Bought this old bench grinder and after connecting it to power (single phase), this is what happens when connected (video attached).
The motor is lacking a start capacitor so it needs a push. It makes that noise when connected, which otherwise disappears at power disconnection.
Other than that, it has a few issues like slightly worn bearings (which I cleaned of old grease and re-greased) and a slightly bent shaft in the grinding stone area (probably from a drop on the stone from an angle).
Electrically, there seems to be two identical windings with 3 wires each, coming from the left and right side of the winding, as seen from the top of the power switch box.
One winding was not connected. The one which is connected to the power switch, measures like this:
- Brown to Black 1nd = 28 Ohms
- Brown to Black 2nd = 28 Ohms
- Black 1nd to Black 2nd = open
I have only connected Brown with either one of the Black wires.
Video where the noise can be heard:
https://youtube.com/shorts/7nsSNtZ2pHwAnd pictures attached.
Thank you for any inputs!