Re: How do set home position, running turbo cad/cam

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "cassadaga717" <cassadaga717@...> wrote:

>
> I'm in the final stages of my scratch built CNC and starting to look into the software to run my machine. I have a full copy of Turbo CAD/CAM 11 and after going through the CAM setup I noticed there it no way to detect the limit switches or to jog the machine to a home position. I used the Hobbycnc driver board and their 305oz stepper motors. Although there are inputs for limit switches, it said the inputs are for the software only. I've read all the threads on numerous groups and no one seams to mention about manual moving the machine. Please help, I'm so close and if I don;t get the CNC running, the wife said she was going to burn the wooden monster in the garage.
>

It takes three pieces to do CNC: CAD(Drawing) + CAM (toolpath) and Control (machine interface). While several packages do two or more of the three, your flexibility is limited. You can pick and choose any of the three and there are low cost options for each one.

For Control, as mentioned, MACH3 is a popular choice (10,000+ users) and has a very active list here on the Yahoo Forums. You need a PC and at the simplest level a parallel port. A buffered and isolated interface (aka Breakout Board) between the parallel port and your motor drivers is recommended.

Another alternative is EMC2. It's free but will require you have a little more computer skills to use Linux as the OS.

All of your HOmes and Limits are INPUTS. Your Step & Dir signals for each axis and any relays for controlling the Spindle motor, misters and other laods are OUTPUTS. How those signals are handled (and how many you can use) are a function of the Breakout Board you select.

So with CAM you define HOW you want the pieces cut, WHERE on the material, and WHEN each cut process takes places. With the proper CAM you can define automatic offsets (inside/outside/on-line), lead-ins and things like feedrate, number of passes, start points and things like plunge rate and other parameters. You then need a "POST" that translates the CAM toolpaths to the proper G-Code dialect for your chosen Control.

Things like operator interface, machine math, coordinated moves, motor tuning (velocity, acceleration, steps per unit), G-code load and run, e-stop, and Homing (Reference) are part of the CONTROL.

A lot of commercial machines have the control software and hardware integrated and you just feed it G-code. A more cost effective approach is the PC based Control and is most favored by DIY CNC builders.

Let us know how else to help. There is a LOT of experience here on this Forum.

TOM Caudle
www.CandCNC.com
Totally Modular CNC Electronics