Fine dust extractor

[dzarek1410]

Hello Advice Please
I've got a small workshop already set-up with Scroll saw. bandsaw, belt/disc sander and they are ducted via 110mm to the ordinary Clarke DX with 5-micron bag. I need your advice about a new one.
I've found Axminster Trade AT170E 2HP Extractor which is good however can be a bit noisy and I've got not a very good experience with Axi
https://www.axminster.co.uk/axminster-t ... tor-508336
OR Charnwood W791CF .Has induction motor but I don't know that company at all
https://www.poolewood.co.uk/product/cha ... 791cf-1-3/
Maybe something else up to 1000 pounds? I'm working with MDF only
Thank you in advance

 

[gmgmgm]

Could you put a better bag (or cartridge) on the existing one? I've recently replaced my ancient APTC bag with a newer one, twice the size.

 

[woodbloke66]

Hello Advice Please
I've got a small workshop already set-up with Scroll saw. bandsaw, belt/disc sander and they are ducted via 110mm to the ordinary Clarke DX with 5-micron bag. I need your advice about a new one.
I've found Axminster Trade AT170E 2HP Extractor which is good however can be a bit noisy and I've got not a very good experience with Axi
https://www.axminster.co.uk/axminster-t ... tor-508336

I'm working with MDF only
Thank you in advance

If you're working with only with MDF, the Ax machine won't suit; it's really designed for coarse p/t chippings and sawdust from a tablesaur. Ideally, the machine lurking in the corner of Keith's video clip, the Numatic NVD 750 is better able to handle very fine dust - Rob

 

[dzarek1410]

That's surprising me, to be honest, I've read a lot about different extractors and systems on this forum and mostly LPHV type was recommended.
I've got a similar model to the numatic bought a few years ago but its absolutely useless due to clogging filter really often.
At the moment I've got working https://www.machinemart.co.uk/p/cde35b-dust-collector/ with cyclone cone
Its 850m3 and 5-micron filter. Extractors mentioned above are 2000m3 and 1-micron filter.

 

[Deadeye]

I think you're on the right lines. I had a HVLP blower going via a home-built cyclone. It worked really well, but I vented outside... which made the garage very cold in winter!
I've since bought a more powerful impeller, kept my cyclone just upstream and added a twin cartridge downstream so that I can recirculate the air.
I did look into building my own pleated filter "cube" with 0.3 micron panels. I didn't in the end because a) the panels are expensive, b) I don't use MDF and mostly generate >1micron dust, c) it's a hobby, so limited exposure and d) I've got cancer anyway, so not likely to reap long term consequences.

 

[dzarek1410]

I've decided and bought Axminster one. I haven't a good experience with them before however with quite narrow choose in the UK it looks like the best and most recommended shop around.
I've got 1 more odd question. There state as best will be connected to the 175mm ducting but I've got 110mm already and wondering if will add second about 70 mm air flow will be same?

 

[gmgmgm]

Axminster is usually a safe choice- well done.

The axminster you linked to has 100mm ducting I think. 175mm ducting (7 inch) isn't a common workshop ducting size I think, and it's pretty massive. It will be roughly double the airflow or 110mm.

What workshop machine do you have that states it needs 175mm?

 

[Inspector]

Adding smaller diameters doesn't equal a larger one. You have to compare the areas (Pi x radius squared = area of a circle). The 175mm is 24,053sq mm and a 110mm pipe is 9,503sq mm. There is more surface drag in the smaller pipe so you would need three of the 110 pipes to equal the flow of a 175mm duct. If your DC doesn't have an opening of 175mm or at least 150mm it won't be able to keep the airflow at 20.3 meters per second needed to keep the dust from settling in the ducting.

Pete

 

[dzarek1410]

Thanks for helpful answers. Might be wrong but your calculations are not quite right? My results are 27sq mm for 110 mm and 43 sq mm for 175 mm. So if I'm right adding another 3-inch pipe will be equal as 1 x175mm. Obviously, my machines don't have 175mm connections but if possible I would like add 2nd smaller pipe above sander but not sure if that's is a good idea. Otherwise will lose a lot of air flow on 1x 110mm ducting

 

[Inspector]

Your calculations are wrong.
110 divided by 2 is a radius of 55 multiply that by itself equals 3025 multiplied by Pi (3.14159) and you get 9,503.32 sq mm.
175 divided by 2 is a radius of 87.5 multiplied by itself equals 7,656 multiplied by Pi and you get 24,052.82 sq mm.
A three inch pipe is 76mm so.
76 divided by 2 is a radius of 38 multiplied by itself equals 1,444 multiplied by Pi and you get 4,536.46 sq mm.
Add a 110 pipe area to a 76 pipe area and you have 14,039.78 sq mm. That's a lot less than 24,052.82 sq mm. That is why I said you need 3 of 110mm pipes to get the flow of the 175mm. Remember there is more drag from the walls in the smaller pipe.

Forgive me for not writing the formulas mathematically like they should be but I'm not that good with a keyboard. Only found out how to put a degree symbol when writing angles a few weeks ago. As in 30º. Also there are minor errors due to decimal rounding since I didn't want to type 15 decimal places.

Pete

 

[dzarek1410]

You are absolutely right, my fault
Can somebody tell me what air flow will be with 2 x100 mm ducting if 1,200 m³/hr @ 100 mm / 2,250 m³/hr @ 175 mm

 

[woodbloke66]

I've decided and bought Axminster one.

From the HSE website....

...'There should be an effective dust extraction system in use whenever MDF is machined or sanded. This is often termed local exhaust ventilation (LEV).
Use vacuum cleaners with high performance filters (HEPA) to clean up MDF dust, or use a hose connected to the LEV system.'

As you're working with MDF, the machine you've just purchased (if it is the one) may be the wrong one. A better choice might have have been the Numatic NVD 750 converted to class 'M' filtration with the additional HEPA module - Rob

 

[dzarek1410]

Ok, Thanks for that but the machine recommended by you is only 300m³/hr whilst the new one just bought is 2,250 m³/hr. I've got closed cabinet where DX is located with a fan which removes all smaller particles outside anyway.
Just don't know what additional hose to buy.I've got 110mm ducting already done and don't want to spend money on 175mm which is really expensive. Base on previous advice I will need 3x100mm to cover air flow of 1x175mm but it seems wrong for me because as a state in AXI description air flow is 1,200 m³/hr @ 100 mm and 2,250 m³/hr @ 175 mm. Theoretically difference should be 3 times more between 100mm and 175mm

 

[Inspector]

A 4" / 100mm pipe can flow at max 400 cubic feet per minute (cfm) / 679.6 Cubic metres per hour. You can't move much more than that with a dust collector and a 2hp one would be lucky to get that. Flex hose is even worse. Every elbow you add to the ductwork is equivalent to 10 feet of straight pipe. So a short duct of 15', 2 elbows and a few feet of flex and you have the equivalent of close to 40' of straight pipe. That's a lot to ask of a small DC and 4" ducting.

Dust collector makers/sellers rate their machines by taking the impeller off and only putting a short test pipe on it. Then they take one reading in the centre of that pipe where the airflow is the highest. They do not take readings across the pipe to average the reading to actual, the airflow along the walls being slower. They also do not take any readings with the impeller to filter hose/pipe or the filters, much less seasoned ones. That means the claims of actual airflow are greatly exaggerated. In a simple installation you are lucky to get half the airflow through your system. A bigger pipe will flow more air as long as you have a big enough impeller and the horsepower to drive it. My Clear Vue Max has an honest flow with filters of just under 2000 cfm / 3300 cubic metres per hour with 8"/200mm ducting and it has a 5hp motor. Even it won't pull much more than 400 cfm / 679.6 Cubic metres per hour through a 4" / 100mm pipe. The pipe is the restricting factor for it. Yours is in the size of the DC but you will further choke it with 4" / 100mm pipe.

See if you can find 6" / 150mm pipe (cheaper) and keep your duct run as short as you can.

Pete

 

[dzarek1410]

Thank you that's explained a lot. Ducting is pretty new and doesn't want to change it right now, to be honest. The main idea is to add an extra 100mm flex hose above sander and it will be no more than 2.5 meters long. What difference will be between my current "850m3" and the new one "1200m3"? It hasn't arrived yet.

 

[woodbloke66]

Ok, Thanks for that but the machine recommended by you is only 300m³/hr whilst the new one just bought is 2,250 m³/hr.

It's not the hose or flow rate, but the filter. If you're working only with mdf, the very fine dust produced will blow straight through the filter and back out into the 'shop, simply because it won't cope with that sort of dust. That type of machine is great for larger sized dust particles as produced by a tablesaur or chippings from a p/t, but not for very fine sanding or mdf dust - Rob

 

[Inspector]

Rob the next sentence after the one you quoted said the DC was in a closet with a fan venting outside. If that's the case then the dust isn't getting back into the shop.

Pete

 

[woodbloke66]

Rob the next sentence after the one you quoted said the DC was in a closet with a fan venting outside. If that's the case then the dust isn't getting back into the shop.

Pete

Yep, just seen that Pete...my error. In theory then, the OP should be OK provided the door between the closet and the workshop is a decent fit and the fan vents all the nasty stuff outside - Rob

 

[dzarek1410]

The cabinet is pretty tight I've used 5-micron bag and workshop itself was quite clean.
I've sent an enquiry to the Axminster and they said as with 2 100mm pipes connected each one will have 1,200 m³/hr
Do you think its correct?

 

[Inspector]

The cabinet is pretty tight I've used 5-micron bag and workshop itself was quite clean.
I've sent an enquiry to the Axminster and they said as with 2 100mm pipes connected each one will have 1,200 m³/hr
Do you think its correct?

As I have stated earlier you can't move much more than 400cfm through a 4" pipe. 400cfm = 679 cubic metres per hour. So two pipes can only move at most 1,360 cubic meters per hour. Less with elbows and flex hose. The DC's claimed numbers are only about half and I explained that a couple days ago too. I think if you had the proper equipment and a test duct you would find that between the pipe and the flex hose you want to add for the second line you'd be hard pressed to get 1000 to 1100 cubic metres per hour combined.

So to answer your question. No I do not think this is correct.

Pete