Dust extraction info please

[andy king]

Well at the risk of stirring up a hornets nest, I looked at various types of extractors recently, a single motor Camvac on a 63mm bore pipe system,
a floor oil drum twin motor on a 4in hose from Draper, a Startrite bag over bag impellor type on a 4in hose, and a DeWalt standard vacuum cleaner type using a 30mm hose, plus a Dust Deputy Cyclone attachment.
While the figures quoted from various manufacturers are great for hopefully making a decision, I prefer to see how they perform in the real world.
An example here is the Startrite impellor model (MDE ECO) It's quoted at 800 cubic metres per hour, which equates to 222litres per second, while the Camvac quotes 54 litres per second which equates to 194 cubic metres per hour, so you would assume the Startrite to be more efficient.
I tested each model using the same volume of waste made up of dust, chippings and shavings, each using a 2metre length of appropriate hose, so any bends, blastgates and pipe runs are eliminated to keep the results as 'clean' and error free as possible. The exception was the DeWalt as it comes with a standard 4m hose, but as it's designed for a different waste remove in general, I still tested it for efficency in dealing with bulk volumes.
The results were not comparative with the actual Cubic Metres Per Hour/Litres Per second quoted by the manufacturers.
Here is a quote from my notes taken during the test.

Just to confuse further, extractors tend to give air volume figures relating to litres per second or minute. This equates to 1litre per second = 2.119cubic feet per minute.
Even knowing these calculations count for nothing if the machines don’t perform, I need to see how good they are at picking up waste.
The Dewalt can hold 27 litres of dry waste, so that was my starting point.
While a little unfair on this one, especially as it has a hose longer than an elephant’s nose, the Draper, Camvac and Startrite were all tested with 2 metres of flexible hose of either 100mm, (Draper and Startrite) or 63mm (Camvac) so any timings are based on the same criteria.

The DeWalt shifted the whole amount in 1minute 16 seconds. Using the DeWalt as the power source for the Dust Deputy, I timed the same amount. The even longer hose run put the collection time up to 1 minute and 22 seconds, but more importantly, the Dust Deputy got most of it, not even a mugful made the DeWalt, so it’s easily as efficient as it claims to be.
Moving on to the volume extractors, the Draper was first and swallowed the lot in a very speedy 13 seconds.
Despite the identical hose bore, the single motor with its lower power in the Startrite became evident in this test, taking 46 seconds.
Camvac however, having a 63mm bore, but twice the power coped really well, getting it all away in 19 seconds.

Science may throw up quotions indicating what should be best, but in reality, the performance proves more worth, well, for me at least.
The Startrite's quoted higher volume of air shifting should have made it better, and with a bigger hose bore, should remove it quicker, yet the Camvac, with about quarter the air pulling capacity took the waste away in just over quarter of the time.

Hope this has helped rather than confused the issue...

Andy

 

[stevebuk]

well guys what can i say, all these facts and figures to mull over. My cabin is 10feet x 14ft x 8ft high and i really just wanted to put in a system that is quiet, and i dont have to connect it to the tools, but if you suggest it is better to do this, then i will look into this route.
i mainly cut oak,iroko ,pine and zebrano, the time i actually spend cutting is minutes, as i only use small pieces of wood in my hobby , and i have 3 rather large opening windows too.
i am going back to re-read some more of this facinating post, some peoples knowledge of the tools is shear brilliance.

 

[engineer one]

interesting steve, that i think at least two of the woods you use are now considered to have quite dangerous air borne dust :?

i am sure i will be corrected, but i understand there are now cautions re iroko and zebrano.

things is we all say "oh i only cut for a couple of minutes and i have windows etc" however, this week i have been looking for my router table, and decided i might as well tidy up too i am amazed as to how much and where the dust was.

however the biggest problem is in fact what happens when you transfer the dust from the vac to your disposal situation. i use a trend vac and it is great, but i do need to see what i can do in terms of emptying without covering myself in dust :roll: no matter how far over i put the black bag, the dust still gets to one side somehow

actually of all the comments you made the one which will cause you most problem is the noise one :lol:

good luck

paul :wink:

 

[andy king]

Hi Paul,

i am sure i will be corrected, but i understand there are now cautions re iroko and zebrano.

Well I can certainly vouch for iroko! I used it off and on for years with little or no extraction and suffered no problems, but being exposed to it for a longer period during my boatbuilding days I all of a sudden had a reaction, involving itching, rashes, swollen eyes, breathing problems, swollen glands, everything you would never want!
Now I am sensitised to it, so a whiff of the dust, or minimal contact can trigger the reactions again. I now occasionally find other hardwoods can have me tingling as well if I'm not careful, so the need for good dust control is certainly important. I reckon previous exposure wasn't so bad as it could have been a few years back as the tools that make fine dust were not so prevelant, I was doing mostly handtool work, while the stock was converted on a saw and planer hooked up to extraction.
When I got a reaction I was sanding back big hatch combings with a belt and random orbit sander is an old boatshed with no extraction, so clouds of it were in the air, and all I had was a paper mask.
You learn by your mistakes... :roll:

Andy

 

[Jake]

Science may throw up quotions indicating what should be best, but in reality, the performance proves more worth, well, for me at least.
The Startrite's quoted higher volume of air shifting should have made it better, and with a bigger hose bore, should remove it quicker, yet the Camvac, with about quarter the air pulling capacity took the waste away in just over quarter of the time.

Hope this has helped rather than confused the issue...

That will be the difference between high and low pressure. If you are trying to remove a whole bunch of waste at once, the high pressure vac won't flinch at its hose being nearly full with waste, it'll just suck like hell and keep sucking it through at pretty much the same speed until the waste has gone.

The low pressure one will struggle to keep up its performance as the large amount of waste in the pipes all at once will reduce by a big proportion the amount of air it can (relatively, weakly) suck through the reduced effective bore of the pipe. As it is is relying on the volume of air it moves to shift the waste, its performance will fall off commensurately.

To be fair, performance in that test cannot be directly related to fine dust collection - it's much more complex than that as those test conditions are pretty extreme compared to normal conditions attached to a running machine.

 

[Jake]

Couldn't agree with you more re the Camvac. I bought a twin-motor rebadged (Tyme machine) Camvac hoping it would give me a decent amount of suck. My small Earlex vacuum cleaner from Homebase sucks better.

Unless you are exaggerating for effect, there is something wrong with it. I have noticed that, subjectively, and oddly (and no doubt incorrectly in fact), the third motor seems to add more than a third extra airflow (it turns my 100mm extractor from an a bit too feeble-seeming rush to a blast), but even with two motors on my Camvac outsucks my CT44, which in turn I would expect (maybe wrongly) to outsuck your Earlex.

*warning, no measurements here whatsoever*

 

[andy king]

Hi Jake,

I appreciate that the amount of air speed can have a big effect, (one of the reasons why I chose to use identical hose length on the units designed to deal with bulk waste from planers etc) but none of the machines were forced into the pile of waste, simply allowed to pick up at their own speed so that they were not clogged or overworked at any time.
Bends, long pipe runs, branches and blastgates all have an adverse effect on the extractors ability, so a single short hose seemed a fair compromise to show each extractors ability to deal with volume.
As for a narrower bore coping with bulk waste due to increased suction, this is not always the case. I have a 63mm system in my home workshop, and taking a full width shaving on a 225mm piece of pine will often overwhelm the pipe as it cannot deal with the shavings in a restricted bore.
Startrite and Draper both used a 4in hose, but Startrite quote a massive cubic metres per second air flow, yet the test shows the Draper as a far more efficient tool for fast waste removal. Motor power obviously is a factor here I would say, but for me, practical is better than theory, hence my method testing using a like for like method.
Hooked up to a machine, you have to contend with the machine's own dust kits efficiency, plus adaptors etc. to use it, which while giving a similar reading off of one machine, effectively diminish the extractors own efficiency, which can ultimately affect the result, and can only be relevant to the tools they are tested on.
Maybe not a full on scientific approach, but as I said, seeing the extractor do what it can do at what could be said is it's full whack, is an easy indicator rather than being snowed under with, or relying on figures that may not give a true reflection on ability in some instances.

Andy

 

[Jake]

The point is that the airflow is not the determining variable though - the low pressure Startrite would wolf up a fair bit of waste straight away because it has unobstructed pipes and it's shifting big volumes of air, but as soon as that waste enters its pipes the resistance its motor encounters trying to suck more air through the pipes and through the waste increases, and as it is low pressure it isn't good at overcoming those new resistances, so the airflow rapidly drops below the specified level.

The same happens to the high pressure system, but it is much more powerful at overcoming increased resistance, so its performance won't drop by anything like the same proportion of its specified airflow.

The airflow stats (for all) are all given in static conditions with no filter clogging, clear pipes, etc so can't be directly compared for the above reasons.

I wasn't saying that the narrow bore is good, far from it. It just happens that the high pressure unit you used had smaller pipes because they can get away with it more than a low pressure machine can, and because it increases the airspeed smaller machines can pull (if they are high pressure). With either type the bigger the pipe the better, but you soon hit a ceiling with high pressure stuff at 100mm max because there is a limit to the volume they can shift, unlike low pressure stuff which can go up and up and up (and therefore ultimately win in terms of performance, without question).

 

[andy king]

Hi Jake,

At the risk of getting bogged down in figures and statistics, the units I used were the Startrite MDE ECO (bag over bag) the Draper DE2400 (floor standing drum type) and the Camvac GV286W (wall mounted bag below the unit type)
The Startrite and Draper both had 100mm hoses, the Camvac had 63mm, but is also available in an identical guise but with 100mm hose, so all are designed to deal with bulk workshop waste from machinery.
The bag over bag Startrite, while having the best quoted airflow, was the worst at dealing with bulk waste at it's own pace, but lacking a finer filtration, doesn't deal with finer dust as well either.
The Camvac and Draper both have fine filtration down to 0.5 micron (although efficiency of its sucking power becomes compromised once these filters start doing their jobs) but what I was trying to get across was the fact that despite figures stating high air flow, and thus implying a device capable of outrunning others, it wasn't the case, the two others are more capable at dealing with bulk waste, of which all three are designed for, and sold to do.
I'd be more inclined to hook a Camvac or Draper up to a small extraction system, but the Startrite would lose far to much suction over distance to consider it, and I made the point in the test, it's a close quarters option.
In truth, the Startrite didn't wolf up any huge volumes at the start, it simply ticked over where the other two did wolf it up, and all three are designed to deal with waste from machinery.
Even the small DeWalt HPLV vac pulled well, only the hose bore compromising it. The feature was to see if one extraction type was enough, or whether you need different options for different applications and what can be expected of them.

Andy

 

[Nick W]

I have noticed that, subjectively, and oddly (and no doubt incorrectly in fact), the third motor seems to add more than a third extra airflow ...

I would guess that the cause of that is the other two motors sucking air back through the unpowered motor and the hose. I get the same effect on my 2 motor Record machine. It makes having independently switched motors rather pointless in my view. Certainly I never bother with just the one motor.

Now someone is going to say that they have anti-suckback devices on the motors, aren't they.

 

[andys wood shed]

I have noticed that, subjectively, and oddly (and no doubt incorrectly in fact), the third motor seems to add more than a third extra airflow ...

I would guess that the cause of that is the other two motors sucking air back through the unpowered motor and the hose. I get the same effect on my 2 motor Record machine. It makes having independently switched motors rather pointless in my view. Certainly I never bother with just the one motor.

Now someone is going to say that they have anti-suckback devices on the motors, aren't they.

I think Camvac man offered an explanation here

Andy

 

[Nick W]

That really is a sorry excuse of an explanation. What happens when both/all motors are on and you get an unnoticed blockage? Presumably the first motor to fail allows the others to survive. :roll:

 

[Jake]

I missed that Andy, and thanks Nick too - it makes sense.

I think what camvac bloke was getting at is if one motor stops because it overheats, it still gets cooled down by the others so has more chance of surviving. Makes sense, a couple of times I've run mine (with ear defenders on while planing) until one of the motors is screeching nastily after the drum has filled up totally...

One of the downsides of them is not being able to tell when the solid drum is getting full...

 

[andys wood shed]

One of the downsides of them is not being able to tell when the solid drum is getting full...

I have the wall mounted model with twin motors so you can see when the bag is full.
I also run an interceptor bin when I'm planning. works surprisingly well and makes emptying quick and easy. This might be an option for you to try Jake

Andy

 

[Jake]

Yet another thing to squeeze into what has become a very crowded space... nah, I've learnt my lesson I think, half an eye on the hose and if you can see shavings on the move through the hose, it's getting full. But thanks anyway.

 

[druster]

where did you get the dust deputy from?
can you run it on 4" through a camvac ?
just wondering as I would like to improve the efficiency of my current setup.

 

[ivan]

Connecting an induction motor driven bag collector to 2 1/2" pipe will strangle the air flow down to 100-200 cfm which is not enough to capture the most dangerous fine dust. Most modestly priced mobile type bag collectors are best used with a couple of metres of hose and moved from machine to machine. Look for a 2 micron bag/filter at least. If you add a short fixed pipe run, 110&160mm soil pipe is readily available and not too expensive, especially if you have a small shed!

PS. testing by 'hoovering' up a dust sample will give an advantage to the vac type extractors which give a much lower pressure in the hose - that's why vac cleaners are made that way. The Sartrite big air mover will be better at collecting from a machine dust port.