Failed build - what next?

[johna]

So many reports of successful builds on this forum. Sad to say my first attempt hasn?t worked out. I?ll briefly describe what I did, what I think is the problem, and what I plan to do next. Any comments / advice would be much appreciated.

I?m in the UK so my measurements are imperial conversions of metric and might seem a bit odd.

Canibalising the 2hp blower from a Jet bag over bag collector, 5 ?? pipe, I built a 19 ?? diameter spin chamber (out of bendy mdf), about 6 ?? tall, side inlet, with the exit pipe extending down into the chamber about 2 ??. Result is that a significant amount of dust (guess 40%) seems to go straight to the exit, which I presume means that the diameter of my chamber is too small.

For my next effort I am thinking of going to the diameter of a 55 gall drum since that is what several people seem to have successfully used. Is that 22 ?? or 24? ? I?ve seen different dimensions on different sites. Do you think it will make a significant difference to my 19 ?? effort?

Should I keep the internal height of the spin chamber the same as the diameter of the pipe and stick with the distance the exit pipe extends downwards being about half the pipe diameter?

I don?t want the mass and weight of a 55 gallon drum filling with dust and chips. Since it seems to be accepted that the shape of the space below the baffle does not impact on performance, my thought is to construct it square, initially larger than the baffle, but then ramp it down on all four sides to create a funnel to a smaller collection drum. If that explanation makes sense, does the plan seem reasonable?

Thanks for reading.

[retired2]

So many reports of successful builds on this forum. Sad to say my first attempt hasn?t worked out. I?ll briefly describe what I did, what I think is the problem, and what I plan to do next. Any comments / advice would be much appreciated.

I?m in the UK so my measurements are imperial conversions of metric and might seem a bit odd.

Canibalising the 2hp blower from a Jet bag over bag collector, 5 ?? pipe, I built a 19 ?? diameter spin chamber (out of bendy mdf), about 6 ?? tall, side inlet, with the exit pipe extending down into the chamber about 2 ??. Result is that a significant amount of dust (guess 40%) seems to go straight to the exit, which I presume means that the diameter of my chamber is too small.

For my next effort I am thinking of going to the diameter of a 55 gall drum since that is what several people seem to have successfully used. Is that 22 ?? or 24? ? I?ve seen different dimensions on different sites. Do you think it will make a significant difference to my 19 ?? effort?

Should I keep the internal height of the spin chamber the same as the diameter of the pipe and stick with the distance the exit pipe extends downwards being about half the pipe diameter?

I don?t want the mass and weight of a 55 gallon drum filling with dust and chips. Since it seems to be accepted that the shape of the space below the baffle does not impact on performance, my thought is to construct it square, initially larger than the baffle, but then ramp it down on all four sides to create a funnel to a smaller collection drum. If that explanation makes sense, does the plan seem reasonable?

Thanks for reading.

johna,  there are an awful lot of successful separators reported on this forum that are built to nearly the same dimensions you described.  As a matter of fact, I am about to start building one that also comes very close to those dimensions.  So, I sure hope that isn't the problem.

Before you start building a larger one, I would be looking elsewhere, like air velocity.  You haven't said anything about your piping system.  Is your DC stationary?  Do you have a ductwork system that has high friction losses due to size and configuration?

Have you tried just hand feeding the separator with no pipe attached?  Do you still get a lot of dirt getting to the outlet pipe?

Regards

[Vodkaman]

I agree with Retired2. Explore what you have already built. First I would experiment with the exit pipe height. Start too low and gradually raise it.

Dave

[phil (admin)]

Post some pics of what you've got so far.

And check for leaks.  It seems like leaks are the largest cause of bypass I see.

[johna]

OK good advice to try some more to fix it before abandoning.

With the bag over bag collector I used 5yds of flexible hose. With my newly constructed separator I got the same result both with the hose connected and when just chucking dust and chips straight into the inlet.

I've got a 5' straight section of metal pipe which I'll try - it might help separation.

If that does not work, I guess all I can do is to take off say 1/2" at a time from the metal exit pipe.

I'll report back

PS Just saw your comments Phil. Thanks. I'll post some pics but I'm away for the weekend so it'll be a few days. I'll also investigate leaks. My tests so far have been conducted by gaffer taping joints, prior to completing weather seal. I thought I'd been thorough but I'll try again before hacking at the exit pipe.

[Vodkaman]

If that does not work, I guess all I can do is to take off say 1/2" at a time from the metal exit pipe.

I think you may need to extend, not shorten.

Dave

[WayTooLate]

I agree with Dave. 

My first attempt had a fitting centered in the lid.  At first start-up, I forgot to install the short piece of pipe to extend into the separator space.  It hardly worked at all.  It seems that when the air at the top is allowed to escape through the exit, it prohibits the circular motion that is needed to separate the debris. 

A few pictures would help explain a lot to us.  If it isn't convenient to post pics, how tall is the space between the top and the baffle?  And, how far down does the exit pipe extend into that space? 

Don't give up on your build - I think it can be salvaged! 

- Jim

[johna]

Thanks all for the encouragement and advice. Phil was correct - leaks were the problem, plus my probably unrealistic hope of zero visible fines escaping. Performance is greatly improved and should now be considered a success not a fail. I'm almost finished with my through wall vent for the cleaned air and will post pics in a new thread soon -with a positive title!

[Don_Z]

Glad to hear you made it work! BACON FOR EVERYBODY!!!!