Where will I find "motor curves" thats a new term to me.

The seller may have them for the motor. Most name brand motors have motor curves and usualy they are done for 24 or 36 volts along with
the different winding configurations. As a prep on your learning curve  you may want to have a look at the first few threads of this link which is
about a lathe retrofit i did.
http://www.machsupport.com/forum/index.php/topic,12484.msg80823.html#msg80823

Then go to the Gecko Drive site and read all the info that they have posted. Then maybe read Jones on Steppers, if you want to get into more detail,
and you will have a good understanding of the power supply, drive and machine  relationships.

So it seems what goes in  from the power supply via the board gives you more power at the motor

Not quite right in the big picture.  If you were to design a cnc system you would define the machine application, then select a proper machine,
then analyze what the axis needs to do along with the machines physical aspects and after some rationalization select the approriate motors
and power supply to do the  task. Computer may also come into play in all of this.  Once you have determined what is required and selected the
 item off the shelf you then pay the price...or...... go back to the beginning of the design and make comprimises.
You are ask backwards in the approach, let not your heart be troubled, since most of us do the same thing and the saying "doing it right the first
time is echoed".

RICH

Hi All
I want to have more powerfull motors than 263oz I have presently.
I have  seen these
http://www.ebay.co.uk/itm/Stepper-Motor-4Nm-Nema23-566oz-1year-Warranty-cnc-parts-/120811893754?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item1c20f333fa
and want to know will the TB6560 drive them? and are there any other problems?
thanks Graham

No problem, just make sure the motor is rated at or under 4.5A. The TB6560 can handle that draw and up to 36V.

You will need the proper power supply, it will need to provide the Voltage required by the motor used and the Amperage for the motor used. Do not supply more voltage than the motor needs or heat will be generated, and the power supply will need to have the proper wattage to run all three motors at once.
So for a three axis machine with one motor per driver the required wattage is dermined by the following:
These motors require 2.8V and 4A in parallel plus you will have three of them so Wattage needed is 33.6W.

You will also be under the max rated Amperage and supplying 2.8V is no problem, you will probably want to supply 5V. Just remember the Logic power!!

Cheers,

Rob

http://Http://www.whatisacnc.com

From memory, the TB6560 chip has a peak output current availability of 3.5 Amps.

The imported controller board (sold as TB6560) recommends stepper motors drawing 3 Amps max.

It may be that connecting stepper motors rated at 4.5 Amps might just be asking for trouble.

Tweakie.