DIY CNC Controller 3 Axis Assembly Instructions

From A Quick CNC Wiki
Jump to: navigation, search
DIY CNC Controller 3 Axis
Finished DIY CNC Controller 3 Axis.jpg

For assembly instructions for the 4 Axis kit, please see: DIY CNC Controller 4 Axis Assembly Instructions.

Thank you for purchasing our DIY CNC controller board. In these instructions you will find the information needed to assemble your DIY CNC controller board, as well as how to configure an already assembled board.

PLEASE NOTE: If you are not comfortable with soldering electronics, working with high DC and AC voltage, please do not use this controller. This controller is capable of driving dangerous machinery, and if not used properly could cause injury or even death. We are not responsible for any injuries or accidents that may occur when using these electronics or any CNC machine. If you do not agree with these terms please discontinue the use of these parts immediately.

Specifications

  • Accepts 5, 6 or 8 wire unipolar stepper motors (4 wire type not compatible)
  • 40 volt DC maximum input voltage, 24 volt DC recommended, 12 volt DC minimum.
  • 3.0 amps maximum current per phase, 0.5 amp minimum. (Fully adjustable)
  • 12 volt DC output for computer style case fan (not included).
  • 1/1, 1/2, 1/4, 1/8, & 1/16 microstepping.
  • Patent pending circuit protection built in to protect against short circuits.
  • Inputs for limit switches and e-stop.
  • Easy to build and easy to use terminal blocks for connecting wires.

Recommended Assembly Tools

To ensure proper assembly, there are several items that are necessary and recommended to complete the process efficiently.

  • Soldering iron
  • Rosin core solder
  • Small flat blade screwdriver
  • Wire clippers
  • Multimeter or voltmeter
  • Power supply for testing

Parts List

These are the parts that are included with your kit. Please verify that all parts are present and accounted for before beginning. Each part will also be identified using a short code, which will match up with the spots on the printed circuit board (PCB).

IC1, IC2, IC3: SLA7078MPR Stepper Motor Control Chip
IC4, IC5: LM317HV Voltage Regulator
X1: 26 Pin IDC Male Header
TB1, TB2, TB3, TB4: 6 Position Terminal Block
TB5, TB6: 2 Position Terminal Block
C1, C2, C3, C4, C5, C6, C7, C11: 0.1µF Capacitor (Has code 104 on it)
C8, C9, C10: 680µF 50V Electrolytic Capacitor
R1, R2, R3: 10K Resistor (Color code: Brown, Black, Orange, Gold)
R5, R7: 240 Ohm Resistor (Color code: Red, Yellow, Brown, Gold)
R4: 715 Ohm Resistor (Color code: Violet, Brown, Green, Black, Brown)
R6: 2.05K Ohm Resistor (Color code: Red, Black, Green, Brown, Brown)
VR1, VR2, VR3: 1K Variable Resistor Potentiometer
SW1,SW2, SW3: 3 Dip Switch
RN1, RN2, RN3, RN4: 10K Resistor Network

Board Layout

DIY CNC Controller Board Layout 3 Axis.jpg

Assembly

Solder 10 KOhm Resistors

Begin by laying out the circuit board PCB on a clean work space.

Insert the three 10K resistors (R1, R2, R3 with brown, black, orange, gold color code) into the spots located on the circuit board. Flip the board over and solder the connections, and then trim the leads close to the board.

Solder 240 Ohm Resistors

Next insert the two 240 ohm resistors (R5, R7 with red, yellow, brown, gold color code) into the spots located on the circuit board. Flip the board over and solder the connections, and then trim the leads close to the board.

Solder 715 Ohm and 2.05 KOhm Resistors

Insert the 715 ohm resistor (R4 with violet, brown, green, black, brown color code) into the spot on the circuit board, solder the connection and trim the leads.

Finally insert the 2.05 Kohm resistor (R6 with red, black, green, brown, brown color code) into the spot on the circuit board, solder the connection and trim the leads.

Solder 104 Capacitors

Next are the 0.1µF Capacitors (C1, C2, C3, C4, C5, C6, C7, C11 with identifier 104 on the capacitor). Unlike other capacitors, these do not have an orientation. Install them into the holes on the circuit board, and solder the connection. Trim the leads close to the circuit board.

Solder 10k Resistor Networks

Now move on to the 10K resistor networks (RN1, RN2, RN3, RN4). The resistor networks have six pins to be inserted into the circuit board, they MUST be oriented in a specific way. There will be a circular dot on the resistor network, line up that dot with the white dot on the circuit board (close up photo). Solder the connections being very careful to not connect any of the pins together. Trim the leads close to the circuit board.

Solder Potentiometers

Install the three potentiometers (VR1, VR2, VR3), they will only orient one way. Solder the connection and trim the leads.

Solder DIP Switches

Install the three dip switch components (SW1, SW2, SW3), line up the top "ON" portion with the "ON" on the circuit board. Solder the connections and trim the leads.

Solder IDC Male Header

Now install the 26 pin IDC header block (X1) on to the board. Ensure that the center tab on the header block is lined up with the edge of the circuit board as on the circuit board. Solder the 26 pin connections being extremely careful to not bridge any pins. Trim the leads.

Solder Wire Terminals

Next install the wire to board terminals (TB1, TB2, TB3, TB4, TB5, TB6) on the board. TB1 through TB4 will be six wire connections, TB5 and TB6 will have two wire connections. Solder the connections and trim the leads.

Solder Voltage Regulators

Install the two LM317HV voltage regulators (IC4, IC5) into the circuit board. Ensure the voltage regulator is oriented onto the circuit board by matching the flat metal part with the thick white band on the circuit board. Trim the leads.

Solder Electrolytic Capacitors

Finally install the large electrolytic capacitors (C8, C9, C10) into the circuit board. Orient the longer lead into the hole next to the positive (+) symbol on the circuit board. The body of the capacitor also has a negative (-) running down the body. Solder the connections and trim the leads.

Testing the Connections

Before installing the stepper motor control chips, we will test the circuit to verify everything has gone properly so far. We do not want to install the stepper motor chips yet, as any potential errors could cause a short circuit that would damage the chips.

To ensure proper working order, please connect a power source to the circuit board through the TB5 connection. At least 12 volts is required, with a maximum input of 40 volts. Connect the positive connection to the + and the negative to - on the circuit board.

Using a multimeter or voltmeter, measure the voltage at the touch points located on the circuit board. Touch the meter between the touch point and any of the 3 ground points on the circuit board (marked "-"). You should measure around 5 volts at the touch point marked +5V in the center of the board, and 12 volts at TB6 the output for a 12 volt fan. If these measurements check out, it is safe to install the stepper motor control chips. If these voltages are not correct, please check all solder joints for proper connections.

Now would also be a good time to adjust the potentiometers (see section "Adjusting the Stepper Motor Current") if you know what size motors you will be using. If you do not yet know, you should rotate the potentiometer all the way counterclockwise and verify on the touch points ("TP") that the voltage is as close to zero as possible.

Soldering the Stepper Motor Control Chips

If everything checked out with the voltages and all connections look good you can now install the stepper motor control chips. The stepper motor chips are 23 pin SLA package chips that stick out of the board. There is only one direction you can install them in so carefully check to make sure you have them the right direction before inserting them. Some of the pins may have uneven spacing, so make sure to line them up with the holes before inserting the chip into the circuit board.

Once all the pins are inserted, push the chip gently until it can no longer go any further. Line the chip up so it is sitting perpendicular to the PCB surface, flip the board over and solder the connections. Be extremely careful when soldering to ensure there are no bridges between the pins. Once the first chip is soldered, repeat the process for the other two. Line up those chips so they are parallel with the first chip. Once all are soldered, trim the leads.

Before powering up your circuit board for the first time, you should set all your DIP switches to OFF (see section "Setting the DIP Switches"). Only change the DIP switch settings after you have installed a motor.

Finished DIY CNC Controller 3 Axis.jpg

Setting the DIP Switches (Microstepping)

The "DIP" switches on the circuit board controls the microstepping of each axis. There are three separate sets of switches (one for each axis). Setting all the switches to off will disable the axis. Shut off power before setting DIP switches.

We recommend 1/4 stepping. You will have less power than at full step, but a better resolution for increased precision.

Setting Switch 1 Switch 2 Switch 3 Diagram
Disabled
(Sleep)
Off
Off
Off
3 DIP Switch off-off-off.gif
Full Step
On
On
Off
3 DIP Switch on-on-off.gif
Half Step
On
Off
Off
3 DIP Switch on-off-off.gif
1/4 Step
Off
On
On
3 DIP Switch off-on-on.gif
1/8 Step
Off
On
Off
3 DIP Switch off-on-off.gif
1/16 Step
Off
Off
On
3 DIP Switch off-off-on.gif

Adjusting the Stepper Motor Current

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.

Software Setup

For a detailed Mach3 setup, please view our Mach3 Setup Tutorial.

Please note that our control board has a unique pin out that differs from the pin out used in the past with our other kits. Please use the following pins:

  • X-Step: 3
  • Y-Step: 5
  • Z-Step: 7
  • X-Direction: 2
  • Y-Direction: 4
  • Z-Direction: 6

For a full listing of all the pins, please refer to the next section. (Utilize DB-25 values if using a parallel port for control).

Input and Output Pins

It is important to note that the input and output pins on the ribbon cable connection do not correspond directly with the DB-25 parallel port. Pin 2 on the ribbon cable connection does not equal pin 2 on the parallel port connection. This is due to the DB-25 plug reversing the pins on the ribbon cable. This table will help you locate the pins and their corresponding parallel port pins. If using the available parallel port adapter, there is nothing you need to do here. This is only for advanced users who control their boards differently.

IDC Pin DB-25 Pin Description
1
1
Solder Point
2
14
Solder Point
3
2
X Direction
4
15
Input (E-Stop)
5
3
X Step
6
16
Solder Point
7
4
Y Direction
8
17
Solder Point
9
5
Y Step
10
18
Grounded
11
6
Z Direction
12
19
Grounded
13
7
Z Step
14
20
Grounded
15
8
Solder Point
16
21
Grounded
17
9
Solder Point
18
22
Grounded
19
10
Input (Limit X)
20
23
Grounded
21
11
Input (Limit Y)
22
24
Grounded
23
12
Input (Limit Z)
24
25
Grounded
25
13
Input (Limit A)
or Homing
26
NC
Grounded

Limit / E-Stop / Homing Switches

Switches can be wired to the CNC Controller through the available input pins on the circuit board. Screw terminal connections are made availalbe on the following pins: 10, 11, 12, 13, & 15. Additional pins are available through solder points on the following pins: 1, 14, 16 & 17. The screw terminals are controlled through a pull up resistor, they will show +5V steadily unless grounded out. This will ensure a steady signal for your CNC control software. Limit switch and E-stop wiring is fairly simple. Wire a switch between the Ground (GND) terminal, and the respective screw terminal. Make sure your CNC software settings are setup for the correct terminal, and are activated when the switch is triggered. Normally open or normally closed switches can be used for limit switches and E-stop. Normally closed switches must be used for Homing switches, as you will wire up several switches on one circuit.

Typical input ports are as follows:

IDC Pin DB-25 Pin Description
19
10
Limit X
21
11
Limit Y
23
12
Limit Z
25
13
Limit A
or Homing
4
15
E-Stop

Circuit Board Dimensions

The circuit board is less than 5.5" x 2.25". Mounting holes are 5.25" x 2.0" with 4mm holes (#6 screws can be used if 4mm screws are not available).

DIY CNC Controller 3 Axis Board Dimensions.jpg

Heatsink Measurements

A heatsink is required if using the controller with motors rated 2.0 amps and higher. It is best to make the heatsink out of 1/8"-1/4" aluminum, commonly available at a hardware store. The holes on the heatsink are 24.4mm apart. The centers of the stepper motor control chips are nominally 1.8" apart. If you have your controller assembled, it is best to transfer the holes from the control chips to your aluminum as it is possible for the spacing to shift during assembly. Apply thermal paste between the heatsink and stepper motor control chips for even heat distribution. Install a 12v case fan (not included) to help direct airflow over the heat sink. Drill and tap holes in the heatsink to accept #4-40 screws.

This drawing is for reference only:

DIY CNC Controller 3 Axis Heatsink.jpg