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Uses for old vacuum motor?

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Myrmidon

New Member
Greetings all.

I have managed to pilfer 2 vacuum cleaner motors, 1 rated at 1000W and one at 800W.

Just wondering if anyone had any idea for using them for something? They appear to be a.c. motors though of which i have little experience and need to go over my uni notes again.:rolleyes:

I was curious about some kind of generator of some kind.

Any suggestions welcome.
 

Myrmidon

New Member
Interesting.

Have you any idea how useful they could be in a wind generator experiment? I'v tried testing them and spinning the motor to see what kinda voltage is produced but...and rather ashamedly, i can't get a voltage reading at all.

I'm sure i'm probing the correct pins. :p
 

Externet

Well-Known Member
Connect an automobile 12V battery to it. Perhaps mount a sprocket or friction shaft and on a bicycle.

Unless has permanent magnets inside, it will not generate.
 
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Hero999

Banned
Vacuum forming machine.

Inflating machine, if you find a way to concentrate the air blowing out of the fan then you can use it to inflate things such as a dingy an air bed or even balloons. Balloons tend to burst very quickly though.:D
 

Deadwood

New Member
I've got a motor from a vacuum too and came to the same questions. Mine runs at 30,000 rpm...that seems very fast.

I'm thinking about using it like one using compressed air to clean debris off whatever it is you want to clean, without have a tank. Just need to make a nozzle with a small cross section at the exit of the hose to increase the velocity. Have to fire it up when you want to use it, and keep the end open not to create backpressure...don't know if that will burn out motor.

My two cents.
 

MikeMl

Well-Known Member
Most Helpful Member
I'll relate a story about Vacuum Cleaner Motors:

When I was in high school electronics shop class 3/4 of a lifetime ago, my buddy brought an old vacuum to school and took it apart. He had it on the work bench, and rigged a 120V suicide cord to power it. He plugged it in. It began accelerating and began sounding like a siren or screaming banshee...

Mr Allen, the shop teacher was clear across the room, and I remember to this day how he looked up, had a puzzled look on his face, his eyes got wide, and he began running toward my buddy. He only got about 1/2 way across the room in the time that the motor reached (we figure) about 35000 rpm. With no impeller attached, there is nothing but windage in the core gap to limit the speed of a series-wound motor...

My buddy realized something bad was about to happen, so fortunately he ducked under the table. I turned my face away. I still remember that time had slowed and Mr Allen looked like he was moving in slow motion...

Just as the sound became piercing, the motor exploded. Pieces flew radially at right angles from the shaft axis, and fortunately no one was directly in line with it. It punched holes in the suspended ceiling tile above it, broke the florescent light fixture, broke out a window about 15' away, and threw pieces to both ends of the room. Made a hell of a bang.

It was a real physics lesson! First, the speed of series wound motors is limited only by friction; take off the impeller, and there is only a slight load due to windage. Second, when you spin a wound-rotor at ~35000 rpm, the centrifugal force is enough to cause the copper wiring to come out of the slots in the rotor. Third, when the copper wire comes out, you instantly transfer the momentum of the spinning rotor to the stationary stator, which causes an explosion equivalent to about 1/4stick of dynamite.

Bottom line: Do not plug in a vacuum cleaner motor with no load on it!!!
 

Mike_2545

Super Moderator
There was an episode of Mythbusters on US television where they made a hovercraft from vacuum motors... sounds fun
 

Hero999

Banned
I've rigged a vacuum cleaner motor up with no load any nothing bad happened. It was a series wound motor and did spin pretty fast., one of the brushes developed a small chip in it but it still worked. I suppose I was lucky, I now know that series wound motors should never be run unloaded. :D

Most modern motors have the fan fixed to them and the only way of removing it is with a hacksaw.
 

kinarfi

Well-Known Member
Wanna try something scary, disconnect the field winding of a running 50 hp DC motor, first scare is the arc that follows the lead as you move it away from the terminal, the second scare is the sound of approaching doom as the motor starts to build RPMs very rapidly and you know your about to lose your job, if not your life or limbs as it comes apart if you don't get that lead back on the terminal, the third scare is the arc as you force yourself to put the lead back instead of running. You only do this test once in your entire life!!!!! There is also that interesting sound as everything comes back to normal.
Kinarfi
 

crutschow

Well-Known Member
Most Helpful Member
Wanna try something scary, disconnect the field winding of a running 50 hp DC motor, first scare is the arc that follows the lead as you move it away from the terminal, the second scare is the sound of approaching doom as the motor starts to build RPMs very rapidly and you know your about to lose your job, if not your life or limbs as it comes apart if you don't get that lead back on the terminal, the third scare is the arc as you force yourself to put the lead back instead of running. You only do this test once in your entire life!!!!! There is also that interesting sound as everything comes back to normal.
Kinarfi
I accidentally did the same thing in my motor class in school. Fortunately I immediately plugged the field connection back in when I heard the motor taking off. My instructor came over and said "Don't do that again".
 

tcmtech

Banned
Most Helpful Member
Despite my many attempts to purposely destroy a motor by over speed I have yet to do it. :(

I and a friend took a old vacuum cleaner motor and put 240 volts into it without a fan on it and all we got was a big flash as the brushes burned up! It really screamed but never actually came apart! :(
 

colin55

Well-Known Member
Unless has permanent magnets inside, it will not generate.
This is incorrect.
The residual magnetism in the armature starts the generating process.
The generated voltage supplies voltage and thus magnetic flux (field winding) to start the generating process.
The windings should be put in parallel for this to produce the best results.
 

Boncuk

New Member
You could connect the suction port to a desolder pump. Saves some work and is more effective than the piston inside the pump.

Plan for a bypass not to remove solder pads.
 

kinarfi

Well-Known Member
Quote:
Unless has permanent magnets inside, it will not generate.
This is incorrect.
The residual magnetism in the armature starts the generating process.
The generated voltage supplies voltage and thus magnetic flux (field winding) to start the generating process.
The windings should be put in parallel for this to produce the best results.

Also, if you want to hack into the motor and separate the armature and field winding, you could supply a controllable field current to get a steady output voltage. Not practical though because generators have higher field winding resistances.
Kinarfi
 
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Hero999

Banned
You could connect the suction port to a desolder pump. Saves some work and is more effective than the piston inside the pump.

Plan for a bypass not to remove solder pads.
I'd advise adding a filter to catch the solder otherwise those tiny blobs of solder will short the brushes out.
 

Mike_2545

Super Moderator
I'd advise adding a filter to catch the solder otherwise those tiny blobs of solder will short the brushes out.


I did not know that the dirt and debris went into the motor itself. You would think if that were the case more motors would get damaged through normal usage.
 

Hero999

Banned
No, the dirt and debris don't normally go through the motor but are collected in a bag or chamber before the motor.

However, he has a vacuum cleaner motor and connecting a solder sucker directly to the air inlet would suck the solder through the motor.
 
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