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Movable Bed CNC machine 9

Wedge driven in to correct the side wall angle

Wedge driven in to correct the side wall angle

While I was looking at the assembly of the CNC machine from afar, I found that the left side wall was not exactly perpendicular to the movable bed. It was noticeable because the wall was relatively tall, and when viewed against the perpendicular wall of my house, there was a noticeable deviation from the vertical.

Somehow, despite all the careful measurements, marking out, and hand sawing, there were errors. I suspected my try square was not exactly square. Anyway, all the wooden plywood pieces had been cut and assembled. What could I do?

Side wall angle checked with a try square illuminated with a torchlight

Side wall angle checked with a try square illuminated with a torchlight

The answer was to wedge the pieces apart to the correct right angle and then fixing the pieces with glue and screws. Finding slivers of wood to make the wedge that thin (about 1 mm thick) was not easy, but I managed to obtain some thin pieces of wood from veneers that had peeled off a plywood piece which was damaged by the rain. Talking about innovation, this was it. The useless pieces of veneer solved a problem for me. With a little bit of careful sandpapering, and after making several failed attempts, I managed to create one piece of wedge strong enough for my purpose.

Driving and gluing the wedge in between the two pieces of plywood comprising the walls of the cnc machine after loosening the holding screws, and then tightening the latter back after achieving the correct right angles, the job was completed satisfactorily.

Testing the Movement of the X-axis

Now came the time for testing. I needed to supply power to the stepper motors and to control them.

If the previous testings were an indication, the motor should run as programmed. But the difference was that in the previous tests, the motors were smaller in size. Would it still work for the motor installed on the structure, coupled to a lead screw and actually driving a mechanism? I just had to test and see.

One worrying factor was the fact that things could go awfully wrong and the mechanism might crash into the structure and ruin many months of hard work. So I had to figure out how to avoid that. Fixing an emergency stop switch button seemed to be a good idea.

In order to do that, I had to study the software and its program to see how to link the commands appropriately. After many hours of tweaking the configuration on the software, looking and learning from forums on the internet, doing some programming, modifying the control circuit with pull-up resistors, installing wiring, and doing many other actions, I came to the conclusion that either the software was not able to respond or the parallel port PCI board that I was using was not functioning as it should.

Being a person who had been operating heavy machinery on so many occasions, I felt uncomfortable running my prototype on power without some sort of emergency stop. I also read somewhere that switching off power to the motors might not bring it to a complete stop effectively due to momentum. And doing the wrong action might cause damage to the electronic boards. So, even before I hooked up the motor to the lead screw and the movable bed, I wired up the emergency stop button to the stepper motor driver board so that it could stop the motor in case things did not go as planned. This seemed the best action to take.

I also wired up some limit switches, again for the purpose of avoiding unnecessary damage to the structure if things went haywire, but later I found that I could not or did not know how to control them by the program. Perhaps more tweaking and programming was needed. At this time, I am still learning as I go along.

The video below showed how the machine performed. I would consider the movement test on x-axis a success. At least, I was able to know how fast, or how great the forces were. During the tests, which I did many times, I had experienced many crashes, but found that the forces were too small to cause any damage. This was quite reassuring.

However, in the future, I might be fabricating bigger machines, and I needed to know how to handle them. The learning experiences from these movement tests would be extremely helpful when I next expand my fabrication activity to include the Y and Z axis of the machine and to other future machines to come.

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