Abra CNC ENGRAVER 01 User manual

ABRA CNC ENGRAVER
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ABRA CNC ENGRAVER
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Table of Contents
BILL OF MATERIALS ....................................................................................................................................... 4
INTRODUCTION ............................................................................................................................................. 5
1-ABRA CNC MACHINE .................................................................................................................................. 6
1.1-SAFETY CONSIDERATIONS .................................................................................................................. 6
1.2-MATERIALS REQUIRED ........................................................................................................................ 7
1.3-HARDWARE DESCRIPTION .................................................................................................................. 7
2-ASSEMBLY INSTRUCTIONS ......................................................................................................................... 7
2.1-ELECTRICAL ASSEMBLY ....................................................................................................................... 8
2.1.1- CONTROLLER BOARD .................................................................................................................. 8
2.1.3- MOTORS ...................................................................................................................................... 9
2.2-MECHANICAL ASSEMBLY .................................................................................................................... 9
3-GRBL CONTROLLER SOFTWARE ............................................................................................................... 10
3.1-INSTALLATION ................................................................................................................................... 10
3.2-FIRMWARE LOADING ........................................................................................................................ 11
3.3-SETUP AND TESTING ......................................................................................................................... 12
3.3.1- CANDLE ..................................................................................................................................... 13
4-SETUP AND CALIBRATION ........................................................................................................................ 18
4.1-BASIC CONFIGURATION .................................................................................................................... 18
4.1.1 SETTING END LIMITS AND HOMING .......................................................................................... 18
4.1.2 CALIBRATING MOTOR STEPS...................................................................................................... 20
5-MILLING ................................................................................................................................................... 20
5.1-FILE CONVERSION FOR CNC .............................................................................................................. 20
5.2- GCAM SVG to G-CODE ..................................................................................................................... 21
5.3- FILE UPLOAD (CANDLE) .................................................................................................................... 22
5.4- AXIS CONFIGURATION ..................................................................................................................... 22

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BILL OF MATERIALS
USB to Mini USB
Cable
CNC Controller
Board
Zip Ties 240mm V-Slot Railing
x2
220mm V-Slot
Railing x4
200mm V-Slot
Railing x2
M8x218mm Lead
Screw Rod
M8x238mm Lead Screw Rod M8x260mm Smooth
Rod x2
M8x240mm
Smooth Rod x2
2020 Corner
Brackets x 10
Aluminum Motor
Brackets x2
M5\M3\M2.5\M2\M1.5Allen
Key
M5x10mm Screws x60 M5 Washers X20
M5 Nylon Washers
x4
Aluminum
Heatsinks x3
M5 T-Nuts x60 M2x6mm Screws x8 Springs x2
M6 Brass Flange x2 M6 Couplers x2 T-Nut Screws/Washer/Wing
Nut x4
Brass Couplers x2 7K RPM DC Motor
Z-Axis Module +
Stepper Motor
M8 Smooth Rod
Clamps x8
DC Motor Connector Drill V-Bits M8 Pillow Blocks x4
M8 Lead Screw
Pillow Block
M8 Lead Screw
Pillow Block Y and
X
Stepper Cable to Controller x3 Corner Supports x2 Stepper Motor x2
CNC Table Power Supply 0.68µF Capacitor Rubber feet x4 ER11 Collet

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INTRODUCTION
This mini CNC (Computer Numerical Control) engraving machine is ideal for use on non-
metal materials such as plastics, wood, acrylic, PVC and PCB.
The machine is low profile, lightweight and easily connects to your preferred GRBL CNC
software via mini USB. This kit is ideal for hobbyists interested in rapid prototyping and
manufacturing.
The CNC is a 3-axis removal machine. This ABRA Kit includes all the necessary
equipment and instructions to be ready for operation within a few hours.
GRBL is a high-performance, low cost alternative to parallel-port based motion control
CNC milling. The system runs on the Arduino IDE Atmega 328 platform (Uno,
Duemillanove, Nano) in C code, however G-code and M-code commands can also be
sent to the machine's EEPROM directly.
GRBL has full acceleration management techniques using look-ahead algorithms. The
controller will look up to 18 motions into the future and set its velocities accordingly to
deliver a smooth acceleration and jerk-free cornering.
The CNC Machine is equipped with many failsafe measures and error feedbacks to
protect the machine and user to allow for easy debugging procedures.
The machine is ready-to-use but can be easily adjusted on-the-fly. Advanced users can
directly modify the firmware and configure preferences.

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1-ABRA CNC MACHINE
1.1-SAFETY CONSIDERATIONS
The use of this machine may pose many safety risks that must be addressed:
 Always wear the appropriate eye protection, breathing mask and ear protection
needed for each job.
 Always inspect the CNC machine for any visible problems before each operation. It
is recommended to test each motor axis before beginning a mill.
 For the safest operation, store the machine in a well-lit, well ventilated work space.
It is a good idea to have an open space surrounding the machine, so it does not
become cluttered.
 The CNC machine will be loud and will produce a lot of shaved material. Be sure to
keep the machine in a space that can accommodate the sound and dust. Always
keep the machine clean and dry before and after each job.
 The CNC machine may vibrate and move during a job. If possible place rubber feet
or clamp the unit down to prevent skidding.
 The CNC spindle spins at a very high speed with a very sharp bit attached to it.
Never place your hand or body part near this part while it is activated. For assembly
and calibration, it may be wise to slow down the motor or unplug it entirely.
 The CNC machine is plugged into a very strong power supply and will draw a lot of
current in use. Always be careful that the power supply is safely connected with the
jack connected to the CNC controller board first prior to connecting to a power bar
or wall outlet. The power supply may pose a fire threat if misused. Always consider
electrical protection when using the CNC machine. Try to avoid plugging multiple
tools into an outlet at the same time. Always unplug from the wall outlet side before
disconnecting from the controller board.
 Do not manually move the motors when they are off. This can produce a reverse
current and damage the CNC controller. Always unplug the motor connectors before
manually moving them.
 Never leave the CNC machine unattended during a job.
 Understand the level of difficulty involved with this machine and understand the
machine's intended applications and limitations before beginning.
 Refer to this manual or other references before attempting a repair or adjustment.
 See additional document for In-depth Assembly Guide.

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1.2-MATERIALS REQUIRED
This kit comes with everything you need to get the CNC machine functioning. You must
have a computer capable of supporting the Candle, GCAM and Arduino software.
Tools Suggested for Assembly:
 Precision ruler or caliper
 Marker
 Test board for calibrating Mill.
 Loctite screw thread-locker
 Tweezers
 Soldering Iron
1.3-HARDWARE DESCRIPTION
CNC Machine:
 Weight: 11.7 LBS (5.3kg)
 210mm (w) x 290mm (d) x 290mm (h)
Limitations:
 Maximum carving thickness: 30mm (Varies on bit used)
 Head travel dimensions:
o X: 13cm
o Y: 10cm
o Z: 7.5cm
2-ASSEMBLY INSTRUCTIONS
An additional manual provides a step by step, detailed and photographed list of
assembly instructions.
We recommend beginning the assembly by testing the electrical components and
board. We can test each part individually and determine if any need replacing or
servicing. This facilitates debugging and calibration later. You can mount the machine
frame and then install the working hardware. To properly test the board and motors, skip
to section GRBL CONTROLLER SOFTWARE, then return to ELECTRICAL followed by
MECHANICAL assembly sections.

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2.1-ELECTRICAL ASSEMBLY
Figure 1- Electrical Assembly
2.1.1- CONTROLLER BOARD
The controller board is where all the hardware is connected. The power and programmer
cables are connected as well as the motors and drivers. Connection is done as shown
below in Figure 3.
Figure 2-Board Diagram
Z-AXIS
X-AXIS
Y-AXIS

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(Note: We observed the maximum voltage the motor and controller board can take is 36VDC.
We also noted as the voltage supplied to the motor is not constant and alternates causing
reduction in performance. To fix this issue we suggest to solder a capacitor at the spindle motor.
We provide the capacitor in the kit, if you wish to improve the quality of your mill, you will be
required to solder them, and polarity is not of concern, since the capacitor is bi-polar.)
2.1.3- MOTORS
Motors and motor drivers are connected to the board and mapped to the controller pins
depending on their axis. Motor direction can be inverted in the software and firmware
later. The stepper rate can also be adjusted in the software; however, it may be useful
to tune the motors from the potentiometer on the driver. (Loosening results in more
current and larger step, tightening will result in smaller step. Please note this has
already been fine-tuned to work straight out of the box).
2.2-MECHANICAL ASSEMBLY
Once we are certain all the parts are included in the kit and function correctly, we can
proceed to the frame assembly. The CNC Machine’s precision is determined by the
precision of its assembly. To reduce vibrations, be sure to tightly fasten each piece and
perhaps use LocTite thread-lock for the screws.
Follow the link for video demonstration of the frame assembly or refer to the additional
manual.
https://www.youtube.com/watch?v=rU2FLyrUuoo

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3-GRBL CONTROLLER SOFTWARE
In this step, we establish connection to Candle CNC to test our motors and load our milling
files. Using this software, we can also issue G-code commands to modify the machine’s
EEPROM firmware.
To properly install and operate the CNC Machine kit, Arduino software and libraries
must be installed. Some computers may also require the CH340 serial drivers to be
installed. Please note, that some laptops may not be able to support this CNC
Machine. We recommend using a desktop computer with USB 2.0 port if possible.
3.1-INSTALLATION
Several different software options are offered for running the CNC machine. The ABRA
Kit uses Candle. Different users prefer different versions. Usually the code is open-
sourced and is updated frequently. The firmware is also available for download. Become
familiar with the versions and decide which is best for you.
Figure 3- GRBL Controller Software
Candle: [MUST BE ON GRBL FIRMWARE 1.1f]
https://github.com/Denvi/Candle/releases/download/v1.1/Candle_1.1.7.zip
Firmware 1.1f:
https://github.com/gnea/grbl/releases/download/v1.1f.20170801/grbl_v1.1f.20170801.hex
Arduino:
https://www.arduino.cc/download_handler.php?f=/arduino-1.8.5-windows.exe
CH340 driver:
http://www.arduined.eu/ch340g-converter-windows-7-driver-download/
http://www.arduined.eu/ch340-windows-8-driver-download/
GCAM:
https://github.com/blinkenlight/GCAM/releases/download/v2015.05.13/gcam-se-win32-
2015.05.13.zip

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3.2-FIRMWARE LOADING
Your CNC Kit should have already come with firmware 0.9j installed and you should
not need to re-upload it. If your machine is acting incorrectly or you wish to factory reset
your kit, simply download the firmware from the link above, save it in my
documents>Arduino>libraries as grbl folder with the content inside and load it onto the
board using the Arduino software (IDE).
There are Three methods to programming the board.
Target Link: https://abra-electronics.com/3d-printers-en/cnc-machines/cnc-kit-01-cnc-
engraving-machine-kit.html
Visit the target link suggested above, and click on Attachments to download getting-
started.zip
Method 1:
 After installing Arduino IDE, Connect the board using the USB cable to the computer.
(Please ensure you have no motors or external power connected to the board.)
 Open Arduino IDE and select the following settings:
o Tools>Boards>Arduino Nano
o Tools>Processor>ATmega328
o Tools>Port>Whichever com port this board is assigned
 Click upload to flash firmware or Serial monitor for a pop-up window to communicate with
the board. Set the baud rate to 115200 to see the screen printout GRBL Version #.
Method 2:
If you cannot program and get the error message “avrdude: stk500_getsync()” attempt this second
method.
 Open Arduino IDE and select the following settings:
o Tools>Boards>Arduino/Genuino Uno
o Tools>Port>Whichever com port this board is assigned
 Click upload to flash firmware
Method 3: Should method 1 and 2 fail, try this final step before consulting for support.
 Open XLoader software.
 Press … icon to locate hex file to program to the board. Select GRBL_V0.9J.hex.
 Select as Uno(ATmega328) and the assigned comport with a baudrate at 115200
 Press upload. If the system freezes and you observe on the controller board the LEDs do
not blink, simply disconnect the cable and reconnect the cable.
o The software will automatically close.
o Re-open XLoader and set as Nano with the same Com port and baud rate.
Should all three methods fail, feel free to contact the vendor.

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3.3-SETUP AND TESTING
In this section, we establish connection with the GRBL Controller software host. We must
connect on the appropriate port and set the correct Baud rate. Baud Rate: 115200
If the motors, board and power supply have been installed we can connect the unit and
test the system.
If the Arduino drivers and software are up to date, the CNC Machine should be recognized
automatically as it is plugged in. First, we set the machine’s communication baud rate
and port so we can send files and modify parameters.
Once connection is established, the parameters are displayed. We can then unlock the
machine and move the motors for calibration.

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3.3.1- CANDLE
Figure 4 - Candle port connection
(Note: If you cannot connect and have the same status message as shown in figure 4 under
console section. Close any software that is communicating with the board such as Arduino or
any other CNC software.)

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Figure 5- Candle Unlock
(Note: Alarm lock will only occur if you use Hard limits and print in the console the warning
message. To reset you use this button or type $X in the window and press the paper airplane to
send to the controller.)

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Figure 6- Motor Movement
(Note: Jog allows movements, if we press up the table should move outwards and inwards for
the bottom button. Left and right will move left and right respectively. The white button will move
the z-axis up or down respectively. Movements are done in mm and are set so accordingly to
the firmware settings. From the dropdown menu choose the step or distance to travel by and
feed for the speed to travel at.)
Observer
Y +
Y
-
X RIGHT >
X LEFT <

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Figure 7- Zeroing before Milling
(Note: Both buttons in one rectangular box are used for zeroing Z-axis and XY-axis. This button
is important as you must zero the machine coordinate before every mill project you want to
send. Home feature can be used once the coordinates are zeroed to return back to that zeroed
point. You can verify if the location is zeroed by looking at the work coordinates to see 0 on all
three dialog boxes. Z-axis must be zeroed when the drill bit is touching the material you wish to
work on).
Observer
Origin
X
-
ax
is
Y
-
axis

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Figure 8- Spindle Speed and Enable
(Note: By clicking on the three lines you can expand options for the spindle and set the speed to
10000 for a speed of 7000 RPM. By clicking on the spiral icon, you can activate the drill motor
and it should start spinning. You will do this action every time before you send your file to mill!)

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4-SETUP AND CALIBRATION
Your CNC machine is almost ready to use. At this stage, we should have the entire frame
assembled, the power properly connected, established connection to the GRBL software
and control of each motor axis. This step will show us how to fine tune the machine for
precise milling.
The objective is to configure the motors to their maximum working range at their optimal
step rate.
Before calibration, we recommend attempting a default mill without the Drill bit.
This mill will most likely be unsuccessful but will serve as an important guideline for
calibration. If the milling job succeeds, congratulations you are one of the few users who
were lucky enough not to need calibration! Enjoy your new CNC Machine. Proceed to
step MILLING, observe the errors and results then return to this step if needed.
4.1-BASIC CONFIGURATION
Enter commands directly into the Candle console.
Figure 9- Candle G Code Command Console
4.1.1 SETTING END LIMITS AND HOMING
This kit does not come equipped with hard end stop limit switches. We must control the
spacing and dimensions using soft limits.
In hard limit mode, the machine will send all its axis to maximum position until they trigger
the limit switch (not equipped).
Instead, our soft limit mode uses the dimensions of the table and known relative distances
to stay within bounds.

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 Using GRBL Control- Axis Control Menu, move the X and Y motors to their
minimum position (0 position).
 Move the Z axis to its minimum position.
 Click “Zero Position” (or “Zero XY” and “Zero Z”). This command has stored these
positions as zero in the machine’s EEPROM. (See figure 7)
This step can be repeated if necessary.
Now that the zero positions have been set, we can configure the maximum positions.
In GRBL Control enter the following commands *ignore comments in [ ] :
 $0 = 10 [step pulse, usec]
 $1=25 [step idle delay, msec]
 $2=0 [step port invert mask:00000000]
 $3=5 [dir port invert mask:00000101]
 $4=0 [step enable invert, bool]
 $5=0 [limit pins invert, bool]
 $6=0 [probe pin invert, bool]
 $10=1 [status report mask:00000011]
 $11=0.010 [junction deviation, mm]
 $12=0.002 [arc tolerance, mm]
 $13=0 [report inches, bool]
 $20=0 [soft limits, bool]
 $21=0 [hard limits, bool]
 $22=0 [homing cycle, bool]
 $23=0 [homing dir invert mask:00000000]
 $24=25.000 [homing feed, mm/min]
 $25=500.000 [homing seek, mm/min]
 $26=250 [homing debounce, msec]
 $27=1.000 [homing pull-off, mm]
 $100=800 [x, step/mm]
 $101=800 [y, step/mm]
 $102=800 [z, step/mm]
 $110=5000 [x max rate, mm/min]
 $111=5000 [y max rate, mm/min]
 $112=800 [z max rate, mm/min]
 $120=10 [x accel, mm/sec^2]
 $121=10 [y accel, mm/sec^2]
 $122=10 [z accel, mm/sec^2]
 $130=200 [x max travel, mm]
 $131=200 [y max travel, mm]
 $132=200 [z max travel, mm]

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4.1.2 CALIBRATING MOTOR STEPS
This step is crucial for a precise milling. This tuning ensures that the motors travel the
exact distance they are commanded.
Repeat this procedure for each X,Y and Z axis motor:
 Send motor to its zero position.
 In GRBL Control, command the motor to move 10 units.
 Accurately measure the actual distance travelled.
 Calculate the new step by:
o New_step = Current_step * (commanded_step / actual_step)
o Ex) New_step = 800 * (10/10.32) = 775.1938
o The default step for each motor axis is 800
o Your results should vary from ours but we determined:
 X_step = 792.079
 Y_step = 741.256
 Z_step = 775.194
o Repeat the steps and measure, iterate the calculation until the value stabilizes
to obtain an optimal precision.
 To save these values in the machine’s EEPROM, enter the following commands:
o $100 = 792.079 (use your values)
o $101 = 741.256
o $102 = 775.194
 This step can always be repeated and reverted, but generally doesn’t need to be
done once it is saved.
5-MILLING
Unlike 3D printers which are additive machines, CNC Machines are removal machines.
3D printers operate in the positive direction axis frame, where CNC machines operate in
the positive and negative Cartesian planes.
Before each print, we must convert and upload our file then setup our axis.
5.1-FILE CONVERSION FOR CNC
If this is your first mill, we recommend finding a sample file online that is already
formatted (.nc).
Otherwise, there exists several software that can convert a CAD design into Gcode
instructions. You can choose from the list below.
 Sketchup
 Conversational CNC
 Scan2CAD
 GCAM (Highly Recommended)
 Alternatively, you can access a template file from our website under attachments
for this product!