Closed-Loop Stepper Motor Kit

FAQs

Will you be selling the closed loop stepper motors on their own? 

Yes, we do plan to sell the closed loop motors on their own. Watch for upcoming announcements. If you own an AltMill and need replacement/spare parts soon, please contact us on this page. 

Will you have installation instructions for my specific CNC machine (Shapeoko, Onefinity, OpenBuilds, X-Carve etc)?
No, we will only have instructions for LongMill MK2/MK2.5 machines. Although our team will try their best to provide information, technical support will be limited for third-party machines and accessories.

Furthermore we cannot guarantee that third-party accessories will be compatible with the SLB-EXT controller, please see our SLB manual (it applies to the SLB-EXT as well) to check if your accessory can be hooked up to the controller.

What’s the difference between a closed-loop stepper system and an open-loop stepper motor system?
With open loop motors, a command is sent to the motor driver, and the motor driver tells the motor to move some amount. Whether or not the motor actually moves that exact amount is unknown to the rest of the system. If there is some sort of resistance, disturbance, or obstacle in the way that prevents the motor from spinning its intended amount, the motor will ‘skip steps’ and we’ll essentially lose track of where we think the motor is.

With closed loop motors, a command is sent to the motor driver, and the motor driver tells the motor to move some amount, while simultaneously monitoring the position of the motor using a sensor. If the motor position is lagging behind where it is expected to be, the motor will receive more power to ensure that the motor gets to the specified position without any skipping. In the case where the motor is somehow obstructed from spinning entirely, it will enter an ‘Alarm’ state and shut off power to prevent any damage. The motor driver will communicate back to the machine controller to let it know that something has gone wrong, and the controller can halt the entire system to prevent any sort of damage.

Asides from no potential for loss of position, there are a few other benefits of closed loop stepper motors:

• More efficient operation when idle since extra power is only used if some torque is applied to the motor’s shaft and the motor must react to maintain its position
• More efficient operation overall, since the motor will only use as much power is needed to move
• Less heat buildup in the motor since idle and operational efficiency is improved
• Less noisy
• Faster maximum running speeds