Beginner with Harbor Freight 44991 Mill--right choice for CNC?

[j beede]

Hello,
I am interested in building a small CNC mill for hobby use so I bought a Harbor Freight mini mill as a starting point. I just got it uncrated and am wondering if I picked the right machine. I have cleaned it up and begun going over the mill. The spindle and chuck run pretty true, maybe 0.001" of runout with no perceptible axial or radial play in the bearings. The table's X-axis is smooth and firm, seems good. The Y-axis makes a knocking sound once per revolution and it gets looser as the table moves inward toward the main column. The Z-axis seems almost unusable. The fine Z-control is very stiff to turn, I wonder if a stepper motor could even turn it. I realize that for $500 you can't expect too much, but I do want to build a functioning machine. The motor spins up fine and the gears are noisy as expected. Before investing another $500+ in CNC upgrade I need to decide if this is the right machine to move ahead with. What do you think?
...j

[Bobbyr70]

My thoughts are to upgrade to a better mill. I started out learning on an x3 from syil and found out fast, it was just too small to do most of the work I wanted to do. I retrofitted a round column mill drill (the 999 model from harbor freight) or the Grizzly. What ever they call it. That machine works pretty good but has draw backs when you need to change from a mill to a drill. you have to reset zero on the axis. other than that it is a little work horse. Now I am retrofitting a full size 10x50 Lagun knee mill. some of the items I want to work with are slightly larger and I can't fit them on the smaller machine. The round column machine was built from ebay surplus ball screws. I fabbed up a motor mount that fit right into the quill microfeed and purchased all the steppers and drives from keling. Used a cnc4pc breakout board and upgraded to a pulse generator for positioning also from cnc4pc. It all cost around the 3000 dollar mark including the mill.
Nothing cnc is cheap if you want it to last. I am proud of the work and glad everthing works so well. no real problems but quite a learning curve to overcome.

[noisillator]

Originally Posted by j beede Hello, Before investing another $500+ in CNC upgrade I need to decide if this is the right machine

I doubt you can prep any Chinese mini-mill for CNC conversion for only $500. Too many parts have to be remachined or replaced. Your budget probably dictates a large, used manual mill or (if you can find one) a used Taig or Sherline CNC. On the other hand, if you're not pressed for time (i.e., no pressing projects that need immediate completion), you could do worse than to use an inexpensive machine like this as a learning tool.

[Deviant]

You need to decide on what your wanting to do with the machine now and later.

I have a x2 and x3. The x3 should be able to do most of what I want. But I expect that I will be upgrading it at some point.

The x2 is used for most of my small manual work. Personally, I hate the way that the z axis works. The rack sucks... period. You can work through it, but with a cnc machine you will throw that away.

Most people mount a screw along side the z column and tie it to the head. You should be able to find more than a few examples. You will have to leave the taig forum though.

I actually like the x1 mechanics better, if your just looking to bolt motors to the ends and hope for the best.

[j beede]

Agreed. The Z-axis is poor. I decided that the Y-axis needed work as well and now I see that I would have to rebuild this mill top to bottom before thinking about cnc conversion. The cnc conversion kit I was conidering comes with stepper brackets and a new z-axis only. I mistakenly thought the steppers and controllers were included I am now thinking about mocking up a 3 axis router based mill as a lower cost entry point into the world of cnc. If I use nema23 steppers and peripherals I am hoping I can reuse them and the Mach software when I migrate to a Chinese mill. Is this reasonable?
...j