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Movable Bed CNC machine 17

Before - Motor wires hanging loose.

Before – Motor wires hanging loose.

With all the testing successful, it’s time to consolidate and improve on the overall machine. What I wanted to do was wire management. My wires had been dangling around, and were made up of all sorts of wires. In order to make the circuits work, I had used whatever wires I could find. I had stripped and taken them from 110V power cables, 230V power cables and even from TV signal cables. As long as they could connect electrically I would use them. After all, most of the connections were for low power, low voltage applications.

Before - Control board hanging on the trolley

Before – Control board hanging on the trolley. Power supply wire hanging loose. Long wires.

During the construction and modification of the CNC machine, I had placed the whole assembly on a trolley with wheels. In this way, it was relatively easy to move the machine about – near to the computer when I needed to test, and kept aside when I was not working on it. I was also able to move it to well lighted locations when I wanted to do more detailed work.

Wire management of circuit boards and motors

After – Wire management of circuit boards and motors. Mounted on the cnc machine body.

At that time, the control electronics and power necessary for the working of the CNC machine were all temporary, although most of them were soldered on. What I had needed then was just a means to test out the system. I had used an electrical insulating board to mount all the electronic components and just hung it on one of the legs of the trolley. In this way, all the wires for connections from the electronic boards to the motors was long enough to reach their terminals, while still allowing me to dismantle some parts along the way.

Wire management of power supply

After – Wire management of power supply. The switch is for starting the spindle. Power supply taken from 24VDC 13A supply.

Now that the CNC machine was in working condition, I thought it would be good to replace all the wires with standard ones, lay them out neatly and make the machine a complete unit. First, I mounted an insulating board at the back of the machine, which was not in the way of the moving parts. The breakout board and the stepper motor driver boards were next mounted in place. I had made some spacers out of pvc cut-offs so that the electronic boards would have some air circulation in between the insulation materials for cooling. The wires were replaced. Most of the electrical connections were soldered on. The wires leading to the stepper motors were clamped in place so that there was minimal chance for them to break off in use. Most of the electrical wires were held in place by tying them with thin copper wires led through drilled holes in the cnc machine body. There were two items that needed to be supplied with power. They were the three stepper motor driver boards and the spindle. These were taken from a filtered 24 VDC 13A power supply, the latter being taken from the mains supply with its own switch. The stepper motor driver boards could be switched on and off just by flicking the main switch. For safety purpose, the spindle needed another switch for controlling its operation. I would not want it to be running while I was still setting up the work piece! I found an old switch, modified it and used it as a switch for the spindle. Overall, the cnc machine now looked better with the wires laid up neatly. It would also be easier to move around later.

Handle for turning Z-axis lead screw manually

T-shaped handle for turning Z-axis lead screw shown on the left. The improved version is shown on the right with the set screw.

Another item that I needed to improve was the handle for turning the Z-axis lead screw. Currently, I was using one made from plywood laminates glued together for the shaft and with a T-shaped handle for turning.   Although I had made one side of the lead screw shaft flat by filing it, I was not able to make a corresponding matching hole in the handle . So the handle would sometimes slip when I turned it. The handle was able to drive the shaft merely because it had quite a nice fit. It was a very rough solution for enabling me to turn the Z-axis lead screw so that I can position the milling tool in the correct home position.

Z-axis lead screw knob installed in place

Z-axis lead screw knob installed in place. The knob was easier to turn than the T-handle.

I had tried to use epoxy resin to cast a hole with the corresponding shape of the shaft, but it was not easy, especially as I did not want the assembly to be permanently glued in place when it set. I needed the handle to be removable. I decided that an electrical screw connector that I found could be a good component to use for fabricating a new handle. It was not exactly fit, and I had to drill the center hole slightly larger in order to take in the lead screw shaft. A few pieces of PVC tubes of various sizes were cut and glued together to make a workable handle. The new round knob worked better than the previous T-shaped handle. And it looked better.

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