[TheForge] Buffalo forge blower/ Magic of motors

[paul]

Bob Smolen wrote:
> I am cleaning up an old #50 Buffalo blower. It wouldnt turn so I cleaned out
> a mud hornet nest and other crud, disassembled the motor and one brush
> seemed hung up. Motor is now working outside the forge so I will reassemble
> and hope for the best.
> Question: The motor plate says always run with rheostat. I dont have a rheo
> and was going to use an air gate. Will this cook the motor?
>
> This is a beautiful blower and I would like to retain the original motor..
> The motor has a spring loaded hinge on two small compartments that allow
> access to the brushes. The motor plate says it will run on DC or AC current
> and many different cycles. Sure is nice to see what great mfg. was done here
> years ago.
> I would appreciate an electrical person telling me what I can do to evaluate
> a motor and why it may not be running which was the case before I got lucky
> with the brushes which is  about the only thing I know about motors. From
> freshman science in 1962, I recall the field windings on the outside create
> a magnetic effect causing the armature to turn due to attraction/ repulsion
> of north and south poles? Somehow the commutator keeps changing the poles so
> the armature spins--or something like that?
> Thanks you your comments.
> Bob
>   

Hi Bob
I rebuilt a champion electric blower a few years ago. Before you go much 
farther I would suggest connecting a VOLTMETER from the motor frame to 
ground and verify that you have no stray voltage present.
I found that my commutator had collected a lot of carbon dust (wonder 
where that might come from in a blacksmith shop...) which created a 
leakage path from the commutator to  the armature shaft, through the 
bearings and then to the motor housing... mine had about 65 VAC present. 
Nasty shock potential.
The solution was to pull the armature, and clean all the carbon dust 
out. Mine also required removing the brass ring and mica insulator that 
retains the commutator segments opposite the end that has the wires 
soldered on. The insulation value can then be tested with a MEGOHMMETER 
(MEGGER) see:
 
http://www.tpub.com/content/neets/14175/css/14175_50.htm

 but you might want to take it to a motor shop if you have any doubts as 
to your electrical skills.
A universal motor (AC/DC) will operate perfectly happily with a SCR 
dimmer rated for inductive loads, or check out speed controllers listed 
for use with a router. When that motor was manufactured only as few 
theoretical physicists might have had even an inkling that the 
possibility of solid state controllers might some day exist, hence the 
reference to Rheostat.
As to the pole switching reference, that is accomplished by the 
commutator and since the motors field windings and the armature 
experience the the same reversals of alternating current the motor quite 
happily keeps turning in the desired direction. To reverse a universal 
motor you must change the polarity of only the field or the armature. A 
permanent magnet motor must only run on DC, and to reverse it you simply 
change the polarity suppling the motor.
Great blowers anyway. Have fun and stay safe

Paul