SCARA Robotic ARM assembly guide 1

IMPORTANT 1 BEFORE STARTING: Most of this Robot elements have been “3D printed”. The “official” KIT comes with PLA Ingeo 870 printed parts, much more durable and with higher resistance to impact than the regular PLA. Of course, you can print the parts by yourself in ABS or PLA but keeping this in mind: You can break it if you apply too much force or tight a screw more that you should. We will let you know, during this assembly guide, when you can tighten the screws as much as you can or where you should just fix a part to another not forcing it at all.

If you choose to print the parts by yourself: every filament (PLA, PLA+, ABS, PETG…) has its own set of “perfect printing” parameters in order to achieve the flawless 3D-printed parts, if you overheat the filament, the layer thickness will be increased and the different part´s tolerances may be compromised. This should not be a problem but using a knife to clean the parts a little bit may be mandatory.

During the design process, we have tested many 3D printers and a bunch of filament brands and if you print the parts carefully, you will not find problems at all.

We have uploaded a 3D model of the SCARA Robot Arm to Skecthfab as a visual reference. If you get lost or just want to get a good idea of where everything goes, just check it out


SCARA Arm 3D printed parts
NEMA 17 stepper motor (MT-1703HS168A or equivalent)3
MOTOR CABLES (45 cms)2
MOTOR CABLES (14 cms) 1
16 teeth GT2 pulley 2
Linear Bearing LM8UU2
Linear Bearin LM8LUU1
Circular Ball bearing 623zz5
Circular Ball bearing 608zz1
Circular Ball bearing 6002RS or 6002ZZ3
SERVO MG92R (to open/close gripper and wrist)2
Steel Rod (Stainless 304/306) Ø 8mm 250mm3
Threaded Steel Rod (Z axis) + nut Ø 8mm 200mm 1
Timing belt 280 GT23
Cable SERVO extender 50 cm2
Cable wrap 50 cms (not mandatory but recommended)1
Aluminium axis coupler (8to5)1
Evo Foam 15 x 30mm (to increase the gripper friction)1
Rubber bands (25mm diameter aprox.)4
DEVIA control Board (or equivalent Arduino M0, ESP8266 + 3xstepper motor shield)1
Motor drivers A4988 + heatsinks3
USB cable 1m (micro USB connector) 1
12V/2A Power supply with 2.1mm POWER JACK1
M3 6mm bolt 26
M3 10mm bolt 10
M3 15mm bolt 8
M3 45mm bolt 3
M3 nuts10
M3 washers4
headless M3 bolt2
ALLEN Key (hexagonal) 1.5mm1
ALLEN Key (hexagonal) 2mm1

FRAME. Setting everything up

First, gather all the elements to create this Robot. If you have printed the parts by yourself, gently remove the burr and the support of the FOREARM piece. With the kit you will get 2 Allen type keys but you will need a screwdriver and maybe pliers too.

GRIPPER. Assembly guide

Follow this link to the Gripper assembly guide.

jjRobots Robotic Clamp Grabber

ELECTRONICS. How to connect everything

We will to precisely move 3x Stepper motors and 2x Servos. The SCARA Robotic Arm will be controlled via USB cable or WIFI. We have opted to create our own Robotics Control Board, the DEVIA. It has a powerful ARM Cortex M0 processor and a bunch of input/output ports + sensors. Perfect for this purpose. Below, the diagram of the electronics in charge of controlling the Robot.

scheme V1
Above: Electronic Scheme of the DEVIA control board and how every actuator is connected
DEVIA Board fixing point
You can fix the DEVIA control board to the SCARA´s BASE using two M3 6mm bolts as above.
Pybot connection scheme

Above: Connect the motors and servos as indicated. Use the SERVO CABLE Extenders (50cm) to connect the servos to the electronics and the pick the right motor cables length according to the scheme. Never connect, disconnect anything while the power supply is plugged in to the Control Board.

Pybot connecting everything with LIDAR
Cables set
There are two types of cables to be connected to the control board, the motor cables and the servo extenders. Double check the connections. It is easy to make mistakes: they have the same colors! The cable wrap will save you problems: Pack several cables up inside the the wrap and fix it to the base and between the motors on the Z-platform. The SCARA´s frame have several holes / channels meant to be zip-ties fixing point.
Running cables Fixing points

Cables slack: Keep in mind that the cables must let the arm move freely. If they are too tight, they will limit the robot movement (and possibly they will get broken). So, run the cables from the actuators to the control board and move the robot´s arm to its physical limits ( fully retracted, fully extended, gripper completely rotated, raise the Z-BASE to the top…). Once you are sure the cables are not interfering with the movements, fix them using zip ties. You can use the cable wrap to tidy everything up a little bit.

NICE! The SCARA Robotic arm is ready to rock. The video above shows a repeat-ability test once everything has been properly set and adjusted.