servo vs stepper

[diegope]

hello all

we'll buy a machine soon from a chinese vendor. we'll start a business with it and have the option of choosing between servo and stepper. we've been doing a bit of online research on this with no final conclusion.
it'd be great to hear some first hand accounts on what's best. in terms of reliability, speed, maintenance (bear in mind we probably won't have much support from the anufacturer)

many thanks.

[Al_The_Man]

Servo's are considered the better choice, steppers are mainly used to keep the cost factor down.
AC or BLDC servo's are very reliable now, due to no brushes, (I am assuming the machine has these?) If you have DC servo's then there is a maintenance issue of keeping track of brush wear over a period of time.
I would find out what make model they offer and the future availability of motors and drives.
Al.

[AJ Solutions]

Stepper motors are the better choice for raster engraving, servo is better for cutting. The stepper word says it already : it makes tiny steps. When raster engraving you will find these machines faster, they have less accelleration and decelleration. Servo do not make these tiny steps and when cutting acrylic you will have a smoother result as compared to stepper. This result is drastically different!!

I have sold ULS (steppers) and Epilog (servo) in NL (Holland) so I know the differences quite well...

[Al_The_Man]

Originally Posted by AJ Solutions Stepper motors are the better choice for raster engraving, servo is better for cutting. The stepper word says it already : it makes tiny steps. When raster engraving you will find these machines faster, they have less accelleration and decelleration. Servo do not make these tiny steps and when cutting acrylic you will have a smoother result as compared to stepper. This result is drastically different!! I have sold ULS (steppers) and Epilog (servo) in NL (Holland) so I know the differences quite well...

One only has to read of the application contests won by the likes of Galil Motion etc to refute this.
I presently am using 2000 count encoders with a resolution of x4 and am positioning servo's with an in position error of zero to one pulse resolution of .000062".
And 2000 count encoders are considered rather coarse by today's standards.
One example I alluded to for ultra servo control.
http://www.galilmc.com/support/servotrends/st_10_08.pdf
Al.

[AJ Solutions]

Ofcoarse you can have very good results when using a stepper. Only you have to set the DPI/PPI settings higher when doing so. This means you have to work slower and this is mostly not the way people want it. I sold these machines 8 years ago so in the meantime the steppers will have improved.

8 years ago the differences between the cutting on 600 dpi/ppi between ULS and Epilog was very noticeable.

I only shared my personal findings as well as the sales criterium of Epilog itself...

[hub]

Originally Posted by diegope hello all it'd be great to hear some first hand accounts on what's best. in terms of reliability, speed, maintenance (bear in mind we probably won't have much support from the anufacturer) many thanks.

Reliabilty, speed, maintenance.. Servos. (AC)