Originally Posted by
joeavaerage
Hi,
Modern AC servos on the other hand have constant torque up to their rated speed, and typically have short duration torque overload capacity of three to four times their
rated torque.
I have three new 750W B2 series Delta AC servos for my new mill. They will EAT any stepper ever made! They have a rated torque of 2.4Nm, which is modest by comparison
to a similar sized stepper, but unlike a stepper when the load comes on my servo will deliver 7.1Nm whereas the stepper will just stall. Delta is a Taiwanese brand manufactured in China, good quality, good back up, good documentation and most importantly, good set-up and tuning software at very
fair prices, certainly much cheaper than Japanese/US/European made stuff. There are even cheaper Chinese brands but questionable quality, support, crap documentation and
critically NO set-up and tuning software....avoid like the plague.
A good stepper and high voltage drive might set you back $150-$200 per axis where an AC servo from a decent manufacturer will set you back about $300-$400 per axis,
so servos are still more expensive but 'by crikey do they ever go like hell!'
Craig