Electronics for New Machine + Chinese Spindle + VFD

[JAZZCNC]

Am I right in saying that I don't need a separate BOB if I go for that polkeys 57CNC?
It seems to suggest that the motor outputs are isolated and having looked at the manual I can't see any reference to a bob? How would I connect it ?
It also looks like I might have to wait a while if i want one of these in the UK.
Looks like that 57C is happy on a network as well, so i could eliminate USB.

Techinicly you don't need a Bob but you will need some form of connection board. While I've been testing 57C I used one of these IDC type terminal blocks.
http://www.ebay.co.uk/itm/IDC-Male-H...-/151166076305

Like I say Not a good idea to Run any Cnc machine over a network. Use it to send to pull and send files but I wouldn't run it over one. It will work but not something I'd trust.

Also I read something in the manual about not putting a switch in between the mains and the VFD. Couldn't really understand that.

It means No Switch between VFD and Spindle. You can switch the VFD mains power but it's not recommended for anything but Emergency conditions. So basicly no Stop starting by Switching VFD ON/OFF only when you HIt the Oh SHITE button should it be switched.!!

As far as spindle speed goes. I have guessed up to now with my old machine to be honest. Based on the sound of the cut I have sped up or slowed down my router until it sounds happiest. I'm sure you will laugh. It would be nice to be able to control that via the software.

Nope not laughing at all and that's how it's been done for many many years and your senses are the best guide by far.
One good thing to help with cutting is to have the VFD display Amps rather than speed and monitor the Load. This along with your ears give you many clues to how your cutting. Often when I'm cutting my ear pics up the first signs of trouble and my eyes look straight to VFD for comfimation. Often they go hand in hand.

So would 50V be enough?
I am running these 4NM Steppers...
and planning on using these drivers which seem to be recommended by CNC4You for those steppers.

Oh this annoys me.!! They sell motors that will happily run on 70vdc with 50v drives which no doubt they sold you a 36V PSU to run them on.!!!

Pisses me off because there's no excuse. Yes they will work and run with 36v but they will work so much better with more voltage which then follows more torque further up the speed curve.
The reason Companys sell 36V PSU #1 it's a nice safe margin for the 50V Max limit on the drive so they don't get so many returns. #2 They are cheap regulated switch mode supplys so they can't afford any return voltage from motors other wise they trip.
They don't give a shit that they strangle the performance.!!

Those motors would perform so much better if they where run with 80vdc drives using 68Vdc Unregulated PSU using Capacitors.

Anyway rant over.!! . . You can't run those 50V drives with 50V because you need a certain amount of safety threshold for back EMF or the dynamo affect with voltage being returned to drives from the motors. So for this reason the Max you would run those drives at would be approx 44Vdc and that would be using a Unregulated supply which handles Back EMF better.
Regulated PSU's like you probably have need more safety margin hence why 36V is sold with 50V drives but like my little rant said they come at a cost. 10V loss is lot when you only have 36v to start with. 30V loss compared to what motrs can handle is massive. The reality is your running motors at half power what there capable of producing if runnng on correctly sized drives with decent voltage.