5 years ago, I bough a small mill, a Proxxon BFW 40/E from a local dealer here in Turin, just because I needed a easier way to cut simple shapes in aluminum, for my various hobbies.
Together with the Mill I bought the
Compound X-Y table KT 150. I was pretty satisfied by this mill, except off course when I needed to cut non-orthogonal or round shaped forms.

I also tough about doing a CNC conversion, since there are so many info on Internet. I bought 4 step motors from eBay (Pacific Scientific P21NSXC-LSS-NS-03), but I soon realized that nobody had done it before on this Mill model (I guess the MF 70 is better suited for this...), probably because there where so many modifications needed.
The project stalled for almost 5 years !

Then, on our friendly tuesday poker, we were joined by a nice guy (Pino), a professional mill and lathe operator, owner of an incredible shop, full of professional machinery.
He offered to help me out, so I landed him the XY table to figure out what could be done. The following week he bought me back the XY table with the stepper already assembled (Ok...this is a little more then help out...).

On this page I am going to report my progress on the Mill conversion.
(NOTE: you will excuse my poor english...)
01/11/2009
This is my Mill, as I bought it, without changes (around 530,00 Euro).
Has a working area of 200x200mm, with a max display range of 150x150mm. Enough for my needs.
The feed is 2mm per revolution with a fine adjustment scale of 0,05mm. The spindler turn from 900 to 6.000 turn/min
No rail bearing, no backlash regulation, not really precise but I hope, once modified, to get it better.

At this time I had the mill, 4 step motors and some vague ideas on what I needed.
I had to spend a lot of time on Internet to figure out if it could be done, what coud I expect, what was needed, etc.

A great help came from
www.cnczone.com, a Forum for everything connected to CNC.
I can suggest also these Links:

www.cnccookbook.com
www.hobbycnc.com
www.cnika.it
www.kelinginc.net
www.5bears.com
These photos show the stepping motors that I had bought from eBay on 2004. I bought 4 of them for 30,00 euro (40,00$). That is 7,50 Euro each !!!
I was a little confuse by the doc referring to the motors (
see this), since it was referring to Powermax "II" and talking about "Hybrid" step motors (I still do not know the meaning of this...).
I also was sure that the wiring would have been a problem, both for the connector and the termination info.


Below you can also see the XY table modified by Pino.
After having read about bearing, ballscrews, preload, etc I was a little confused/amazed at seeing that there was no coupler. The guy had managed, hopefully, to put motor, screw and nut in a correct axis.
I could not try the motor yet (I had no controller) but, judging with my hand, the thing was turning easily.
You have to notice tough that the table does not have bearing so it is hard by himself.

When Pino told me that the XY table was complete and ready to run (?), I rushed to CNCzone, looking for help on choosing a controller and a power supply.
I would have preferred buying a complete kit (power supply, controller, switch, box, etc) but nobody was willing to sell them with motors.
I ended up ordering from HobbyCNC a "
PRO Chopper Driver Board Kit" controller for 4 axis for $99,00 and from Keling Technology a "KL-320-36 36V/9.6A 110V/220V" power supply for $59.95.
Of course, when you add taxes and shipping, costs are different but, thanks god, the dollar is low...
The "commercial" picture.
09/11/2009
The label
See the connector: just 1-2-3-4-5-6-7-8 !
This is the bottom of one axis, where you see the connection from the motor to the lead screw
Pino had changed the lead screw to a 12mm diameter, 3mm per turn screw. He made a hole on them so to fit the motor shaft.
See also the aluminum plate to hold the step motor
The table upside down next to the Mill
I have not dared to take apart Pino's job, yet, but I believe this hold the new nut. We will care about backlash later on, once I will be able to run the stepper and understand how big the problem is...
I wonder if the stepper will be able to move all this....
While I was waiting to receive the electronic, I took apart the Z axis of my mill, to see what needed to be done.
I know now that it is more difficult to do the Z axis then the XY axis (beyond the fact that Pino has done most of the job).
As you can see from the pictures the thing works in two ways.
As a drill, you move the big lever on the right: the dirll goes then up and down pretty grossly.
As a Mill, you rotate 90° the little lever on the right, below the big lever, so that the half nut works on the screw for (?) minimal adjustment. This is exactely the reverse of what I need: The screw move up and down, so I cannot fix a motor to it (not easily...).
I think I will redesign completely the z axis, may be getting some rail bearing (at least here) and replace it completely. I can do it because it is possible to remove it. I could even have the spindler to rotate on another 5 axis, even if I am not sure how useful this could be....
Before taking it apart
See the little lever that turn the drill into a mill