Hello!
I would need help with selecting optimal drives for my Bernardo BF30 machine that I'm equipping with CNC stuff. First of all, I've gone through all builds on this site and found out that some of people run steppers like 3 and 4Nm on all axes directly, while others run 8 and 12Nm with reduction, which is kinda huge difference. I don't want to under-power the axes or get poor performance due to too large steppers. User "Ger21" warned people not to go into "too big motors" trap....
I've also thought about getting servos, as I got quite good offer on them. So my first choice was:
X and Y: Direct drive 86M-DHT-A6MK1 (750W servo) + DYN4 AC Servo Drive (directly on 230VAC) on 5mm pitch ballscrews
Z: 1:2 belt reduction on same servo (with added brake!) and same driver.
I know servos need fine tuning on each axis, but I'm prepared to do that, after all I'm designing PID controllers and doing PID tuning on tons of projects for last 8 years. I'm not sure about performance issues on Z because of drive belt. (I could also use direct drive stepper (closed or openloop) for Z to avoid belt)
Second option was:
X and Y: Direct drive Nema34 8Nm motors + EM806 + 60-70V DC power supply
Z: Direct drive Nema34 12Nm + brake + EM806 + 60-70V DC power supply
Third option was
X and Y: Direct drive Nema34 4Nm motors (Closed loop!) + appropriate drivers + power supplies
Z: Direct drive High voltage Nema34 8Nm (Closed loop!) + appropriate 230VAC driver
As you can see, I'm really in trouble of finding out what's the "smartest thing" or which combo of X, Y and Z is going to work as it should. I don't want to invest too much, definitely don't want under-power or over-power -> to avoid performance issues.
Can you please advise me what's best choice for that machine? I'll be eternally thankful for information!
Best regards,
Jure