Hi All,

Small progress update; welding and grinding on the frame and bed is completed, I'm currently prettying it up, and will start painting soon. Once my ugly welds are covered up sufficiently I'll share an updated photo ;) I've got the Epoxy sorted, so that'll be the next job on the frame once the weather improves sufficiently.

I'm starting to ponder the electronics, and its all a little overwhelming. I don't think my budget stretches to servos, so steppers it is, and from the quick calculations I've done it appears I'll be wanting the standard ~3nm steppers with a ~70V homebuilt PSU. I'll be putting more thought into specifics and posting my thoughts before ordering them, but I'm utterly lost when it comes to narrowing down drivers.

Lets take Zapp Automations 3.1nm NEMA 23 stepper for example (it appears to me to be the standard) - it has a bipolar parallel (which appears to be the standard config) max rated current of 4.2A, so I'm thinking any stepper motor driver able to cope with >4.2A will be able to use the motor to it's full potential (more to the point, I'll have to limit the current on the driver). I'll probably want a motor driver capable of microstepping - and in this regime there appears to be named brand and off brand:

Gecko G2xx Drives - the difference appears to be the native stepping resolution and their microstepping capabilities, generally all in the £100+/ea region. I've seen a few US-based bloggers I trust using these and seem quite happy which is tempting.
Leadshine as used by a few people here... £50-100/ea from that I can see.
Random Brands, Same black box... £40-50/ea

Regards microstepping I have 2010 on X, 1610 on Y, and 1605 on Z (currently all planned for 1:1 but pulleys so room to gear) - lets take the 10mm pitch screws, 1.8steps/degree means half stepping nets 0.025mm/step - is that a reasonable target?

So can anyone shed some light on Drivers and point me in the right direction? Maybe point me to a resource which explains whats what, and what I need to look for to identify a reasonable product?


Second, I had originally thought of using a CSMIO/IP-M controller - I liked the ethernet functionality, 24V lines, and the fact that it was well documented, recommended, and provided a command buffer - BUT - I've been very aware that it has two very key draw backs for me: no good slave axis functionality for my dual x-axis screws, and four axis limit which would be a pain in the future if I wanted to add a 4th axis. I'm not keen on the cheaper parallel port breakout board style (rightly or wrongly, I'm kinda dumping the UCxxx controllers in here - please correct me if I'm wrong), but I have been thinking about the ESS ethernet smoothstepper. From what I can tell, it has the capability to handle up to 6 motors which allows future expansion, and can handle the dual screws and independent homing well - but it needs to be combined with a suitable BoB and only provides me with 5v IO which I'll need to put more effort into sorting.

Can someone tell me if I'm on the right lines, or if theres something drastic I'm missing or some better option? I'm really keen to have a robust and smooth machine.

Thanks for listening to the fevered rant this far - double thanks if you're able to put me straight on a question or two!