Unipolar CNC Controller Setup
|Manufacturer||A Quick CNC|
The Unipolar CNC Controller is based on the DIY CNC Controller from A Quick CNC. This version was last sold on the CNC Building Blocks campaign on Kickstarter. It has been replaced by a newer version of the same kit called the Unipolar Motor Driver.
REMEMBER. When configuring your CNC electronics, please unplug all connections from the back of your control box. Then wait a few minutes before opening your control box to make adjustments. It is possible for the on board capacitors to store a charge and potentially cause a shock. Please use extreme caution when working with high voltage sources. We are not responsible for damage caused to your electronics, computer, or motors.
Setting up Microstepping
Microstepping is possible with our control board. Microstepping is a way to force your stepper motors to move a fraction of a step instead of a full step. You can potentially increase the precision of your stepper motors by 16 times the standard amount for smaller movements. Note that due to the nature of microstepping, your electronics will reduce the power to the motors when microstepping, effectively reducing the torque produced by the motor. A high microstep setting will give very small movements, but much less power. The lack of power can cause your motors to not have enough power to move and can stall them.
Our electronics allow for a range of microstepping options. You are able to set microstepping in increments of 1/1, 1/2, 1/8, & 1/16. A setting of 1/1 means microstepping is not turned on, where 1/16 is the highest setting, which can allow the motors to spin in small amounts, with less power.
To set microstepping. Ensure the electronics are unplugged and no power is going to them. Let them sit for a few minutes before opening the cover and servicing. After waiting a few minutes you can open the cover by removing the four Phillips screws in the corners of the enclosure. Do not remove any other screws.
With the cover removed, look for the DIP switches with 4 switches in a row. There will be three of these switches in the center of the control board, one for X, Y & Z. Using a small screwdriver, finger nail, pen or other small object, flip the switches in accordance with the table below for your desired setting:
|Setting||Switch 1||Switch 2||Switch 3||Diagram|
Setting Stepper Motor Amperage
The controller has variable power output for each axis that will allow you to use a motor rated between 0.5 amps and 3.0 amps. Determine the current of your motor from the specifications sheet, or by contacting the motor manufacturer. Values can differ greatly between motors, even if they appear to be the same size.
With the motors disconnected (or all DIP switches set to off) carefully apply power to your CNC Controller using a power supply with at least a 12 volt DC output.
Using a multimeter, touch the negative (black) probe to the ground connection coming from the power supply. Carefully touch the positive (red) probe to any one of the three touch points located on the circuit board and labeled TP1, TP2, & TP3. Here you will measure the motor current setting. You will need to adjust the potentiometer clockwise to increase TP voltage and counter clockwise to decrease TP voltage. The TP voltage measured is what tells the stepper motor control chip how much current to deliver to the stepper motor. If set too low, the motor may fail to function, and if set too high the motor or controller may sustain damage.
Use this formula to calculate the voltage at this point:
TP Voltage = 0.14 x Motor Current
If your motors are 1.0 amp, adjust the potentiometer clockwise until the TP voltage reads 0.14 volts. If you have a 2.0 amp stepper motor, adjust until it reads 0.28 volts. If you have a 3.0 amp stepper motor, adjust the potentiometer until it reads 0.42 volts.
NOTE 1: If you are driving a larger stepper motor (2-3 amps) you MUST add a heatsink to your CNC Controller to help dissipate heat. Failure to add a heatsink could result in the failure of the stepper motor control chip.
NOTE 2: If your motors are extremely hot during operation, consider decreasing the TP voltage by 0.1-0.2 from the calculated value. This will decrease the stepper motor temperature without much loss in power.
Once you have changed your settings, you can put the cover back on your electronics, plug everything in and power the controller on. No further changes in software or configuration will be needed.