The Best Steppers/Servos Setup Thread

[JAZZCNC]

are they actually proper servo's or "Chinese" servos?

the price is great, cheaper than I was expecting to pay for a new setup and if they work well then excellent

http://www.ebay.co.uk/itm/CNC-Leadsh...c=1&rmvSB=true

They are 100% steppers not servos. They are however 3 phase steppers rather than 2 phase which is standard hybrid stepper. This means they run little smoother with slightly higher torque. Also take note that larger motor sizes above 3Nm are only 2 phase so offer no advantage over normal stepper.

Now don't be fooled by Comparison Zeeflyboy posted because IMO it wasn't a fair comparison.? They made no mention of the open loop stepper drive used and given the results which are massively off from my experience between open and closed loop steppers suggests to me they used Old technolgy drives.

New modern Digital drives like EM/AM from lead shine are world apart from old Analog drives and my experience with using both (I was one the first to test leadshine Closed loop drives) is that other than being little smoother because of motor difference there isn't much between them. In fact the AM/EM can be run with more voltage so can be run faster.

The Example Zeeflyboy gave of motor playing catch up is great when playing on the bench but in real world means very little because if did fall behind the error will still show in the finished part. The controller knows nothing about the error because the loop is only closed between drive & motor. This means there will be discrepancy and errors between axis has the controller just carrys on pumping out pulses for each axis and doesn't allow for fact one axis falling behind.
This means there is no difference between Closed or Open loop in real world of cutting provided the open loop is correctly tuned/sized.

The only difference or advantage of closed loop is that you can set the Max following error allowed in which case it will then fault the drive. This is exactly how servo drive works and why they get the name "Hybrid servo" because they work just like servos do. However they don't have the positional accuracy or linear torque servo's provide.
People think that because they always return to same place due to encoder positioning this is good. Which it is to some small degree. However it can also mask other issues in the system which show in the work but would normaly be seen due to not coming back to same place.!! . . . Things are not always good as they appear.!

To me bottom line is if you want high feeds/accelleration/smoothness then you need REAL servos. If you just want accurate machine which is reliable and easy to setup etc then save your money and go with standard stepper system with Digital drives like EM/AM.