stepper vs. servo

Prototyping a design, unsure of best motor to pick.

I am currently working on a design that required 4 linked drive shafts to be controlled by a motor. I am using # 25 roller chain and sprockets to link the shafts which will each have about a 1.5-2lbs of work mounted to them. I am looking for a motor that can spin consistently at about 350 rpm without too much vibration. The motor in question will have to spin at variable speeds based on input from a proximity sensor if that makes any difference. I should also mention that I have both a big easy driver and an Arduino motor shield at my disposal to control the motors: the design will be able to be hard wired to a wall/ adapter.

I am new to both Arduino control and the world of tiny motors, your patience and consideration are appreciated.

http://www.everychina.com/p-z52dbd1b-98413557-350rpm-high-torque-gearbox-stepper-motor-42hsg-step-motor.html

Calculate the Newton Meters or foot -lb torque spec you need for the motor .

@derekbruno, I think you should clarify what you mean by a servo.

Most of the time on this Forum “servo” means one of the things used to operate the controls on a flying model aircraft. The output arm normally only works through an arc of 180 degrees.

I wonder if you mean the type of industrial servo used to drive CNC machines as an alternative to stepper motors?

…R

350 RPM with a load of 4 times 2 pounds.

is that foot pounds ?

spinning without vibration at 350 rpm is all about balance. your chain will be noisy and contribute to the overall system vibration.

you may need to have a smaller drive and a larger driven pulley and run the motor at much higher speeds.

the steppers properties are such that they deliver high torque at low speed. also, due to the design,there is an upper practical limit for steppers. you cannot get large motors. the force to make them step becomes almost as great as the resistance from the magnets.

the industrial servo (really just a DC motor with controls) can spin very fast and deliver less torque. the servo is designed to be reduced by pulleys and such.

without knowing if you have a 2 pound weight on a rolling cart or 2 foot pounds, the actual motor spec cannot be determined.

I think that as you define the problem, the answer will present itself.

http://www.anaheimautomation.com/marketing/estun/servo-motors.php?gclid=CjgKEAjwnfGbBRDlxoHrl6uikyESJAD-nzCF1vG8nfqoWcAtw09erG-DtE5H6o0X5E5Y-gf9dTJkCfD_BwE

http://www.automationdirect.com/adc/Overview/Catalog/Motion_Control/Stepper_Systems

http://industrialmotorresource.com/category/variable-speed-motors.html

dave-in-nj: without knowing if you have a 2 pound weight on a rolling cart or 2 foot pounds, the actual motor spec cannot be determined.

each shaft will weigh roughly 2 lbs. and are held in alignment by a thrust bearing at the bottom and a regular ball bearing at the top. I suppose that equates to 4x (2lbs on independent rolling cart) ,

It looks like a variable sped DC motor with its own power supply would be ideal, with the arduino controlling the speed.

It looks like a variable sped DC motor with its own power supply would be ideal, with the arduino controlling the speed.

Still need a torque spec.