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19th November 2017, 02:43 PM #1SENIOR MEMBER
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Thoughts welcome on controlling dust...
G'day wood types..
I'm mainly a metal worker, which can make a mess but not dust.
I'm finding I'm starting to dabble with wood as well, managing to squeeze a triton bench (saw/router) , stanley scms, and an aldi thicknesser into my tiny shed. (3x5)., along with the lathe mill metal bandsaw.
The wood bandsaw has to live under the verandah.
Reading this forum, I probably should do something about dust. A dust collector is probably not in the budget for a little while.
I have an old evaporative cooler in the wall which I only ever use as a fan. I was wondering if it would be worth modifying it to suck instead of blow? Would that make any difference? I try to also use an (industrial) vacuum cleaner on the dust port where available.
I also have the blower out of an old ducted heater. I could fit that in the wall I guess, would that be (more) effective?
Thanks in advance
Russ
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19th November 2017 02:43 PM # ADSGoogle Adsense Advertisement
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19th November 2017, 04:49 PM #2.
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Sorry but this is not correct.
Because I have a rare condition called sarcoidosis and one suspected cause it metal dust I have investigated this in some detail and now wear a personal dust sensor in my shed while doing wood and metal work.
The sensor clearly shows that anything involving welding, grinding, sanding and abrasive cutting of metal make large amounts of fine dust that simply cannot be seen.
As of this March this year ALL dust has been implicated in life threatening health issues, not just lungs, nose and throat but a major contributors to cancers, heart disease and strokes.
After removing all the other factors like poor diet, smoking and access to health services etc, dust in general has been raised from the 8th leading cause of death worldwide to the 5th leading cause of death.
For metal working the dust is not just from the metal but also from abrasives that contain large amount of resins, fillers such as fibre glass and combustion products arising for the high temps used to work metals.
To reduce the effect of metal dust in my shed I have installed a vented welding booth/fume hood and some of my cutting and grinding in now attached to my DC ducting with the DC itself located outside my workshop.
Metal working can easily produce as much fine dust as wood working but it has one advantages over wood work in that metal dust falls out of the air much quicker than wood, the metal dust does not stay in the air for as long. The fillers and resins in abrasives hang around a bit longer than metal but not as long as wood. The combustion products however do hang around as long as wood dust.
Some metals are worse than others. e.g. Ni in SS can serious affect some people and they will suffer from mild to severe allergic reactions to it.
Wet cutting, machining and turning also helps reduce dust.
Abrasive cutting and linishing are amongst the worst offenders. As abrasive disks wear during cutting, it nearly all ends up as dust.
Reading this forum, I probably should do something about dust. A dust collector is probably not in the budget for a little while.
I have an old evaporative cooler in the wall which I only ever use as a fan. I was wondering if it would be worth modifying it to suck instead of blow? Would that make any difference? I try to also use an (industrial) vacuum cleaner on the dust port where available. I also have the blower out of an old ducted heater. I could fit that in the wall I guess, would that be (more) effective?
At my mens shed we have an LARGE DC and a LARGE Evap AC in the middle of the roof and we run the Evap AC without the cooler to vent fine dust from the shed. My testing shows this is very effective. Even just keeping the doors and windows open helps.
To comment on whether your blower and evap air cooler fans would do any good I'd have to know
a) the size of your shed
b)the CFM (cubic ft/min) or cubic metre per second rating of the fans.
If you post some photos of these fans I may be able to give you a ball park figure for the fans.
Suck versus blow depends n the fan grunt and size of the shed.
Small fan and large shed - suck works better
Small Shed and large fan - either way works.
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19th November 2017, 08:30 PM #3SENIOR MEMBER
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Thank you for your response Bob. It's easy to make assumptions like 'metal dust is heavy and so will drop'.
Sounds like I had better do a bit of planning..
I'll work on getting some pics of the evap fan. Should be able to look up the specs of the other blower, it came out of a Vulcan cx60 heater.
And maybe work out how to accommodate a dc.
Regards
Russ
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19th November 2017, 08:48 PM #4.
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The drop out rate depends on the metal and the size of the particles.
Al dust stays suspended in air almost as long as the resin and fibre glass fillers do.
The other thing that surprised me was how quickly the fine dust spreads around a shed. Unless I use dust extraction, within 30 s of using my multitool linisher measurable dust has spread up to 3m away from the source and within two minutes it's more or less everywhere inside the shed.
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20th November 2017, 03:40 AM #5GOLD MEMBER
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Russ you said you are metal worker but didn't say whether a welder, sheet metal or a machinist. If you are of the first two you are in a good position to make your own dust collector. As you read the posts in the forum you will find a lot of recommendations to Bill Pentz and his site. In it there is the information and plans for making a very good cyclone. Then you would only need to find an impeller and motor to mate it to. The overall cost to you would be a lot less than the store bought options and more efficient than the asian imports. You could even build a pair of cyclones using the same blower. One for the wood and after switching to the second (blast gates) suck up the metal products, taking care of those health issues.
Many of the assumptions made about safety of dust and chemicals we all grew up working in and with are being found to be very wrong. It is always better to get as much dust when you make it and deal with the escapees (ventilation) too if needed.
Welcome to the side of woodworking that doesn't end up looking pretty in the house but allows you to enjoy your work for a lot longer.
Pete
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20th November 2017, 06:28 PM #6SENIOR MEMBER
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Thank you for your comments Pete
I'll check out that site. Mainly a wannabe machinist, but can weld, sort of, (and blacksmith, sort of). And I have some sheet metal...
Could be a good project.
I've been reading about the different types, hvlp and hplv.
Any reason hvlp seems more popular? Was wondering about noise, since I live in the 'burbs.
Russ
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20th November 2017, 06:49 PM #7.
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HPLV (is ~100 cubic Ft/min) is used mainly because its cheap (e.g. $99 shopvac), more portable, and is supposed to work better on collecting chips from powered hand tools with point sources of dust generation. It only really works if the dust pick up point can be really close to the dust source, even then a considerable amount of fine dust can still escape to contaminate a shed.
However, HPLV cannot pick up (especially the fine) dust from most machinery especially where the dust is generated in large volumes over a wider area e.g. belt/drum sander, jointer, table saws etc. To be confident of collecting the fine dust LPHV is used but even then ~1000 cubic Ft/min (at the source of the dust) is required to achieve this.
HPLV more easily fits the small 25-35 mm hose sizes used by power tool but if the tool has a built in fan, my testing shows it is just as effective to use a 50mm LPHV system. If using a decent size DC, using a 50 mm LPHV hose will leave HEAPS of reserve collection available for general scavenging of escaped dust.
The problem is compounded by manufacturers claims regarding LPHV systems which are in practice only about half the manufacturers claims when real ducting, machinery connects, and cyclones are added. This translates into at least a 3HP DC for a small to medium size shed to 3-5HP for a large shed and even more for a very large shed.
1000 CFM is simply not achievable by standard DCs unless 6" ducting is used.
If 4" ducting is used fine dust can be reduced by using forced ventilation but it is not considered quite as effective as grabbing the dust at source.
And like all PPE, unless you remember to use it, it's not work a row of beans.
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21st November 2017, 08:42 AM #8
Bob
I never cease to be amazed at how tirelessly you volunteer all your information on Dust Extraction. I guess it is your mission in life and a very worthy one at that. I doubt we will ever know how many lives you have extended and how many respiratory diseases you may have prevented, but I am sure it is significant. To use a phrase I never use, "good on you."
Russ
Bob is our resident dust extraction guru and has conducted a huge amount of testing to back up his assertions. This is just one of his threads on dust collection:
The Generic 2HP DC
I hope you enjoy a drink, because it is a long read and you may well require some alcoholic refreshment part way through. I prefer preventative measures and start off with a drink, but each to his own. There are, of course, many more threads that you will find useful. Think in terms of the largest grunt in DCs you can afford, smooth pipes (150mm where possible) and gentle bends necking down at the last possible moment to your machine and you have made a good start on which to build. Bob has a number of modification that can be made to the machine ports and piping which improve performance (bell mouths).
Happy reading.
Regards
PaulBushmiller;
"Power tends to corrupt. Absolute power corrupts, absolutely!"
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21st November 2017, 09:19 AM #9SENIOR MEMBER
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Thank you Paul, yes I've seen a few of bobl notes and he certainly willingly shares.
Now the idea is planted, I'm starting to plan out what may be possible.
I'm sort of thinking a modified 2hp dc, installing it outside, with a single 6" solid duct to a central point, from where I will run a flexible hose to the machine in use. (they are all mobile). I might be able put it under the floor, with a port near the ww corner.
I'll do the sums and see if something bigger might be viable.
Just what I need.. Another project...
Russ
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21st November 2017, 10:26 AM #10.
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Cheers Paul. Talking about dust (including "bull") was so much part of my past day job I can't seem to shake it and these forums seem to enable me to keep doing it. The one thing we never used at work for dust control was ventilation as we wanted to keep every bit of dust out of the labs.
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28th November 2017, 03:39 PM #11SENIOR MEMBER
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Ok, just a bit more thinking out loud.
A 'cheap' 3hp system.
An outdoor cupboard, somewhat sound proof. With a baffled air discharge.
6" duct to inside, with maybe 2 outlets, one on the 'dirty' bench which has grinder, drop saw, sander, and one for the triton bench (saw/router)
Maybe another split to the bandsaw, which is under the shed verandah
Now, I don't think I need dual bags, for the use I have.
. I'm thinking, replace one filter bag with a cartridge, and close off the other side. This makes the whole thing smaller. Cartridge with higher flow compensates for loss of filter area..
I might then be able to put the air compressor in the cupboard to quiet it down.
(yes, I need to filter its input, away from the discharge...)
Thoughts?
Russ
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28th November 2017, 05:17 PM #12Woodworking mechanic
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Most larger units require the two bags/filters due to the larger air flow. My modified 2hp DC needed an extra filter unit as the increased airflow was being strangled by the single cartridge filter (it was better than the needle felt bag).
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28th November 2017, 05:20 PM #13SENIOR MEMBER
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I believe this will cause alot of back pressure therefore reducing the flow. Don't believe a pleated filter is 2x greater than a single bag for flow.
Also have read a bunch of things saying negative effects on a compressor inside a dust enclosure as it ultimately ends up sucking in dirty air.
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28th November 2017, 05:35 PM #14.
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According to BP
I assume they are needle felt bags. If so each clean filter bag on a dual bag setup contributes 1" of back pressure so 2 bags will have held 0.5" of back pressure.
Pleated filter back pressure depends on the size of the filter, but in all cases the pressure is <0.5"
So about the same
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28th November 2017, 08:01 PM #15
Another thing to check: With a lot of 3hp DE with twin bag dual outlets, each outlet is usually a lot smaller in diameter that the main inlet, so if you block one side you may have to modify the remaining outlet all the way from the impeller housing to the single outlet so that it is equal to, or larger than the main inlet diameter, otherwise it will cause a HUGE reduction in flow rate due to even more back-pressure on top of just using a single bag or even a pleated filter.
Mike.(1) Our small workshop layout __ (2) Bandsaw circle cutting jig __ (3) Spindle sander modifications __ (4) Dust Sensor
(5) Router table redesigned ____ (6) DC and where it all began __ (7) Bandsaw dust extraction build
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