Thread: Ideas for making a motor fan

I found an Italian 2 speed, 3-4 kW, cast iron electric motor in pile of old gear. It's a bit rusty, but it Meggered fine and the coils are giving consistent readings commensurate with its ratings.
One bearing seems to be a little stiff but the other is fine and that should be easy to attend to.
What is missing is the fan.
Anyone have any ideas for making one?
Would a fan cut out of some galv sheet metal and screwed/bolted to a steel collar be sufficient?

If you are planning to run it from a vfd, what about forget the original fan and install a seperate cooling fan, then you'd have a motor that could run for longer periods at slow speed without worrying about cooling problems.. seperate forced air cooling is a factory option on some motors.

Ray

Bob, I think making up a fan would involve a lot of work and you would need to balance it well.....how about using a steel fan from a vehicle. The modern plastic ones would be too noisy and probably viscostatic, you would need to secure one from an older vehicle and maybe just have to make a boss to attach it to the motor spindle

When I needed to replace the fan on my little compressor I went to a motor rewinder and showed him the one I butchered getting it off. He rummaged around and found one similar and gave it to me. YMMV.

Thanks Guys - all good ideas.

I don't need a fan on it to just try it out and i'll decide on what sort of a fan if I can get it running.

I like the idea of the separate fan.

Freebie from a motor rewinder would be worth a shot but you can buy new plastic ones from a motor rewinding supplies shop if that fails...

I cleaned up the motor innards (a bit of rust in there) and on the endcaps, and I cleaned out and repacked the bearings.
Then I had to sus out the connections as there was nothing on the motor plate or the inside top of the connection box.
Fortunately I found all the technical details and connections on the web.
It turns out to be a YY and ∆ connectable motor, 3kW/2880 rpm on the YY and 2.2kW/1440 RPM on the ∆ wiring.
I wired it up to a 3HP VFD and it runs smoothly and only draws 0.3A free running which is the second lowest of all my motors.
So now I guess it's worth sorting out a fan.

This motor has a 100 mm long 28 mm diam shaft on it which makes it a very useful beastie.

Hi Bob,
What are you going to use it for? Isn't it going to be series ∆? so its going to be a little low on hp. (Cant say how low as there was a mess up on my scale order so my tests have been put back a little)

Stuart

What, no pictures??

Paul

Originally Posted by Stustoys

Hi Bob,
What are you going to use it for? Isn't it going to be series ∆? so its going to be a little low on hp. (Cant say how low as there was a mess up on my scale order so my tests have been put back a little)

Stuart

I don't have any plans for it, I'm using it as a learning motor.
It was sitting in a pile of scrap metal headed for the scrap merchants and I saw it as a bit of a challenge to see if I could get it working.
The shaft (still with keyway rusted on) and parts of the external casing and terminal block were rusty ,and the rotor barely turned but I thought I would give it a few minutes worth of my valueless time.
When it meggered fine and the coils gave the same resistance values I thought it was worth at least opening up.
That's when I found it had no fan, and it also has no terminal block cap.
The end caps were rusted on but a couple belts with a wooden mallet got them off.
There was some rust on the inside of the end caps and the rotor but the bearings still has plenty of old grease and the insulation looked OK.
I put the rotor on the lathe and ran some fine a alox cloth over it and the shaft to get them clean.
Then I repacked the bearings and it came together well and the rotor turned very smoothly.
Re-meggered it - still fine, so time to (carefully) add some juice. All good

Re: series ∆. Yes it is, and it will be low on power (it should be about 1.5HP) compared to its normal rating.
I note in my first post I said it was a 3-4kw motor but have since found out it is a 2.2-3 kW (3 - 4HP) motor
I might think about getting into its guts and see if I can convert it into parallel ∆.
I dunno - I just like getting old stuff running again

I did a spare 3P motor inventory yesterday - I need to stop collecting as they are starting to take up too much room.
<1HP (3), 1HP (2), 2HP(2), 3HP(2), 4HP(1), 5HP(1), plus a couple of DC motors and the 3 single phase motors I replaced with 3P motors on my lathes and DP.
The only motors I have plans for are I want to use one of the 3HP units for a sander and I am thinking about using the 4HP for a blower.

I finally had the 4HP 2850rpm WEG on the bench yesterday. That thing's bloody heavy.
Anyway it runs very smoothly, and it has the right mounting for a blower.
Now I need an impeller!

Paul, you want photos of motors? One old motor looks pretty much like the other to me but I will see what I can do.

Bob I have an impeller from a woodwork dust extractor you can have may be a little on the the small side though.

Originally Posted by welder

Bob I have an impeller from a woodwork dust extractor you can have may be a little on the the small side though.

Thanks Andre that is very kind of you to offer this but I have managed to find a 240V, 120 mm diameter fan and will be installing this in the intermit.

Originally Posted by pmcgee

What, no pictures??

Paul

Here you go
Here is the 4HP WEG


This is the one I worked on.
The end caps were rustier than the rest so they got a lick-o-paint.
The Connector box cap was missing so I added this die cast box as a cover
In the background you can see the 240V 120 mm fan I'm going to use for cooling

I fitted the 240V 120 mm fan inside the regular fan housing and ran the motor for 2 hours last night. The shaft temperature after a 2 hour run was 29º (Ambient was 25º) so it seems like it's running OK.
I don't like the noise the fan makes, some of this is probably the grille profile - might have a bit of a fiddle with that and see if I can improve it.

Originally Posted by BobL

Here you go
Here is the 4HP WEG

I like pictures ... don't understand the words part ...