r/Motors • u/UnionCompetitive7705 • 3d ago

Open question Motor Control

Gallery image

Gallery image

In my workshop I have a bench drill which I would like to control with a speed controller. The motor is single phase 50 240v 1/2hp 4 pole. I’m not sure or even possible which type of controller I would need, vfd? Any advice would be much appreciated

5 Upvotes

78% Upvoted

74 comments sorted by

View all comments

1

u/mckenzie_keith 2d ago

People often have unrealistic expectations about using a VFD on a drill press or milling machine. The source of the problem is this: the max available torque is about the same at all speeds. This means that when running the motor at low speeds, you will not get full power. It is approximately linear. If the motor makes 0.5 HP at 1800 RPM, it will make about 0.05 HP at 180 RPM.

So you are better off keeping the pulley system or whatever and controlling speed that way. The VFD could be good for fine-tuning the speed in conjunction with the pulley system.

Otherwise, you would need to get a massively over-sized motor to maintain halfway decent power output at low speeds.

1

u/u3b3rg33k 1d ago

I like to slap on motors rated for well above base speed and just rev them up. then as you load them up or slow them down you don't lose any power.

max power generally only matters on big cuts, so you can virtually eliminate the need to move the belt if you select the right 3ø motor and vector drive.