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Beat the heat (monster fan mod)

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dan

Thu Jul 20 2006, 10:09PM

Registered Member #223 Joined: Mon Feb 20 2006, 06:42PM
Location: Ottawa, Ontario, Canada
Posts: 125

Well it's f***ing hot and my big box fan's motor recently started to seize. The bearings were shot and I was lucky to get the damn thing to start a few times. (no I donâ€™t have A/C) So I decided to mod it to accept a larger induction motor from a drill press.(I bent the shaft of the drill part so the drill press was useless but the motor was still good.) At no load the motor is rated at 1450rpm. The exact power of the motor is unknown but it is more then twice the size of the original in the fan. I had to drill and tap new mounting holes and cut some of the rear screen guard to make the new motor fit. One thing I'm concerned about is that the blade is only plastic and a little on the old side. At these much higher RPMs(about twice as fast as it used to run) Iâ€™m worried it may fly apart eventually under this stress. It's fully enclosed so there isn't much danger from the shrapnel but it would be rather startling. Plus the added power consumption is probably 4 times the original. Probably still better then A/C though.

The results are spectacular.. From across the room the modded fan can keep me nice and cool and blows lose paper off my desk. One major problem is the new motor hangs off the back of the fan making it necessary to add some weight to the stand to keep it from falling over. Itâ€™s also very noisy but it doesnâ€™t really bother me. I rather put up with the noise then sweat to death.

I guess I could have just bought an industrial sized high volume fan but..

Steve Conner

Thu Jul 20 2006, 11:18PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Well, you have an industrial sized high volume fan now, anyway

Nice mod! I wish we had one of those in the office where I work, it got over 30ÂºC in there today.

dan

Thu Jul 20 2006, 11:50PM

Registered Member #223 Joined: Mon Feb 20 2006, 06:42PM
Location: Ottawa, Ontario, Canada
Posts: 125

In canada we get some extreme temprature ranges. ~+40C in summer and ~-40C in winter. I have been running the fan for just over an hour now and the motor is really hot. Too hot to touch for more than a second. I guess it wasn't designed to run continuosly but I don't smell anything burning so I guess it's ok.

It only took an hour and a half to complete the mod and i'm rather impress how it turned out.

It's only got a on/off switch but I would like to be able to control the speed of it. Any idea's? I know an inductive load like this wouldn't like a light dimmer at all. Maybe a variac

I have heard about generating AC at a variable frequency will run an induction motor at different speeds but thats probably more trouble then it's worth.

Desmogod

Fri Jul 21 2006, 02:35AM

Registered Member #139 Joined: Sat Feb 11 2006, 11:01AM
Location: Perth, Western Australia
Posts: 358

Steve Conner wrote ...

I wish we had one of those in the office where I work, it got over 30ÂºC in there today.

Awwww :P
Want to come and visit for a holiday?

Steve Conner

Fri Jul 21 2006, 09:33AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Maybe in winter when it's 4Âº, pouring with rain the whole time, and only 5 hours of daylight

I actualy like the heat, as long as I don't have to work in it. So maybe I just don't like work.

I think you could regulate the speed easily. I've seen "Fan speed controllers" that are similar to lamp dimmers, and I think the fancy lamp dimmers sold for use with halogen lighting would work too. I've used one of those to control the speed of a universal motor, but never tried an induction motor.

I did once try reducing the speed of a big industrial fan with a variac. Me and some students were using it to cool an engine in the university test cell. After a few minutes, one of the capacitors on the motor exploded releasing huge clouds of foul smelling smoke. I think it was a capacitor start motor, and we had slowed it down enough that the start switch closed and cut in the start cap, which isn't rated for continuous use. A plain capacitor run motor should be fine.

Psyko

Sat Jul 22 2006, 03:26PM

Registered Member #81 Joined: Thu Feb 09 2006, 11:57AM
Location: Paris, France
Posts: 43

You triggered my today's project. Quickly built from two industrial 120v fans ( in series ), a tripod used by musicians, in other words, all parts were scavenged. It blows pretty good, and it's incredibely cheap.

Part Scavenger

Sat Jul 22 2006, 05:54PM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

I've thought many times about hooking up a few MO fans from the drawer.

Conundrum

Sun Jul 23 2006, 12:27AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

I have two 1.35A monster (65CFPM) vortek 80mm fans here if anyone wants them :)

you will need to replace the connectors but they work fine.

make offer.
-A

Michael W.

Sun Jul 23 2006, 01:17AM

Registered Member #50 Joined: Thu Feb 09 2006, 04:07AM
Location: Vernon, B.C, Canada
Posts: 324

My room is the only room in the house that doesn't get alot of A/C because of how the ducting is, so I put one of those MO "cyclone" fans on it to bring in the cool air...

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