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best motor: high torque or high resolution?

Posted by Day_sleeper 
best motor: high torque or high resolution?
February 25, 2013 10:19AM
Hi everybody,
i have a question:
which is the best motor?

4200 g/cm of torque and 1.8° of resolution
4800 g/cm of torque and 0.9° of resolution?

For the Z axis i think that there is no problem of torque and resolution, but i want to know whic is the best motor for axis X and Y.
Re: best motor: high torque or high resolution?
February 27, 2013 02:41AM
currently i am testing what a manufacturer claims to be a NEMA 23 400step/rev 120 oz-in stepper. it is worse than my NEMA 17 42 oz-in sanyo. i have tried voltages ranging from 10- 26v and all current ranges up to 1.2A (the stepper is rated @ 0.4A 12V) ... im wondering if i missed anything. or its just my luck my first try at other motors and its a lousy motor factory?

my thinking about 400step/rev motors is that to achieve their rated torque, they have to go 1/2 the speed their normal 200step brothers. there is a torque curve speed thingy correlation. they MAY be better in terms of step/rev ... but i have yet to see accuracy (which i will try on this spooky unit soon).

TBH, i think you should go for torque and a motor that matches your driver/current/voltage

*edit* ... i think reserve 400steps/rev for a good extruder

ok tested, surprise surprise ... 400step/rev in this case (this model, and setup) works really well for very fine works, BUT VERY LOW SPEED usage. [youtu.be]

Edited 2 time(s). Last edit at 02/27/2013 06:01AM by redreprap.
Re: best motor: high torque or high resolution?
March 01, 2013 02:23PM
Day_Sleeper are you talking about chineese made motors from a new company called "Long motors" ? or logomotors i cant remmeber?

Anyways according to my experience both motors are pretty much alike.. 0.9 motor is has a smaller step (so remmeber to update your firmaware accordingly), with 0.9 you get a better resolution than the 1.8 degree, as the accuracy is higher.
4800 g/cm or 4200 g/cm are pretty much the same.. 4800 is slightly stronger = better as the motor will not put too much effort.
Its very important that you look at the CURReNT rating of the motors aswell or what is called current/phase.
if the current phase is higher than the current that you can supply - then you wont be able to reach that torque.

example: a 4800 g/cm motor with 2A/phase will not reach its 4800 torque! and in that case i would prefer a 4200 g/cm 1 A/phase motor over it! (incase i was using the regular 4988 stepper driver).
Note that the 4988 driver can reach 1Amp only, the new versions can reach UP TO 2A ONLY IF YOU COOL THEM PROPERLY.

Hope this helps!
Re: best motor: high torque or high resolution?
April 02, 2013 10:23PM
whats the amperage and inductance of the motors?
Re: best motor: high torque or high resolution?
April 04, 2013 12:49PM
The 4800g/cm motor is technically a "better" motor, but you'll need to feed it twice as many steps, so there are two limits, first, max travel speed will probably be reduced from what you can achieve with a 1.8 degree motor, and second, you may run into buffer issues for travel distance, since the reprap translation is based on stored counts from "system zero" instead of using real positional feedback.
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