# Fume extraction for metalworking?



## sploo (15 Feb 2021)

Any suggestions for fume extraction for a small mill and lathe?

Doing a moderately long job on the mini mill at the weekend generated a lot of fumes (vapour from oil being used as lube/coolant) and in my well sealed workshop it really wasn't pleasant (and likely pretty bad for health).

I've found a few carbon filter based fume extractors for soldering (e.g. https://www.amazon.co.uk/Solder-Abs...JMJ2R44WRHH&psc=1&refRID=AH2T3JG19JMJ2R44WRHH) which I assume would be better than nothing, but wonder if there's something better for a mill. Obviously I'm thinking tens to low hundreds of £ and suitable for a bench top; rather than thousands of £ and sized for an industrial unit.


----------



## Jelly (15 Feb 2021)

You don't really need a filter pack per se (and I wouldn't recommend filtering and recirculation as it will be ineffective unless there's a huge airflow through the filter) just increased ventilation to the outside.

A Bathroom/kitchen extractor fan would probably be sufficient, although there are LEV hoods/which are designed for metalworking (really welding fume) which would probably do a better job, albeit for a lot more money.

In an ideal world you'd aim for about 10 air changes per hour in the workshop with the fan on... Sizing of hoods/arms is more complicated as you're aiming to move less air but capture at source, so it's dependent on the geometry of the whole setup.


----------



## sploo (15 Feb 2021)

Jelly said:


> You don't really need a filter pack per se (and I wouldn't recommend filtering and recirculation as it will be ineffective unless there's a huge airflow through the filter) just increased ventilation to the outside.
> 
> A Bathroom/kitchen extractor fan would probably be sufficient, although there are LEV hoods/which are designed for metalworking (really welding fume) which would probably do a better job, albeit for a lot more money.
> 
> In an ideal world you'd aim for about 10 air changes per hour in the workshop with the fan on... Sizing of hoods/arms is more complicated as you're aiming to move less air but capture at source, so it's dependent on the geometry of the whole setup.


The "outside" bit is the problem; my workshop is basically a reinforced concrete bunker. Great for insulation (pretty easy to keep it between 10-15C all year round), but a non-starter in terms of venting outside.

The door is an insulated roller shutter type, so also not suitable for putting a hole through; hence the need to filter rather than extract.


----------



## Ozi (15 Feb 2021)

I used to inspect LEVs as part of a previous job. Have seen some very effective home made set-ups using 110mm pipe and extractor fans meant for bathrooms. The trick is to only extract what you need to extract by getting the inlet as near to the source as possible and drawing air away from the operator towards the source. I know that is a statement of the bleeding obvious but so many extractors pull the pollutant up past the operators face. Exhaust really does need to go out side, could you put up with a short pipe extension passing under the slightly open door. I have seen a set-up where a man was making stain glass windows, he built a full door width box section the door set down into that allowed the pipe to pass through without creating a draft, pit extreme but could be lifted out on the occasions he needed to wheel anything through the door.


----------



## Droogs (15 Feb 2021)

In that case @sploo have a look at microclene MC420 second hand on the bay or rubbertree
they go for around 100 - 150 second hand and are superb for the environment you are in.


----------



## Spectric (15 Feb 2021)

I would question what cutting fluid you are using, having worked in many engineering sectors and seen many machine shops I cannot recal any issues with the engineers and fumes from lathes, mills etc. Not sure if the fluid has changed but the stuff we used was a white concentrate that was mixed with water.


----------



## Jelly (15 Feb 2021)

sploo said:


> The "outside" bit is the problem; my workshop is basically a reinforced concrete bunker. Great for insulation (pretty easy to keep it between 10-15C all year round), but a non-starter in terms of venting outside.
> 
> The door is an insulated roller shutter type, so also not suitable for putting a hole through; hence the need to filter rather than extract.



You're unlikely to find a wholly satisfactory solution off the shelf in that case (at least not in your price range). 

But, if you mounted several of the filters you linked (or similar) in one wall of an airtight box, which then links to some flexible ducting and a hood which can be positioned close to source, then you d likely achieve substantially better than nothing. The closer you can get your ventilation to the vapour source, the less airflow is going to be needed.

Also, it's worth considering if the unpleasantness is caused by a genuine gas/vapour where carbon is likely to be the best filter, or if it's actually oil mist and/or smoke particulates, in which case a HEPA type filter will be effective making it easier to find larger off the shelf solutions.

Thinking through other strategies there is elimination as an option, it's a completely separate solutions (with its own wholly separate issues, which are significant and messy) but I would think switching to flood coolant would solve your smoke/vapour issues.


----------



## Jelly (15 Feb 2021)

Spectric said:


> I would question what cutting fluid you are using, having worked in many engineering sectors and seen many machine shops I cannot recal any issues with the engineers and fumes from lathes, mills etc. Not sure if the fluid has changed but the stuff we used was a white concentrate that was mixed with water.



I would assume it's a heavy sulphonated cutting oil, with an appearance similar to runny honey, which is applied undiluted from a brush or oil-can.

Gives good results on aluminium, and can sometimes help on gummy mild steel, it's commonly used by hobbyists and small job-shops, but would only normally be seen in an industrial capacity as the coolant in gun-drills.


----------



## Spectric (15 Feb 2021)

So rather than look at solving the problem just change the cutting fluid and no problem. I suppose the issue is if the machinery has a sump/pump arrangement to circulate the coolant. If not then use the more freindly coolant and apply with brush.


----------



## sploo (15 Feb 2021)

Very useful responses; many thanks all.

@Droogs: I do actually have a couple of air filters in the garage (I usually cut dead tree rather than metal). They're cheap Rutlands copies of (I believe) a Record Power extractor (Buy Premium Air Filtration System online at Rutlands.com). However, looking at that, and indeed the Microclene MC420, I think they're really just for dust (i.e. no carbon filter for vapours).

@Ozi: when we first moved in I was looking at ways to vent outside (I did that for my old garage, for extracting wood dust into a hopper). The roller door is motorised, so is designed to just fully open or full close - so it doesn't really lend itself to being partially closed (at least, not to a particular position). I did consider drilling a hole through one of the walls but I'm told it's reinforced concrete so I'd probably need an oxygen lance to cut through the rebar!

@Spectric, @Jelly: Depending on what I'm doing, it's either CT-90 Cutting & Tapping non drip compound, or 3-in-1 oil. Both do produce a fair bit of smoke and unpleasant smell. I guess I could/should look for a better alternative?

The mill does have a drain port on the table, and I had considered getting a small pump/sump system at some point for circulating coolant.


----------



## Spectric (15 Feb 2021)

You will find that with a good supply of coolant flowing you can get good finishes and better cutting tool life without the fumes.


----------



## Ozi (15 Feb 2021)

I used one of these to cut a hole in a concrete wall, admittedly not very thick but reinforced, it survived and went on to cut through 24" of mud stone wall to fit a friends bathroom extractor, completely knackered now but under £20 for both jobs seemed OK.


----------



## Ozi (15 Feb 2021)

sploo said:


> Very useful responses; many thanks all.
> 
> @Droogs: I do actually have a couple of air filters in the garage (I usually cut dead tree rather than metal). They're cheap Rutlands copies of (I believe) a Record Power extractor (Buy Premium Air Filtration System online at Rutlands.com). However, looking at that, and indeed the Microclene MC420, I think they're really just for dust (i.e. no carbon filter for vapours).
> 
> ...


Not sure what make of door you have but there will be a limit switch, could you adapt it to fit in two positions?


----------



## sploo (15 Feb 2021)

Spectric said:


> You will find that with a good supply of coolant flowing you can get good finishes and better cutting tool life without the fumes.


Indeed. Certainly on my "to get" list.



Ozi said:


> I used one of these to cut a hole in a concrete wall, admittedly not very thick but reinforced, it survived and went on to cut through 24" of mud stone wall to fit a friends bathroom extractor, completely knackered now but under £20 for both jobs seemed OK.
> View attachment 103596


I do have an SDS drill, but I'm unsure if that hole cutter would do the job. As far as I understand it's 3-4" of breeze block followed by 12" of reinforced concrete.


Ozi said:


> Not sure what make of door you have but there will be a limit switch, could you adapt it to fit in two positions?


Good question. I've not spotted any switches. I think it "knows" where the top and bottom of the range should be (certainly it's gotten confused a couple of times with power cuts and then only opens half way until I reset it).

There's definitely some safety switch (maybe current based); as if there is something in the way of the door closing it will cut out - after giving the obstruction a bit of a squeeze that is. I could make use of that, but I assume that's really only intended as a last resort emergency cut out.


----------



## Inspector (15 Feb 2021)

Spectric said:


> ............... having worked in many engineering sectors and seen many machine shops I cannot recal any issues with the engineers and fumes from lathes, mills etc. ............



I worked in an aerospace machining plant for 27 years. Large aluminium and hard metal parts. At one point the air would sometimes be so thick with oil and coolant the hazy lights at the other end of the plant 75 metres away were all you could see, not the walls. After a couple dozen years of working there one of the machinists became sick with emphysema/COPD symptems and was away for six months. When he came back to work he was as sick again within a week and Workmans Comp pensioned him out. I have been away and always have a little mucus in my throat that never goes away. There is a reason there are oil particle limits in the workplace. 

Sploo wear a cartridge mask until you can find a clean air solution. Our newer machines had oil mist separators, basically a rotating drum that spun out the mist and then Maintenance added electronic air filters after them to better control the oil mist. They had to be cleaned frequently. A less obvious reason to remove the oil mist is that whatever you don't breath ends up sticking to everything in the room. Gets grungy after a while. I'm with those recommending venting through the wall. Filtration a distant second. I don't use my mill or lathe a lot and cut dry as much as I can. I wear a mask if using cutting fluids. The one downside to flood coolant is it is messy unless the machine is enclosed.

Pete


----------



## sploo (15 Feb 2021)

Inspector said:


> I worked in an aerospace machining plant for 27 years. Large aluminium and hard metal parts. At one point the air would sometimes be so thick with oil and coolant the hazy lights at the other end of the plant 75 metres away were all you could see, not the walls. After a couple dozen years of working there one of the machinists became sick with emphysema/COPD symptems and was away for six months. When he came back to work he was as sick again within a week and Workmans Comp pensioned him out. I have been away and always have a little mucus in my throat that never goes away. There is a reason there are oil particle limits in the workplace.
> 
> Sploo wear a cartridge mask until you can find a clean air solution. Our newer machines had oil mist separators, basically a rotating drum that spun out the mist and then Maintenance added electronic air filters after them to better control the oil mist. They had to be cleaned frequently. A less obvious reason to remove the oil mist is that whatever you don't breath ends up sticking to everything in the room. Gets grungy after a while. I'm with those recommending venting through the wall. Filtration a distant second. I don't use my mill or lathe a lot and cut dry as much as I can. I wear a mask if using cutting fluids. The one downside to flood coolant is it is messy unless the machine is enclosed.
> 
> Pete


For cutting dead tree I have an airfed mask. I do have a mask with filters for organic/inorganic aerosols; so that would probably help for metal. Certainly I don't want to be breathing in as much as what was generated by the job at the weekend. No fun at all.


----------



## Jelly (15 Feb 2021)

sploo said:


> I do have an SDS drill, but I'm unsure if that hole cutter would do the job. As far as I understand it's 3-4" of breeze block followed by 12" of reinforced concrete.



One (possibly more than one) of those TCT core bits will do the job, and do a _ok_ job if you frequently disengage from the cut, clear out the dust/chipped concrete and cool the cutter with water. Because they require you to use the hammer function, and have a lot of surface area in contact with the concrete, they're are pretty brutal to run as a result (especially when they're biting into rebar, which they're not great at), you should reasonably expect it to take a good while and be a serious workout.

If your SDS has the option to turn hammer off (mine doesn't ), then using one of these diamond core cutters (Toolstation is cheaper than Screwfix, and in both cases buying their respective kit is a much better option than buying the bits individually) could be a good alternative. To do a 16" deep hole you'd have to cut to the full depth of the drill, then disengage, switch to breaker mode and chip the core out and repeat, at least once, probably twice to get all the way through; they're not really affected by rebar though which is a big plus.

A IMO the best option would be to hire a diamond core drill and bits, Tedbar Tinker Hire are based in Yorkshire (North of Sheffield), and hire out proper diamond drills (Dry 240v and Wet 110v) from as little as £49 for a weekend, which works out cheaper than buying a core drilling kit for your SDS drill, whilst almost certainly making the job a lot easier too.





sploo said:


> For cutting dead tree I have an airfed mask. I do have a mask with filters for organic/inorganic aerosols; so that would probably help for metal. Certainly I don't want to be breathing in as much as what was generated by the job at the weekend. No fun at all.



The P3 filters used in an air-fed hood are usually rated for dust/mist (check the technical documents for the specific part number on the manufacturers website to be certain), and it sounds like what you're experiencing is an oil mist rather than combustion products from the oil (where the organic filter would be more appropriate).

The filter will clog much more rapidly with dust after it's been exposed to oil mist, so it would be worthwhile keeping two sets of filters in separate sealed bags, one for wood dust and one for oil mist; which should allow you to get your full 30 hours out of each.


----------



## Sideways (15 Feb 2021)

Like Pete above, I've seen the fume and the oil y surfaces created by machines running high volumes of and sometimes high pressure coolant.
On enclosed CNC machines, a "filtermist" would be standard equipment to try and reduce this.
Not the same type of machine but I'd look at thor / microclene type air filters as a start and see if you can place them close to the machine to maximise the effect. This would need a few filters so that you can swap them out frequently and hopefully find a way to clean and reuse them. I think paint spray booth filter media is one of the cheapest ways to buy - again IF that stuff can stand up to machine oil.


----------



## Woody2Shoes (15 Feb 2021)

Would a fume extractor/filter - as used by welders or solderers - be any good? A positionable fume hood/nozzle on a flexible boom...


----------



## Jelly (15 Feb 2021)

Woody2Shoes said:


> Would a fume extractor/filter - as used by welders or solderers - be any good? A positionable fume hood/nozzle on a flexible boom...



The advantage of being able to catch the mist at source before it can get to your face is substantial, and certainly worth looking into... 

But short of a lucky EBay Bid, they're probably out of the desired price range.

You could use an extractor or filter unit to act as one using ducting, as long as the powered bit could move sufficient air, which is definitely worth looking into whatever route OP goes down.


----------



## Woody2Shoes (15 Feb 2021)

Jelly said:


> The advantage of being able to catch the mist at source before it can get to your face is substantial, and certainly worth looking into...
> 
> But short of a lucky EBay Bid, they're probably out of the desired price range.
> 
> You could use an extractor or filter unit to act as one using ducting, as long as the powered bit could move sufficient air, which is definitely worth looking into whatever route OP goes down.


Absolutely, something like this would do (and I can imagine making one out of scrap plywood) Axminster Woodturner's Universal Dust Hood


----------



## sploo (16 Feb 2021)

I had a rummage around my "I'll keep it just in case" bucket last night, and came up with a 120mm PC fan, a 12V DC motor speed controller, and a 12VDC PSU. Squares of activated carbon filter foam are cheap, so that might be a better-than-nothing start (i.e. a DIY version of the Hakko solder fume extractor). I could always add more fans for more power - perhaps even one blowing across the mill to push fumes towards the filter + fan that was sucking (as pushing air tends to have more "range" than just trying to pull it).

I don't think my air fed mask (Trend Airshield Pro) has a filter option rated for gases, so it would definitely be the passive make with canister filters.

I'll take another look at where/how I might get a hole in the side of the garage. Indeed it would be the easiest solution to just vent such fumes.


----------



## Keith 66 (16 Feb 2021)

I use a syntheticstraight cutting oil in my Harrison 140, its simply that soluble oil (suds) has a limited shelf life & needs to be changed regularly, Also tends to gum up with crud on the machine if its not used all the time. The straight oil leaves the machine pristine all the time. It smokes if you are doing heavy cuts but i have a small inline fan & 100mm flex pipe that deals with it.
I have also fitted a decent extraction system with 150mm ducting & 1200m3 pr hour centrifugal fan.
It was primarily installed for a laser cutter but is also used when im welding. 
What you do have to watch is that you must allow for air intake into the building, my set up will pull the door shut once it gets about 4" ajar & you then really notice the pressure drop as it starts pulling the air out of the building. Gotta have an air intake too!


----------



## sploo (16 Feb 2021)

Yes, that is a concern. When we moved in I wanted to build a cyclonic separator for a 3hp impeller extractor unit, then eject the separated air outside (for the woodworking tools). But, given the garage is pretty well sealed with the door closed it would likely need a separate inlet vent. I suppose a low volume fume extractor might be OK, but it's not ideal.


----------

