The world could be a better place if all people would agree to use the same measure, voltage, frequency, etc., but this is not going to happen soon. For me, constantly moving forth and back and living on various continents, this causes additional hardship. In the US, I own a 1″x30″ belt sander, which is available from Harbor Freight, at about USD 50. That’s a remarkable price, because the unit is actually quite well-build, has roller bearings, polyamide rollers, a motor, a cast-aluminum case, a base plate, and so on. No idea how the Chinese make this for less than USD 50 – the 4 6202RS bearings alone are more than $10, if not more.
Moving back to Germany soon, this nice litte machine will be a heavy doorstop – because there ain’t no 115 V power in Germany. What about the motor?
As it turns out, it is a capacitor motor, more precisely, a permanent split capacitor motor – the capacitor remains permanently connected to one of these windings. Such motors don’t have massive torque at start-up, and are typically used for fans, pumps, and the like. While some of these motors can be easily re-wired to 230 V, the belt sander motor only has 4 wires coming out.
So, we need to have a look inside. Make sure not to damage any of the windings!
A quick schematic – there are two main coils, and one started coil. Great! This means, we can rewire it…
Be sure you know what you are doing – this is all mains voltage, and the wires need to be properly wrapped and insulated (especially, the now exposed connection point inside of the motor).
Still puzzling how such a nice machine can be made for so little money… the motor alone – just rewiring it takes the better part of 1 hour…. all nicely wrapped.
The capacitor, a CBB60 grade, 250 V, PP metallized capacitor. 12 µF.
Finally, the belt sander assembled again – and ready for 230 VAC.
Some consideration of belt speed – the sander has a 95 mm diameter drive roll. A 60 Hz 2 pole induction cage capacitor motor will have about 3300-3400 RPM at full speed – that’s about 16 m/s grinding speed – OK for most materials (you might want to go a little faster on steel, and slower for touch-up and last steps of sharpening of knives, and similar objects).
Running at 50 Hz will reduce the speed to 13-14 m/s, fair enough.