Made my own rolling cyclone dust collector

[ryanjg117]

Apologies for the multiple posts here. FOG choked on all the images, even though I scaled them down.


Finished product for the TLDR crowd:
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I happened about a cheap Baldor 1hp motor/blower with variable frequency drive a few months back, and it collected dust as I wasn't sure how I wanted to use it. I was thinking maybe I could build a downdraft table or I could add some filters and use it as a HVLP spray backdrop.

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I've been getting into sandblasting lately, a great complement to another new-ish hobby of mine, welding. I recently scored a new-to-me sandblast cabinet but it didn't come with a dust collector. I've come to discover sandblast dust management is a real problem/mess. Cheap 100 cfm cylindrical dust collectors are typically sold with sandblast cabinets but they are terrible; a huge pain to empty since you have to take them apart from the middle, and with cloth filters that almost immediately get caked up with the extremely fine abrasive dust coming out of the cabinet. Cleaning is a huge mess and you basically have to take it outside to empty.

Econoline, the maker of my sandblast cabinet, recommends a 400 CFM dust collector. Not finding any good dust collector new or used that I was really excited about, I checked the specs on that Baldor motor/blower to discover that its capable of ~600 CFM. This is actually the same (or very similar) motor/blower they use on their pedestal grinder dust collection kits. So I figured this motor/blower/VFD would work well for a mini-cyclone style dust collector that I could dedicate to my sandblaster.

I figured I would "take inspiration from" Oneida's mini-gorilla design, but make it more stout. I don't have good tools or experience in sheet metal forming, so I decided to purchase Oneida's standalone 5" steel dust deputy cyclone. For an output HEPA filter, Dick at Wynn Environmental recommended their 13R230NANO filter stack. With 230 square feet of filter area it is way larger than the 95 square feet that comes with the Mini Gorilla. Here's the Mini Gorilla:

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I don't need the ability to store a large volume of waste, so I went with a small 3.5 gallon bucket with gamma seal lid. This would make it easy to simply twist off the bucket to empty, and would only require a very simple piece of sheet metal to adapt the cyclone to the bucket. Easy to just twist on a 5 gallon bucket or larger if I ever need the extra capacity.

With the core parts identified, I just needed to make some of the transitional pieces. I set out to design the filter transition, filter bottom sphincter, gamma seal lid adapter, rolling carriage, and VFD cabinet.

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I designed all of these parts in 3D CAD, exported to DXF, and used SendCutSend.com to laser cut these parts from sheet metal, and ship them to my door. Instant quotes online, no human intervention, very cool. I'm a huge fan of SendCutSend and amazed how they can do this all so cheaply--here is a part they laser cut out of 1/8" steel and bent to my specifications for $58 shipped to my door. They even threw in a second one, at no cost- “We just happen to have an extra after setting up for bending so we decided to send it to you instead of throwing it away.” Did I mention this service is awesome?

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[ryanjg117]

Laser cut parts still require some clean-up for TIG welding, but it's quick and easy. Below is the filter transition in the process of being welded. I mostly TIG brazed with silicon bronze on this project, since I didn't need the full strength of a penetration weld and brazing allows you to input less heat into the part, which leads to less deformation especially on thinner sheet metal. This was one of my first TIG brazing projects, hence why it doesn't look all that great.

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And here's the adapter piece joining the cyclone and gamma seal lid. All holes cut by laser, no welding needed.

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Comically large cyclone on top of tiny 3.5 gallon bucket:

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[ryanjg117]

I cut out most of the gamma seal lid top, easy with the dremel:

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Test fitting everything together. It fits. Not as tippy as it looks but without support there is a lot of weight against the plastic gamma seal lid in the picture below.

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Next was the bottom filter funnel/sphincter/plug. The Oneida has a cool design that enables you to hook up a vacuum to the bottom while knocking the filter to make it really easy to clean. I borrowed that idea but decided to add a funnel to aid in coaxing dust downward.

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[ryanjg117]

Luckily, the tubing here is the perfect diameter to fit my 35mm hose end snugly. Also, a size 7 rubber stopper plug is a perfect fit for this tube, which is how I will keep it capped.

On to the rolling carriage. I thought it would be cool to hold the cyclone in a ring, with three tripod-style legs similar to the Mini Gorilla. I decided to use some scrap metal tubes I had from a cheap import boat awning which collapsed under heavy snow a couple years back. It's 1.5" diameter, .04" wall thickness.

Cleaned up the ends, coped some of them:

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Little fixture I made on the welding table for the angle welds:

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More silicon bronze TIG brazing:

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Testing it out with casters installed:

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[ryanjg117]

I was worried that it would be tippy but it's fairly stable. I poured kid's play sand down each leg through the opening at the top. I will locate the control box opposite the filter stack to act as a counterbalance later.

On to mounting the VFD. I kicked around the idea of just mounting this onto a bracket and placing it at the top, but it's best practice to put the VFD in an enclosure. I purchased a 10x10x4 NEMA box and installed the VFD, along with a main power pushbutton, 20a circuit breaker, EMI noise suppressor, and muffin fan. A tight fit; I definitely should have stepped up to the 12x12x4 enclosure.

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If you're not familiar with variable frequency drives (VFDs), they are capable of adapting 3-phase motors to work on 1-phase power. But they also have a number of other benefits, one being speed control. This is beneficial in sandblasting since I only want enough dust collection to clear the cabinet and allow me to see what I'm blasting, but not so much that all of my media gets sucked into the dust collector; my cabinet is actually designed to recycle spent media through a valve at the bottom. So it can be expensive to vacuum up more media than necessary. Fortunately, the VFD that came with this motor/blower accepts a 10 kOhm potentiometer input to manage speed control. Here's the back side of the pot with my soldered connections.

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I built a handy box to house an on/off potentiometer. This sends the signal to the drive, putting the motor into FWD and then adjusting the speed as the pot is turned clockwise. I added a magnetic pad to the bottom so I can mount this to the front of my sandblaster to increase/decrease vacuum on the fly. I connected the potentiometer over Ethernet and found a nice, heavy coiled Ethernet cable that can stretch about 15 feet.

For the inlet, I designed a custom 5” + 2.5” to 5” wye transition, and had a friend 3D print it. I wanted the option of being able to attach my shopvac hose (2.5”) to the inlet and use it to vacuum the floor from time to time. It works, but after testing I discovered the 2.5” hose is just too airflow restrictive to provide strong suction at the end of the floor nozzle.

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That's it. Pretty happy with how it came together, and I can see myself using this DC not just for sandblasting but perhaps even replacing my whole-shop 5hp ClearVue cyclone for when I don't want to wake up the neighbors.

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[Michael Kellough]

Very impressed, and envious of your range of skills.

 

[Cheese]

Nicely done Ryan...that Baldor motor/squirrel cage is indeed part of the bench grinder dust extraction kits they offered some time ago. The tip-off is the square connection as most other competitors were round.

I also like the idea of silicone bronze TIG brazing, didn't know that was an option.  [smile]

Also, thanks for mentioning the SendCutSend connection. They offer a lot of different material choices.

 

[RKA]

Really nice work Ryan!  I haven’t crossed the bridge from fabricating with wood to metal.  I would like to someday, but it just feels like a huge leap.  But I love seeing some of you guys make things like this!

 

[ryanjg117]

Very impressed, and envious of your range of skills.

The project included every skill but woodworking. And I posted it on a woodworking forum.  [blink]

 

[ryanjg117]

Really nice work Ryan!  I haven’t crossed the bridge from fabricating with wood to metal.  I would like to someday, but it just feels like a huge leap.  But I love seeing some of you guys make things like this!

I'm totally just a novice, but 90% of getting good results with welding in my experience comes down to prep. Getting the parts to fit up nicely, and then cleaning them. Angle grinder and a lot of acetone. At least for the process I use (TIG). Having the ability to design and then on-demand laser cut to insanely good tolerances also helps a lot. It's a nice combination of skills to learn.