King Midas mill conversion

[Jonathan]

- The one I was looking at, is this. Is it any good?

Wattage 400 Watts
Input Voltage 240V AC
Output Voltage 36V DC adjustable +- 2.5V approximately
Output Current 11 Amps

No good, why spend more on 70V drivers then use them on only 36V? The torque from a stepper motor is inversely proportional to speed and proportional to voltage, so if you get a 70V PSU you will get almost twice as much torque from the same motors. It's risking to operate right on the limit, so look for something just under 70V. One of the cheaper ways to do it is to use a toroidal transformer.

- Perhaps my preference is machine / cutter longevity and accuracy.

Cutter longevity is a vague one... if you feed a cutter too slow it can break just as quickly as from cutting too fast. You need to estimate the feedrates required for the materials you wish to cut taking into account the range of cutter diameters. Then make sure it will go a bit faster to be sure. However clearly you don't want to optimise the system for a high feedrate, and thus low resolution, if the vast majority of the time you'll be using much lower feedrates. You could select different size pulleys for each axis and swap them round / experiment to find the best compromise.

In my calculations,perhaps half budget is for mounting hardware. On Ebay there seems to be great bargains, for example I like these mounts:
http://www.ebay.co.uk/itm/Aluminium-...item3f148563db

Good an idea to make home-made mounts etc., though worry a bit about increased complexity.

It should be decreased complexity if you make your own mounts for pulleys. This is what I started out with on my milling machine as it was easy to make without CNC and does the job. You can see them, briefly, in some of my very old videos:

http://www.youtube.com/watch?v=tasl9...eature=channel