Bringing home a new project – a Rong Fu 45 Mill
A few weeks ago, my Craigslist RSS feed returned a listing for a mill for $300 only a half hour from my house. It was an RF-45 clone that the seller described as a “project.” The RF-45 is a much more substantial mill than the X2 mini mill I currently have, so I was intrigued to say the least. After a bit of thought and contemplating if I had room in the garage, I decided to give it a shot and contact the seller to get some more info.
It turned out that the previous owner had begun a CNC conversion on it, and in the process had milled a large pocket under the table in an attempt to fit a much too large ballscrew on the X axis. The mill was disassembled, but all the stock leadscrews and handwheels were included, except for the Y axis acme nut. The seller had intended to finish the CNC conversion that the previous owner had so poorly started, but never got around to it since he already had another CNC set up in his garage. Fortunately, he held on to all the parts necessary to run the mill manually. I’m not quite ready to jump into the world of DIY CNC just yet :-).
All in all, it seemed like a pretty good deal, so I arranged to pick it up the next day. Now I had to figure out how to move it. 700 pounds of chinese cast iron doesn’t just jump in the back of a truck…
Fortunately, Ben was coming over for the weekend to work on our paintball gun project, so I enlisted his help for the move. We were able to break the mill down into manageable chunks fairly quickly, allowing us to move the mill by hand into the truck.
Removing the head proved to be the trickiest part. I’d guess it weighs around 150 pounds, and it had to be disconnected and lifted off the mill while reaching over the bench it was sitting on. We ended up stacking blocks between the base and the head as a temporary support while we removed the nuts holding the head to the column. From there it was a bit of an awkward lift to get the head off the blocks, but we managed it without incident.
We ended up with the head and motor, the column, the base, the table, and a box of miscellaneous parts. We layed everything out in the bed of my truck, using blocks and straps to keep things from shifting around.
Once we got it home, we got the column and head reassembled. We basically reversed the process of blocking up the head, then attaching it to the column. We worked the blocks in one at a time, slowly raising the head. That way we didn’t have to lift the head the full height in one go. We left the bed off for now since it will need some work prior to using the mill.
To make the mill usable again, I’ll have to make a few repairs. My biggest concern right now is the bed. The pocket milled out of the bottom has left the bottom of the center t-slot uncomfortably thin. The mounting points for the x-axis leadscrew have also been messed up in the conversion process.
My current plan is to drill and tap into the thick sections of the bed from the bottom, and attach a steel plate of the appropriate thickness with several small socket head screws. I think (hope) that will return enough rigidity to the bed.
I’ll also have to come up with a nut for the y axis along with a mount for it. I may try the procedure described here to make a low backlash nut out of Acetal, and machine the mount using my other mill.
There’s still quite a bit of work to be done before I’ll be able to use it, but I’m excited about the possibility of having a bigger mill in the shop someday soon!