[Jackflash65]

Anybody ever do a cnc conversion on a Harbor Freight Mill? Any possible kits to do this available. I have mach 3 program. Just need info on setting up the mechanicals on the mill. Thanks for any feedback.

[pthomps2]

I have everything you need for Harbor Freight mills. Only $320. See paulcnc.com

[Jackflash65]

Hi Paul Thanks for the info. I will measure the z shaft diameter and get back with you.

[tyson77]

i would avoid the Fusion kit. try mbbilici Conversion kits for home machines his kit looks better thought out and his responses were timely.

[CS900]

I have everything you need for Harbor Freight mills. Only $320. See paulcnc.com

what kind of backlash do you see with those gears?

[pthomps2]

Almost nothing. There are 80 teeth per revolution and that is 0.100 inches of travel or .00125 inches per tooth. So, if clearance is as much as 1/10 of a tooth (it is much less than that), that amounts to .000125". And backlash compensation completely gets rid of even this small an amount.

[pthomps2]

Backlash compensation gets rid of all backlash. You can jog the table .0001" back and forth. Where it causes an issue is if the table is accurately positioned and cutter forces push the table .020" or whatever the backlash is. It always leaves extra material so the worst case is you have to cut again. This doesn't usually happen on a light finish cut so you may never know the table moved while roughing. If you adjust the gibs a little tighter, the table is harder to push and the problem goes away. Ball screws with no backlash at all are no more accurate than the stock lead screw and rolled screws might be slightly less accurate. The point contact of balls are not as solid as the area contact between a lead screw and nut and this reduced stiffness could affect surface finish or very fine accuracy although this is more theory than actual problems. Where ball screws shine is low friction which allows higher table speed. Lead screws can be spun up to about 30 inches per minute (the handles are a blur at this speed) without undue wear on the nut. The low friction of a ball screw lets it drive harder and this, with the higher speed, means a greater chance of damage when you run into an obstacle or end of travel. This is especially bad when oversized motors are used. Many people converting to CNC start with ball screws so they have no point of reference when it comes to lead screws and CNC. I, on the other hand, have no point of reference using ball screws so take what I say with a grain of salt.

[Heavymetalcnc]

We sell conversion kits at heavymetalcnc.com. They are direct drive, and they come with everything included.