[Sparky_NY]

Just swap the bearings to AC bearings and do a belt drive conversion. I would use microv belt and pulleys, I did the timing pulleys and they vibrate and are quite loud.

Also, I recommend the belt conversion that drives the upper barrel and use one of the vibration dampner rings that helps quiet down the spline rattle. That conversion puts the torque much closer to the upper bearing rather then at the top where it is less rigid.

If you want high speed, you can do a double pulley setup. If you go with a 1.5 - 2 hp 3ph inverter duty motor and VFD the motor should easily spin 6000rpm with some excellent torque, so you could do a 2-3 and 3-2 ratio pulleys setup and have some really good torque for larger endmills and high speed for smaller endmill.

No need for a different spindle. Just remove all of the quill components and lock the spindle set screw, that's pretty much what everyone does with these and they do well enough if you use good AC bearings and kluber grease and are careful with setting the preload and break them it properly.

I use a BLDC motor and it does fine, it has a range of 400-6500rpm, but I do wish I had gone 3ph+VFDz they seem to have a much steadier rpm output and the constant torque helps keep the spindle from bogging during the initial cutting contact. Also it would be nice to have a lower rpm for specialty jobs and steel cutting. The BLDC recovers fine, but it is audible even with small endmills and definitely doesn't like low rpm.



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Can you give some more info on the vibration dampner rings you mentioned? I have not seen this in any of the threads I have read.