Quote Originally Posted by m_c View Post
At least you're aware of the limitations.


That sounds fine.
I would recommend learning a bit about G-codes though, and how they work on whatever controller you're using, as there can be slight differences in how they're implemented.

The machine home does not have to be 0,0,0, however it depends on if grbl supports it not being at 0,0,0. Depending on machine layout, home can be at the opposite travel limit i.e. to keep the gantry at it's furthest away point to improve access for loading/clamping.
Once homed, you would then normally define a work offset. For changeable repeatable tools, you'd also use tool offsets, but I don't think you really need to worry about tool offsets.

Alternatively, as this sounds like not that powerful a machine, use the KISS option. Don't bother with homing switches, set home at 0,0,0 for the work piece, and ignore offsets.
This is how I use my digitising machine, as it removes complexity and it just stalls if it does run out of travel. I certainly wouldn't use this technique on my mill of lathe.
Thanks for the advice!
I'm familiar with Gcode (again having come from the 3D Printing world) but respect that it may be implemented slightly differently in CNC.
I personally would have it at 0,0 given my machine layout!
So what's the precise difference between the work and tool offset? If I were to manually change a tool I would expect to home again, swap tools and then set the offset with the new tool. That way it takes into account the different length of bit.
I got endstops from the scrapped Rapman and I don't see any reason why not to make it as good as I can while maintaining the budget approach! It's a bit of a quandary, I know, but though I'm keeping costs minimal I do want to do the best I can with what I have :)