Dust collection for metal

[Whiskeymike]

Anyone using a cyclone dust collector for metal sanding or cutting? How does it work? I understand that a traditional dust collector doesn't work well for metal because of the exposed impeller. I was thinking of using a cyclone with shop vac connected to bench sander to collect aluminum dust. Also looking for solution when hand cutting using plasma. After I'm done cutting or sanding the dust seems to be everywhere.

If you use a cyclone and like it, can you recommend a brand?

 

[rcktsled]

I can't recommend any equipment but I have a word of caution. I worked in a plant that made aluminum baseball bats. We had dust collectors on the sanders used to polish the bats and we had several fires. The aluminum dust and magnesium in some aluminum alloys is very flammable and difficult to extinguish so be careful.

 

[Pitt Grease Monkey]

Industrial cyclone dust collectors have a blower connected to the top of a very steep conical chamber. This is the outlet. The inlet is located tangential to the circumference of the cone a short ways down from the outlet . As air enters the chamber it spins around and out the outlet. Dust particles have a higher inertia than gas particles. Therefor, they do not change direction as fast as the air flow. They hit the sides of the chamber (where the air speed is much lower) and fall down to the bottom of the chamber.

Cyclones are quite energy efficient when used in industrial settings, especially compared to other dust collector types (bag houses, wet type collectors, etc.) and when they are properly set up.

Rcktsled is right to warn about dust collection. All dust is explosive in the right concentration. Even flour and sugar facilities have been known to explode. Another warning, if you collect metal dust, do not allow it to get wet in an enclosed container. The metal oxidizes, stripping the oxygen from the water and releasing the hydrogen to the atmosphere. If you inadvertently contain the hydrogren gas, you are creating a significant hazard.

Now that the warnings are over, I say go for it. A properly set up dust collection system makes for a much cleaner shop and easier cleanup.

 

[ZRX61]

If it ends up containing iron & aluminum *dust* you have just created thermite...

 

[Cyberbear]

You need to do some research to find the correct type of cyclone collector for your particular application.
For many years we owned and operated the family metal polishing business. The metal dust never came into contact with the fan impeller, it just circled inside the cyclone collector until it fell out the bottom into a metal 55 gallon drum. These are simple dust collection devices and require no filters to replace, unless they are industrial types governed by OSHA. that filter the very fine particles.

 

[McLean]

I'm curious about this also. Tried to find answers in the past with no luck so hopefully this will spark some good conversation.

The cyclone seems like a good way to keep your filters cleaner, but at the expense of another component (5 gal bucket + cyclone), I'm not convinced it's worth it for a mobile vacuum. Maybe if it was used for a dust collection system?

What about consumer grade/light industrial dust collection systems? Anything available that's more reasonably sized/priced than a Donaldson Torit collector?

I have done lots of hand cutting with a plasma and lots of sweeping up after it too. I think your best bet would be an enclosed table to cut on- think 55 gallon drum with a grate on top or some type of water table like a cnc plasma table has.

 

[Whiskeymike]

Is there any reason to think a cyclone for wood working wouldn't work for metal working? Seems the particles would have more mass than wood particles and should work better.

 

[Pitt Grease Monkey]

Unfortunately, it's not usually a good idea to use a system designed for the collection of one type of material for a different material. All materials have different conveyance velocities needed for good collection and to ensure no drop out. For metals, the minimum duct velocity used to be 4500 fpm per NFPA 484. This is so that if anything drops out during shut down it will be picked back up when the system starts again.

My experience is only with metal dust and chip. That said, I would imagine that a system designed for wood dust/shavings has a lower duct velocity and air velocity within the cyclone itself relative to a system designed for metals. This would mean poor performance.

My suggestion would be to look for a system designed specifically for metals dust collection. When making/installing you duct, use an online calculator to determine your duct velocities, like the one linked to below.

http://www.engineeringtoolbox.com/ductwork-equations-d_883.html

I would keep velocities 4500 fpm for the safety aspect and if you want a lower maintenance system (less duct cleaning down the road).

 

[kart-racer]

I use a Dust Deputy for Wood and Metal collection. It is connected to a Craftsman Shop Vac. I have no issues using it to collect metal chips from the drill press or my small mill. I have 4 ports plumbed through out the shop with 2inch PVC and switches at each location to turn on the Vac.
Very little wood or metal particles make it into the actual shop vac canister.

 

[Pitt Grease Monkey]

kart-racer,

That's a nice setup. I guess I am coming at this from my industrial frame of mind when really what was asked was some experience with home use systems. Sometimes I need to remember to take off my engineer hat and put on my garage hat.

For home DIY use, those setups look great. They are also a nice improvement over using a shop vac on it's own. I've killed a few vacs using them too heavily for dust collection. My only pet peeve would be all the plastic, which could generate static charges. If it finds a ground path it could spark; not good with wood dust and certain metals. We deal with this by electrically connecting and grounding the duct sections.

 

[turbowoodworker]

Metal chips in a dusty bucket spells fire.
PVC should be grounded too for the same spark deterrence. Most woodworkers do not use PVC for that reason but those that do run small wire, like bell wire, down the inside of the duscts to ground and prevent spark.
Kart racer has a nice setup but not necessarily the safest setup.

 

[Regnar]

Used a Dust Deputy on my CNC Mill for years with no problems at all!

For the Plus's
1. Filter doesnt get covered in Chips and Coolant so there is no loss of suction
2. 16 gallons worth of chips is heavy as hell. 5 gallons is not bad at all.
3. Change out buckets for different material and recycling. Keep the steel and aluminum separate.
4. It works with water!
5. It works with dirt! Used it to dig a mail box post. Dirt in 5 Gallon bucket and not all over driveway or grass!
6. Works with dryer vent hose lint! Try getting that **** off a filter.
7. No need to ever buy a Vac Bag again or a filter for that matter.

For the Negatives
1. Akward as hell when trying to wheel around. (Fix: Buy a 20ft vac hose)
2. Takes up more space
3. Gives your vac a light Howling sounds. Drives my wife nuts.
4. Drywall dust seems to be its enemy. Does separate but more like a 75/25. 25% making it the vacuum.

The 60.00 price tag is kinda up there. But you figure it only cost 2 Hepa Filters or 1 Crappy Filter and 4 Bags it doesnt seem that expensive.

 

[Beemer533]

I am in the process of building one of these: http://www.jpthien.com/cy.htm for my CNC router.
Granted, the CNC isn't creating dust, but chips...

A lot of folks have built these things over the years with good results. Cheaper and not as tall as a Dust Deputy as well..

 

[404]

Metal chips in a dusty bucket spells fire.
PVC should be grounded too for the same spark deterrence. Most woodworkers do not use PVC for that reason but those that do run small wire, like bell wire, down the inside of the duscts to ground and prevent spark.
Kart racer has a nice setup but not necessarily the safest setup.

The pvc will have a charge on it at first, but as it gets covered with a layer of dust or dirt the ability to charge goes away. I made my cycle from a water softener pressure tank. Turns out a cyclone does not need to be a cone to work well. A straight cylinder is okay.

 

[kart-racer]

Metal chips in a dusty bucket spells fire.
PVC should be grounded too for the same spark deterrence. Most woodworkers do not use PVC for that reason but those that do run small wire, like bell wire, down the inside of the duscts to ground and prevent spark.
Kart racer has a nice setup but not necessarily the safest setup.

I have never noticed any static charge on the PVC, but I did install a small (20ga) copper wire inside the PVC run. Its grounded at both ends as well as in the middle of the PVC run.

Not a great picture, but you get the idea.

 

[SM Racing]

Very timely discussion as I am looking at down draft tables to help cut the dust in my shop. Wonder if there is another arrangement I could use to catch the grinding dust from my tubing and plate grinding. Cleaning up the chips from my lathe and Mill aren't really an issue, I just sweep those up or vacuum those.

 

[Retrosmith]

Currently going through much research on this for my dust cyclone. Visit http://billpentz.com/woodworking/cyclone/index.cfm. He's got more details than you'd ever hope to find in one place. Same principals but as Pitt says 4500 fpm instead of the 4000 for wood. Bill has a spreadsheet on his website that you can use for calculating static pressure drop through your system.