Which motor to cannibalize for homemade dust collection?/ Are they enough? 1

[panwest]

Hi, I am planning to build a dust collector for myself. For my small mainly hand/power tool shop, with dewalth planer and table saw. I am getting a 4x4feet CNC and recently read the Bill Pentz article which is what made me decide on this upgrade as my SO has asthma.

Ill make the 14-15inc impeller and housing, cyclone, filter myself and I am pretty confident in fabricating things like this. But would love any help, links or advise

What I am not confident is... anything that has electicity running through it. I did take courses at ME uni but I have always avoided practical experience on it. It wasnt until few months ago where I got in to machining/wiring and started learning and research.

The motors i can cannibalize in Question;

Waterway PF-50-1N22C4 5HP hot tub motor & pump connects to Gecko control board. [How simple would it be to wire this up to be a dust collector?]

McMillan Electric 3HP 120VDC Motor 24.5A with mounting frame. Model # S3456B3698

Centry pool & spa motor BN41 230VAC, 12A, single phase

Expectations;

In short I want it to be overkill. CFM has alot of confusion surrounding it for me to figure out, but "1000-1350 actual cfm" or 2k cfm? Or maybe its better to say I want to beat the oneida air mini gorilla and it would be cool if I could get the airflow of from their supercell. If I could do that I would be satisfied... or getting performance equal to lagunatools p-flux-2?

 

[BrianE22]

Speed would be important. For your pump have you calculated about what RPM you need?

 

[panwest]

All 3 motors were rated for 3450, I dont know of a way to calculate that without actually building the impeller and blower and getting readouts from air coming out .

 

[waross]

Put your biggest motor on the fan and then throttle the discharge until the current comes down to about 90% of the motor rated current.
That's about the best you will get.
You will probably need a belted drive with a lot of speed reduction.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[panwest]

Hmm I have a few questions on that, I've read a few articles on woodworking forums like woodgears, and watched other ppl build theirs. There, they dont use a belt drive for a dust collector, straigt from motor to impeller no conversion. Belt drive is usually reserved for bandsaw.
It seems that all of them try to make sure the motor doesnt explode, and get the highest speed from the motor as possible. Usually just hook it up and get correct amps. Wouldnt using a belt drive introduce more torque and more stress on the dust collector? Its going to see extended use, as in ill turn it on and maybe have it running for the full day would that cause any problems?
As you said probably going with the waterway as thats the strongest 12amp(3450) 5hp(the part number says 4, but 2 5hp stickers on motor and pump though) 60hz 230V. I pulled these motors from a guy who bought a new hot tub for 200tot, so im not super confident in them they have been used. Which is why I was thinking of going 85%eff. but honestly im so new to this that I change my plans as I hear more from people.

 

[waross]

Are you familiar with the fan laws?
A centrifugal fan designed to draw 5 HP at 2500 RPM will draw about 14 HP at 3500 RPM.
Dusty air draws more HP than clean air.
A belt drive allows you to match the fan motor combination to the ducting installation.
Your problem is not a motor problem.
Your problem is how to design a fan which will not overload a 5 HP motor.
Belts make it easy.
Or not. Good luck with that.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[panwest]

I see what you mean more now, Im not very familiar with anything related to this to be honest, which is why im asking around for help, mostly self research on this topic since im doing it for my hobby. Going to follow these 2 videos for the design of the fan, he uses a 3 phase 3 hp motor that looks beefy and old and gets some pretty decent results

https://www.youtube.com/watch?v=GcfHYYkxTh4&t=1s&ab_channel=MariusHornberger

https://www.youtube.com/watch?v=zN1QW_BTArQ&ab_channel=MariusHornberger

 

[panwest]

Could you maybe give me the formulas for those calculations? Not just cfm related but motor ones like whatimpeller it can spin how fast etc would also be helpful. Its hard to find information, i think because im not experienced in the topic.