The TK-421 got a shot of adrenaline today with the addition of new 150 oz/in triple stack Nema 23 motors. These things absolutely rock for being unipolar motors. I will have to upgrade the power resistors on the machine though because the new motors draw almost 5a!
The upgrade went fairly smooth. The shafts on the new motors were a bit longer than the original motors, so I had to modify the lead screws on x any y a bit. I also switched back to my original solid motor couplers. Everything seems to be much tighter now.
I haven't cut anything yet, but I'm guessing that I should be in the 25-30 ipm range now with plenty of torque to break even the most expensive carbide bits!
The z axis shows the most noticeable improvement. It always bothered me how long it took to raise and lower the router, but it should be quite a bit faster now.