In my never ending quest to think about building a Thien Separator (but never actually getting round to making one)...
I noticed that Cosmas Bauer has a separator design that has a completely circular baffle (no 120 degree section that's connected to the side of the separator body), and instead the baffle is supported by the outlet tube (which comes all the way down from the top and touches the baffle). He's cut away a section of the side of the outlet tube, as obviously the end is sealed against the baffle.
I can see that would be useful in stopping larger material getting caught on the leading edge of the larger (120 degree) segment of the baffle (as there is no larger segment - just a gap all the way round). However, I assume that drawing air from a cutaway at the side of the outlet tube would cause a lot of unwanted turbulence.
The original Thien design (pictured at http://www.jpthien.com/cy.htm) uses three rods coming down from the separator's top plate (to support the baffle). I assume they will catch longer (e.g. planer) shavings, and also affect airflow.
So... what I'm wondering about is to create a baffle with a slot/gap all the way round (i.e. a perfect circle), but supported by a single rod or pipe from the center of the underside of the baffle, which would be attached to the bottom of the collection bucket; basically a bucket with a tall table (with a round table top) sitting inside.
I assume the air speed in the center column underneath the baffle should be low/zero (i.e. the supporting pipe shouldn't affect airflow), and with a 1 1/2" (38mm) diameter metal pipe the baffle should be fairly rigid. A tapped hole in the top of the pipe would allow the baffle to be easily unscrewed for tipping waste out of the bucket, and the air outlet above could be a nice open bell mouth.
Does that sound like a good idea, or have a missed something?
PS I understand that a thin material for the baffle is a good idea. With the baffle supported from the middle of the underside, it should sag less than when it's supported from the side by a 120 degree segment, so it would be interesting to find some really thin sheet materials (1/16" aluminium, or carbon fiber). With it attached by just a single screw from the top it'd be easy to test out different slot gaps and baffle thicknesses.
I noticed that Cosmas Bauer has a separator design that has a completely circular baffle (no 120 degree section that's connected to the side of the separator body), and instead the baffle is supported by the outlet tube (which comes all the way down from the top and touches the baffle). He's cut away a section of the side of the outlet tube, as obviously the end is sealed against the baffle.
I can see that would be useful in stopping larger material getting caught on the leading edge of the larger (120 degree) segment of the baffle (as there is no larger segment - just a gap all the way round). However, I assume that drawing air from a cutaway at the side of the outlet tube would cause a lot of unwanted turbulence.
The original Thien design (pictured at http://www.jpthien.com/cy.htm) uses three rods coming down from the separator's top plate (to support the baffle). I assume they will catch longer (e.g. planer) shavings, and also affect airflow.
So... what I'm wondering about is to create a baffle with a slot/gap all the way round (i.e. a perfect circle), but supported by a single rod or pipe from the center of the underside of the baffle, which would be attached to the bottom of the collection bucket; basically a bucket with a tall table (with a round table top) sitting inside.
I assume the air speed in the center column underneath the baffle should be low/zero (i.e. the supporting pipe shouldn't affect airflow), and with a 1 1/2" (38mm) diameter metal pipe the baffle should be fairly rigid. A tapped hole in the top of the pipe would allow the baffle to be easily unscrewed for tipping waste out of the bucket, and the air outlet above could be a nice open bell mouth.
Does that sound like a good idea, or have a missed something?
PS I understand that a thin material for the baffle is a good idea. With the baffle supported from the middle of the underside, it should sag less than when it's supported from the side by a 120 degree segment, so it would be interesting to find some really thin sheet materials (1/16" aluminium, or carbon fiber). With it attached by just a single screw from the top it'd be easy to test out different slot gaps and baffle thicknesses.