Thread: Dust Extraction for new shop

Have you thought of using bendy ply instead of MDF? Easy to form into a cylinder.

Buy Bending Plywood 'Bendy Ply' sheets - AU & NZ Delivery - Bord Products

The motor is a 380V 4kW 3P and draws 8.2A at 50Hz.
This makes it possible that it is a 14" impeller
A smaller impeller at 50Hz would cause the motor to draw about 6A.
But it could just be an inefficient motor

What is very unusual about that motor is that it is a dual 240V 3p and a 380v (415V) 3P
This is fairly rare on DCs with 3P motors.
This means you could run that motor from a 240V Single Phase )SP) GPO using a 240V SP to 415V 3P VFD.
You would probably need at least a dedicated 20A 240V GPO to drive it especially if you want to drive it drive it at 60Hz.

It would work on a BP type cyclone but you would have to modify the cyclone size to fit the impeller.

Hi Bob,

I might hold off as it sounds like this one isn't quite right. I really would like to find a 15" impeller if I can. I also found this one but I think at 10 HP this would be oversized? I'm guessing the impeller that goes with this unit is probably larger than 15" and possibly larger than 18".

Dust extractor - Painting Tools - Sydney, Australia | Facebook Marketplace

I'm a little confused when you say I would need to modify the cyclone to fit the 14" impeller. The BP cyclone has an 18" diameter cyclone with an 18" upper cylinder. I am planning on building all components of the cyclone including the housing for whatever impeller I end up getting my hands on. If I built a housing for the impeller that fit on top of the upper cylinder (18" diameter) would I be able to put the 14" diameter impeller inside or would the 4" diameter difference make the system less efficient?

Hi Lappa,

I did think about using bendy ply but it is a bit more expensive and I wanted to try to use cheaper materials for the moment as I try to wrap my head around the build. I just finished marking everything out on the MDF and I think I have everything marked out properly. It definitely took a few tries!

Funnily enough I actually found a large sheet of sheet metal that the previous tenant of the factory space I'm in left behind! I think I am going to try to build the cyclone, cyclone outlet, and upper cylinder out of the MDF and then use the sheet metal to make the cyclone inlet as I expect to run into problems figuring out a way to make the 90 degree bends required.

I also found these. I read on a forum posting that the Holytek are good dust extractors? Any thoughts on these?

3 Phase Dust Extractor - Small Kitchen Appliances - Sydney, Australia | Facebook Marketplace

Cody, I very much doubt that you will find a 15" impeller in any small generic Asian machine.

Originally Posted by codycook

Hi Bob,

I might hold off as it sounds like this one isn't quite right. I really would like to find a 15" impeller if I can. I also found this one but I think at 10 HP this would be oversized? I'm guessing the impeller that goes with this unit is probably larger than 15" and possibly larger than 18".
Dust extractor - Painting Tools - Sydney, Australia | Facebook Marketplace

I think that one has a an 18" impeller - which is consistent with the 10HP needed to drive it.
Its very similar to several I have seen at men's sheds.

It's not only oversize for your shed but expensive to run, 10HP is nominally 7500 Watts - so it will cost 7.5 x 28c/kWhr or~$2/hr or $80 a week to run.
Of course you won't have it on all the time but i still adds up - have you got solar?

I'm a little confused when you say I would need to modify the cyclone to fit the 14" impeller. The BP cyclone has an 18" diameter cyclone with an 18" upper cylinder. I am planning on building all components of the cyclone including the housing for whatever impeller I end up getting my hands on. If I built a housing for the impeller that fit on top of the upper cylinder (18" diameter) would I be able to put the 14" diameter impeller inside or would the 4" diameter difference make the system less efficient?

BPs cyclone is designed for a 15/16" impeller if you go to a 14", I know its counter intuitive but the cyclone has to be made larger
The Holytek you posted a link to is either a 12 or 14", most likely a 12" as its only 3HP.

Like Chris says you will really struggle to find a 15/16" impeller - I looked for about 2 years and came across only one that was was in such poor shape and was also a straight vaned unit which are very loud.

Somewhere in the confusion of BP's site he talks about his initial design where he used a 14" impeller and abandoned that to use a 15" version.

Hi Bob, what are your opinions on if I were to build the BP cyclone with 18" Diameter and power it with an impeller that is slightly underpowered? I have just had a conversation with Stephen at ClearvueOz and he said he won't be able to get another shipment of impellers for approximately 3 months. If I build the Cyclone with the intention of upgrading the impeller/motor when he has stock available would the 18" diameter cyclone powered by a 14" impeller be any good for dust collection in that in-between period? I'm really not sure what to do here. No one seems to make a 15"/16" impeller and stock from Clearvue is a 3 month wait.

It seems like getting proper dust collection at this moment in time is impossible!

Originally Posted by Chris Parks

Somewhere in the confusion of BP's site he talks about his initial design where he used a 14" impeller and abandoned that to use a 15" version.

Hi Chris,

I'm still having no luck finding the 15" impeller. I have been working on building the cyclone. I had a go with bending the MDF into a cyclone shape and the MDF did not want to cooperate. The 150mm diameter at the bottom of the cyclone was just too tight of a radius for the MDF. I think I am going to abandon the MDF and get my hands on some sheet metal. After doing the measuring and marking on the MDF I am confident I can make one from sheet metal. As having one constructed from sheet metal is my ultimate goal I will consider the MDF as a practice run!

Originally Posted by codycook

Hi Bob, what are your opinions on if I were to build the BP cyclone with 18" Diameter and power it with an impeller that is slightly underpowered? I have just had a conversation with Stephen at ClearvueOz and he said he won't be able to get another shipment of impellers for approximately 3 months. If I build the Cyclone with the intention of upgrading the impeller/motor when he has stock available would the 18" diameter cyclone powered by a 14" impeller be any good for dust collection in that in-between period? I'm really not sure what to do here. No one seems to make a 15"/16" impeller and stock from Clearvue is a 3 month wait.

It seems like getting proper dust collection at this moment in time is impossible!

One effect effect of using a small impeller on a Cyclone designed for a larger impeller is that the back pressure generated by the cyclone will reduce the overall airflow. That's teh main reason BP uses a 15/16 impeller to overcome this back pressure.

The other thing is it will not separate as much of the sawdust from the really fine dust. If you are (and you should be) venting the exhaust air outside moe of the fine dust will escape. If you live on a big block this is no problem but otherwise you neighbours might notice.

The other solution is to buy and install a basic used DC. Then build the BP Cyclone correctly - ie ned Ron pressure and eventually then sell the used DC - in most cases you can usually get what you paid for it. The bulk of the work in setting up a DC is setting up the ducting and gates and modifying machinery ports etc - if this is done right first time you should not lose any of this.

How about some numbers for a little perspective here?

All else being the same:
-- A 14" fan will generate approximately 7% less flow and 14% less pressure than a 15" fan.
-- A 14" fan operating at 64 Hz will generate approximately the same pressure and flow as a 15" fan at 60 Hz
-- Reducing the flow in a cyclone by 7% will increase the cut size by about 3.5%
-- A 15" fan at 60 Hz or a 14" fan at 64 Hz will consume about 23% more power than a 14" fan at 60 Hz.

Hi Dave,

Thank you for breaking this down. If I'm understanding correctly I could get nearly the same performance from a 14" impeller operating at 64 Hz as a 15" impeller at 60 Hz?
And if the fan is running through a VFD I would be able to control how many Hz the motor is operating on?

Originally Posted by BobL

One effect effect of using a small impeller on a Cyclone designed for a larger impeller is that the back pressure generated by the cyclone will reduce the overall airflow. That's teh main reason BP uses a 15/16 impeller to overcome this back pressure.

The other thing is it will not separate as much of the sawdust from the really fine dust. If you are (and you should be) venting the exhaust air outside moe of the fine dust will escape. If you live on a big block this is no problem but otherwise you neighbours might notice.

The other solution is to buy and install a basic used DC. Then build the BP Cyclone correctly - ie ned Ron pressure and eventually then sell the used DC - in most cases you can usually get what you paid for it. The bulk of the work in setting up a DC is setting up the ducting and gates and modifying machinery ports etc - if this is done right first time you should not lose any of this.

I think I am going to go take a look at the dust collector I mentioned in a previous reply:

Dusk collector - Watering Equipment - Sydney, Australia | Facebook Marketplace

If the impeller is a 14" impeller I think I will buy it with the hope I can run it through a VFD at higher Hz as Dave mentioned and get it to perform more like a 15" diameter impeller. If it is not a 14" impeller do you think this would be a good candidate as a basic used DC?