[davef2f]

Hi All
I just got hold of a central machine bench top mill, round colum, like new condition (free ).
I want to make this a cnc over the winter. I have a dell computer, and plan on buying mach3, but i have no idea of what else i need, motors, drivers & the such.
Any advise I will truly be greatful for.
I've been a machinist all my life, I can set them up & program cnc's but have never built 1.
thanks all
Dave

[grinderdust]

Dave, take a look at Art Eckstien's page, where you will find a brief description of how he installed ball screws and such on a round column mill. If your mill is similar to the rf-31 this should give you some Ideas.

http://bellsouthpwp.net/A/r/Arts%5Fhome%5Fpage/cnc/

I emailed him with some questions and he supplied me with drawings of the ballnut yokes. Following Art's advice, I got rolled ball screws and nuts from Roton. They are affordable and I think ground screws would be overkill considering the quality of the mill. Nothing against the old rf-31. I like my mill but it is what it is.
Gecko drives seem to be the drive of choice for a mill of this size whether you choose steppers or servos. They are easy and fairly foolproof to get set up.

Lastly, the gibs adjusting screws will need to have the play taken out of them. The slot in the gib was way bigger than the head of the adjusting screw on mine. This allowed the gib to slide in and out when the tables were moved, making the proper adjustment impossible. I made a gib screw that fit tighter in the threads and fit the gib with just enough play to move. You can also just use shims for a quick fix. Really more of a general tip but this can be overlooked, and can affect the accuracy and the amount of torque required to move the tables.

[Bubba]

dave2f,
Be glad to help if I can. If you want to look at the web pages, better do it fairly soon as that will be coming down as I have changed ISP. Bell wouldn't ever get around to giving me decent speed (dsl) and I got tired of 17kbs connections.
I still have the drawings and will be more than happy to share them. They are more like rough sketches, but evolved over the time that I made the conversion.

For me, the RF31 is a real workhorse and for a small hobby shop, better than anything I had before (which was nothing). Would I do it over again with a round column. Yes especially if I got it for your price:})