Thread: Under bench dust collector

Originally Posted by Redbeard

. . . .
500cfm doesn't seem like much, even if just for a single lathe?

It won't even be close to 500 CFM for the reasons.
Firstly the 500cfm will be done without the bag or the hose and performed using an old Australian Standards procedure that is incorrect.
Then single bag filter dust bag is highly restrictive especially as it fills up
The result will be on average <200 CFM.

Can the two bag units be mounted horizontally?

They can but this orientation won't separate the dust from the air very well and you will end up with a layer of sawdust in the filter bag which is where the air has to escape do they will have even lower flow rates.

Is wood turning your only dust making activity?
How often do you do it?
Have you thought about locating a DC outside?

Originally Posted by BobL

It won't even be close to 500 CFM for the reasons.
Firstly the 500cfm will be done without the bag or the hose and performed using an old Australian Standards procedure that is incorrect.
Then single bag filter dust bag is highly restrictive especially as it fills up
The result will be on average <200 CFM.


They can but this orientation won't separate the dust from the air very well and you will end up with a layer of sawdust in the filter bag which is where the air has to escape do they will have even lower flow rates.

Is wood turning your only dust making activity?
How often do you do it?
Have you thought about locating a DC outside?

So... 200cfm probably not enough hey?

For the foreseeable future the lathe is the only dust maker of concern. Everything else is small enough to be moved outside when needed. Actually, everything has to be moved outside to get to the lathe... And by everything else I mean a little Ryobi band saw and a chair.

My "workshop" is a 2.5 x 2.2 metre garden shed. My nearest neighbour's house would be only 10 metres away with my teenage daughters bedroom window about four metres from the shed door. With the carbatec m900 large, a pressed metal framed bench, and some wood storage there's barely enough room to work. A dust collector which didn't go under the bench would have to be capable of being moved to and operate from, outside the shed.

Oh, and of course, I'm renting so modifications to anything are out of the question.

As a result of the noise from the lathe in the shed I limit my turning to daytime, and because I'm a wage slave that means I'm limited to weekends.

Even during the day I'm conscious of the noise levels. When you live so close in suburbia you have to stay on each other's good side.

I'm contemplating ditching the old metal bench and the lightweight legs on the lathe and replacing both with a purpose built bench, which should free up a bit of space, maybe enough floor space for a small two bag dust collector but under the bench would be even better, space wise.

Are the base model units H&F or carbatec sell worth it? With the custom bench option I reckon I might fit one in permanently(ish).
https://www.machineryhouse.com.au/W332

From the criticism I've seen directed at the cheapo units they don't sound worth the money though.

What about the high pressure, low volume units, or are they just glorified vacuum cleaners? https://www.timbecon.com.au/extracti...dust-extractor

The dust ain't going to stop me but it would be nice to tone it down, even if just a bit.

Sheesh, what an opus!

Cheers
Redbeard

It's far from ideal but a Hydroponic type exhaust fan (they are quiet) and a bit of 6" or bigger flex starting from behind or above the lathe out the door, for the fine dust and a Vacuum cleaner for the chips will be better than that under bench DC. I'd be wearing a mask and be aware you run the risk of becoming allergic to wood dust.

Originally Posted by BobL

It's far from ideal but a Hydroponic type exhaust fan (they are quiet) and a bit of 6" or bigger flex starting from behind or above the lathe out the door, for the fine dust and a Vacuum cleaner for the chips will be better than that under bench DC. I'd be wearing a mask and be aware you run the risk of becoming allergic to wood dust.

So you don't like the basic two bag collectors? Not entirely surprising.

Something like this?
https://rover.ebay.com/rover/0/0/0?m...2F192566019170
Maybe in the eight inch version? With some long, tapered reducers to six inch hose?

Yes, I use a mask, especially when sanding. With a family of old school carpenters and general woodnuts I've been exposed to ridiculous quantities of dust many times over the years. If I'm not allergic now I probably never will be (touch wood).

Originally Posted by Redbeard

Are the base model units H&F or carbatec sell worth it?...
https://www.machineryhouse.com.au/W332

Absolutely not, you'd be better off getting a big fan and just blowing everything toward an open door. We have one at work for when we're turning fibre reinforced resin for gear blanks and it does about 3/5 of stuff all.

Originally Posted by Redbeard

So you don't like the basic two bag collectors? Not entirely surprising.

A two bag systems would be fine for your setup PROVIDE it was vertical and enclosed and the enclosure vented outside the shed but it sounds unlikely in your situation.

Something like this?
https://rover.ebay.com/rover/0/0/0?m...2F192566019170
Maybe in the eight inch version? With some long, tapered reducers to six inch hose?

They are low powered RADIAL fans that won't generate much back pressure so are less able to overcome the pressures that hoses generate.
The better ones have a proper impeller that generate a higher pressure..
https://www.ebay.com.au/itm/INLINE-C...d29AsgeLTLp9dA

Yes, I use a mask, especially when sanding. With a family of old school carpenters and general woodnuts I've been exposed to ridiculous quantities of dust many times over the years. If I'm not allergic now I probably never will be (touch wood).

OR you could already be on the edge and tip over at any time.

Originally Posted by BobL

A two bag systems would be fine for your setup PROVIDE it was vertical and enclosed and the enclosure vented outside the shed but it sounds unlikely in your situation.


They are low powered RADIAL fans that won't generate much back pressure so are less able to overcome the pressures that hoses generate.
The better ones have a proper impeller that generate a higher pressure..
https://www.ebay.com.au/itm/INLINE-C...d29AsgeLTLp9dA



OR you could already be on the edge and tip over at any time.

If my bench plan comes to fruition an enclosed two bag DC might be doable. The cabinet would be in the corner, beside the door where it would be possible to vent out the door, which is always open when I turn. Would the outside vent be a primary source of noise to the outside world? What sort of noise levels are we talking with these DC units? I have seen some fairly fancy baffle arrangements which control noise but let air through.

Thanks Bob, for letting me pick your brain. You're helping me come up with an arrangement which just might work.

Cheers
Redbeard

These units do work better than the opinions offered above.

Yes they are limited in their filtration by having the breather and catcher in the one bag.

They can be used under the bench as described but can also be wall mounted which acts a lot better as the waste drops to the bottom of the bag allowing better draw.

You have to be diligent in keeping the unit and bag clean. If you are not diligent then the bag will block up with the dust build up and reduce the effectiveness of the extraction, this is a common thing with all dust extraction units.

Dust extraction on a lathe is only really used when sanding and this is where these units excel. You can still use the extractor to help clean up after turning but the bag will fill up quickly.

Originally Posted by Jim Carroll

These units do work better than the opinions offered above.

Yes they are limited in their filtration by having the breather and catcher in the one bag.

They can be used under the bench as described but can also be wall mounted which acts a lot better as the waste drops to the bottom of the bag allowing better draw.

You have to be diligent in keeping the unit and bag clean. If you are not diligent then the bag will block up with the dust build up and reduce the effectiveness of the extraction, this is a common thing with all dust extraction units.

Dust extraction on a lathe is only really used when sanding and this is where these units excel. You can still use the extractor to help clean up after turning but the bag will fill up quickly.

Thanks Jim for chiming in with that info. Can you tell me how tall the unit would be if it was up on end?

Thanks
Redbeard

Originally Posted by Jim Carroll

Dust extraction on a lathe is only really used when sanding

While I agree that sanding is by far the dustiest task with turning, anytime I turn dry wood, there is some level of dust created.

Apart from any discussion of efficiency, my opinion is that it is just a GIANT PAIN IN THE AR#S emptying chips from one of those under bench bags.

Originally Posted by Fuzzie

Apart from any discussion of efficiency, my opinion is that it is just a GIANT PAIN IN THE AR#S emptying chips from one of those under bench bags.

No different to emptying any bag on a dust extractor, all messy if care not taken

Originally Posted by Jim Carroll

No different to emptying any bag on a dust extractor, all messy if care not taken

Not really. Emptying chips out of a dust bag with a 100mm collar is a quite different experience to tipping the contents out of a big bag. Maybe if it wast just dust and ran out like sand it would be OK, but my experience was chips tend to lock together and not come out of the restricted throat with any simple upend and shake.

Dust extraction during turning is a variable feast and depends on who is turning it and and what is being turned.

This table may provided sobering information for all wood workers but more so for turners.
I have highlighted in red those that significantly exceed the nominal OHS dust levels of 5mg/m^3 for European softwoods
exposure-by-occupation.jpg
The data above is for professional turners. It does not take into account dust particle sizes/profiles, type of wood (some are more toxic than others - especially Aussie timbers) and the age and pre-existing health condition of the turners. If these are taken into consideration then all of the categories would have mean exposures above the recommended safety levels.

Until a newbie becomes skilled at both turning and sharpening, my testing shows that newbie turners make and scatter significantly more fine dust than pros. Newbies also use a lot more sandpaper than skilled turners. Like testing for dust from most wood working machines it's not much use performing simple spot dust measurements as the dust accumulates over time. The relevant danger levels of dust exposure depends on the age and health condition of the turner. The older and unhealthier the turner the less dust they can tolerate.

To illustrate this here are two direct experiences I have had in measuring turning dust.

At the mens shed there's only one turner that really knows what he is doing, the rest (fortunately not many) poke blunt or inappropriately shaped tools and lots of sand paper at rough looking bits of wood thereby generating lots of fine dust at all stages of turning. We don't have dust extraction on the lathes because they are rarely used (2 -3 times and we have excellent ventilation but it must be turned on. The ventilation is in the form of the many kW fan of the Evap AC unit that cools the shed. My measurements shows the AC fan takes about 10 seconds to clear the dust from the air around a lathe/turner (to that equivalent to outside air) that has been turning for for about 30 minutes. The area where the lathes are located is also large (~14 x 7 x 4.8 m) which is not the case for most DIY especially the OP who has a tiny shed which concentrates the dust to a greater degree.

In contrast to the above, at an annual WA turners convention there was a highly skilled turner demonstrating in a room with more than 100 people present and the demonstrator was using a large room air filter unit behind his lathe bench. I just happened to have a dust particle counter operating during his demonstration and the RAF not only managed to keep up with the small amount of dust he was making (everything was pre-roughed to shape) but the RAF was slowly during the demo making the room cleaner than it was to start with. The Demonstrator was stopping and talking often so not continually turning AND he did not use sandpaper for more than a few seconds every 10 or so minutes. The RAF in use was one of the bigger units (1000? cfm) running at half speed so maybe 500 CFM. I doubt many DIY turners would be at this level of skill.

Then it depends on things like what is being turned, a pen makes less dust than a bowl, hardwood makes less dust than softwood, dry makes more than wood with some moisture in it.Bill Pentz does not have any air flow figures on his website relating to lathes but my testing shows that even a skilled turner (not performing a demonstration where there may be as much talking as turning) needs at least 400 CFM for small stuff and more for larger stuff. A newbie or irregular turner will need more that this.

In practice the DC referred to by the OP will idraw less that 200 CFM when the thing is clean, and it's down hill from there. It does not need to be full as one session of sanding will create more than enough fine dust to clog sugar a small bag. One of these DCs I tested was less that 10% full but was so badly clogged with fine dust it was drawing