Electric Motor question

[Garrett Lowell]

I have a very old Peerless induction motor, 1/3hp, which I use on the Boice Crane bandsaw. It sparks alot. Can anyone point me to a website or a book about how to troubleshoot and rebuild electric motors like this? Thanks.

Garrett

[nedL]

as I remember there are two typical reasons for arcing. Dirty or worn brushes & commutator (easy to fix) or a short in the armature (not easy to fix).

[Tom Robb]

Yellow pages. Electric motor repair.

[epoxyboy]

If its an induction motor, there aint no brushes or commutator, and if its sparking something is seriously wrong.
On the other hand, if its a brush motor some sparking is normal. There may (or may not) be a capacitor connected across the brushes to help reduce sparking - if it is a really crusty old one it may no longer be working as intended. also, what NedL said. A quick commutator cleanup with some fine wet and dry (about 600 grit) can work wonders if the com isnt too worn - also clean the gunge out from between the segments. Note that the brushes dont necessarily aim at the middle of the shaft, in which case there is a right way and a wrong way to refit the brushes. I motors like this the brush end will be bevelled so it is pretty obvious which way around it should go.
Remember, the zappy stuff in the wires can KILL.

[pipefitter]

If the motor has a centrifugal starting switch, which would include a mechanical set of breaker points inside the rear end bell,they could be past the cadmium layer and into the copper layers of the points. They could also be pitted or crusty from arcing. If a brush motor,a worn bearing can cause the armature to weigh more to one side contacting one set of brushes while leaving less contact on the above set of brushes and is more common with horizontally mounted motors. The centrifugal switch is that click you hear when shutting off a motor as it slows down. There is several different types and sometimes the part of the switch that holds tension on the points can become fatigued from heat or long usage and not provide a strong contact. If the switch can be adjusted,it should be checked with the centrifugal governer collapsed to ensure that the points do seperate fully.

Also,motors on saws should be periodically cleaned out with compressed air to keep the dust out of these parts and to ensure that the cooling flues are kept clean.

[TMny]

At a minimum, all motor questions should include description of power supply, as A.C. , D.C. , voltage, rated current or rated HP, and number of phases , if A.C.

Assuming the motor in question is single-phase, 120 or 240 V....

>>If its an induction motor, there aint no brushes or commutator,
This statement is true only regarding run-of-the-mill induction motors. A type of motor called "Repulsion-Start, Induction-Run" (or similar) is often supplied for "Farm Duty' , or where voltage may be low at end of line, and where good starting torque is required (as compressor service). These are rather fine devices {and more expensive}. These feature commuter/brush action when starting, and then do something weird , and run like a routine induction motor once within some range of rated RPM. If the Peerless is of this type, it may need a little bit of commutator cleaning, and possibly dust removal and cleaning. Motors often crap out after many years of abuse; the insulation degrades. A shop can test the insulation after you clean it up, and make an appraisal. Special proprietary 'electric motor cleaner' is available in spray cans at shops, or probably Grainger , as CRC brand .There are books and courses describing electric motor design, service, and construction .... i think Audel's series has a decent one. The lathe should be high precision; but a little commutator cleaning can be done without , being careful to use suggested abrasive, and good cleanup. Worn, dirty brushes could be the main issue.... but as the (particularly armature) coil insulation degrades, the electrical and magnetic characteristics fall off. Repair shops sell spray insulating varnish which can restore some capabilities.

[merlinron]

at one time several years ago, i took a router motor to a repair shop because i though it might need a commutator cutting/ cleaning. the guy at the shop took my motor, started it and then fed a small round chalk-like stick onto the commutator. it cleaned the commutator and seated the brushes all in about 20 seconds, and the motor has been fine since. he gave me a chunk of this stick and i have used it on a few other motors with the same results, but i have since lost track of it. i have no idea what it was but it sure worked like a dream..... anyone know what this might be?

[Bob Adams]

Called a commutator cleaner, Ideal makes one. Stone on a stick.

[Garrett Lowell]

Sorry, just getting back to this. This motor is a repulsion-induction motor, 110 VAC, 1/3HP. 1 phase 60 hz. It starts and runs, but sparks are visible through the small access door on the side.

[merlinron]

sounds like you might just need the communtator cut/polished and a new set of brushes.

[pipefitter]

that cancels out the start switch scenario then.