I considered buying the motors from Sherline, but they want $65 apiece for their stepper motors. I knew I wanted NEMA 23 size motors, with reasonable torque, voltage, and current ratings, and dual shafts (the mill handwheels attach to the other shaft). So I checked the usual suppliers, and ended up buying a set of three from a seller on eBay.
Here's the note in the Sherline assembly instructions manual, explaining that the motors are required in order to operate the CNC-ready version of the mill manually. Had I realized this originally, I probably would have gone ahead and ordered the motors along with it.
Here are the stepper motors I got today. It turns out they come with nice knobs, but I'll be using the handwheels that came with the mill, so the knobs go in the parts stash.
The assembly instructions for the motors states that the shafts should have a flat machined in them so the burr from the setscrew doesn't cause the shafts to bind in the couplers, making them difficult or impossible to remove. The motors I bought have flatted shafts, but on the wrong end! Gee, what would be a useful tool to machine flats in the shafts? I know! A mill! Rather like the SparkFun soldering iron kit, you need one to build one! Fortunately, I have a bench grinder. Unfortunately, I never put it together. So I take a step back, unpack and assemble the bench grinder, and use it to grind flats on the stepper motor shafts.
With the stepper motor shafts prepped, I finally get to go back to step 1 in the mill assembly, and install the stepper for the X axis.
You can see the X axis motor, along with the nice 1.5 metre wires, along with the handwheel that will be attached to the remaining shaft sticking out. You can also see the stepper motor mount for the Y axis on the left.
Here's the mill with the Z axis column and all three stepper motors and handwheels installed. It's starting to look like something now. The next step is to assemble the motor, spindle, and speed control assembly and attach it to the Z axis sled.
There it is, completed. It's a nice piece of equipment, solidly built. The motor purrs like a kitten. I need to round up a chunk of wood to bolt it to, and I'll be ready for some Quality Shop Time. One of the first jobs I have in mind is to make a mounting plate for the new air assist head for the laser cutter. It's pretty simple, just an L bracket with some screw slots cut in it. Since I haven't done any real machining in several years, I'm going to start off with simple things. Once I get my skills back, I'll start playing with ideas for driving those steppers and getting into CNC machining as well. See comments on the previous mill post for thoughts on that subject. Originally posted at Dreamwidth.org comments