Return Air system

P. McKinley

P. McKinley

Joined
Jan 27, 2008
Messages
2,010
I've been doing some renovation to my little shop of horrors. One of my needs was/is an upgraded dust collection/evacuation system which I have mocked-up (in the photos below) to see how it will all go together. I purchased a General 574cfm dust collection system from a place called Fundy Grinding in Truro, N.S. Last year their store was flooded and they lost over $1,000,000.00 of inventory off the showroom floor, some of which they purchased back from the insurance company for in-house reconditioning and resale. I purchased this unit with the bag and rolling stand for $115.00.

On a whim, I placed the top piece over a 5.5 gal pail and the damn thing fit near perfect. Even the pail lid went in place, upside down, with a firm press fit.:thumbup: So, I knew I had the bucket size I wanted to allow the top piece to be used for the spark trap exhaust.

What I'm still working on is an enclosed return air system so I won't be sucking cold winter air into my basement shop through every crack in the walls... even heat from the house above. I want to port the make-up air into basement through a 4" hole in the foundation, and duct it(reduced to 3") into the back of the spark catcher where it will just be sucked back out. I can maybe see the need for a shield over the return air duct opening in the spark catcher.... possibly.

Do I have this right?


-Peter



 
Unless you are venting it outside, you don't need return air.
 
For best air cleaning, you have to bring the air into the shop behind the grinder. You will have some shop air cooling, but it will be largely in the exhaust air path.

If you brought the air return into the trap directly as shown in the photo, the air would be in a loop circuit and would not suck the dust and grit from the grinder. It wouldn't be much more than a spark catcher bucket. Try and have the input air at least a foot away from the exhaust port ( the spark funnel), or behind the grinder. IIRC, it was Rick, who posted a thread about how he made his grinder input-exhaust loop for Canadian air. It was a box chamber behind his grinder. I'll try and find that thread.

Here it is.... http://www.bladeforums.com/forums/s...-made-a-dust-evacuation-system-for-my-grinder
Just substitute your blower and spark funnel for the bucket in his setup, have the incommoding air at the top of the box, and the exhaust from your trap go to the exhaust port outside the shop.
 
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Stacy - Thank you.

I've read Rick's thread quite a few times and I understand what he was able to do with his grinder and his particular set-up.
However, I'm finding that the steel casing of my Wilton prevents using same closed system design. My goal though is the same, to get the dust outside, out of my small, 12' x 15' basement workshop. I think this blower is powerful enough to suck a lot of cold air from the adjacent unfinished rooms in the basement, and heat from the house above if I don't have a make-up air system.

I can picture exactly what you've described above, but I can't figure out how to install it without having cold air blowing unabated into the room - with my set-up. If you have any additional suggestions, I'm all ears... errrrr, eyes.

The return air is one thing, getting the spark trap right is another. At this point it sucks like crazy, but the cyclone effect created by the metal cap is pulling water up the sides and into the exhaust tube. I need to stop this. I've adjusted the water height and down tube clearance with no joy. I even turned the metal cap upside down - reversing the direction of the internal funnel and orientation/direction of the circular air flow. It still pulls water up and into the exhaust tube.

Frustration is on the horizon. :confused:

Any thoughts?

-Peter







 
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Suggestions:
Put 2-3" of sand in the bucket and put enough water in to make the sand wet. That should stop the water climbing as much. Another thing that will help is a taller catch pail. You may have to take two pails and make a taller one. It looks like you setup can take a 6" longer catch pail.
Put a PVC flange to fit your inlet hose on the side plate of the Wilton. You should be able to do this from the motor side with ease. That will make all the incoming cold air be drawn through the grinder box and out the spark trap.
 
Perhaps an elbow on the bottom of your intake tube, so you are not blasting a direct air column into the water
 
John - Thanks. I modeled this system based loosely on your drawing in a recent similar thread and I'm considering adding that elbow, but just haven't tried it yet.

I've decided that that plastic bucket, although almost perfect, just ain't working. I can't get a good tight, removable, waterproof seal with any thing I've tried. A local HVAC shop can construct a proper bucket to fit the lid for just a few bucks. I think that's the ticket.

Stacy - I like the sand idea. I'll try that.

I've have also considered adding a 2-3" gated branch line off the exhaust leading out of the spark arrest bucket. Thoughts?

Thank you,

Peter
 
Your Cyclone is set up backwards. Suction out the top, dust intake from the side. You either need to ditch the cyclone config and put both hoses out of the top(from grinder goes low, to blower is high)... or switch your intake/blower hoses to use the unit you have, correctly. I personally don't think a cyclone bucket would make a good spark arrestor for a small set up like yours. I'll call you, bud.

IMO, a cyclone collector and spark bucket are very different. One uses gravity to separate heavy debris(cyclone) and the other hurls hot sparks into water(spark bucket). It's the difference between a vortex and turbulence. That's why gusts blow and a tornado sucks
 
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I just added a bit to my response, Peter


and this...

cyclone_dust_collector.jpg
 
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Rick, I feel dumb not spotting that. I was looking at the inlet and the cold air situation and not paying attention to his cyclone. Good catch.

Peter,
You would need to put two elbows on that cyclone. One for the side to fit the spark funnel...and one on the top to connect to the vacuum.
 
Just to point out something while I am looking at the setup;
A cyclone uses a taper ratio to change the velocity of the air streams. IIRC, the ratio is 1:1.64 ( don't know why that number is in my head?). It needs a fair length to get the effect.
The shorter straight side bucket will still work here, as we don't really care how much dust and grit is trapped and how much is exhausted.
 
I'm hesitant, but I'll try it.

With this design I wouldn't even need water in the bottom to arrest the spark, right?

-Peter

eta: .... and I doubt a plastic bucket is the proper container.
 
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Peter, I wouldn't use the cyclone thingy on the bucket. Just a straight drop like you have with the pipe about 3" off the water for the intake and a straight out of the top exhaust to the blower. (like you had with the shop vac setup)
 
But, I really want to use the ridiculously cool cyclonic vortexualizer thingy. :( ;)

I'm slowly coming around. I'll set it up tomorrow with and without the "RCCVT" and see what happens.

-Peter
 
There's no way I would give up on the ridiculously cool cyclonic vortexualizer thingy either :0)
 
The ridiculously cool cyclonic vortexualizer thingy is ridiculously cool.
Peter do you have enough room under that bench to run a dual filter system?(Ultimate ridiculousness)
Make a conventional spark bucket and a cyclone... and make it(gate it) so you can switch from one to the other. It is definitely possible... maybe a little work but think of the time saved in cleanup when you aren't mixing wood, steel and water.


I have ideas for you that wouldn't be to difficult with your current set up.
 
Love the lobster and tongs!

Other than that I've nothing to add. I want a dust extraction system, but don't want to worry about the fire hazard.

Greg
 
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