EEZYbotArm MK3

by daGHIZmo, published

EEZYbotArm MK3 by daGHIZmo Apr 19, 2018


Liked By

View All

Give a Shout Out

If you print this Thing and display it in public proudly give attribution by printing and displaying this tag.

Print Thing Tag

Thing Statistics

9924Views 1544Downloads Found in Robotics


This is a 3D printed robotic Arm.
It follows the success of my previous two designs: EEZYbotARM and EEZYbotARM Mk2

It has the same dimensions of the first one, so it is extremely cheap and fast to print only the main base requires a little bit more time to be printed.

This version was created with the willingness to replace the servo with economic stepper motors, and this is the result.
During development I found the stepper a little weak for the purpose, so I redesigned the transmissions on vertical arms, and apply a modification on stepper from unipolar to bipolar.

As the previous two arms it has been designed without a definite purpose, the aim is educational, providing a suitable hardware that allow to concentrate on exploring all its potential applications.

The making video: EEZYbotARM mk3 - The making
The preliminar tests video: EEZYbotARM MK3 tests

Print Settings

Printer Brand:




Doesn't Matter


Doesn't Matter






All pieces are designed to avoid supports and orientered correctly, so you can disable them. This decrease the printing time and avoid post printing finishing



As for previous designs I prefer to get all holes slightly tight. That to adjust the holes diameter using an exact drill bit allowing to recover any kind of possible misalignements and also to use non metric screws.


Here following the list of parts necessary to built the MK3 robotic arm.
You need some 3D prinded parts and some commercial items.


Q.ty Description P/N
1 Vertical Arm EBA3_001
1 Horizontal Arm EBA3_002
1 Main Base EBA3_003
1 Swivel Base EBA3_004
2 Straight Arm Link EBA3_005
1 Angled Arm Link EBA3_006
1 Vertical Axis Driven Gear EBA3_007
1 Rear Cover EBA3_008
1 Vertical Axis Drive Gear EBA3_009
1 Geared Arm EBA3_010
2 Transmission Gear EBA3_011
1 Gripper Link EBA3_012
1 Triangular Link EBA3_013
1 Geared Joint EBA3_014
1 Finger Pin EBA3_015
1 Left Finger EBA3_016
1 Right Finger EBA3_017
2 Parallel Key EBA3_018

EBA3_010 has two versions : one with 604 bearing, one without, your choice.

Q.ty Description SIZE
3 Stepper Motor 28BYJ-48
1 Servo SG90
2 Radial Bearing 606
1 Radial Bearing 604

I used metric hardware and all joints rotate on M4 or M3 screws.
Q.ty Description SIZE Note
1 Button Head Screw Flanged M4 x 25 ISO 7380-2
1 Button Head Screw Flanged M4 x 20 ISO 7380-2
1 Button Head Screw Flanged M4 x 22 ISO 7380-2
2 Button Head Screw Flanged M4 x 20 ISO 7380-2
2 Hex Socket Head Cap Screw M3 x 08 ISO 4762 UNI 5931 DIN 912
5 Hex Socket Head Cap Screw M3 x 10 ISO 4762 UNI 5931 DIN 912
2 Hex Socket Head Cap Screw M3 x 12 ISO 4762 UNI 5931 DIN 912
2 Hex Socket Head Cap Screw M3 x 14 ISO 4762 UNI 5931 DIN 912
1 Hex Socket Head Cap Screw M3 x 20 ISO 4762 UNI 5931 DIN 912
1 Hex Socket Head Cap Screw M4 x 18 ISO 4762 UNI 5931 DIN 912
3 Cilindrical Head Screw M 1,6 X 6 UNI 6107-67
1 Cilindrical Head Screw M 4 x 35 UNI 6107-67
1 Hex Head Screw M6 x 45
3 Self Tapping Screw 1,5 x 8
11 Hex Nut M3 UNI 7473
1 Hex Nut M6 UNI 7473 - UNI EN 28673
1 Self Locking Nut M3 UNI7473 - DIN982
7 Self Locking Nut M4 UNI7473 - DIN982
11 Washer M3 ISO 7089 UNI 6592 DIN 125-A
11 Washer M4 ISO 7089 UNI 6592 DIN 125-A
1 Washer M6 ISO 7089 UNI 6592 DIN 125-A


Assembly tips

On screws are to be used selflocking nuts. They are to be tightened till the locking of the joint, then consequently you have to loose them until you obtain a smooth movement with the lower clearance between components. On the two axis of the main vertical.arm I used M4 threaded rods

An important thing is that you have to made the conversion from unipolar 5wires 28BYJ-48 stepper motor to bipolar 4wires to increase the torque output. There are several tutorials on the web how to make it.

At this time I do not had time to make available an assembly instruction, I'll try to make one available soon.

As for the previous issues, there are several ways to drive the arm. It depends on what kind of results you want to obtain.
Mainly depends if you want to freely move it or make it repeat a loop.
At this time I do not have developed a software I've only made movements test using different hardware like CNC shield or easy driver.
Remember that after the modification of stepper you cannot use ULN2300 drivers

Final Notes

This is a non commercial license.
I do not earn money on making it. I spend money and time (that for me is the greatest wealth) so please do not sell it without permission, and if you share provide attribution.

This encourage me to to develop more things like this.

Carlo Franciscone
have a look at www.eezyrobots.it

happy roboting !

More from Robotics

view more

All Apps

Auto-magically prepare your 3D models for 3D printing. A cloud based 3D models Preparing and Healing solution for 3D Printing, MakePrintable provides features for model repairing, wall thickness...

App Info Launch App

Kiri:Moto is an integrated cloud-based slicer and tool-path generator for 3D Printing, CAM / CNC and Laser cutting. *** 3D printing mode provides model slicing and GCode output using built-in...

App Info Launch App
KiriMoto Thing App

With 3D Slash, you can edit 3d models like a stonecutter. A unique interface: as fun as a building game! The perfect tool for non-designers and children to create in 3D.

App Info Launch App

This is such a cool design. Congratulations! I'm not that much into code, so I would like to ask something. Is there a way of programming the arm, so that you can command movements to the tip of the tool (gripper) instead to the individual motors? To achieve linear a precise movements on the gripper.

Kind regards!

Hi eezy,

this is VEEEEERY interesting and I really wanna make this.

Can I ask u some tips? I have a prusa I3 proB similar to yours and I prefer to use PLA. Is PLA in the making video?
I have problems in areas as in the EBA_003 that is the basement. Because I saw in the video that u didn't use supports but if I do that, it don't print well.. I obtain a surface irregular and deformed. I print too much fast?? (80 mm/s. With bed T=60° and the extruder T is 200°)

Can you give me some tips with your parameters?? I use REPETIER-HOST with CuraEngine.

Thank you and NICE WORK!!!!


good job.
I have all your robot, MK1, MK2 and now MK3.
Its a great job, for student, because have a low cost and in places as Africa, student can use it.
I finish to mount this MK3, but have only one problem with servo movement. How move pin.
Can you upload a photo of this mecanical part.? Where you use piece "EBA3_015"?


This is mny first time trying to make a robotic arm. Just a quick question. Parts 10 and 14, do I have to drill a hole all the way through them? I mean it looks like they have to be attached to the main arm (EBA3_001). I am assuming I get a long screw and it goes through 10, 14, 1, and 4?

I also would like some clarification on this. Any pics or explanation? Thanks.

Did you solve the Problem? I'm also interested to know how to assemble parts 10 and 14

your design models are very amazing
Thank you for sharing them.


I print out the parts of the aperture is wrong, I want to get the source of this document, so that I can better modify the aperture,I am looking forward to getting your help。My Email is [email protected]

I love your design, I printed a MK1 for my 3 & 5yr old last Christmas. I'm loving the use of these steppers too!

My only disfavor for the design is I see the bolts as largely unecessary. on my christmas build I used some old nails and hotglue. My thought is, a 5-8mm D-shaped printed cylinder, layed flat when printing, is plenty strong for these light-weight designs, and printing plastic is way cheaper than a box of various metric hardware. So... would you be willing to put out a design with larger holes and these D-shaped cylinders? Specifically a D-shaped cylinder with a D-shaped head, and tight fit washer shaped press on "nuts". I also have a quite small, printed side laying, threaded bolt/nut print that you might find better than the D-shape cylinder idea... I'll try and post a thing of both of these in the next few days.

Comments deleted.

Nice update! Cool.

It's design looks really pretty and refined

thanks you for this amazing design,
thanks for sharing.

Finally! I have been waiting for the release for a few months now :))
Now to get making it.
What do you think about using a nodemcu for the microcontroller and using it untethered, via the blynk app or something like that?
I'll post if I manage to get it working as described.
Thanks again! You rock!