[musicmkr]

My company has me building a 3 axis mill/router for repetitive tasks milling aluminum extrusions. There are basically six different programs this thing will run for the first year of it's life so instead of running it from a PC & parallel port I am building a stand alone controller based on a PIC 18F452. The PIC will provide step/dir signals to drive the three geckos.

The reason I am doing it this way is because no one in our shop has ever used any type of CNC machine, so I want it to be simple "push button" operation. Also I want the machine to home before every operation and it's very simple to get the PIC to do this automatically, however with a PC the operator would have to tell it to home.

My first question is; has anyone on this board done anything like this before? I've been making huge progress on the ASM code but I don't want to re-invent the wheel if I don't have to. I've been on luberth's site but his project seems to be based on a trickle link from a PC, and I'm pretty sure the PIC is the motor driver itself.

Next I'm wondering if anyone has any insight as to which is the better method of Pulse Modulation. I could use software to pulse the step pins with calculated delays to determine the phase, or another method is to use timers and interrupts. But that leads to the possibility of interrupts "butting heads".

My last question is regarding two axis circular interpolation. Has anyone done this to any level of accuracy using a PIC? My application shouldn't require very precise circular interpolation, and I'll probably just have the software break down any curves into small line segments, but I was just wondering if anyone has any experience in this area.

Thanks for any insight you may have. I've asked a few of these questions on PIC boards but most of those people don't understand the importance of accurate step pulses in the CNC world.