I started to feel insecure with the conventional 250 w motor, so I purchased 400 w products and replaced them. Since horsepower has increased, it became a bottomless sound, but it is good to use as much as you worry about, without increasing the noise.
I bought it by replacing the motor of the benchtop drill machine that became sick. Because it is totally closed type it seems to be strong against dust and is satisfied with price. It took a lot of time for wiring (because there are four wires even in single phase), but switching was easy and power up to 300 W was also possible. Since I was waiting for about two weeks at double price so far, I am satisfied because I could repair it too smoothly.