New build – input/comments appreciated

[JAZZCNC]

blackrat - sorry for mixing up the X and Y axes. I expect that you mean the X axis according to my new drawing? Maybe it is better, but it will also reduce the effective Y-axis work length. Anyone to comment on this?

There is no right or wrong it's how you view the machine. From the front it makes more sense to call long axis Y.

JAZZCNC - with respect to extending the top rails (Y-axis), I am not quite sure what you mean by "placing gantry in space using a short cantilever"?[*]With respect to BOB - I have noticed that you are not happy with cheap Chinese boards - and very understandable so, if you have had bad experience with them. My reasoning was that the signal "processing" (Smoothstepper) is the critical part and that the BOB is really a fairly simple device which is not so likely to fail or give problems. A concern with the PMDX 126 (which is undoubtedly very good quality) is that it does not have controller for spindle and pump.

Argh but your assumption that the BOB is fairly simple device is mistake often made. BOB is actually the single largest cause of trouble and strange happenings with CNC machines.! Cutting corners here is recipe for trouble believe me.
The thing you have to realise is that the BOB handles all the signals and if it's low quality with slow opto's or poor circuitry then those signals get strangled, distrorted and weakened. There's no point having an external motion card which gives nice fast crisp pulses if the BOB is going to bottleneck them and distort the signals.
Like anything in life the CNC machine is only good has the weakest link and cheap BOB will be just that then some.!!

The PMDX 126 does have Spindle speed controller daughter board pmdx 107 with Relays for controling pumps etc.

With regards to Cantilever overhang then like this.
Attachment 16024 Attachment 16023