
A Knelson concentrator is a deep cone but with concentric rings, not a spiral groove, as well as other patented special high tech features.
I couldn't find any new vids that answer my question. Sorry.

 you may need to cut and paste or search the name of video on y tube.

MM35 knelson concentrator:    https://www.youtube.com/watch?v=h1NEG0xQI-g&feature=youtu.be

  Knelson Batch - How It Works:  https://www.youtube.com/watch?v=Y02WRGzbt-o

 

Small scale gold mining - Knudsen bowl gold concentrator: https://www.youtube.com/watch?v=Egik4BPfVX8

A good description of the Knudsen bowl concentrator with pictures and the patent number from 1942 can be found at the following location.

https://riosuerte.com/in-the-beginning-there-was-gold/day-81-placer-gold-recovery-methods-xxi/

At least two YouTube vids that explain how the thing works using a cut away Knelson bowl to see what it's doing, as well as other vids on this equipment.
Love to see one live operations

Bill