Open Source Robotic Arm (Lite Arm i2)

by Armatec, published

Open Source Robotic Arm (Lite Arm i2) by Armatec Oct 12, 2014
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57885Views 15214Downloads Found in Robotics


Dave Beck is making serious progress:
Update January 2nd, 2015
Changes are as follows:
We are working on the forward and inverse kinematics, and had to make changes to part 13B, 15B, and 18B, they are all followed by a "C" instead of "B" to note that a change has been made. The changes make the lengths precise to make perfect alignment in the geometry of the linkages. We will be adding the files for the electronics and software very soon. I archived the files from 2014 so the changes we make to the STL's moving forward will not erase the work from the past, so you can note the progression or access the early files for whatever reason.
We have a great team working on the development of this arm, and we hope to make this a very useful and dynamic tool in 2015!

UPDATE 12.21.14

Added 14B_and_17B 2.1.stl (a cleaner part)

Replaced 14B and 17B with:
14B_and_17B 2.0.stl due to unstable files

Replaced 8B with 8B2.0 There was a discrepancy in part symmetry in association with part 7B.

"Lite Arm Iteration 2" is a further improved iteration of the first project:

Special Thanks to contributors to this project!
My local team:
Robert Cordtz -R&D (Bay Area California)
Chris Beck -R&D (Bay Area California)
Emmanuel Mota -R&D (Bay Area California)
Myself- Lance Pierson -Structural Design & Chief Agitator (Bay Area California)

My Online Contributors: (on Thingiverse)
David Beck /Dacb -Electronics and Software (Pacific Northwest)
Billie Jamerson /Reichenstein7 -Structural Design & Media (DC Metro)

Thank you to everyone else I did not mention!

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First of all, thats an awesome project! I actually made one for a uni-project in my product design class :-)
I am wondering, does anyone maybe have CAD-Files of the assembled robot? If yes, would you mind to share them here?
Thanks tons!

Aug 8, 2016 - Modified Aug 8, 2016

I have inverse and forward kinematics working in Robot Overlord. The developer version has a dedicated instance of uArm. I need the critical dimensions to adjust the size of my simulation so that it matches the real thing. I hope from there it's not too challenging for someone to add joystick support.

Edit: Added! https://hackaday.io/project/12971-robot-overlord/log/43439-added-uarm-support-aka-how-to-add-your-3-axis-arm-to-robot-overlord

Hi! Has anyone tried installing Marlin on it? ;)

Try a plastic screw driver when you adjust the pot. You likely are inducing noise in the circuit with a metal one.


This is a great project, thanks for sharing ;)

i am going to buy servo's and accessories for the project,
but i found that the recommended servo,
Power HD 1501MG RC Metal Geared with 3 wire,
and the one used for uarm shield v.1.1 with 4 wires

The 4 wire version have analog position feedback,
can you recommend a servo with analog feedback?
I can only find one servo in this size with analog feedback,
from adafruit but this one only have plastic gear


;) michael

Is it possible to get the models in the format used by the design program you used? I would like to try adjusting this to use metric fasteners.

I think that this is the Arduino for Robotics, whit the idea of a open-source robot, every one can build his own robots and improve it!
So congratulation for your idea!
I have to buy servos for this project from Amazon or Arduiner; can you help me for the choise of the correct one?
Awesome job guys!

Hey, from what I've seen most of these arms have a maximum reach of around 34cm. I need an arm that has around 50cm reach; would it be possible for someone to come up with a way to extend the reach of the arm without limiting it's functionality? Any help would be much appreciated.

is there a metric partslist available? :)

This comment has been deleted.

Armatec, thanks for the project I have had a heap of fun printing and building it over the past month.
I have recently discovered Blynk for arduino, and have attached Ethernet shield to mine, to control the arm via dual twin axis joysticks.
Still assembling the arm, but have tested the arduino and it works great with Blynk.

Will update you with the code (realistically mid November), some videos and I will add some photos to the made section.

Kick ass!

Awesome design! I was wondering if its possible to get the parametric models if their available so that I can modify it to use nema 17 steppers?

Sorry I don't have parametric models, looks like you just volunteered to make them :) I hope

Well done! impressive Sketchup work! thanks for sharing

Glad you appreciate it!

Thank you! I'm glad you opened the file, a lot of work went into it. Now it belongs to everyone :)

I have a new, more in depth guide for assembly up if you would like to add it to the description under "Thing Info". " http://www.ebay.com/gds/Assembly-of-3D-Printed-uArm-for-Arduino-KIT-/10000000205623447/g.html "

I still have a couple of kits for sale, along with a new purple version here:
" http://stores.ebay.com/Cipher-Computer-and-Robotics/Robotics-/_i.html?_fsub=18137687018 "

Has anyone tried implementing it in Marlin? As it can answer the movement gcodes, the only task to do would be wiring it to a ramps and change the movement routines to the ones in its firmware
If anyone is interested (I suppose that @Armatec will be) we could work together :D
@Armatec, congrats, it seems to be awesome, next week will print it :D

Hi! That sounds fantastic! I am a poor programmer. I am working on developing my skills further, but this project needs to move forward and not be delayed by my timeline. If you could get this to work on the ramps set up I will find the resources to compensate you for your work! We need software to catch up. I have a lot of add ons and mods for the hardware side but it's useless without the intelligent interface


I am using up plus 3d printer. It seems that there are some parts that are out of the printing area.
do I have to scale it down all the parts or just the big parts that not fit with the 3d printer or do you have any other version that fit.

Thank you.

Sorry, the print is designed for a 200 x 200 mm build platform. I guess up plus is only 140 x 140 mm. The design could be modified for the large pieces to be printed in halves, then they could be glued together. I don't want to take the time to do that, but the sketchup file is there for you to modify as you see fit.

I have a 150 x 150 mm build plate, and can confirm that 14b_and_17b_2.1 is the only file you need to split... due to it's construction you can split them in different parts of the arm, and it still maintains the rigidity as both joined together.

Hello, firts of all i want to inform you that i am a beginner. These 3d models are pretty good but i dont have 3d printer. My question is: are u able to make the same 2d model (for example in pdf) that i can attach it on plywood and cut out?

Best wishes

Download the files from the below link

Uarm plans

Simple answer, no.
I suggest you download a free version of google sketchup and take the measurements you need to cut this out from within that program. Or look for uarm PDF on google, almost identical design for 6mm plywood lazer cut parts

This comment has been deleted.
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I'm a student from Vietnam. I am looking for a model of robot for final thesis. I have read more time about UArm of Ufactory Team. But I have waited a long time. I'm so impatient to wait their Source Code.
I'm very happy when I see your robot. I want to say thank to you and your partners.
I hope your model can help me in final thesis. Thank again

Happy to hear that, hope it helps!

Build instructions?

Here is the best we have so far, this instruction does not have the bearings

Mar 7, 2015 - Modified Mar 7, 2015
prittstift - in reply to Armatec

You may want to rework the page a bit. Too many images on one page takes forever to load and it will be interesting to see what happens to your webserver when you get featured by an internet "news" outlet ....

Cool arm!

EDIT: Ohh your images are uncompressed on preview as well .... that is ~2MB per image ...... nuts.

Mar 8, 2015 - Modified Mar 8, 2015
Armatec - in reply to prittstift

That is Reichensteins website
I have not released build instructions yet. I am swamped with my new startup so I won't be able to add to this project for another 3-4 months. We will be releasing a new model at that time that uses steppers

I appreciate your input!

i'm having trouble in the calibration sketch of the uarm. Its having an error in compiling but the other sketches work.

Not familiar with the uarm software/hardware

I'm starting a build of your arm and just wanted to say thanks for all the work you have done.

Your very welcome! It's a group effort I really have to give props to all those involved and those who inspired the project like uFactory for making the uArm and not responding to my emails which caused me to design the Lite Arm in the first place LOL! no hard feelings to those guys. I really want to thank Dave Beck for all the work on our control electronics development.
You can join the discussion or get updates on the progression of the arm here:

Lance Pierson-

Hey I really like your design! But why is the 13C part fixed at the main body? With another servo, the end of the arm might be movabel too.

Good observation, that would be a perfect mod for a digger/shovel attachment someone else requested. I did not add that initially to keep it simple for the kinematics

Alright but it would be awesome if you would consider it in you future iterations! Wouldn't it also be better to use stepper motors instead of servos? Thinking of more accuracy and torque?

Steppers will be used in the next model to be released in a year or so, our main focus now is on getting the control worked out for this configuration. I always appreciate people adding ideas, it makes the project better.

Thanks for putting this set together! One thing that would be really helpful would be a dimensioned drawing, at least of one or two of the key pieces (e.g. 21), to help confirm that when importing the STL into various software, the scaling is correct. Or just some key figures, like the length between the pivot points on part 21, might be equally useful. Thanks!

Added image, its the third one in the photo gallery. Let me know if this helps.

Nice work, on the new pieces. They are printing now!

Dec 22, 2014 - Modified Dec 22, 2014

Thanks for the new design pieces. We were just about to finish assembly and saw them in time!

Edit: are there any grippers on thingiverse that are compatible with the arm?

If anyone is interested I have started posting assembly examples in the "I made one" section. I am going to step-by-step with the next one out of the printer.

That's Awesome Reichenstein7!
Looking forward to seeing that progress

Picture assembly manual
Suggested parts list
Other resources and etc.

(Formatting works out better).

I would like to sell a modified version of this i2 version online, maybe do a limited run.

Check out the modifications under the "made" section and tell me what you think.

Thanks for the great work!

I've been working on firmware for the i2 assuming I was going to use G-code to do control. Recently, I'm not sure that's a great idea. Before I go too far with it, I'm curious to know what others are using or thinking would be an optimal control interface.

dacb - in reply to dacb

I finished the hardware design for my control electronics, which you can find here: https://github.com/beckdac/uArm-MicroView-esp8266

The idea is to use the super cheap ebay'able adjustable LM2596 regulator boards to provide 5v and 3v3 to the servos and the MCUs, respectively. The board accommodates 5 servos (L, R, Rot, Hand Rot, Hand Actuator). The servo timing is handled by the MicroView (an Arduino with an OLED in a single 16 pin package). The MicroView uses the VarSpeedServo library to provide smooth servo motion and the OLED display uses five 0 to 180 linear widgets to show the current destination positions in degrees. Communications is handled by an ESP8266 WiFi highly integrated board also ebay'able for about $5 US. The ESP-01 board provides serial passthrough, station and AP modes and (at the moment) a HTTPd for configuration and sending movement commands. Both the MicroView and the ESP8266 are firmware upgradable on the board using the ubiquitous FTDI ft232r 3v3 cable.

I milled out a PCB and tested it. Works great. Firmware is being posted in a separate GitHub repo. I'm still torn regarding what should be sent to the client, e.g. GCODE vs. direct commands. The ESP8266 has plenty of CPU power left over to be a GCODE parser and translator from linear to radial motion, I'm just not sure if GCODE is really the most usable input.

Armatec - in reply to dacb

Dacb! You are awesome!
Keep up the good work, you are inspiring me!
As far as Gcode interpreter go with your gut instinct on how you think it is best controlled/ instructed. Let me know if you need anything from me.
Those LM2596 modules are awesome I own 4 and just bought 3 more last night for my ddwrt drone routers .

dacb - in reply to Armatec


Look at the ESP-01 modules too for your projects. So far, I can't say enough good things about them for IoT stuff. The -03 and up modules have lots more pins for GPIO and PWM (3).

The MicroView has unused pins in this configuration. They could be used as home switches or to drive PWM for a vacuum pump, etc. I'll think more about what would be useful.

I just posted the box to mount the PCB to the uARM: http://www.thingiverse.com/thing:584136

One thing that remains for me to figure out on my arm itself is how the L/R axis assembles. In my hands, they don't move smoothly. I'm thinking about drilling out the center holes in the servo horn like pieces that don't actually mount to the servo horn and then putting bearings in there with an M5 screw keeping them centered but allowing them to rotate freely while preserving a single center axle. I don't know if that word picture made any sense.

LiteArm / uArm control electronics box for MicroView + ESP8266 (ESP-01) board
by dacb
Dec 9, 2014 - Modified Dec 9, 2014
dacb - in reply to Armatec

This is fantastic! You've nailed it. This is exactly what I was trying to accomplish with the bearings and hardware. Thank you!

Here is the firmware github (WiP): https://github.com/beckdac/uArm

It supports the following GCODE like commands, FXXX (like feed rate = servo speed), G0 (rapid move, no speed control), G1 (speed control) + WX (where X is wait for command completion) and a list of possible servos to move and M commands with addresses that reset the MicroView, print available space between heap and stack and M112 (emergency stop).

Edit: it seems markdown doesn't work in thingiverse.com comments?

Armatec - in reply to dacb

Guess not, it would be a nice addition. This is awesome! Do you have any video??
I really appreciate your contribution to this project! Maybe you can send me an email with your name and number and I will give you the credit you deserve.
[email protected]

I also need to publish a proper instruction manual.

Done! Finally. Here is the make:

I've put some videos up on youtube showing super simple operation. Thank you so much for a terrific design.

Now... to implement inverse kinematics on the host.

Open Source Robotic Arm (Lite Arm i2)
by dacb


Did you use all of the same fasteners listed in the uarm assembly instructions (http://www.ufactory.cc/downloads/documents/uArm_Assembly_Instructions_v1.2.3.pdf) ? If not what fasteners would you recommend that work best when assembling the i2? Thanks.

For the base yes, the upper parts use a bolt through the printed spacer with nuts on either end, same bearings but everywhere there is a bearing on the uarm we have two facing each other, an instruction on the assembly and parts list is long overdue and will be complete by Jan 2015


I got one more parts question. What size servos are needed to fit in parts 6, 7, and 8. The uarm parts list lists 2 types of servos. A 9g servo and another servo which is not labeled. I can't figure out what the other servo is.

Power HD 1501 MG Servos

(MG stands for Metal gear)

Not exactly, we are working on a g code interpreter with multiple end effectors for CNC tooling

I know the i2 is supposed to be easier to build and cost less so I thought I'd throw in my $.02. My robotics club is building a pick and place bot, but we are incredibly limited as to being able to buy parts, but there is no limit on 3D printed stuff. We actually 3D printed the main bearing assembly using this scad bearing: http://www.thingiverse.com/thing:40559. We also printed spacers and bumpers in place of standoffs.

Here's a short video of the operation: https://www.youtube.com/watch?v=0e-DPaNfR2U The movements will eventually be pre-programmed, but this is just in simple joystick mode (using a VEX cortex and RobotC.) The effector end will be an electromagnet when we get to that point, probably in another week or so.

It's a little bit wobbly, but the only parts we had to buy were the #6 nuts and bolts (we were supplied 3 futuba servos, and used the standard horns.

Parametric ball bearings
by holgero

Where is the like button? :)

Hey, I was printing the i1 model parts for eBay. Do you care if I do the same for this version?

Only if you sell me the first one.
I have been too busy to print it myself, and your printer is calibrated nicely :)

Ha. No problem. Looks like I won't get around to it for at least a few weeks. I'll let you know.

Oct 12, 2014 - Modified Oct 12, 2014

i2 is more stable, less wobble and flexing.

2 days ago
Armatec -(originally) in reply to dacb
New parts are everything above the bearing assembly, i2 base is the same as you have, 2, 3, 4 is the same 5 is a little tighter around the bearing, but is compatible, everything else is thicker, and 6 has to be wider to accommodate. We will be resin casting based on moulds of the printed i2 parts, and a video is in the works so you can see our team and get an idea of who we are.

so what is the main difference to i1? i am now printing i1 can i reuse some parts ?

Have a look at the image set... nearly twice as thick plates and fewer small standoffs required (replaced by spacers).