Quote Originally Posted by swarf-boy View Post
I do have a couple of questions for you that are specifc to this conversion, if you would be so kind.

Overall expendature and effort worth it? For me, yes. I had already CNC'd it without the benefit of CNC and as a budget job I got what I paid for. If you want to get the tolerances down, and keep them down, I think preloading nuts and screws is a good idea. The mill has 2 problems when you try to cut better than .001". The column flexes, the quill is sloppy. Grease the quill, try to keep the head wound right down when milling. Value for money? I did it because I became obsessive about seeing a couple of zero's after the decimal point on my calipers, value for money depends on how freaky you are.

The 'Z axis arangement' works well. Setting up a mill is a time consuming business, so putting in two 8mm screws to lock the Z is not exactly onerous.

Motors and controllers? I used 3.5Nm NEMA34's and Garys 240 volt drivers that come straight off the mains with no seperate PSU. The motors were rated 3A wired in series, the lowest setting on the drivers was 3.18A RMS, 4.5A peak. They seem unstallable, snapped a 12mm end mill like it wasn't there when I had a whoopsy. Not sure how fast they go, my computer can't keep up. I'm quarter stepping at 200 steps to the mm. They run a bit hot but it doesn't seem to worry them.

Anything I would change? Yes, I would mount the Y axis nut 12mm towards the front so I could have gotten the tool centre in line with the front of the bed when I cut it flat. The bolt heads collide at the back. Also a few annoying clearance errors. The Z axis digi scale top interferes with one of the bolts holding the cheeks in place, had to miss the bolt out. The Z axis handle comes very close to the Z stepper conduit clamp. I was slightly concerned that the heat from the X axis motor might be getting on to the lead screw but it doesn't seem to get above blood heat so probably okay.