Purpouse of parts + functioning of coffee grinder motor

[Gregg]

If you power the motor with mains power (and the incandescent light in series, I hope) be sure to tie it down to something as it may want to twist out of your hand when starting.  If it has a shorted or open turn, it may run after you give the shaft a twist but you'll soon be able to tell by the vibration that something is wrong.

[todorp]

@todorp, did the motor behave strangely just before it failed?

The motor was given to me by another person just saying "it doesn't work anymore"...

So, using the bench power supply i cranked up the DC voltage using current limiting: the motor started spinning at around 30V@170 mA. I suppose this is a good sign. Next I will take the plunge as many have suggested and try to connect mains power using all precautions mentioned in this thread: light bulb, well fixed motor...

Do you people think a variable transformer (something like https://www.amazon.it/Bronson-1000-Trasformatore-Variabile-Variac/dp/B07JKZGQT8/ref=asc_df_B07JKZGQT8/?tag=googshopit-21&linkCode=df0&hvadid=346278921589&hvpos=&hvnetw=g&hvrand=6340046301626428526&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1008141&hvtargid=pla-636920724950&psc=1) might be useful to perform tests on motors like this one using lower AC voltages? Or is it just a waste of money?
Thanks a lot,
    Tod

[Gyro]

Ah, ok.

The motor running sounds hopeful, increase the current limit and it should stabilize - as the motor spins faster, it generates more back EMF, which lowers the current it takes (relative to not spinning).  Yes, I think you're good to go to the mains + lightbulb test (repeating the warnings about securing it so that you don't have a mains powered motor jumping around your bench).

It's hard to know whether it is worth you getting a variac. It depends whether you are going to get decent use out of it for other stuff. The price is much higher than ta replacement  motor or grinder. They're useful to have for testing, but a bulb test will usually get you most of the way when testing power supplies on small appliances etc. 1000W is a big one too (although those are probably optimistic watts). You can often find a, good brand used one on ebay cheaper.

[Zero999]

@todorp, did the motor behave strangely just before it failed?

The motor was given to me by another person just saying "it doesn't work anymore"...

So, using the bench power supply i cranked up the DC voltage using current limiting: the motor started spinning at around 30V@170 mA. I suppose this is a good sign. Next I will take the plunge as many have suggested and try to connect mains power using all precautions mentioned in this thread: light bulb, well fixed motor...

Do you people think a variable transformer (something like https://www.amazon.it/Bronson-1000-Trasformatore-Variabile-Variac/dp/B07JKZGQT8/ref=asc_df_B07JKZGQT8/?tag=googshopit-21&linkCode=df0&hvadid=346278921589&hvpos=&hvnetw=g&hvrand=6340046301626428526&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1008141&hvtargid=pla-636920724950&psc=1) might be useful to perform tests on motors like this one using lower AC voltages? Or is it just a waste of money?
Thanks a lot,
    Tod

Yes, the fact the motor is turning is an encouraging sign it's good.

A variable transformer can be a handy piece of test equipment to have, but it's not worth it if you only want it for this test. One important thing to be aware of is the secondary will not be isolated from the mains. The output will share the same neutral as the primary and will need to be treated with the same respect as mains, even if the voltage is set to a non-hazardous level. This is even more important if you live in a location without polarised mains plugs, meaning the neutral can be either conductor.

[todorp]

Hi guys, I just tested the motor attached to the mains 220V using your suggestions: the motor works!
So the fault was with the thermal fuse. I will be ordering a replacement for the fuse and hope to have everything re-assembaled soon.
I will try to improvo the ventilation of the motor and not use it for long continuous runs to avoid another thermal problem.

I just wanted to say a big thanks to everyone who gave me suggestions and helped explain a bit the workings of these kind of motors (and various parts found around the motor).

Cheers,
    Tod