Electrical motor in Jigsaw

L

lord_emperor

Limp Gawd
Joined
Feb 1, 2003
Messages
487
A couple of days ago I took apart my jigsaw, something had gotten caught in it and messed up some of the wiring and broken the fan. I decided to repair it myself, I took some notes on how it came apart so I could put it back together.

Murphy's law kicked in and my note paper wandered off.

The only thing that is really questionable is the wires going to the motor. There are two (obviously positive and negative), one goes to the brushes and into the middle part of the motor, the other goes to the outer part of the motor. Assuming the motor is only meant to turn one way, which is most likely which?

It occurs to me this is an AC motor so it may not matter, but I still need confirmation before I go plugging it in and see what happens =)
 
if you look in the bottom of the brushes you should be able to see which way it turned. also -- remember the right hand rule of inductence. AC motors operate only because of alternating current so there isnt too much you can mess up.
 
If you do happen to wire it wrong, you'll have two opposing magnetic fields and it won't turn. It will draw a rediculous amount of power though, and will probably pop a breaker. When you go to test it the first time, just quickly tap the trigger and see if its going to go. If not, unplug it right away. It really doesn't appreciate having two hard opposing fields on it.
 
If one of the wires is connected to the motor casing, it's almost certain that it's the neutral (negative) wire. Motor casings (for that matter, just about any casing, including computer casing) are almost always ground.
 
http://www.safety.ed.ac.uk/policy/part3/53.html

Teancum, that's not always the case. Most portable power tools around here (Canada) actually have insulated cases (double insulated such as it were), and generally only have two conductors, and no ground. There are no guarantees these are at ground potential.
 
Thanks for the replies. I hooked it up and it seems to work. Cut some wood for a test and nothing caught fire or exploded. :D
 
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