Quote Originally Posted by irving2008 View Post
I think Cam is confusing resolution with accuracy. To be accurate to 0.1mm you need to resolve to something better
This is exactly what I was driving at, I just missed the terminology by a mile. To re-phrase I wanted to know what sort of ratio you give between resolution and desired accuracy. From what you are saying double is OK a little more is better (5x), but a lot more (x10?) will be lost in the machine.

When I posted I was thinking an order or magnitude, i.e. 10 fold between the two but back then I was also considering microstepping. That said although my understanding has improved very considerably my gear ratio is going to be very similar, rather good luck ! This because I have reduced to considering half stepping as the smallest finite usable resolution, but also lowered my resolution to accuracy ratio.

I have looked in to other peoples machines which is probably why I ended up at more or less the right ratio even if it was for the wrong reasons. I just wanted to check they had done there homework correctly, no point copying a bad design :)

For the record the machine will be ally, hopefully quite rigid, no unsupported rail, a router was only and after thought it will primarily be a laser cutter so no cutting loads.

Thanks for all the help, very useful.