New Cyclone & Duct System

[Ben Mitchell]

Well, after 2-3 months worth of full weekends on the project, I finally have a new dust collection system.

It cost a bloody fortune and about a pint of blood, but boy does it suck!

I found a CL deal on a DustHog SC3400 collector. This 700# monster moves an incredible amount of air through two big conical filters via a 7.5HP 3PH motor, but upon getting it home I realized that its catch bin was incredibly small.

So after building an elevated outdoor shed to put the collector (and an air compressor and a phase converter) in, I started thinking about a pre-separation cyclone. This led to Oneida and eventually to Bill Pentz's designs. The big problem is that nearly all the "home" style cyclones are based on much smaller air movers, and they'd be hopelessly overmatched by the 7.5HP motor in my collector.

Oneida sells a standalone industrial cyclone that had the requisite 30" diameter, but it was about $2000 which was more than I could justify. So I scaled up Bill's plans and went to work on the sheetmetal. 20ga sheet is a bear to form and weighs a lot when the assemblies get this big, but necessary with the pressures involved in a system of this size.

Here's the finished exterior of my shop as of this weekend. Note that accessing and installing that exterior corner fitting was somewhat nightmarish when the closest I could get is where that ladder in the photo stands:

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The primary trunk is all ducted in 10" 20ga spiral duct. I ran an 8" flex drop to my big CNC router through a big ball joint, and 6" drops to everything else. After years of MDF dust escaping router projects and covering everything around in a fine, toxic dust I'm so excited I can hardly stand it. My metal working machines are smiling almost as much as I am.

[Dominik Dudkiewicz]

Awesome! Looks great. Bit of a pity you needed such an agressive bend on the intake to the cyclone though. As you're probably aware, a straight run into the cyclone is very important to increase efficiency. Though hopefully with such a powerful system it won't matter too much!

Enjoy! I'm excited for you.

Cheers, Dom

[Marty R Schlosser]

Super job, indeed, Ben! Anyone who has even looked after ducting in an already existing cyclone has a bit of an appreciation for what you've accomplished here. Outstanding.

It'd be interesting to see what sort of CFM this system is capable of. I would imagine that despite the intake ducting bend at the cyclone, the sheer brute force the 3,400 CFM generation ability of the DustHog SC3400 will be able to push through and still provide you all the capability you'll ever require.

Again, outstanding.

[Carlos Alvarez]

I suddenly feel so inadequate.

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[Ben Mitchell]

Thanks, gents.

The intake angles are a bummer, but not as bad as it might appear from that angle. Here's another shot. It goes through one 90 and then a 45, then through the round-to-rectangle and the into a truncated section of the rectangular entry Bill designed. That 45 gives a pretty gradual inlet slope. Not ideal, but there are a lot of positional considerations to accommodate. Needed to deal with what the roof trusses inside would permit for running the trunk that leaves the building, where the pad could be put to house the collector, and so forth.

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This would have been well neigh impossible if I didn't have a whole bunch of sheetmetal tooling in the shop in addition to the woodworking gear. Came up with some new approaches to sheetmetal projects thinking this through, too. For the rectangle-to-round I did the template in CAD and then scribed it onto the galvy sheet with a diamond engraving tool on the CNC router, then just cut it out on the shear and the bandsaw and folded along the pre-scribed lines. Worked beautifully.

I haven't bothered trying to measure the true airflow or anything but I'm sure it will vary wildly depending on what gates are open. For the tools that have a 4" connector this whole system is going to be pretty choked down. For the big router with an 8" flex venturi-ing through 4" right at the dust shoe I'm sure I'll do a lot closer to the rated capacity.

We'll see soon enough. This weekend I'm hoping to get the final connections to the machines sorted out.

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[Dan Friedrichs]

Beautiful sheetmetal work, Ben!

[Mike Heidrick]

Can I see pictures of the 9" drop to cnc setup please?