Need help decide stepp or servo?

[schrupphobel72]

Can anyone help me to choose the right drives/contoller for my new cnc ? I'm neebie in building a cnc Mill, any suggestions are welcome? Whant to use the mill for Alu.

Thanks

[blau_schuh]

I'm no authority on this subject yet... but these are the usual questions:
1) how accurate do you want to be? 0.01", .001", 0.0001"?
2) how much money do you have to "invest"?

check out this link: http://www.cnczone.com/forums/showth...itch#post67528

[schrupphobel72]

The finished part(Alu) has to stay within .005"to.007" otherwise it would be useless for me. Knowing this tolerance will put my budget a lot higher. Right now my guess would 500$ for Motors and controls?

[blau_schuh]

Originally Posted by schrupphobel72 The finished part(Alu) has to stay within .005"to.007" otherwise it would be useless for me. Knowing this tolerance will put my budget a lot higher. Right now my guess would 500$ for Motors and controls?

from my limited experience (as I haven't started to construct my machine yet, just collecting parts), $500 minimum, probably closer to $650.

I bought 3 servo motors for about $90 each, and currently have one gecko 340 drive ($130) for testing. You'll need 3 gecko 320 drives, and they are $110 or so each. I think there are cheaper drivers out there, but I just decided to go with what seems to be a solid, known product. powersupply for all this... prolly another $100-150. You're looking at $700-800 before you get into screws/rails and the raw material to build your frame.

not sure about steppers, but from looking at a bunch of sites.... motors/drivers are probably going to be $250-350.

someone else can chime in...

[vger]

Having worked for many years with various types of servo and stepper systems, here are some observations. Stepper systems are less complicated, less expensive, and less powerfull. For servos, the opposite is true. As for accuracy, repeatability, and reliability, that comes down to how well the machine is designed and constructed, as well as the quality of the parts used. Steppers without some sort of positional feedback can "skip" steps if the machine binds or loads too much and will have to re-home to correct. Servos require positional feedback to operate with NC and as long as there is no connection or communication loss with the controller don't have the skipped/missed step problem.

Just my $.02

[schrupphobel72]

OK,than i will go with servo System. Any ideas what is good setup?
Thanks

[blau_schuh]

there are dozens of threads about this subject. do some searches and check the build logs in the DIY section.

[CJL5585]

Here is a link to a thread about Steppers Vs Servos.

Servo or Stepper for CNC?

Contains a lot of excellent information.