Thread: dummy

IMAG0073.jpg
Sadly, the link to this photo does not work over at the Metalworking forum....
It shows my very old Servian drill press upgraded to a 3-phase 1Hp motor with a sensorless vector control VFD.
It is now able to go slow enough and with enough torque to drill at least 1" holes in steel, and at the other end of the scale run at more than double the speed of the belt-pulley setting for 50Hz.
The vector control maintains the rpm irrespective of load, increasing and decreasing required torque on the fly.
The VFD also allows almost instant reversing at low speed, allowing me to 'rigid' tap holes on the drill. But I find that not having any feel for the forces applied to the tap, I'm unlikely to try this below M12 threads. I havent' tried to find out the maximum capacity of the motor and VFD combination for thread cutting yet. I rather suspect it might be limited by my clamping ability of the workpiece than the available torque of the motor.....