This is the Alpine Minor milling machine. It is about twenty five years old and came from Tiwan.

First job was to strip it down, clean off the old oil and grease and reassemble, adjusting lead nuts and slides for minimum play and backlash but still ease of movement. The stepper motors that I am using are quite powerful 263oz/inch but you still need to make sure there are no tight spots over the full travel of the table. I had to use a bit of packing on the X lead nuts vertical position after reducing the backlash in the nut as it was slightly out of line causing binding on every half turn of the wheel. This cleaning and adjusting operation was well worth the effort, it is better now than when I first bought it.

Stage 1 is to fit the X travel stepper motor.

I am using Nema 23 type stepper motors for all three axis. The bracket was made from some 1.5 inch aluminum angle with 1/4 inch wall thickness. The end was machined square and a 1/4 inch aluminum plate was fastened to the end of the angle with four 4 mm bolts. Next slots were machined for fitting the stepper so that the belt can be fitted and then tightened. Two dovetail plates and bolts hold the whole assembly to the side of the bed. The pulleys are 28 teeth on the bed and 14 teeth on the motor giving a 2:1 step-down. A 400 mm X 9 mm belt links the two together. Although I have fitted the motor on the front of the bed you could always fit on the end making for a shorter drive belt. Unfortunately I personally are restricted for room at the end as the machine as it is quite close to a wall. Although the fixing looks quite primitive it is in fact remarkably solid. When everything is up and running I will construct cover plates to protect the whole assembly.

Notes: 2inch angle would have been even sturdier if available.

Stage 2 Y Axis stepper motor fitting.

Fitting the second motor to the Y axis consists of just a plate of 1/4” aluminum with four holes for motor fixing and two slots for belt adjustment and fixing. Countersunk 4 mm head screws at the back with nuts on the front fix the stepper motor to the plate. The motor is fitted so that use is made of the rear shaft to drive the table. The front shaft is sawn down to clear the machine base. I use the same pulleys as for the X axis with a 2:1 step-down ratio. A 330mm belt links the two pulleys.

Stage 4 Test the system works

Temporally connect up three stepper drive boards to the motors with connector block to see if it works. I am using my old PC with a 850 MHz AMD Duron processor running windows XP. A television swing support bracket holds the LCD monitor and keyboard. The computer can live on a shelf under the lathe. The software is Mach 3 by Artsoft which outputs the stepper motor signals via the parallel port. I am using a bench power supply for testing purposes and the motors run fine on 15 Volts without missing steps. In the final setup I intend to use a 24V supply so I can increase the travel speed.

It works!
A more recent example of CNC operation using modeling board. These are 15 mm height letters cut with a 1.5mm router bit to a depth of 1 mm.