New to MyCNCuk

[JAZZCNC]

As its a PCB drill rather than a mill, with 0.7mm holes being the most common size I'm drilling, I thought I would get sufficient resoltion if I were to buy / build a controller that supports half step drive. While it sounds interesting to develop I don't think microstepping is needed.

Really you should look to get the resolution you want from the pitch of the screw not the drive stepping. Higher Micro stepping(10x Max) does help but more for motor smoothness than resolution.
What you need is a low pitch ballscrew say 4mm or less, I recommend you don't try the cheap route and use threaded rod or cheap Acme screw and nut.!!
Because of the nature of what your wanting to do you'll need repeatabilty has much as resolution and threaded rod and cheap Acme which usually come with rubbish nuts which just can't give you what you'll need.

[m1ptr]

Really you should look to get the resolution you want from the pitch of the screw not the drive stepping. Higher Micro stepping(10x Max) does help but more for motor smoothness than resolution.
What you need is a low pitch ballscrew say 4mm or less, I recommend you don't try the cheap route and use threaded rod or cheap Acme screw and nut.!!
Because of the nature of what your wanting to do you'll need repeatabilty has much as resolution and threaded rod and cheap Acme which usually come with rubbish nuts which just can't give you what you'll need.

Useful info thanks, In my current design based on a http://www.rockcliffmachine.com/ plan I'm using 6mm stainless machine screw with a nylon nut. I'll plan to run some tests to check repeatability now I know what to look for. I should be able to upgrade to a ballscrew if its an issue. Cheers Pete