It sat idle for a couple of years because something always came up that prevented me from working on it. Finally, at the end of last year I started to piece together a plan of how to complete the conversion. There are a couple of bolt-on kits that you can purchase, but I figured it would be an interesting project to try and assemble it from scratch.
The first things I purchased were the three ball screws and ball nuts to control the movement. I ended up buying them on eBay from Asia Engineer, along with couplers and six thrust bearings for $180 CAD.
Next was to disassemble the mill so that I could begin fitting the ballscrews. I started with the X-axis since I thought it would be the easiest to modify since I could re-use the end plate that houses the thrust bearings.
After a bit of work with a Dremel, I managed to cut down the ballnut enough to clear the channel. One thing I didn't realize was that there was an exposed grease hole that was now filled with metal filings. I had no choice but to disassemble and clean it... a complete pain.
I managed to find a good deal on the stepper motors (425oz-in), drivers, and breakout board from eBay for $325 CAD from wantaimotor. The motors are more than sufficient, and the drivers look very well made with aluminum heat sinks.
Not having the right tools for metal work made this job a bit harder. All of the motor mounts and aluminum work was done with a hack saw, Dremel tool and a drill press. If I only had a mill to make the parts, things would be so much easier :)
Next I worked on the Y-axis. Before starting the fitting, I needed to open up the throat so that I would not lose any travel since the new ballnut was larger than the original leadscrew nut.
Both the Y and Z-axis needed to have the thrust bearing housing made along with the motor mount. With the proper tools, this would be easy to make out of a solid piece of aluminum, but I needed to come up with different approach that would not require any milling. I ended up making the housing out of three separate pieces of aluminum.
A hole saw in a drill press was used to cut the larger holes on the two outside pieces of aluminum. Smaller screws held the three pieces together until the main mounting bolts sandwiched the pieces securely. Duplicating this setup one more time for the Z-axis, and all three ballscrews and motors were mounted.
Some details about the Z axis of the machine. There is a plate attached to the top of the Z column that extends off to
the right side of the machine by about 3 inches, and extends forwards
(towards you if you are facing the machine) about 1 1/2 inches. This is
where the Z axis stepper motor mount is located.
Underneath the 1 1/2
inch overhang is another plate that is attached to the top of the Z axis
saddle. This is where the ball nut is attached. Its basically the
same as the Y axis, except instead of the motor and rod being centered
with the saddle, it runs off to the side.
Instead of buying a separate enclosure for the electronics, I ended up mounting the drivers, power supply and breakout board inside the mid-tower case and added an extra fan for cooling.
Today I had a chance to test out the mill by having it draw out the sample file that comes with Linux CNC. Even though the pen was vibrating quite a bit, and stumbled a few times with direction changes, it does demonstrate the capability of the mill.
