I have a nice old Bridgeport BOSS 5 CNC mill that I’ve converted to Gecko drives and Mach 3. Everything works fine, but the machine is not very nimble. I still have the stock old monster NEMA 42 stepper motors. With the acceleration rates that I have set for these motors I sometimes cannot achieve my target feed rates for example when cutting a helix. Several years ago at the CNC workshop I was advised by the guys at the Automation Technology booth that I should change the machine to smaller NEMA 34 motors as the new 34’s have more power than the old 42’s and they would accelerate much quicker. At the time they did not sell NEMA 42’s now they do. I was wondering if a modern new 34 is really better than a modern new 42. Yes the 42 has more rotational inertia, but it also has gobs more power to fight that. The price is irrelevant as the 42 is only a few bucks more and should be a direct fit where the 34 I’ll need to adapt it. Another issue is the Gecko 203V drivers only put out 7 Amps. The 42 only needs 6 amps, but the 34 needs 8.8 amps for max power. As I only have 7 amps to give it, the 34 motor will not be operating at full power.

Again the goal here is acceleration should I go with a NEMA 34 like this one?
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Or a NEMA 42 like this one?
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Or leave it alone?

The other concern is that with all of this extra power if I accidentally crash the machine will I seriously damage it? I don’t really need more power, just acceleration.
Thanks!