More dust collection work

WEll, I am setting up my cyclone, and have been super frustrated with the off the shelf HVAC fittings. For example, Oneida clearly states that their super dust deputy XL takes standard 6" crimped fittings - well it doesn’t, at least not the ones from Home Depot. Rather than continuing to fight with crap, I decided to make my own stuff on the CNC.

I made a bunch of the parts for doing this, but some background. I have a harbor freight dust collector that was upgraded with a larger Rikon impeller and Wynn cartridge filter. I wanted to get the dust collector off the cart on the ground, and open everything up to 6" pipe and hoses.

I took the collector apart, and used the CNC to cut out a mounting plate for the motor - I could have just drilled the holes but I have a precision machine, so might as well us it. CNC drilled out that perfectly, also perfectly milled a shelf to set the cyclone on as well. .

The next complicated pieces are the connections from the output of the impeller, and the filter cartridge. Online I saw some folks had used a regular 10" square to 6" round HVAC adapter - with my last experience with the metal stuff, I said to hell with that waste of time and designed a stacked set of square rings that converted to a 6" PVC fitting. Was actually a lot easier than I thought though the first prototype was a bad design, the second used through bolts glued in and is very strong.

Last bit was the filter. I did some measuring, and laid out the circles for the PVC and the outside filter diameter. I then measured the inside lip and was able to draw a circle halfway in, and then circumscribed a hexagon on that. Once I had the hexagon I just put in the holes for my bolts where the hexagon met the circle.after cutting that out I used it as a drill template on the filter, drilled all my holes and I was read to mount the filter.

Here are a couple pictures of the work I did on the CNC

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That’s quite the set up, Mike. I have a 2HP dust collector, not a cyclone. It’s an older Craftex/generic unit. I got rid of both bags, put a Wynne filter on top and a large barrel on the bottom. Then, I made a Thien separator to keep most of the nasties out of the filter. Yours is much prettier than mine. I have to use flex hose to my machines, as they are all on wheels. I really like how clean your system looks.

How do you find the Dust Deputy? Does it keep your filter relatively clean? I take it that your filter runs horizontal, yes?

I’ve not finished it yet, so no long-term results, but I expect it will keep it pretty clean. only the very fine particles go through the impeller to the filter. I did use it last to clean up theist couple days I worked in the barn and its fun watching the dust spin into the can.

Opening everything up to 6" really posted the airflow on the unit - the three main upgrades, opening it up, bigger impeller and the wynn filter get it much closer to its advertised flow - I saw someone with a similar setup and some measuring devices getting a bit more than 800 CFM at the end of their run - which is pretty good in my opinion.

Other benefit is any pieces of wood that get sucked in spin down the cyclone as well as they cannot be suspended in the air column - so nothing will hit my impeller again it seems.

Thinking about it more I really should set up my filter so it has a pass through, so all the stuff blows straight throw to a bag or something at the bottom and then the finest particles are trapped. I’ll probably move it, as this is kinda a learn-as-I-go project in a lot of ways. I learned last night that its pretty hard to rotate the elbow and fittings on the pipe and take it apart, that 6" pipe has a lot of surface area and friction. I also realized my plan to just “hang” the pipe up was not great, so I am making some brackets out of wood with a 6" semi-circle to hard mount the pipe to the ceiling.

If you have any more questions feel free to ask, I’ll add something else when I get to hooking it up to the CNC, but I think I’ll end up making myself an adapter to the little rocker dust-right hose - though they do make an adapter.

I have no real suggestions, Mike. It seems like you have things well in hand.

The big issue with my setup is that chunks can and do hit the impeller. I have to trade that off with the problem that I don’t really have space for a Dust Deputy.

Is your filter mounted horizontally? If so, it would seem to me that the fines would all settle to the bottom. That may not be good, but I’m far from expert.

There is a kit you can get from
Rockler with two 4” screw on adapters that would let you make a separator out of a garbage can. Not very expensive and would keep stuff from hitting the impeller. I also found a guy how made a separator and made it all fit mostly in the existing cart, I’ll find the video later and post a link.

It may look like I have it well in hand but have been making it up as I go. :stuck_out_tongue:

Lee Valley has separator lids for trash cans, too. I just don’t have space for another barrel that big. I would be very interested in video you are talking about. Tks.

A holesaw, glue gun and a few plastic pipe fittings and your can turn most anything into a cyclone collector. I made mine out of a paint drum and it works a treat.

Yeah. I have a Thien baffle in my collector, which does much the same as a cyclone. It lets the chips fall into the barrel and only the very fines get sent into the filter. The issue with “my” design is that the baffle is after the impeller. That makes for a smaller footprint, but carries with it the issue of chunks hitting the impeller.

@gwilki Here is part one of the three part video - pretty straightforward maybe will give you a interesting idea

Tks, Mike. I’m going to look at it now.

If you’re using PVC for your ductwork, don’t forget to ground it. The high static electrical charge that builds up can cause hefty shocks and possibly sparks that could lead to fires. If its too late to run a ground wire inside the PVC (ideal), you can drill 2-3 inch screws into the pipe every few feet and run a ground wire on the outside of the pipe with a wrap around each screw and attach to the housing of the dust collector.
Always practice safe suction…

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Bumping an old post but I’m responsible for safety where I work and we’ve had some close calls with dust collection. Every shop accident is obvious in hindsight. It would be terrible to see an awesome company and community like this to be affected. Going from the dust created by a chop saw or table saw to the sheer volume from a busy cnc. router can be very surprising, too!

We have two big panel saws (à la Home Depot cutting Centre) , a 60x72" production router, two upcut extrusion saws, two Amada turret punches, two Amada cnc benders and a small herd of hydraulic press brakes and assembly presses.

Here in Québec the rule is that all ductwork has to be non-flammable, conductive and grounded all the way through.

Another absolutely critical one is to never, ever, ever mix aluminum dust with wood, and if you’re milling aluminum, definitely never use pvc fittings! Remember old time flashbulbs? Aluminum dust is an extremely explosive material. One little spark… The actual regulation is to never vacuum aluminum dust with a dry collector unless it’s a certified explosion proof device. ($$$$).

Wood dust can explode too, and there’s a maximum safe CFM that I don’t remember.

For deburring aluminum, we finally settled on a hydrotron dust booth with a water impinger. It has an air knife at the front and a couple of belt sanders and dynabrades inside. Not within reach of a home shop ($60k) but just to illustrate how dangerous aluminum dust is considered to be.

For wood dust, the maximum permitted volume of dust in a collector is 0.5 cubic metre, and emptied regardless at the end of each shift. For aluminum, if the dust is under water they allow us about a week between cleaning the sludge out, which must be stored outside.

We’ve also had fire start from a cnc router bit suddenly burning out and generating enough heat to send a couple of sparks up the flue. Luckily we had an open system so no pressure was able to build up and create an explosion. A guy took out the burning collection bag, which at less than 0.5 Cu. M was feasible (but he ignored the fire extinguisher next to it :roll_eyes:) , and hosed it down outside. Seemed ok… but next morning we found it burned out. Glad it was outside.

Steve, your post really caught my attention as I just started experimenting with milling aluminum. I had run my collector a few times previously (mostly with small cross cuts on the chip saw, but also on a few small CNC jobs). I definitely won’t be doing that again during an operation.

Once the operation is over though, I had one hell of a mess to clean up and concerns about the dust in the air. I do have a high rated furnace filter taped to a 20" box fan that I use as an air cleaner and I had that running during and after, so hopefully that grabbed some of the smaller airborne aluminum dust.

I looked up online and I would say, a likely counter to safe practices, it seems extremely common for CNC users (both on pro CNC forums and on hobby forums) to ultimately vaccum up their aluminum shavings etc. when they are done. I tried my best to clean up by hand but I just could not contain the mess and had to resort to vaccuming up what was left over.

To be honest, your professional insight and discovery of just how serious it is pretty much put me off wanting to mill aluminum without a much better collection plan. Looking in to what that would entail made my eyes pop.

Ideally it sounds like using a handbroom to clean up visible shavings is one relatively safe way, but that doesn’t help with the finer things spread all over the shop and in to the peg holes in my wasteboard. It gets on everything.

@BillKorn how have you handled clean up from aluminum milling?

@SteveFossey any insights in to what a home/hobbyist could do to keep clean and manage the risks? I do run the home depot filter bags in my vac, so as long as they are properly attached around the inlet the aluminum dust shouldn’t be reaching the motor, but it would be in an area that has had or does have wood dust. Would using a clean bag just for aluminum work be a viable alternative to lower risk?


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Jeff, I’m glad Steve brought this up. Everyone using this type of equipment should survey his setup to be sure it’s as safe as possible. I’m sure it never dawned on quite a few of us that this could be a danger. It could take out your machine, and your house.

Dust is a real concern, whether it’s metal dust or wood dust. If you’ve ever seen a grain silo fire it’s amazing to realize it was caused by static and dust.

If your cut settings are correct, you’re making chips not dust. Chips should be less of an issue because due to their mass they heat up slower, they are father apart when moving through the hose, and they tend not to clump together or move as a cloud like dust. I am certainly not a static or safety expert, but I think the vac hose is usually short enough and the velocity low enough that the threat is probably lower for us hobbyists than a professional installation where a long central system using high velocity blowers are used.

I’m still careful - I don’t walk away while the router’s cutting, especially if it’s doing aluminum or stainless. I have the vac and the open end of the hose grounded, even though static buildup is a surface phenomena so grounding plastic and rubber is less effective than grounding conductive materials. I use the override in UGS or CNCJS to increase the cut speed during the run so it’s fast enough to get out of dust territory up to making chips (Besides, it’s better for the mill). I do use the open end of the vac hose to clean up the table and floor. And I ALWAYS empty the vac cannister when I’m done to make sure nothing gets a chance to smolder in the vac.

I hope everybody considers Steve’s warning.

This is correct. Chips have to be protected from fire, but they are not an explosion hazard. I’m sorry, I should have made that clearer.

You’re right about the velocity, too. I’m not sure what the limit is off the top of my head, but it’s out there.

I’m itching to try my machine with aluminum. I made investment casting moulds from aluminum, and machined robotics components, but only on manual milling machines. Typically you’d use a 5 or 7 tooth carbide face mill some 3-4 " diameter for making blocks, but pockets a d features would be relatively low rpm high speed steel, anywhere from 1/32 to 2". You’d be producing a stream of dry chips with the face mill, but you’d be able to flood the smaller end mills with an oil/water emulsion, which both cooled and carried the chips away. However, youd be running at 1600-2500 rpm, not 10000.

So I don’t know what the best approach is but there’s always a way. Safety is always more productive when you carefully analyze your situation, and there has to be a safe, cost - effective solution for hobbyist level budgets.

@BillKorn is right, chips are not the same risk as dust at all. Keep the dust out of the air.

At lower rpms I’d use a squirt bottle of coolant, but I’m not sure if that’s feasible with a router. I don’t think you want anything that could be a solvant getting into your delrin parts or electronics. Or lungs.

I’ve done quite a bit of aluminum and SS milling. Even on multi-hour runs in aluminum I haven’t used, or needed, coolant. The part does warm up, but as long as you’re moving fast enough to make chips instead of dust it works fine. I mostly use 1/8" bits with conservative/moderate DOCs and cutting speeds, and a fairly high RPM. Stainless steel is a similar. I use 1/4" bits - you have to go even slower with 1/8" than in aluminum so runs get long - about the same DOC and speed, lower RPM. If you move fast enough to make chips the heat buildup is no too bad. The Sienci dust shoes both do pretty good jobs of capturing the chips in both aluminum and SS.

Thanks again for adding this topic to the list of safety topics, like E-stops, fire extinguishers, and high speed rotating equipment. We should be helping each other stay safe.

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The “high static electrical charge” myth has been disproven so many times now that I’ve lot track of it.