Thread: 1000 c f m

Originally Posted by mannum3

It was suggested that 1000 cfm is a magical figure, not practical for a hobby workshop.

I believe 1000 cfm or better can be achieved at reasoable cost with careful planning.

I am sitting back waiting for "bites" (a fishing term)

Cheers Barry

Do you have a secret to tell us? Or was this some backwards approach to asking a simple question "how can 1000cfm be achieved using common power supplys in home shop without it costing the earth?"

I think everyone goes through a fairly consistent progression as they get into the sport. They start small and get big...as the problems grow....

For example, mine was:

-- Festool vac with 28mm hose (second hand)
-- A length of 50mm hose from carbatech
-- A cute little Dust Deputy cyclone as I was sick of emptying the Festool
-- a 1hp dusty second hand with pleated and 1 metre of 100mm hose...this was moved machine to machine
-- a 2hp dusty second hand with pleated and 4 metres of 100mm hose
-- various connectors to make the machine moves easy

I think this is where most people stop. I was lucky as both duties had pleated filters and I'd read much of what was written here and the advice of BobL, otherwise this would have been next...

This isn't without rationalle. Who is going to say "I'm starting woodworking, I need a $1200 dust extractor and hoses". Even then, $1200 only buys what we are lamenting as inadequate here.

The next step is 150mm hose and opening up the opening on the dusty a bit, which is already 140mm due to so redicoulous 2-into-1 adapter... So close, yet so far (why do manufacturers even DO this?)... Maybe even getting brave and chopping up the dusty and putting the thing into a cabinet and mount the blower on top.

This is why I think this discussion is important. I think it isn't wise to prod various people, for I think they have talked themselves to death on the issue.

What we need to do, is come up with a clear plan of what is wanted, as a group and say to an Australian manufacturer "MAKE US THE WOODWORKINGFORUM MAX-O SUCK 1000".

Give them specs. Show there is demand. Heck, they could even just make the components and we DIY the rest....

We can argue over semantics of pipe placement etc, but let's agree on the machines specs and the use of 6" pipe.

I will make a good knowledge piece for newbies.

Originally Posted by Kuffy

Do you have a secret to tell us? Or was this some backwards approach to asking a simple question "how can 1000cfm be achieved using common power supplys in home shop without it costing the earth?"

Well I guess its mostly the second part,but when you consider/calculate restictions and losses, do not include any restriction due to filters.

What I dream up is a motor, fan/impellor, housing mounted about 2 metres above the ground outside the workshop.

200mm piping is connected to the fan inlet and runs straight through the wall into the workshop ( no bends so far).

I have a computer programme "Digital Pipe Fitter" which can provide print out cutting patterns.

With this programme I am able cut large radius bends junctions in various sized pipe.

for example you can make a junction with a 15 degree 150mm offset from a 200mm pipe, follow this up with 5 sections of 15 degrees ending up with 90 degrees in a long slow bend.

the woodworking equipment would be located within 6 metres from point where the pipwork enters the work shop.

the smallest pipe used would be 150mm. in the past I have used 150mm DWV piping with 150mm stormwater fittings Y & 45 degree bends.

BobL, thanks for the link, I have been flat out all day and hav'nt read it in depth as yet,(copied and paste to my Dust Control folder) no doubt I wil have more questions to follow up.

Cheers Barry

Is the clearvue cvmax able to easily achieve 1000cfm with 2 ports open 10meters away from blower?

I don't know if the question was directed at myself, if it is I'm am very sorry that members feel i may have mislead people on this site. but there is no secret that i can see in what i have been doing for the last 12 months, but after looking for a fixed system on the information from our own members, as well as Bobl, and Bill Pentz web site.

i found there was limited products for the home market that wouldn't come close without major operations, what I did find when i stated looking was a huge amount of information in relation to "backward curved radial fan design" but very limited in the home workshop other than the rebuilding of old blowers or building DIY units. until i came across this video

https://www.youtube.com/watch?v=_7MfDRiO8zU

can the same idea be used but bigger, and how much bigger does it need to be to but no bigger than 400x400 @ 600mm long with motor, get the results. Mark started designing the impeller. this is when the trouble started, his bosses informed him that he had breached company guide lines, no outside work on companies computers or software. as well copyright laws. and because he was using the companies computers, they now have property rights to the design.

To overcome the copyrights laws, the design has been changed to meet this, and in doing so put up different problems. does anybody know how much a block of machining grade Aluminium cost, you better sit down

Can it be injection moulded - yes it can at 10,000 lots @ $ per unit. for a proatype not viable
Can it be machined - yes it can once again the cost for a one off is to high
can it be printed.- yes and at a good price and but what type of material to be use. but once printed and tested the design can be used to make injection mounding neg die's

After talking to Mark last night, it was decided to put it out their. So i will put it out their I'm sorry if members feel i miss lead this site was not my intention to do so.

Originally Posted by Opelblues2

but why are we still using backward curved radial blowers, why cant this be used


Airfoil wheelsincorporate a blade design with the cross section of an airplane wing. They arethe most efficient design for moving large volumes of air. They are commonlyused for ventilation, forced cooling at higher pressures, and on dustcollectors, where the fan is on the clean side of the collector.

has anybody pulled a part a DYSON vac, a turbo charger, a waste transfer pump (the Air Side)

Airfoil blades are used but require a higher level of manufacturing know how and as a result are more costly to make, also from when I was doing some reading on this type of wheel they can suffer from (I've got cavitation in my head) but it's not that, basically they don't like operating in a no flow situation (gates closed)




Pete

Originally Posted by aldav

That's a very high and mighty attitude. Thanks mate! I'm disappointed.

Reading back through this thread it is clear to me that I overstepped the mark here and I would like to unreservedly apologise to BobL for any offence.

Originally Posted by doug3030

Well, I think I can see where Bobble (how else would you pronounce BobL) means by this.

If all you have to go on is "I have a secret but I can't tell", what does he have to comment on? We all seem to agree that if a device that meets the specs can be produced for the home hobbyist it would be a good thing. But seriously, how can you expect him or anyone else to comment with the scant information available on the specifics of the design?

You've hit the nail on the head there Doug.

What is posted on this forum as something new is a fraction of what gets sent to me for advice and comment and not just related to dust so I get tired of dealing with all these things. I've had to deal with this sort of thing my whole professional life and I am supposed to be retired. I'm not that interested in fan design or construction. My interest is in measurements of real flow rates - not those done by the Australian Standard which are incorrect - and a resulting fan pressure/flow curve.

Talk of using bigger ducting and computer programs is nothing new.

There's some talk about makings things cheaper, but large diameter pipe, essential for a large shed, is not cheap - try pricing some 225mm stormwater pipe. If DIYers want to save money they can always build their own large cross section ducting and junctions out of MDF. DIYers can probably save more by this approach than anything else.

The problem for most situations is not usually the fan, or the filter, but the use of small ducting, and most importantly the restrictions at the machines - including the DC, which is why I put up the Generic 2HP DC thread.

If a machine uses a 2" dust port and is hooked up to a standard DC, irrespective of the size of the ducting used, there never going to to be more than 70 CFM through that machine.

I see this in many industrial situations where they have 6/8/10/12" ducting and a massive DC outside, and then they hook up a $5,000 BS with a 4" port and they wander why there's dust everywhere. I tell them to get out an angle grinder and install a 6" port and they look at me like I'm the devil!

If a DC can be built that has 4 times the vacuum pressure (unlikely) this won't give 4 times the flow - it only generates 2 times the flow so a machine with a 2" dust port will allow a whole 140 cfm of flow - like WOW! On top of that it will sound like a jumbo jet.

Any fan design improvements are going to be, size for size and RPM for RPM, at best minor and will not solve DIY woodworkers dust problems. There's unlikely to be more than a 20% improvement in flow for any new fan design, which is not going to make that much difference. If you want a quick 20% increase in flow get a 3phase DCS= and add a $200 VFD to it and run it at 60Hz, but beware the increase in noise levels. This is why I tend to yawn when I hear about new fan designs.

The other thing a lot of DIYers forget is that for a very small (3 x 3 x 2.4) shed a standard large 3HP DC (e.g. a DC7) located outside the shed is effectively right next to most machinery in that shed. More importantly the DC7 will vent the entire volume of that shed in less than 1 minute. This means in about 10 minutes the air in that shed could be as fresh as outside air. It seems like over kill but provided the machinery has been opened up and allowed to breathe that is all that is needed for such a small shed. The last time I looked new DC7s were not that expensive and they come up fairly often in the classifieds.

The problems come with bigger sheds. The elephants in the corners are still the restricted machines, which mean more dust escapes at source and being a bigger shed it is more difficult to scavenge all the dust out of the air.

Instead of speculative small improvements to fans it would be more helpful to post working examples about improving air flow through machinery and DCs. Unfortunately this is difficult to demonstrate because measuring real improvements in air flow is not easy. Pressure changes can provide a useful indication of improvement but it does not measure the actual flow.

Originally Posted by aldav

Reading back through this thread it is clear to me that I overstepped the mark here and I would like to unreservedly apologise to BobL for any offence.

None taken, so don't worry about it.

Thank you BobL, I fully understand you being overwhelmed with questions.

I do not known of any other "local" who can answer our questions with authority, I was particulary impressed with your research and post regarding metal cutoff saws, the dust created, and how long the dust was suspended in the air, worthy of a Honours Degree, DFC and Bar.

I do not want to re-invent the wheel, but what if, in a typical setup of bandsaw, pipework DC, filter, you had a smaller fan at each machine rather than one large DC fan.

I recall reading that "fans blow more than they can suck",


I am convinced of the value of "Brainstorming", ideas being put up in a postive enviroment, sparking a new approach to a problem.

Back to the saltmines for now, Cheers Barry

Greetings to all and sundry,

I have received a PM that has me scratching my head, some where along the line I have or hav'nt said...... "what"??

I am the first to admit I may talk in circles, that others find hard to follow. crossed lines or on the wrong wavelength, translation required

I started this thread "1000 cfm" to clarify a few issues and get the group "brain storming", as far as i am corncerned it has been a great sucess.

Possitie thoughts welcome, constructive critics also welcome.

Time now to print out Bill Pentz's article to study in depth.

I will be making a call to sort out any missunderstandings.

Cheers Barry

Originally Posted by mannum3

Greetings to all and sundry,

I have received a PM that has me scratching my head, some where along the line I have or hav'nt said...... "what"??

I am the first to admit I may talk in circles, that others find hard to follow. crossed lines or on the wrong wavelength, translation required

I started this thread "1000 cfm" to clarify a few issues and get the group "brain storming", as far as i am corncerned it has been a great sucess.

Possitie thoughts welcome, constructive critics also welcome.

Time now to print out Bill Pentz's article to study in depth.

I will be making a call to sort out any missunderstandings.

Cheers Barry

Can't speak for the others, but I reckon that saying "I believe it can be done" and "I'm waiting for bites" is like having a giant flashing billboard that says "I know something you don't!! Ask me about it!!"

Originally Posted by mannum3

Thank you BobL, I fully understand you being overwhelmed with questions.

I do not known of any other "local" who can answer our questions with authority, I was particulary impressed with your research and post regarding metal cutoff saws, the dust created, and how long the dust was suspended in the air, worthy of a Honours Degree, DFC and Bar.

I do not want to re-invent the wheel, but what if, in a typical setup of bandsaw, pipework DC, filter, you had a smaller fan at each machine rather than one large DC fan.

I recall reading that "fans blow more than they can suck",

This is not desirable because then the ducting is under positive pressure and the smallest leak becomes a PITA.
What is worthy of consideration is to use a fan in a machine or tool attached to a DC

This already happens in power hand tools like sanders where there requirement to be portable limits the size of duct ports.

I have done sone measurements of these, see https://www.woodworkforums.com/showth...37#post1600637 and they definitely make a difference for small dust ports.

The essential thing here is to ensure that any fan used in the tool / machine
a) matches the flow the DC can take away i.e. ensure the tool remains under neutral or slight negative pressure.
b) does not block the air flow that a DC could generate through the same hole. It's hard dot believe that would be the case but fans do get in the way of air flow.

In general its better to have a source of "suck" that machines can be connected to and free the air flow up through a machine than to try and stuff fans into a machine to force more air through it

Thank you for your input.

I will re-word the post

I believe 1000 cfm can be achieved with reasonable cost and careful planning, I could be wrong, what do you think?

Lets kick around a few ideas and see what we (all of us) can come up with?

No offence taken or intended to be given.


Cheers Barry