[Havelock]

Hello there

Joined today having spent weeks looking at various DIY CNC things on the web. Tom Mcguire's Stepper controller seems a popular start point so I'm going to attempt it as well.
I have 10 years experience running CNC routers. One was the step4 basic 540 which was used to cut parts for R/C aircraft kits. We also acted as agents in the UK for Step4 at the time. I also ran a much larger american CNC machine, about 1 meter sq. working area, the name of which escapes me.

So I'm looking to have fun implimenting a CNC build. It wont be big and I appreciate the limitations of the Mcguire circuit. I have also been doing electronics as a hobby for six years so the circuit build will be easy for me. I can also make my own PCB's using the toner transfer method.

One thing I am conscious of is not breaking my PC's integrated Parallel port by accident. To this end I have drawn up a single sided PCB and schematic with opto Isolators added to protect the PC against the possibility of the magic smoke being freed.

Budget is key here. As I have very limited funds. I am carer for my wife nuff' said.

Heres the schematic with the addition of the opto.

Attachment 275130

Fingers crossed it all works when built.

Havelock

[Havelock]

Hello there

Well I realised I had only done the schematic with only one opto-isolator rather than the three required. :withstupi

So I redrew it again. Also drew up the PCB. Initially I had it as a single PCB with all three axis. Now I have it as a single PCB with one Instance of the circuit so three will be needed for a three axis machine. I just have to draw up the PCB that the D sub 25 port will be fixed to that the other PCB's will be wired to this. well that's the plan any way.

Here's the corrected schematic and a PDF of the PCB Art done at 300DPI. The PCB should measure 47.25mm x 62mm. Just noticed the LPT signal pins are numbered incorrectly. Clock should be 2, Direction 3, Enable 4. A second circuit would go 5, 6, 7 and the third 8, 9, 14. All circuits have their LPT 18 - 25 wired to all those pins.