Recently, I got hold of some old pc’s with the intention of checking whether they would work for my cnc machines. (One moving gantry cnc machine is coming out very soon, and it would need a computer to work on). As I had intended to load the computers with Linux Debian operating system, which can use LinuxCNC software, I had not discounted their usefulness even though they were old computers using old microprocessors.
Well, after loading one of them with LinuxCNC, running on Linux operating system and then running a latency test for one night, I found that the maximum jitter was extremely high. This meant that the computer was not suitable for LinuxCNC. If I use it for LinuxCNC, it would stop working halfway through any machining job. This was not acceptable at all for operating the cnc machine.
So I had to discard the computer. Actually, it was a very good computer during its time. It was very strongly built and I was sure that some components were built to last. Well, I did salvaged some working components like the switching power supply, audio speaker, switches, hard disk, cdrom drive, floppy disc drive, some ribbon wires and whatever I thought could be useful in the future for my diy projects.
I was about to discard the whole computer casing, when I thought, wait a minute! I remembered that I had an old step-down transformer which I had used for hot wire cutting of polystyrene foam which badly needed an enclosure. Previously, I had salvaged this transformer from an old vacuum tube radio. At that time, I had built a box enclosure out of wooden materials for it, complete with sufficient air holes for ventilation.
Looking at the steel housing of the computer that I had wanted to discard, I noticed that there were two nicely made steel boxes which were used for keeping the hard disk, floppy disc and the cdrom drive. What I needed to do was to cut them out and figure out a way to close them up on two faces, and I would have the steel boxes ready for keeping some electrical components or circuit boards. Naturally, with these steel boxes, I would make sure that the holes were small enough not to allow any contacts with the live circuits. I would also make sure that the steel body were earthed and connected to the ground earth of the house.
After carefully studying the joints of the steel plating and marking the lines, I cut the steel with an angle grinder with thin cutting discs. Naturally it was not as straightforward as cutting a flat piece of steel plate. Once the enclosures of the hard disks and cdrom drive were cut out, I had to figure out how to attach other plates to cover the open sides of the boxes.
Again, as I was trying to maximize usage of the steel materials, I tried not to cut on the blank flat surfaces, but to utilize the sides which contained many holes. I attached these plates by using self-tapping screws at some places while cutting and bending slots to hold them in place.
When every face of the boxes had been covered, I made a general finishing grind to even up crooked edges made during the cutting stages. I then did a general hand filing to remove any sharp edges so that the boxes would be safe to handle.
Overall, I think the boxes looked quite nice with their galvanized coatings. And I am keeping the rest of the uncut steel sheet metal for future use.