Metalwork dust/air extraction

[curtisrider]

Hello, this is my first post here so go easy on me! I'm currently a teacher who owns too many tools and misses being in a workshop so I'm quitting my job to go back to my previous job...making and fixing stuff (vague I know but I range from furniture to camper van restoration). My parents own a farm and I am fortunate enough to have a decent sizes building available to me that needs rather a lot of work but at least will be rent free.

I want to get dust extraction sorted early on. I think I have the dust extraction for the wood workshop side sussed out (or at least well on its way to being) but the metal side of things is flummoxing me as there isn't as much information online compared to wood! There are products available but they are far beyond my price range, I also prefer to DIY and recycle as much as possible including making my own tools. I'm trying to keep costs down as the building itself will suck up a substantial amount of my funds, however if necessary I will pay up for something as important as safety as I quite like my lungs as well as wanting to keep the work areas as clean as possible with minimal effort.

I have just bought a Plymo vent arm (£13.50, madness!), this should be good for extracting not so pleasant air away from welding areas. What kind of fan do I need to pull the air? I'm guessing that axial ones won't be suitable (I've got loads of powerful ones hanging about!) as it'll all be dragged through the motor itself and be a potential ignition source/particles will cause wear? Or if it has a filter will that be ok? I have a centrifugal fan that I can use otherwise which I would think would be suitable but I did have another project in mind for it.

I also want to have extraction on a grinding table, belt grinder, pillar drill and 10" bench grinder, this will of course have lots of little metal particles that will be potentially very hot. What kind of extraction system do I need for this? Can I use a regular workshop vacuum with some sort of baffle to allow the particles to cool first? I wasn't sure if using a cyclone separator would be appropriate for this kind of thing. I'm assuming metal ducting material is most suitable, a least for the first few meters of extraction?

I can't post pictures yet but when I can I shall show you the area that i'm trying to sort. Thanks in advance!

 

[Bone]

I would have thought a centrifugal fan in a box, perhaps with an inlet filter to catch the worst of any debris.

Not knowing the airflow you anticipate I would be surprised if you are actually dragging debris through the extraction on your metalwork areas, just smoke and fumes.
In most workshops I have used, metalwork swarf / dust gathers locally and is cleaned up after the event with a shop vac / dustpan & brush. Extraction takes away fumes, particularly from welding area but not dust and debris as you would in a wood shop.

 

[curtisrider]

Hi Bone, thanks for your help.

The grinding table will have a grid/slat top so particles can fall down into a funnel sort of base with a outlet for the extractor, I find I get rather a lot of rust and paint flying about everywhere when refurbishing parts so it would be good to minimise the muck being chucked about. My bench grinder has a outlets for dust extraction already in it. The belt grinder I am making and I will have an outlet to catch a good chunk of the debris. I am perhaps over worrying but I just want to keep it all clean, I know how quickly it can get pretty messy! I could just have a vacuum hooked up directly to each machine/taken to each workspace to regularly clean i guess.

Hopefully soon I can post pictures of my space and what I want to achieve to give you a better idea. I don't know how many posts I need to make before I can post photos

 

[sunnybob]

most of your metal working problems can be cured by buying a good fitting mask and safety glasses, or even the airshield type full face visor with built in fan. Metal rust and paint chips are heavy enough to sink almost at once. Wood dust is such a killer because it will not settle, and blows around your head while working. The mask will also protect against normal fumes. Make it a PP3 spec.

 

[curtisrider]

Hi Sunnybob, I have got the masks already but thank you for the advice, I do intend on investing on an air fed mask at some point for spraying 2 pack paints. As I had said before, I'm trying to minimise the amount of particle build up where possible although I know i'm probably getting over worried about it all. It looks like a grinder table with a tray at the bottom that can be removed and emptied will be the most likely route along with the vent above to take away any fumes. Presumably there will be no issues with me using a normal workshop hoover to clean up with afterwards, I don't need any special filters or anything?

 

[sunnybob]

As I said, your metal debris is heavier than air. it will fall to the floor straight away. So as long as you arent actually breathing it in between the machine and the floor, there is no problem. Very fine dust is to treated with care. anything fine enough to float rather than fall can be a killer. Grinding of standard metals does not produce fumes, but you MUST without fail use safety glasses with a grinder. You cant get another pair of eyes
If you have a mask sufficient for two pack paint spraying, then you have everything you need.

As far as vacuuming it up, an old household cleaner will deal with the vast majority of stuff, just make sure you arent vacuuming anything still hot enough to set fire to the cleaner bag.

If youre going to be sawing, sanding, or cutting wood in any quantity, then you need to study the many threads on here about dust collection because a standard cleaner will not cope with wood dust.

 

[curtisrider]

Thank you for making all that clear, it is much appreciated. It seems that a grinding table and a ventilation arm will be more than sufficient and I already have them (well the table just needs making, I have the parts!).

For the wood workshop side, I have a few options. I already own a small cyclone separator, 3 workshop vacuums, a dust extractor/box collector and 2 oil drum based units with 3 motors on them (one is a Big Brute, not sure on the other make). I was initially going to go for soil pipe (with an earth) going into 1 large unit with a cyclone but I think seeing as I have all these seperate units available then I might as well have dedicated extraction for each machine/a few sharing, this will save having piping everywhere. I also intend on having an air filtration unit to keep the air clean and minimise the very fine dust that hangs about.

 

[sunnybob]

Youre ahead of the pack with that set up. If you have a large smooth floor on your workspace, why not just connect your most used machine to one system, and then use one vacuum on a trolley to wheel between the others as needed?
You will sometimes want two machines running at the same time, but I doubt you will have three on the go at once.
But whatever, always use the biggest bore tubing you have, always use a cyclone of the same bore as the tubing (they are incredible at keeping your vacuum bag clean), always run the suction for a minute after turning the machine off to collect overspill dust.

 

[graduate_owner]

Congratulations on leaving the dreaded teaching profession. I was lucky enough to get early retirement (55) from teaching and never once regretted it. Still not enough time in the day for my wood and metalworkng though.

K

 

[Inspector]

You should get ahold of BobL on the Australian woodwork forums. He works with both wood and metal, and worked in super clean labs on their air systems et cetera.
http://www.woodworkforums.com/members/9450-bobl You may have to join in order to message him.
He tested and measured the dust in the air after using a cutoff wheel in a hand held grinder to cut sheet metal and found the dangerous sub micron dust hung in the air for just as long as the fine wood dust. Kind of puts to rest the idea that metal dust is heavy and falls out of the air quickly although a percentage would be from the cut off wheel wearing.

Pete

 

[t8hants]

You have to be slightly careful with weld fume extractors, I have seen a couple of ducting fires because of weld sparks being sucked up the tubing.

 

[curtisrider]

This is a rough ideas of what my workspaces will be like, just so you get an idea of what i'll be working with:

Metal workshop





Wood workshop





The layout isn't really set in stone and I think will change quite a lot as I buy better tooling. The only things I don't have that are in the drawings are the lift and the rotisserie.

 

[curtisrider]

Sunnybob, a vacuum Trolley makes sense, I think I will do that for the smaller machines, it also saves money on ducting.

Inspector, I shall sign up and contact him shortly!

T8Hants, that is why I was concerned about having some sort of spark arrestor, presumably another solution is just to not have the vent too close?

 

[mind_the_goat]

Looks like your setup would allow completely separate extraction systems, which would make sense form a safety perspective too. It would also make sense to get any metalwork fumes out of the building. In the wood shop you can use filters and keep your warm air in.
I'm sure sparks or hot metal igniting saw dust is rare, but why take a chance. In some cases dust can be explosive, not just flammable
Of course if this is commercial, or you think you may be sharing your space there may be standards already defined. If you are going to be spray painting too then there could be a whole different set of things to think about. Check the HSE web site.

 

[curtisrider]

Yes two seperate systems will be used, I understand the potential dangers of wood dust and some sort of ignition! I do not intend on employing anybody currently, I would imagine by the time I consider that a better workspace will be needed.

I can vent fine dust outside, it wont effect neighbours or the house fortunately, just an old building that will one day be demolished. I will also have an air filtration unit in the wood workshop to be used in winter to retain heat and then a large fan in the wall to circulate air in the summer as the building gets rather warm. The wood workshop has doors that shut it off from the metal workshop which is handy.

Spray painting is something I will eventually do but in a seperate space, I need to investigate it further but I know a proper set up is going to be a painful outlay!

 

[Inspector]

http://billpentz.com//woodworking/cyclone/index.cfm

More reading for you. Bill's site has the plans to make the cyclone separator and since you are handy with metal it shouldn't be an issue to make them. Don't buy the cartridge filters that come with the cheap asian dust collectors of any kind. They can't be cleaned by the filter cleaning companies that do it for industry and you have no guarantees they are rated in any way. Get proper industrial filters.

Pete

 

[curtisrider]

Cheers Pete, that looks very comprehensive. There is quite a lot of conflicting information online, it's sometimes hard to decide who actually knows what they are talking about.

Which filters would you recommend, this is fairly new territory to me so I don't really know what to go for.

 

[Inspector]

I don't know what you have available in Europe. I have Donaldson Torit .5 micron filters that I got form my last job that I will be incorporating into my system this coming winter, after the house is built. I had to have them cleaned and they are good for 3 or 4 more times. The guy cleaning and inspecting them said the Asian ones with the paddles etc., fall apart in his cleaning machine. Try some of the ones below.

http://www.cavendishfiltersltd.co.uk

http://www.dustcheck.com

http://www.c-airfiltration.co.uk

Pete

PS. Forgot to add the big boys all make their systems with the air going from the outside of the filter to the inside and not the other way around like the home dust collectors. Pattern your cartridge box / house the same.