This thread has some information on converting to an AC Induction motor: http://www.cnczone.com/forums/novako...lew_again.html This thread in the Mikinimech forum has lots of information and videos on a similar conversion: http://www.cnczone.com/forums/mikini...t_project.html (VFD and AC Motor replacement project). I talked to Mark about the Adlee BLDC motors and VFDs he's selling at Welcome to Home Machine Shop!. From his experience they seem to be a viable but slightly more expensive alternative to AC induction motors. I've also been investigating servo drives and AC servo motors as a possible conversion which would allow the possibility of instituting rigid tapping. This seems like the most expensive route even buying a used servo on eBay. I've also looked at so called agnostic drives such as the Granite drives, Teknic drives and others to replace the Sangmutan VFD in the NM-145. Problem here seems to be finding a drive that can handle the voltage requirements of the spindle motor as supplied in the NM-145. From the specs I've seen the motor needs up to 300 VDC. I could be wrong on this but that is what I've seen in a couple of places now.
Since getting my NM-145 and finding that I can stop the spindle easily at any speed just using my hand I've started looking into conversion options again. I'd like to find a motor that would fit inside the head. That probably limits me to something along the size of the current 1100 watt motor. The Adlee motors that Mark has videos of on his website are pretty impressive and one of them might fit. I'll have to go back and check their specs again. You can go directly to the Adlee site here: http://www.adlee.com/.
Novakon has their own conversion kit for an AC servo and drive for about $1500 CND. They will also sell an updated version of their NM-145 VFD for $300 or or so. I haven't read any posts where folks have gone either of those routes yet so can't say how they work. stevb946 here actually may have one of the updated VFD boards. Steve, any comments on how your machine is working if in fact you have the newer model board?