Small stepper motor

Stig · Mar 12, 2013

Does anybody have any sources for small stepper motors or servos?

Requirements:
1/4" shaft size or less
built in encoder
compact
24vdc

I have a project with a friend, he is designing the enclosure and wants me to do the electro-mechanical portion, we will be using a small G304K HMI, and PLC to control a stepper motor or servo for bidirectional rotation of a 12" wide disk, we can get away with unidirectional rotation. Approximate disk weight 1-1/2 lbs loaded. The disk will be horizontal with a perimeter bearing for balance and weight distribution. Must be very accurate and have a long lifespan, it is for the medical field. Total size of the unit is not finalized but I'm shooting for the electronics area to be around 16W"x16L"x8H". So there must be room for a drive as well. As for motor or servo, it doesn't have to be quick, but smooth starts and stops. The PLC and HMI will be controlling other functions as well on the unit.

I should add at points of its operation it might just step, others it may have to rotate 364 degrees, depending where the disk currently is at.

kolyur · Mar 12, 2013

Check out Oriental Motor, they are a big player in the stepper market. The CRK and CMK series steppers are 24V-powered and encoders are an option.

www.orientalmotor.com

CalG · Mar 13, 2013

Encoder built in or on? rare thing

Though closed loop steppers are done, very likely you will need to consider an encoder feedback as a "user add on".

It's just the way they work. If you do your load and power calcs correctly, dropped steps are no likely. Drive and motor need to be matched for best performance. Volts amps, windings and henries need to matched up.

Every system should have a "home", errors will be nulled out there.

For a rotation application, absolute position is the way to go. there are even algorithms to take the shortest direction to the next move.

Sounds fun.

(I appreciate the Parker products for their quality and flexibility)

Stig said:
Does anybody have any sources for small stepper motors or servos?

Requirements:
1/4" shaft size or less
built in encoder
compact
24vdc

I have a project with a friend, he is designing the enclosure and wants me to do the electro-mechanical portion, we will be using a small G304K HMI, and PLC to control a stepper motor or servo for bidirectional rotation of a 12" wide disk, we can get away with unidirectional rotation. Approximate disk weight 1-1/2 lbs loaded. The disk will be horizontal with a perimeter bearing for balance and weight distribution. Must be very accurate and have a long lifespan, it is for the medical field. Total size of the unit is not finalized but I'm shooting for the electronics area to be around 16W"x16L"x8H". So there must be room for a drive as well. As for motor or servo, it doesn't have to be quick, but smooth starts and stops. The PLC and HMI will be controlling other functions as well on the unit.

I should add at points of its operation it might just step, others it may have to rotate 364 degrees, depending where the disk currently is at.

Stig · Mar 13, 2013

I have been looking into it and decided that having it return to home after every cycle or power failure would be best. That would prevent misalignment and errors, both mechanical and human, especially considering the purpose of the system, could mean life or death.

Highland Controls · Mar 13, 2013

I think you will need some kind of gearing. A 12" disk coupled directly to a NEMA 23 stepper is going to be a pretty big load to motor inertia ratio.

RoTaTech · Mar 13, 2013

Several times I have used Quicksilver. It is a motor, encoder, and amp all in one unit. Just give it power and program it. It has IO too, for limits and handshaking. Very nice unit.

shooter · Mar 19, 2013

find a old printer or copier, i have a big box with steppers and other motors.
if the PLC has relays outputs it can still be used for stepper motor (wiill be slow but it works.)
use two simple spdt relais to control the current direction in the motorcoils. so with two simple outputs you can control one stepper motor.
on the assembly make a switch to see zero position. When you mount it the disc should be able to run over te switch and just give contact.
the voltage for the motor can be different from the plc this way.

Small stepper motor

Stig

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