[paulrounsavall]

I have a Harbor Freight milling machine that I am wanting to convert to CNC. My 1st step is motors on the X and Y handles. I have lots of experience with 3d printer stepper drive and driver boards but no experience at this scale. I've read that I should have 600 oz-in or more for direct drive of the lead screws. I'd like to be in the $100-ish per axis for motors and drives. https://www.aliexpress.com/item/33006846902.html seems to fit that description at ~$210 for a set of 2. Anyone have experience with these/similar setup? Any other suggestions near my price point? Thanks!

Paul

[Jim Dawson]

You will also want to look into a ball screw kit for your machine. You won't be happy with the result without ball screws. I don't have a specific recommendation for closed loop steppers, I'm sure most of them work OK. There are also a bunch of them on eBay and Amazon. You might pay a bit more from a USA based vendor, but at least you might have someone to scream at if things go south.

[paulrounsavall]

Jim, thanks so much for the feedback. I do plan on changing to ball screws as well, but I wanted to do this 1 step at a time. I'm retiring from the Air Force and moving to Ohio next year. I haven't decided if I'm going to keep the milling machine or get a different one. I don't like the round column that loses registration when I run out of quill travel. The x and y motor setup should be portable to a different mill, but the ball screws wouldn't.

Paul

[rcheli]

I have a Harbor Freight milling machine that I am wanting to convert to CNC. My 1st step is motors on the X and Y handles. I have lots of experience with 3d printer stepper drive and driver boards but no experience at this scale. I've read that I should have 600 oz-in or more for direct drive of the lead screws. I'd like to be in the $100-ish per axis for motors and drives. https://www.aliexpress.com/item/33006846902.html seems to fit that description at ~$210 for a set of 2. Anyone have experience with these/similar setup? Any other suggestions near my price point? Thanks!

Paul

Getting a square column mill would be much better. Ball screws are a must if you want an accurate and free moving machine. With ball screws you don't need 600oz steppers. You want to find motors with low inductance so that you can get decent speed out of then without running really high voltages. The ones in the Alie link don't give that spec and they are Nema 34s so they are big and likely slower than Nema 23 would be.

I have a Harbor Freight mill (Sieg X3) that I converted. I'm running Nema 23 381oz-in steppers KL23H2100-35-4B open loop at 48 volts on the X & Y and they work really well. On the Z I have a Nema 34 960oz-in KL34H295-43-8B open loop at 48 volt belt driven 1.28:1 ratio. To calculate the voltage that you want to run the steppers at you multiply (32 times the square root of the motor inductance) Example my X&Y motor have 2.8 mH. So 32*SQRT(2.8) = 53.5. 48 volts was the closest power supply that had the amps I wanted at the time so that is what I went with.
I got my steppers and power supply from here:https://www.automationtechnologiesinc.com/

When you only have one mill it is hard making mounts and parts to do a CNC conversion while you have your mill all apart. I am in PA and would be glad to make parts for you for the cost of materials and shipping. If you send a sketch with accurate measurements I can draw it up in CAD (Fusion 360) and make the part. I'm all tooled up and don't have anything to make

I hope this helps and good luck on your build.
John