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dust extraction

dust recirculation

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Types of dust extractor

Types of dust extractor

An introduction to the different kinds of extractor

bob higgins 128/11/2011 22:05:34
1 forum posts
My chip extractor is great for moving dust away from the lathe when I am sanding BUT a great deal of the fine dust comes through the filter back round the workshop.
 
I have 2 options? Putting the whole extractor outside and the 4"pipe through the wall OR
Taking off the bag filter and making a fitting to take all the exhaust air outside?
 
Apart form the obvious removing all the heat from the shop are there any other reasons to avoid this?
Eric Harvey 128/11/2011 22:08:02
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221 forum posts
81 photos
what you need is a proper dust extactor,chip extractors aren`t built to catch the fine dust
Geoffrey29/11/2011 02:04:48
10 forum posts
Hi Bob
 
Eric is correct but you can also take the approach you thought of. In most industrial setups all the collectors would be outside as this takes any dust explosion and fire risk out of the building, also removing the dust recirculation problem. Many large scale collectors use cyclone technology for the dust and chip separation from the airflow.
 
You are correct that heat will be lost. There are no other real issues doing it this way other than ensuring adequate weather protection. You also need to think about neighbours and noise and where the pipe points! Covering someones garden/car/washing/plants with dust might not be helpful. The best option is the whole unit outside and still using the bag filter. If you make up a pipe then try to fit the bag filter on the outside end.
 
If you decide to purchase a dust collector/vacuum be very careful. I am currently researching this for a forthcoming article and many are actually not suitable for fine dust collection, especially if including hardwoods or MDF. You need one specifying a category M or H filtration level. many are category L which is not sufficient so you would have exactly the same problem as you have now (less of one but still releasing dust).
 
Hope this helps Geoffrey (ex HSE Inspector)
 
 
BillW29/11/2011 10:48:43
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711 forum posts
21 photos
I have no HSE or Environment qualifications but I would have thought that if you are classed as industrial it would be illegal to discharge dust into the environment maybe even as a private individual.
 
Do you have any information on this Geoffrey ?.
 
I am experimenting at the moment with a domestic extractor to take the fine dust from turning (mini lathe) and blowing it outside, I have no qualms about this because I live about a mile from a quarry and land fill site, the dust on the road is unbelievable despite complaints from residents for many years and the road sweeper coming past at least once a day..
 
Bill.
daveO29/11/2011 17:20:28
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250 forum posts
32 photos
bob welcome
i actually tried this myself with the chip extractor from my table saw once, and yes it will take the heat away very rapidly- but i also found that at this time of year because the filter is really nothing more than a cloth bag I also found that even during the day it was getting damp and quickly clogged up, thus cutting down the level of performance.
I think eric's suggestion would be the best all round.
 
bill
i think venting to atmosphere is permitted at certain levels provided the exhaust is above a certain height, as for home use I dont think the regs apply or can be enforced, but maybe geoffrey could confirm that.
 
and geoffrey whilst on this subject maybe you could give us your opinion on the reccuring
topic of the need or not to earth ducted extraction systems whether they be steel or pvc
regards dave
BillW29/11/2011 21:45:07
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711 forum posts
21 photos
A bit of information that some may find interesting.
 
It would be over 15 years ago I was working on a machine in Denmark, dinner time came along and all the machines shut down then I kept hearing a "hiss" every few minutes, on investigating I spotted way up in the ridge of the factory little water jets spraying water mist.
They were making MDF furniture parts so I presume it was for dropping the dust that was not extracted.
The MDF dust had even got into the electrical cabinet I was working on behind the machine.
 
Bill.
steve h29/11/2011 23:17:21
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403 forum posts
128 photos

Hi Bob,

I found exactly the same issue with the big chip collectors and finding a constant layer of dust on everything started to bother me.

I started at looking at various ways to control it - but found venting it outside a non starter due to the heat loss (as mentioned by the lads)

I have spent a lot of time (and money) on this and found that the way for me to tackle this was to put in a first line of good extraction and then an air cleaning secondary system.

The first issue is that all vacuums pull air through motors one way or another and filters have to be in place as all the dust etc will damage them.

As Geoffrey mentions - cyclonic extraction is the way forward and this is really how and when it all started to get really interesting for me.

Anyway, to cut a long story short, I did install a small cyclone system with a dump bin just before the extraction unit and it works fantastically well. Hardly any of the dust and bigger wood particles get anywhere near the actual extractor itself because of the cyclone. I also change the paper filter bags on the extractor as per manufacturers instructions and wash the other cotton bag very frequently, giving me excellent machine extraction.

I then have an overhead fine filter air cleaner which hopefully picks up anything my extraction system misses. (which runs all the time I am in the garage)

I do find the biggest issue is the hand-held power tools and controlling the dust on these - and as everyone has mentioned - MDF is a nightmare for creating massive volumes of airborne particles.

That's my next purchase - a very small cyclone unit with dump bin for my small vacuum system - if the dust does not get to the vacuum, you are eliminating most of your problem.

As a matter of interest, both mine run down to 0.5 of a micron filtration..

There are loads of posts from lots of people about cyclonic extraction, just type it in the search bar above to see all the posts.

Steve.

Mike Jordan01/12/2011 15:22:16
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166 forum posts
17 photos
My own solution is to put the extractor in a room out of the working area. Yes it takes away heat but that has never been an issue even with only a two KW fan heater keeping me warm. Its also quieter and you gain a little space!
The only other method would be to use one of the fine filter cartridges in place of the top bag. Have a look at them in the axminster catalogue.
I had a similar set up to yours until a beam of sunlight showed me how much rubbish I was inhaling. The air filtering machines may improve things a little but they are only sharing the dust with your lungs!
All effective solutions cost money but not sorting the problem can make you unwell.
Mike,
Geoffrey23/01/2012 13:19:51
10 forum posts
Hi everyone, sorry for the lack of any response since my last post., particularly to BillW.
 
If you were 'industrial' you would be subject to emmisions controls. Even as a private 'user' there is always the possiblility of a neighbour complaint to, or the local authority Environmental Health Dept spotting a problem, and they could intervene. Hence to comments about where does the pipe point etc.
 
If the extractor/collector is inside you should only be using a H designated system (vacuum cleaner type) or a bigger system that quotes a capture standard (preferably 0.5 micron). The H standards for - surprise HIGH standard of filtration and unfortunately many vacuum units sold for this very purpose can be L - guess what that is.
 
Cyclones are not the total answer as they are not all good at seperating from the air very small particles. They are excellent for larger chips. I am intending building a cyclone, possibly for a magazine article - very unlikely to be this magazine! and I will top it off with a HEPA filter. The advantage of doing it this way is the HEPA filter will be the last barrier and will take a long time to become clogged as almost all airborn bits will be cycloned out with the filter giving nice clean air back into the workroom. Cyclone design is, or can be, a very scientific process and I've had to try to read some pretty intense stuff to deside how I am going to do this. There are various plans available online and I have to say some are pretty useless.
 
Treat any wood dust as potentially harmful. MDF gets a lot os stick but how many know beech is rather bad? and many others. Spalted timber even more possibl hazards due to spores becoming airborn. This is useful http://www.hse.gov.uk/pubns/wis30.pdf
 
Mike Jordan mentions the beam of sunlight. This is an actual method used for investigating dust problems. Usually using a powerful sotlamp to get the same effect - it can be very enlightening in ever sense! Try using a powerful torch with most lights switched off iunless you hit the two days this year when we have sunlight
 
Have a good year and remember the next catchphrase - 'Thats Magic' - and how to make fingers disappear' with much sypmpathy and apologies to Paul Daniels and also wishing him a speedy recovery. I hope he does not mind being used as an example of someone with finger/hand manipulation abilities beyond almost anyone else, who still managed to get it wrong with a circular saw - a reminder to all how easy it can be.
Geoffrey
 
 
Geoffrey23/01/2012 13:21:14
10 forum posts
and apologies for some of the stupid spullin in my last post!

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