The power feed control left for the X travel is home made. Its central knob is the speed control potentiometer. It is wanted work complication. One could ue a separate DPDT switch for direction reversal and a separate potentiometer for feed speed.
The LED at center is a pilot that the 12VDC power is arriving to the unit.
The pushbutton on the right is for quick speed to return the carriage.
To circuit diagram of Powerfeed
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I have a small milling machine, a drill / mill machine and a wood copying device with carriages. I wanted to power feed them, but the units available on the market, thus nice, were too expensive to fit 3 machines.
A few articles which I read had a demultiplication through pulleys and belts to get the low spindle RPM feed needed and I had not the room on every machine to do it.
I remembered that the battery operated machines I had had a high demultplication with high torque. On top they had a torque adjustment if needed and above all a mechanical clutch coupling.
With that kind of motor there is no need to have microswitches at the end stops, the clutch coupling out warns to stop the power feed by its sound without destroying any thing on the mill, the carriage spindle or nut.
I tried a number of 12VDC power supplies for ham/CB rigs to see what was adequate and decided for a 20Amp feeding 2 machines at a time.
The first thing to start with was making a housing out of 3/8" and 3/4" aluminum plates.
Power feed
with motor of battery operated drilling machine
The bottom of the pic is the back of the housing.
In the center the motor, the demultiplication with planetary drive, the torque adjusment unit and the drill chuck. The latter, through a ball bearing in the small aluminium flat on the right, is driving directly the feed screw of the table.
At the back left a disc through which the potentiometer axle is passing. The two screws push against one of the 2 visible microswitches giving power to the motor for one direction.
At the top center a small printed circuit bearing a power relay for direction reversal of the motor, a small power supply feeding the LED and the power relay.
The integrated circuit (voltage/current regulator) being the heart of the power supply is just not visible over the 12VDC power socket at the bottom.
I do not recommend to use the battery of the drilling machine. You would mill very long. But for trying how it works just unscrew your handle on the carriage feed screw, hold the drilling machine extremely well (I am not responsible for broken twists!) and have a go. You will be surprised.
