[CallahanMW]

Hello, Just signed up.

I am converting a Bridgeport Boss 3 (?) CNC machine to modern control software and motors. I bought this machine with most of the control system missing from a dude nearby last weekend. I have been browsing Stepper and Servo options for this machine and I need some advice and info.

1) What kind of rapids are considered reasonable for a machine such as this one (1:1 pulley ratio, dovetail ways etc)

2) Has anyone here done a similar conversion with large NEMA 42 steppers? If so what kind of rapids can you achieve? (I am currently considering 750 watt servos, closed loop NEMA 42's (2830 oz/in), and open loop NEMA 42 (also 2830 oz/in)

3) If not mentioned in my current considerations, what kind of motors (stepper or servo) would be a good replacement for the beehive 800oz stock motors?

Any info would be much appreciated.

Thanks.

[Jim Dawson]

The 750W servos would be my first choice. More than enough power for that machine, and an order of magnitude above a stepper motor performance wise. Servo motors have a nearly flat torque curve through their entire operating range. NEMA 42 steppers are about useless, the torque drops off so fast with increasing RPM that a good NEMA 34 stepper motor will outperform them overall.

As far as rapids, 200 IPM is way more than enough for that machine, I run my BP clone at not more than 100 IPM rapids, but it will rapid at 300+ IPM.

For servos, I have used and recommend:

Delta https://www.automationdirect.com/selectors/sureservo2

LS Electric https://www.automationdirect.com/selectors/ls-servo

DMM https://store.dmm-tech.com/

I have Delta and DMM servos on my lathe and I just installed two 750W LS servos on another project. Documentation is important as is the setup software and factory support. All of these get an ''A'' in all categories.

[danbeckergb4]

Hi, Have you started your conversion? I'm a retiredd EE and willing to answer any questions.