DC motor question / making my own ceiling fan

vonleyser · Oct 31, 2020

I am going to be building a 8 foot ceiling fan out of an old Aermotor Windmill.

I need guidance on

1) size of motor to turn this set of blades. Fan blades probably weighs about 60-70 pounds

2) size of pullies to drive it.
Hub were brake runs is approximately 7"
(what size pulley on motor ?)

3) What type of belt ? serpentine, flat, or V belt ?

4) Since this is set up for horizontal operation will like to know what bearings
would be best to use ? tapered roller or ball bearing. guessing ball for this.

Thanks in advance
Mark

JST · Oct 31, 2020

Well, your questions seem to cover the entire design........

A couple-three ideas for you.......

1) look at blade tip speed, which will give you a clue on speed. So will how much air you want to move, an 8' fan can move a lot

2) Fan power IIRC is a cube function of air speed, so unless you want a tornado, you may not need a lot of power, slow fans use much less power. Weight of blades may not be a big deal once turning.

3) To choose bearings, figure out which direction the shaft loading is in, that tells you what kind of bearing to use.

You can buy those things, you know, all the problems worked out for you, put it up and go back to work!

L Vanice · Oct 31, 2020

Much depends upon what your goal is. If you just want a cool look and minimal air movement, 1 RPM is pretty good for a big fan. That is the speed of the seconds hand on a watch. If you want more air movement, then you will have to experiment with different speeds to see what feels good.

If your motor shaft turns at 1725 RPM, you will need more than one belt/pulley set to get the fan to turn 1 RPM. You might want to look for a high ratio gearmotor first.

Larry

Bill D · Oct 31, 2020

I have seen setups with one motor bolted to the wall and flat belts going to the fans. Gives that old time feel you are looking for. Similar to line shaft drive but turned 90 degrees. They still make the stuff new.
Check Big Ass Fans for rpm ideas.
Bil lD

first link with good pictures, no endorsement.

The 7 Best Belt Driven Ceiling Fans You Can Buy Right Now

vonleyser · Oct 31, 2020

JST said:
Well, your questions seem to cover the entire design........

A couple-three ideas for you.......

1) look at blade tip speed, which will give you a clue on speed. So will how much air you want to move, an 8' fan can move a lot

I will see if i can find information for a wild ass guess, i'm just guess 100 to 200 will move as much as as I need.

2) Fan power IIRC is a cube function of air speed, so unless you want a tornado, you may not need a lot of power, slow fans use much less power. Weight of blades may not be a big deal once turning.

3) To choose bearings, figure out which direction the shaft loading is in, that tells you what kind of bearing to use.
I will be making shaft so i can do as needed.

You can buy those things, you know, all the problems worked out for you, put it up and go back to work!

Yep I know that $4000.00 to start, what is the fun if you can't do it yourself. Small custom house standing on
6' fiberglass piers in a Floodway. I would rather build my own how I want it.

Thanks for the response

vonleyser · Oct 31, 2020

L Vanice said:
Much depends upon what your goal is. If you just want a cool look and minimal air movement, 1 RPM is pretty good for a big fan. That is the speed of the seconds hand on a watch. If you want more air movement, then you will have to experiment with different speeds to see what feels good.

If your motor shaft turns at 1725 RPM, you will need more than one belt/pulley set to get the fan to turn 1 RPM. You might want to look for a high ratio gearmotor first.

Larry

As far as the look i do want that & i want it to function as well. Plus I am hanging the huge tail off as well.

Holy Crap that is slow, Obviously I need a variably speed device, I know its gonna push air, i only need to
circulate gently slow moving air

Thanks
Larry

JST · Oct 31, 2020

vonleyser said:
.......

Holy Crap that is slow, Obviously I need a variably speed device, I know its gonna push air, i only need to
circulate gently slow moving air

Thanks
Larry

Yes..... slow. A few rpm unless you want a tornado.

wheels17 · Oct 31, 2020

At 8' in diameter, 200 RPM, the tip speed will be 5000 fpm. If the vanes are tilted at 30 degrees, the tips will attempt to blow air at 2500 fpm or 28mph. They won't make it, but I think the folks that think your speed is too high are on the money.

thermite · Oct 31, 2020

vonleyser said:
As far as the look i do want that & i want it to function as well. Plus I am hanging the huge tail off as well.

Holy Crap that is slow, Obviously I need a variably speed device, I know its gonna push air, i only need to
circulate gently slow moving air

Thanks
Larry

There's a DIY you could do in "increments".. and with lower risk of killing somebody?

Been in use for over 2700 years already:

Punkah - Wikipedia

The famous / notorious "long bar" at Raffles, Singapore is a replica (then again, so is most of Singapore!)

Punkka-fans - Picture of Raffles Hotel Singapore, Singapore - Tripadvisor

But they still sell those, new as well:

Punkah Fan by Fanimation Fans - FP720AB + FP780AB - Antique Brass Finish

...and a body could easily set up to make a dozen or so "blades", any style as suits yah.

Swinging Ceiling Fan | The Sensu Punkah

Why can a windmill not be utilized as a .... perish the very thought.. .... "windmill"?

henrya · Oct 31, 2020

wheels17 said:
At 8' in diameter, 200 RPM, the tip speed will be 5000 fpm. If the vanes are tilted at 30 degrees, the tips will attempt to blow air at 2500 fpm or 28mph. They won't make it, but I think the folks that think your speed is too high are on the money.

P

This is not all bad.
This set up will probably blow your girlfriends clothes off.

thermite · Oct 31, 2020

henrya said:
P

This is not all bad.
This set up will probably blow your girlfriends clothes off.

Moustache uses less electricity.... DAMHIKT

donie · Oct 31, 2020

"Moustache uses less electricity.... DAMHIKT"

termite, I am simply not going to tolerate, a fake like you calling me a criminal, a drug addict, and insane on this professional forum, when you are nothing but a troll.
The remedy is, you provide some photos of machines or projects, as Mt2 said to give you some street credibility.

thermite · Oct 31, 2020

donie said:
"Moustache uses less electricity.... DAMHIKT"

termite, I am simply not going to tolerate, a fake like you calling me a criminal, a drug addict, and insane on this professional forum, when you are nothing but a troll.
The remedy is, you provide some photos of machines or projects, as Mt2 said to give you some street credibility.

That's odd?? No cats nor dogs about...???

D'you s'pose I've gone and tracked a tiny smear of squirrel-turd into the Tee Vee studio on the sole of my shoe?

Oh, hallo, little donie! Almost didn't recognize you!

Tiny-turd-shaped-mind? You can't even give orders to your own pompous anal sphincter, can you?

Not only "tolerate" .. you HUNGER for any kind of attention AT ALL!
You even go out to stalk and BEG FOR it, you bent, mendacious Masochist!

Keep right on groveling, Walla Walla Whining Wild Turkey!!!

STILL YET painting YOURSELF all the nasty, nasties, you deranged suicidal fool!

Tried HARD to resist stalking for almost a whole two days.. then failed, didn't you?

Failure suits you perfectly!!!

Everybody has to be good at SOMETHING, and you have a whole lifetime of practice at it.

Always the fault of "others" of course!

What did yer Mum say when you told her you had pronounced her dead of COVID so prematurely as another of your chronic "wound seeking" attention bids?

One seriously sick puppy, you are, small-d-the-drama-queen.
Helplessly and uncontrollably so!

In the public record.

Yet again another time!!!

Ah, so... FAME as a FAILURE!!! You LOVE it too much to be sane!!!

donie · Oct 31, 2020

you go on and on, but, pony up some photos troll boy!

Strostkovy · Oct 31, 2020

@thermite Please ignore him
@donie Please shut up

@op

I'd reccomend a Nema frame DC motor (Last I checked Surplus center has lots of options; I've used some from there before. I'd expect 1/4-1/2 HP to be plenty or more than plenty, but you won't need to mess with it.

Then get the largest V belt pulley you can on your fan shaft. Grab an assortment of pulleys that would give you 1-3 rpm, or a stepped pulley, and just try arrangements that work well. I recommend verifying the DC motor shaft spins at the 1800 rpm mark or whatever it's rated for to make sure you aren't getting the fan speed you like by bogging down the motor.

From there I would get a 90V motor control circuit board (PWM is better, SCR is okay but may be a little noisy) from ebay or similar that has an adjustable current limit. This will make starts smoother.

Worst case if the motor isn't right, any other same NEMA frame motor will bolt up. I think the NEMA56C motors on surplus center go anywhere from 1/4HP to 3HP, and just stick out the back longer.

thermite · Oct 31, 2020

Strostkovy said:
@thermite Please ignore him

Tried that. It only makes him WORSE!

Once he gets his "bitch-slap fix" from "one of the GROWN UPS!!!", he apparently wanders off to his crib to masturbate over how IMPORTANT that showed him to be for nearly a full day?

Check the time-stamps.

Net-net, PM has LESS noise that way than if he has to whine and beg in seven or eight threads, same damned day .... until he gets smacked and sent to his room.

Sore NEEDY little parasite, he is! Never outgrew the "terrible two's"

Nature of the "wound collector" affliction. He cannot control himself any more than an ocean can decide to not be wet.

I'd expect 1/4-1/2 HP to be plenty or more than plenty, but you won't need to mess with it.

Disagree. Off HVAC experience.

"Slow" or not, enough air is being "grabbed" that any really large fan's outer blades have leverage - mechanical advantage such that it acts like a pretty fair brake. More to it than HP draw. It is also where on the load curve the motor spends its time.

This puppy could easily need a full one HP just to not overheat the drive motor?

Surely would miss the quiet and inobtrusive goal if the motor ends-up needing a cooling fan of its own? OR has a noisy drivetrain.

Look at how the old Line AC direct-drive ceiling fan makers do it.

"Many poles", sort of inside-out arrangement to shed heat easily rather than trap it?

EPAIII · Oct 31, 2020

If you are set on using a belt drive for the appearance, you may want to use a gear motor to turn the first pulley. One with a worm gear drive for a big step down may be the ticket. Many are available on the used market.

thermite · Oct 31, 2020

EPAIII said:
If you are set on using a belt drive for the appearance, you may want to use a gear motor to turn the first pulley. One with a worm gear drive for a big step down may be the ticket. Many are available on the used market.

My Bodine and Bison DC ones are right rudely noisy off the "two pulse" 120 Hz rectified AC waveform. Contrast those with an automotive gearmotor running off far CLEANER 12 VDC?

I think flat belt - if not deformable ROLLER drive - is the way. Arbitrary length is easier than with Vee, PolyVee / MicroVee, and they can be legendary quiet.

Studio-grade audio turntables were quite often flat belt rim-driven - linen belts or textile-reinforced elastomer, "back in the day" of physical platters.

Consumer grade audio turntables were driven by "geartrains" of elastomer-rimmed wheels. Lots of potentially sutable goods out there. Pallet-jack rollers or hand-truck wheels, bandsaw wheels with "tires" - could get the ratios needed?

9100 · Oct 31, 2020

A standard induction motor works well with a Variac controlling speed. The reason is that the voltage sets the torque and the torque requirement of a fan varies with square of the speed. Once off the starting winding, the motor will run smoothly and quietly at a stable speed.

Bill

vonleyser · Oct 31, 2020

wheels17 said:
At 8' in diameter, 200 RPM, the tip speed will be 5000 fpm. If the vanes are tilted at 30 degrees, the tips will attempt to blow air at 2500 fpm or 28mph. They won't make it, but I think the folks that think your speed is too high are on the money.

Thank you thank you I will works towards a max of approximlity of no more than 75RPM
and include a fan speedcontrom.

DC motor question / making my own ceiling fan

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