George's Coco CNC Milling Machine
Repacked Coco Page

Modifying a
The base plate is 1/2 inch thick. I expect it will be sturdy enough to keep things aligned. The vertical angles the dremmel is mounted on will get some bracing that will go diagonally down to the base plate to ensure they don't move. The angle iron is hardened steel and only in the past two weeks was I able to drill the holes in them. I had to buy a drill press that would go slow enough ~300 RPM to do so without burning drill bits. Small holes, <1/4 inch weren't a problem.
Here is a close-up of the Y axis where I built the roller bearing slide..

I can't find any play in this setup and the effort to move the slide is quite small.

The Dremmel

As you can see, it is mounted with a roller bearing slideway. The end mill mounted in the dremel is a 4-flute square end 1/8 inch unit. Solid carbide and has never been used.... yet. This is the tool I'll use to cut the pocket for the permanent lead nut into the X axis slide.
A few weeks ago, I finished the dremel clamps. Here's how they look now..

Now I can easily remove the dremel when I need to use it on something else.
What drives the stepper motors? It's this little box that contains a 24 volt power supply and some chips that are darlington transitor arrays designed just for this sort of application. They came out of something I pulled years ago. I don't remember what it was now. The 5volt logic from the coco drives them.

There are a total of 9 DB-9 connectors on this box. The four on top are inputs from the coco's output latches. The four under them(hard to see) are the outputs to the steppers(with an input from the home switches) The one on the very bottom goes to the coco's input buffer for the reading of those switches.
That little cabinet used to be a modem... as is the cabinet the coco is mounted into.


That's it on top. Inside that cabinet is a 512K CC3, 3.5" floppy and controller, the eight port I/O board and a switching power supply. I'm thinking of adding and RS-232 port so I can sit at my PC and do programming... or!!!
I've done this before. alter OS9 to use /t2 as /term, lose the graphics and video drivers, keyboard driver and use a terminal on the /t2 port to operate it Of course, without a new ROM in the coco, I still have to have some buttons to type DOS <enter>. If I do something like this, I may get one of the gurus on the coco mailing list to make a new rom for me that will boot os9 for me. I NEVER use RSBasic except to boot OS9
Btw... losing the keyboard driver gives the PIA a new I/O port for the coco! Imagine that!

I need to clean all this up once the hardware is all done. It looks to be a mess right now. Yes?

Once this is all done and I'm happy with the mechanical part, it will be totally disassembled and media blasted, painted and reassembled. It should look good. I need to figure a way to run the wires and shield them. I expect I may just run them inside some copper tubing or something quite similar.
Page two for more CNC mill photos