Stepper motors sure are complicated

So, I have been bashing my head against the wall for a few weeks now, trying to figure out this stepper motor stuff - it seems everytime I think I have it straight, something else crops up, and I am not an electrical type of person.

So, to business:
I wish to purchase stepper motors for my prusa, which is sadly only a shell at the moment.
I am in the UK.
I found this which I hope is good for my extruder. And if it is, should I just buy five of these? The price seems resonable, will having extra torque be a problem for the axis control motors? Does that cause overheating?

Any help is much appreciated!

Those are listed on the wiki as tested and working with mendel. Go for it.

You are better off with 5 of these: [www.zappautomation.co.uk]

They take less current for the same torque and are cheaper.

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[www.hydraraptor.blogspot.com]

yeah those will draw a too much current for the typical setup (using pololu drivers)

Please keep in mind inductance and supply voltage - See here:
[www.geckodrive.com]

The ideal (Maximum) power supply for the first motor is about 42V.
For the second motor (From Zapp) it's about 53V.
The voltage will affect the high-speed performance.

Pololus are only rated to 35V maximum, so realistically you'll want to keep them under 30V.

As mentioned, Pololus are rated to only 2A maximum (With good heatsinking), therefore you'll have a trade-off on your hands:

High speed torque (First stepper motor) or low speed torque (Second stepper motor).

Neither will cause overheating, you just have to lower the current. (Which will reduce torque, of course)

As we use belts for the X and Y axes, better low speed torque would probably be best for these.

As we use fine-pitch lead screws for the Z axis, better high speed torque would be best for this.

For the extruder, I'd guess better low speed torque would be more ideal but I'm not sure - It's already geared down on a 3:1 ratio.