Still trying to get my head around dust

[Wizard9999]

All

More dust questions.

As I understand it, when it comes to HVLP extraction size matters. The benefit of 150mm ducting over 100mm is not in relation to the diameter but to the area of the cross section of the hose, i.e. 150mm is not one and a half times better than 100mm but rather more like two and a bit times better (ie 75 x 75 x 3.142 vs 50 x 50 x 3.142).

But for both my bandsaw and tablesaw the inlet that I would attach any extraction pipe to is 100mm.

So my first question is whether there is benefit to using 150mm up to the inlet to a machine, or whether all the benefit between extractor and inlet is lost as soon as the diameter is reduced to 100mm for the short section of the inlet itself?

I also understand that there is a limit to how much the diameter of an HVLP extractor duct can be reduced (though I am yet to bottom out what this limit is as I have read conflicting views). On my router table I will have extraction below the table and behind the fence, the plan being to 'split' the air flow between the two just before the table. My second question is whether, having 'split' the airflow the restriction of how much I reduce the diameter is in some way aggregated between the two 'split' flows or whether each needs to be viewed individually when it comes to any reduction in diameter?

As ever, any views and / or experience much appreciated.

Terry.

 

[chataigner]

Restriction of flow is relative to a combination of diameter and length. A short run of pipe will not benefit much from being a larger diameter, but a long run will. There is no absolute rule, but I would suggest any runs of say 3m or more it would be worth using 150mm. Short runs, such as the machine inlets you mentioned can be in 100mm with no significant degradation.

As for the split before the router table, the two runs of 100mm equate roughly to one of 150mm (ie 100x100x2 roughly equivalent to 150x150) so all other things being equal, the flow should divide nicely between the two without loss of performance.

Edit - dont forget 110mm drain pipe - a little better than 100mm and freely available.

 

[Rod]

Due to my current layout, none of my extraction system is "fixed" in situ but the main extractor is a Record DX 5000 which uses a flexible 100? pipe.
For my Router Table (Norm's design) I use 62 or 75mm?? plastic water piping, controlled by a simple rotating flap valve to adjust the suction between the fence and the lower chamber (some operations only require fence extraction).
The water piping connects into the main run with a flexible transition piece.
Plenty of suck even only using one motor and never had a blockage.

Wooden knob controls valve.

Rod

 

[tracerman]

Terry , thanks for raising this vexing and interesting question . I don't have an answer , but I do have the same concerns . Back in the eighties I bought a Startrite Cyclair 75 . It came with a 150mm flexible tube of about 2.5 metres long . This was connected to 100mm brown underground type tubing with push-fit joints , elbows etc . I suppose my question is , by reducing the flow down to 100mm ( over a total length of about 6 metres ) have I deprived myself of the full flow , or has the restriction actually increased the flow at the point of collection ? . I can imagine that if the system had been at 150mm throughout and 150mm at the point of collection ( probably not practical ) then the suction would have been brilliant .
Is there a simple way of measuring the suction at the various points of collection I wonder ? . In recent times the 150mm flexible has been reduced in length to about a metre after which it passes through the extractor shed side , across a short 1 metre flexible( 100mm ) and then into my garage where it is rigid 100mm for about 6 metres overall . Am I getting the best from this system ? .

Steve

 

[chataigner]

Terry , thanks for raising this vexing and interesting question . I don't have an answer , but I do have the same concerns . Back in the eighties I bought a Startrite Cyclair 75 . It came with a 150mm flexible tube of about 2.5 metres long . This was connected to 100mm brown underground type tubing with push-fit joints , elbows etc . I suppose my question is , by reducing the flow down to 100mm ( over a total length of about 6 metres ) have I deprived myself of the full flow , or has the restriction actually increased the flow at the point of collection ? . I can imagine that if the system had been at 150mm throughout and 150mm at the point of collection ( probably not practical ) then the suction would have been brilliant .
Is there a simple way of measuring the suction at the various points of collection I wonder ? . In recent times the 150mm flexible has been reduced in length to about a metre after which it passes through the extractor shed side , across a short 1 metre flexible( 100mm ) and then into my garage where it is rigid 100mm for about 6 metres overall . Am I getting the best from this system ? .

Steve

When the flow encounters a reduction in pipe size (or any other obstruction), the velocity must increase to permit the same volume of air to pass in a given time (flow). The higher velocity in a smaller pipe is no big deal over a short distance, but the friction is higher and so the flow reduces a bit. The longer the small pipe the greater this effect. If you test the air flow with your hand over the end of the pipe, the higher velocity gives the impression of lots of air movement, but there is less flow. At the open end of a big pipe, the sensation is less impressive as the velocity is lower, but the flow (and therefore the dust carrying capacity) is higher.

 

[Wizard9999]

Steve

I think the short answer is yes. I saw a Youtube video where a guy connected 100mm and 150mm hoses to his HVLP extractor, the difference in airflow was pretty significant. I have been looking for the video for a few minutes but can't find it, but if I come across it I'll post a link for you.

Regards,
Terry.

 

[Wizard9999]

Steve

This is the video I was thinking of:
www.youtube.com/watch?v=hXP_2QvtKOg

At least I hope it is, I can't view YouTube in the office so can't check the link. Hope that helps.


I had been thinking of fitting a system of rigid 100mm ducting around the workshop, but some fo the runs would have been pretty long and would include a number of bends. My revised (still not fully formed) plan is to simply move the extractor to the machine in question and hook the machine up when it is in use, using a much shorter length of 150mm flexible hose. I will not be doing any calculations, but I am guessing the use of flexible hose(which creates more friction than rigid) will be more than offset by increased diameter, reduced length and fewer bends. I also realise it may be considered a bit of a faff to hook up each machine when I use it, rather than just opening and closing blast gates, but over and above better performance I will have saved myself the time, effort and money of installing the rigid pipe system. Plus Rob will be pleased as it means the shelf will around two sides of my workshop will still be available for his coffee mug when he comes around .

Terry.

 

[RogerS]

Here's my take.

For most 'light' users ( and 'light' is not meant in any derogatory sense) then 150mm is overkill.

Roger's Rules of Dust Control

Rule 1 - try to remove as much dust at source as you can
Rule 2 - Rule 1 is impossible to do very well on most SCMS. The Kapex is one exception that I know of.
Rule 3 - don't confuse chippings and dust. They are best handled differently.
Rule 4 - Rule 3 only applies if you generate a lot of either - especially chippings.
Rule 5 - what works for one person is not necessarily the best for another

When I first started out I had a small router table, 6" planer and a thicknesser. I used a wet'n'dry type vacuum with various adapters to fit the outlets (when present) on the machines. It worked tolerably well but the final pipe to the vacuum could get clogged up with over-energetic planing - Rule 3 applies. I applied the hose to whatever machine I was using at the time.

I then played around with a small cyclone - not because I thought it might be any good but because it was the 'cool thing' to do. Having said that they DO work! I found my box started to fill up very quickly but that was down to bad design on my part. I could not get hold of a large tin drum which would have been better. However, never under-estimate the dust created when emptying the box into whatever bag you are going to use to take the stuff to the tip.

Then I went through a phase of slightly larger machines but all wheeled. Same sort of extraction....connect-on-demand.

Then I started getting more serious, bought a large Sedgwick planer/thicknesser, drum sander, larger table saw. It soon became apparent that I needed a better way of getting rid of the stuff especially the chippings as I was creating huge amounts. If I used the same extraction system for chippings and dust then I couldn't find anyone interested in taking them. But - :idea: - I realised that machines can actually be divided into two categories. Those that create humungous amounts of chippings and not much dust (the P/T and the spindle moulder) and those that create dust and small chippings (table saw, drum sander, SCMS, router table, linisher). So I got a large Axminster 2200 100mm extractor for the chippings and they went to the stables.

A Camvac took care of the dust. So two separate dust extraction systems. I move the hose between PT and spindle moulder. For the dust extraction I have blast gates on three of the machines and a hose that I move between router table and SCMS - only I rarely ever connect them up which is stupid..especially the SCMS. Thing is that the hose ends up across my walkways if I permanently connect to router table or SCMS. The extraction on the SCMS is about 60% I'd say.

I also have two large recirculating filters that I keep forgetting to switch on. And a dust mask for when I change bags on the Axi 2200 or empty the Camvac....which reminds me, I ought to check it.

Hope that helps

 

[chataigner]

Interesting point about machines that make fine dust and machines that make chippings... I shall reflect on that for my set up. What I have (1.5hp basic extractor with bag in the attic above the shop, cyclone/drop box in the shop, then smooth 100mm pipe with blast gates to each machine) works well on almost everything, but is not very good at picking up all the dust from the TS.

 

[Wizard9999]

That's one hell of a sturdy looking fence Rod :eusa-clap: . At the risk of high jacking my own thread (is that possible :? ), do you have more pictures or can you direct me to a past thread that does if I have missed it?

Terry

 

[Wizard9999]

For most 'light' users ( and 'light' is not meant in any derogatory sense) then 150mm is overkill.

Not completely sure I agree with this, surely dust and chips are dust and chips irrespective and if 150mm is better, it is just better. I can see where you are going if the point is that if you are a 'light' user a massive extra hassle and expense for 150mm may not be worthwhile, but as I am just talking about a short run of hose from extractor to machine I can't see why I would not chose the better option.

Roger's Rules of Dust Control

Rule 1 - try to remove as much dust at source as you can
Rule 2 - Rule 1 is impossible to do very well on most SCMS. The Kapex is one exception that I know of.
Rule 3 - don't confuse chippings and dust. They are best handled differently.
Rule 4 - Rule 3 only applies if you generate a lot of either - especially chippings.
Rule 5 - what works for one person is not necessarily the best for another

These are a really neat set of rules for dust extraction, I like them a lot :eusa-clap: .

Clearly 1 is a no brainer. My workshop is unlikely to have an SCMS in it, I find the front to back dimension a real pain (I think this is a massive design benefit of the Kapex and one of the expensive Bosch models from what I have seen online) and I would expect it will be little used as I am kind of falling into the Norm school with my tablesaw and sleds being used for those type of cuts.

Point 3 is the one that has really been messing with my head, but this is where the insight of rule 4 comes in. I think I have been worrying too much about the theory of it all and not actually thinking about it practically. So I have after far too much deliberation decided to do with a chip extractor, with a cyclone front end to get the big stuff and a filter cartridge to get the really small nasty stuff at the back end. I will then use my bargain Lidl wet 'n' dry for hand held power tools such as the track saw (virtually no dust when connected) and router (still seems an awful lot of dust even with the vac attached. Yes, no doubt this will mean I will have dust mixed in with clippings, but see rules 4 and 5.

Thanks for for helping me get out of my state of analysis paralysis!

Terry.

 

[RogerS]

Hi Terry

Glad to have helped.

Yes, 150mm is probably better but you'd need to have a beefier extractor to get the airflow. For a one-man band who only ever has one machine running at a time then I still say that 150mm is overkill.

You'll never pick up all the chippings from a router simply because it chucks the stuff out all over the place and it will also depend on how clever the chip guards are in enclosing the stuff.

I'd ring up RB Industrial and get their advice. This is the one I got DONALDSON P18116, TORIT BPP22269 Equiv CARTRIDGE FILTER from them. As an aside I weighed a new one (about 5kg) and one that was pretty much blinded with dust (9kg).

I keep meaning to measure the pressure drop across mine with a manometer. Ideally it should be zero which means that the air is passing freely through but leaving the dust behind. As it starts to blind and reach the end of its life then the pressure drop will increase. Probably about time I got a new one.

 

[Wizard9999]

Hi Terry

Glad to have helped.

Yes, 150mm is probably better but you'd need to have a beefier extractor to get the airflow. For a one-man band who only ever has one machine running at a time then I still say that 150mm is overkill.

The SiP I have ordered is 3HP and claims to have an airflow 2526m3 per hour. I've seen a number of comments elsewhere from people saying they don't get that level of airflow but I have a theory on that. The extractor looks like it has a 150mm outlet to which SiP fit a splitter into two 100mm outlets. If I were SiP I would measure the airflow from the single larger outlet, without the splitter on. Then if those that have it are measuring the airflow from one of the 100mm outlets it could explain at least some of the difference.

I'd ring up RB Industrial and get their advice. This is the one I got DONALDSON P18116, TORIT BPP22269 Equiv CARTRIDGE FILTER from them.

I will do as soon as the extractor arrives and I can be sure of sizes. Is it too cheeky to ask roughly how much yours set you back (just so I have some bench mark to test quoted prices against)?

Terry.

 

[Rob]

...And just for the sake of completeness given readers may well use this thread as a reference when considering DX for themselves....Terry also has the "cant live without" 3M 7500 with P3 filters so if he is using the little Vac for hand tools then that would supplement any risk of below 5 micron particle inhalation.
I use the 7500 all the time for any fine sanding operations IN ADDITION to other DX and particularly when turning and power sanding which is literally a cloud creator of fine dust. It works fantastically well, and I don't believe any DX environment should be without one.

 

[Wizard9999]

...And just for the sake of completeness given readers may well use this thread as a reference when considering DX for themselves....Terry also has the "cant live without" 3M 7500 with P3 filters so if he is using the little Vac for hand tools then that would supplement any risk of below 5 micron particle inhalation.
I use the 7500 all the time for any fine sanding operations IN ADDITION to other DX and particularly when turning and power sanding which is literally a cloud creator of fine dust. It works fantastically well, and I don't believe any DX environment should be without one.

That is a very good point Rob. I know the you can get fine dust bags for the Lidl vac down to 1 micron I think, but they only seem to be available as an import from Germany at a pretty steep price (even at the current favourable exchange rate) and I have yet to loosen the padlock on the old wallet far enough to get any. But the 3M 7500 is brilliant. For me an absolutely key feature is just how comfortable it is, which means I am never chomping at the bit to get it off, once on, it usually stays there until I leave the workshop. I have no idea how long fine dust stays in the air, but I bet given its size it is a pretty long while, so wearing the mask and then taking it off immediately after finishing using any particular tool is presumably not good practice.

Terry.

 

[RogerS]

You're probably looking at around £80 at a guess but probably a bit more.

I cut a circular piece of MDF slightly larger than the circumference of the metal cylinder onto which the normal bag goes. Then fixed blocks to the inside walls of that cylinder and then fasten the MDF to those. The seal is pretty good...I might have stuck a bit of window sealing tape around the circumference...can't remember.

Then a hole cut in the MDF slightly smaller than the OD of the cartridge and simply stuck the cartridge down with silicon.

 

[RogerS]

A picture 1000 words

axi 2200

 

[TrimTheKing]

Another consideration, if it hasn't already been mentioned, is an air cleaner hat you turn on and leave for a while like the Jet AFS-500 or similar which I and maybe a couple of others in here have.

I have it on the ceiling and turn it on when I use my first dust making machine and it has a number of settings Slow/med/Fast and 2h/4h/8h. Once I am leaving the shop i put it on fast for 8h which then turns it off at the end. The amount of airborn dust it has picked up is frightening, even With using a 0.5m filter on the DX!

Well worth the investment imho.

Cheers
Mark

 

[RogerS]

Another consideration, if it hasn't already been mentioned, is an air cleaner hat you turn on and leave for a while like the Jet AFS-500 or similar which I and maybe a couple of others in here have.

I have it on the ceiling and turn it on when I use my first dust making machine and it has a number of settings Slow/med/Fast and 2h/4h/8h. Once I am leaving the shop i put it on fast for 8h which then turns it off at the end. The amount of airborn dust it has picked up is frightening, even With using a 0.5m filter on the DX!

Well worth the investment imho.

Cheers
Mark

S'wot I said up there !!

 

[TrimTheKing]

Yeah couldn't be 4rsed reading back! [emoji8]

 

[Woodbloke]

Dust extraction is a mine field, period... and you need to really get your head round it. This is a little piece I did some time ago, which you can find on the Ax site.

http://www.axminster.co.uk/information- ... on-systems

Bear in mind that this has been checked by the techies at Axminster and the info contained is (as far as I'm aware) correct. Hope of some use - Rob

 

[Wizard9999]

Well as you say Rob, what a mine field this is!

Having assembled my new extractor today I have been doing some online research into the topic of filters. One thing that does frustrate me a bit is the fact that manufacturers of woodworking equipment don't seem to quote the filtration of a machine based on the standard classification used by the filtration industry. In some cases (such as the article Rob linked to above) there is reference to an alternative classification used by HSE that I have yet to look into, but so far I have only found Axminster giving this info, but even then I think they only give this for HEPA rated kit.

It seems many manufactures will make claims such as 'filters down to 0.5 microns', but the question I now understand one needs to ask is "what percentage of 0.5 micro particles are retained by the filter"? I fear this is a topic where the marketing men may well be playing fast and loose with the technical fact and may be giving some customers a false sense of security about the benefits of their chosen dust extractors. If a machine catches 5% of 0.5 micron particles it is 'filtering down to 0.5 microns', but many buyers may think that statement thinks it is capturing virtually all 0.5 micron particles.

It would, IMHO be much better if they used the standard classification all the filter manufacturers seem to use. In which case if you buy a machine and it says it has F7 filtration you can look it up and see it will retain 85-95% of 1 micron particles and 60-75% of 0.5 micron particles vs an F8 which will achieve 95-98% and 80-90% for 1 and 0.5 micron respectively.

Terry.

EDIT: I think I was a little harsh on Axminster, whilst they only use the M class point on HEPA machines, for many others they do quote the percentage captured of particles of various sizes. I think they are head and shoulders better in terms of info provided than anyone else I have looked at so far.

 

[Woodbloke]

It seems many manufactures will make claims such as 'filters down to 0.5 microns', but the question I now understand one needs to ask is "what percentage of 0.5 micro particles are retained by the filter"? I fear this is a topic where the marketing men may well be playing fast and loose with the technical fact and may be giving some customers a false sense of security about the benefits of their chosen dust extractors. If a machine catches 5% of 0.5 micron particles it is 'filtering down to 0.5 microns', but many buyers may think that statement thinks it is capturing virtually all 0.5 micron particles.

Correct, spot on, 10/10, gold star, treat yourself to a beer or twelve tonight bscene-drinkingbuddies:
Whichever way you slices it, it's immensely difficult to work out how efficient different dust extractors are. Fr'instance, Camvac are pretty good and as I remember do seem to quote 'filters down to 0.5 microns'...but of what percentage of the dust going through it? Camvac also don't have CEE certification (or so I was informed the other week)... - Rob

 

[RogerS]

Interestingly I see that a woodworking firm was recently prosecuted and fined by HS&E for poor dust extraction.

 

[Rod]

I always assumed that "down to 0.5 microns" meant that all particles above that figure were removed.
IE particles finer got through?

Rod

 

[wallace]

I found something quite amusing recently dust related. I have an extractor housed in a lean too. Whilst using the spindle moulder I found that chippings were getting chucked back at me which was weird as the hood works really well. When I checked the extractor the bag was full and so was the filter bag on top, right to the top.

 

[DaveL]

I found something quite amusing recently dust related. I have an extractor housed in a lean too. Whilst using the spindle moulder I found that chippings were getting chucked back at me which was weird as the hood works really well. When I checked the extractor the bag was full and so was the filter bag on top, right to the top.

Done similar to that with my thicknesses, that's why I have tried to make some sort of warning device when the bin fills up.