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 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.

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 ROBOTIC ARM ELEMENTS (BOM):

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 LM8UU 2
Linear Bearin LM8LUU 1
Circular Ball bearing 623zz 5
Circular Ball bearing 608zz 1
Circular Ball bearing 6002RS or 6002ZZ 3
SERVO MG92R (to open/close gripper and wrist) 2
Steel Rod (Stainless 304/306) Ø 8mm 250mm 3
Threaded Steel Rod (Z axis) + nut Ø 8mm 200mm 1
Timing belt 280 GT2 3
Cable SERVO extender 50 cm 2
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 + heatsinks 3
USB cable 1m (micro USB connector) 1
12V/2A Power supply with 2.1mm POWER JACK 1
BOLTS and NUTS
M3 6mm bolt 26
M3 10mm bolt 10
M3 15mm bolt 8
M3 45mm bolt 3
M3 nuts 10
M3 washers 4
headless M3 bolt 2
ALLEN Key (hexagonal) 1.5mm 1
ALLEN Key (hexagonal) 2mm 1
GET THE SCARA KIT

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.


  • First step: insert the short linear bearings (LM8UU) into the lateral channels of the Z-platform)
  • These too elements and the long LM8LUU linear bearing have to be perfectly inserted to avoid problems with the Z axis. It will require to apply a good amount of force to fully insert them into place.
  • Lateral view of the LM8UU fully inserted. Widen the lateral channels using a plain screwdriver if you are having problems inserting the linear bearings. A small mallet could be useful too.
  • Take 4x M3 6mm bolts and fix one of the stepper motor to the TRIANGLE SUPPORT.
  • Insert (carefully but firmly) the 608ZZ and the 6002 ball bearings as indicated here. Check if there is any burr on the walls of the 3D part receptacles.
  • Using 3x M3 10mm bolts, insert and capture the 3x 623 ball bearings as indicated.
  • Turn around the ARM TOP and insert a nut inside the hexagonal cavity and introduce a 6mm bolt from the back so the nut will stay in place. This bolt will be used to tense a timing belt if needed. Do not let the bolt to stick out of the nut. We want a plain surface on that side of the ARM TOP piece.
  • The top side of the ARM TOP. Check the small ball bearing are moving freely and everything looks tight.
  • ARM BOTTOM part: insert (firmly and gently as always) the 6002 ball bearing
  • REDUCTION: insert the 6002 ball bearing as indicated above. NOTE: This piece is FRAGILE, very. But inserting the bearing properly inside this gear reduction is crucial. This step may require to use pliers to slowly insert the ball inside the REDUCTION, Take your time. It is tight but it fits. Do not let the ball bearing to stick out of the 3D printed part. Push it to the very end.
  • Now, push the long linear bearing inside the ball bearing as shown above. You might need to use the mallet in order to make the LM8LUU going through the circular bearing. The LM8LUU have to stick aprox 18mm out of the circular bearing.
  • Is the long linear bearing loose? Fix it wrapping adhesive tape around it
  • Use adhesive tape to increase the linear bearing diameter and insert it into the 6002. Just one layer will do the trick
  • Place 2 timing belts as above and “close” the arm with ARM BOTTOM piece so the belts will get caught inside. If you forget to do this now, you will have to “open” the arm again later.
  • This is how the arm looks by now.
  • screw a 15mm bolt and capture a 623zz ball bearing with a self-blocking nut on top.Check the ball bearing can move freely after tightening the bolt.
  • Carefully insert the HUB through the 608zz ball bearing. Check for any burr on the top of the protruding knob. It could make it hard to insert the hub. But FIRST, take a look to the photo below: you MUST pass the timing belt around the HUB´s teeth before fitting it.
  • Like this.
  • Use a 15mm bolt and screw it through the CAP to help the HUB´s knob get into the 608 ball bearing. The bolt will pull up the HUB into place. Do it gently until the 3x 623 ball bearings are touching the top side of the HUB. Watch this video, it shows how smooth everything should move.
  • You are almost there. Insert the upper top of the long LM8LUU bearing into the hole of the Z-BASE platform. Again, be gentle but introduce completely the bearing to the very end.
  • This is where we are now. Two belts are correctly set (1 more remaining)
  • Now, pass the third timing belt around the arm so it will rest on the teeth of the ARM TOP gear as the photo shows
  • Push the threaded rod´s nut into the central platform´s hole. It will hold firmly inside by itself.
  • Insert the stainless steel bars into the BASEPLATE sockets. Push them to the very end.
  • Now, run the MOTOR TRIANGLE structure along the steel bars (push the 3 corners at the same time, That will make it easier). Push the motor into its socket in the BASEPLATE
  • This is how it looks. The three steel bars are going up straight and the orange triangle support is holding them firmly
  • Aluminium coupler: Use the 2mm Allen Key to capture the motor shaft inside.
  • TAKE YOUR TIME!: the linear bearings have tiny steel balls inside 4 inner channels. Those balls will keep the bearings moving up and down smoothly. If you lose too many of the mentioned balls, the Z-BASE will crank while moving vertically. Now it is time to insert the 3 vertical steel bars into the 3 linear bearings, everything at the same time. So, carefully align the steel bars + threaded rod and gently (gently!) push the Z-BASE down while you slowly turn the central threaded rod. Doing this, you will control the process just rotating the central rod. If you find resistance, stop, re-align and start over. Watch this video for visual help
  • Almost there!: Set the motors as above and fix them using 3x 6mm bolts for each one. DO NOT tighten them completely, you will need to adjust their position soon.
  • Place the 16 teeth pulleys on the motors shafts. Notice the orientation of the pulleys. Do not completely tighten the bolts. The motor on top will be the motor 2 in the Z-BASE platform, the other one, the motor 1 (see photo below)
  • You will need to re-adjust the pulleys high on their shafts later.
  • Pass the GT2 timing belts around the pulleys and push the motors back until the belts are tighten, then fix the motors with the bolts.
  • If everything went nicely, the belts will not touch the threaded rod.
  • Place the TOP TRIANGLE as above. This part will keep the threaded rod straight,
  • Another view of the TOP TRIANGLE fully inserted. Is your robot behaving like this?
  • Now, introduce the 2x nuts inside the ARM BOTTOM sockets and fix this part with 2x 15mm bolts inserted from the top face of the arm
  • Lets do the same with the FOREARM, Insert 2 nuts into the socket and use 2x 40mm bolts to capture it.
  • The 2x 40mm bolts already inserted in the HUB piece
  • This is how the SCARA looks so far.

GRIPPER. Assembly guide

Follow this link to the Gripper assembly guide.

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.

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

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.

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.

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.
GET THE SCARA KIT

LINKS: