J. Phil Thien's Projects

I agree. the 45 on the outlet is weird. while it would be better on the good side it would be worse on the bad side.

every bend you put in a dc system reduces its efficiency and increases resistance , and reduces air flow. be angling the inlet it means the change in angle of the dust is only 45 degrees ang not 90.. so it should be better

if you build a seperater where the height from the baffle to the top is the same as the inlet dia (or height of rectangular transition) . that's single height .
over the year we have started to build with a higher separator . often 1.5 or 2 times the height are used. it gives the dust more time to spin round and drop out.

that makes a lot more sense. that should work to stop the dust being sucked into the outlet before it has time to spin round. I wouldn't di this on a single height separator because the dust coming around from behind will end up hitting it and creating disturbance or just forces to the inside of it. its one of those things that you would have to test out and see if the benefits (if any) out weigh the negatives ( a few) .

I don't have much experience with this type of separator, I prefer the top hat design with a side inlet. its way better

I think I would need to see a pic of your plan

im not sure I follow exactly what you mean. are you saying that the inlet should be flattened so its entering all along the wall of the separator . a 4" pipe is 12.56 square inchs. if you make it 1" x 12 and a half inchs you will increase the resistance  and losses from the transition.
I don't think it would be a good idea

I have a 200mm dia  inlet and outlet
its double height  seperater . not sure of the dia of the seperater but is roughly 22-23 inchs. its based on the steel barel I have. It is basically that diameter  but a bit wider to create a lip to sit on the barrel

I don't think the juice is worth the squeeze. it could be done . if you build it with a box you will have a lot of turbulence and suction loss from the rapid change in direction.
the commercial versions wold be a a large reducer  , say 12" to 4" with a blank on the 12" end  and then put 4   4" flanges on the blank plate . this means that the dust has a fairly straight run  but they are very big and expensive. .
you would be better off running a main line  with a few runs Td (with Y fittings) 

I think there is too many opportunities for it not to work. you want everything nice and smooth to reduce turbulence. I don't like this type of seperater. I rather the top hat design. it works a lot better and allows more scope to create everything right instead of adapting to the weird shapes of the can

how thick is the baffle plate. reducing the edge thickness can help. adding a tear drop shape at the end may help too but I havnt tried that. unfortunitly its something that happens with stringy shavings. taking small passes shoud reduce the amound of wood in the seperater and give it more time to fall through

i know . just cannot get the time to do it

the idea is to have the chamber  moving as fast as posible to seperate the dust but have below the baffle moving very slowly. the slower the air below the baffle the better . air moving below the baffle will reagitate the seperated dust.

i dont know if something like this would be a good thing or not . my gut instinct tells me that stopping the air spinning  below the baffle can only help. the problem is how to do that without creating other problems. you could create a blockage very fast or stop the drum filling evenly and building up in one side more that others

Quote from: retired2 on October 07, 2019, 07:20:30 PM
SpaceGrey,

I want to compliment you.  You are one of the few people who have built different configurations and then captured data to show what each one is doing.  That is one helluva lot of work, but the data is so valuable.  There has been a lot said about the performance of 2X separators, but unless my memory is failing me, it has all been subjective.  Yours is the first I have seen with actual data.

I agree, it is interesting that the 2X doesn?t seem to care about the outlet pipe ending.

Thanks again for a great piece of work.  Unfortunately, you still don?t have a conclusive answer to why your performance losses are so much higher than mine.

i have to agree with retired 2 . this information is very helpfull. it really needs to be highlighted someway (along with a few other posts that are very important)

there is a real lack of hard data on all aspects of these seperaters. there are too many variables  and build styles to be able to acuratly compare everything.

that is some interesting data. its interesting to note that the single and double  had the same cfm
given they are the same cfm it would be interesting to see if they had diferent seperation efficiency

as somone who has been very vocal about double height seperaters (without hard data to back that up) i would like to see the results

i have meant to rebuild mine in a way that can easily be adjusted and test it better.
i have recently bought a cnc router adn have been toying witht he idea of making a modular version like a jigsaw 

Quote from: retired2 on October 02, 2019, 01:05:41 PM
The first photo in your most recent group appears to show the inlet wall straight rather than curved.  That could cause turbulence in the circling air stream and contribute to flow losses.  The post below illustrates the point.

http://www.jpthien.com/smf/index.php?topic=563.msg3150#msg3150

i think you could be right. the way that is done means that all the air spinning is effectivly hitting a wall infront of it instead of skipping off of it

i dont know. i doubt it. the smaller you go the more resistance there is by changing direction faster. i cant see having a higher seperater helping that. it would help with other areas though.

i wonder would angling the inlet increase the effective radius the dust is travelling in. not sure , it might cause other issues