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Lite Arm_Open Source Robotic Arm (i1)

by Armatec Jul 31, 2014
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what I need for screws and how much

please answer here

Here's a modified lite arm in action at our latest robotics competition:

Cool! You really shold upgrade to iteration 2 we solved the wobble problem that you see in the video, but very cool!

How big is it and What's the biggest can you make it cause i will love to have one

10" tall x 18" long in the 3d image. it fully extends to 7 1/2" tall x 20" long
The size is determined by the actuators, in this case hobby servos, in future cases, much bigger servos, steppers or industrial actuators. We will make a full size industrial robot completely open sourced, time is the main obstacle, that and money. We plan to use crowd funding to take it to the next level, which will pay for the hardware and further software development.


Did you use all of the same fasteners listed in the uarm assembly instructions ( ? If not what fasteners would you recommend that work best when assembling? Thanks.

I made a package of files that we made so we would have to buy less things to make the arm: All it took was a quick trip to home depot for nuts and bolts (we had the servos).

Buy less stuff package for Lite Arm i1
by taitrt

Cool! Airsoft BB's I assume?
I like the initiative, you may need to tighten up the tolerances to reduce the wobble. i2 is all about reducing wobble, the parts are more than twice as thick.
Good on ya!

I just updated the package with a fully printed bearing assembly including both mounting pieces and all of the screw holes. Printed it today and it works amazingly. I decided it was lazy of me to be so bad at openSCAD so I watched some tutorials and made the part perfect.

I included the .scad file if you want to modify it and include it with your i2 version.

Cool! Thank you for contributing to the project. I'll have to check it out

Actually, no BB's. The balls print captive inside of the bearing, no assembly required. Pretty amazing actually. If I was better in openScad I probably would have been able to put in the screw holes, but I'm not, so we just printed 100% infill and drilled them.

Where are the various bushing supposed to go? Are those instead of buying standoffs?

Are you talking about i1 or i2?

anyone have a arduino code or software to control the arm with movement record?

Could you tell me what material you used to print these parts in the 3D printer? I'm really interested in this model, and I want to try to do it. Btw, I'm doing a research project, can I show this design? Obviously I will say who has designed this model.

And yes of course it's open source, do whatever you like with it
Credit for the design is appreciated, also know that it was inspired in part by the uArm project.
Lance Pierson

it is not clear order of part from first - most complicated joint (two servos) what is inside as shaft ? is there any ballbearings ? or some kind of shaft ? (what about wear-out parts ?) and what is between them ? can u post more photos of first joint ? near two servos ?
parts here is different from original


I'll post a video tomorrow 15 hrs from now

oh i am glad

The shaft is 1/4" aluminum tubing found at ACE Hardware in the US. I was way too busy today to make the video. Tomorrow...
Crappy video I'm sorry , I only had 5 minutes of free time.

Could you tell me which servos did you use?

Check the files for "eBay parts list"
Here is a link:

Servos bearings etc. all there

3-Power HD 1501 MG servos

I've been sketching out an atmega328 firmware that speaks GCode for this thing. Is anyone else interested or are most people focused on using the uArm codes?

Let me know how I can help, we need Gcode firmware ABSOLUTELY!!!!
I want to attach an extruder

Thinking some kind of Bowden extruder?

GCode would be awesome.

That is something I would definitely be interested in.

Lite Arm Iteration 2 will be released this Friday!!!

That's great! Of course, I'm halfway through building an i1 w/ i2 base and ring with my 7 year old. Maybe we'll hold off and see what parts we should reprint.

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. One of our guys works for Make Magazine, so you will be hearing a lot more about this project as time goes on :)

Hi how can i put together part with big ballbearing ?
ring around ballbearing is not precise to lock ballbearing it is a gap close to 1 mm

Here you go:
i2 Base with outer bearing ring modified.
ID=47.2mm for a 47mm OD bearing
0.2mm of wiggle room rather than 1.0mm

thank you i repaint this ring with holes in openscad and now i can modify everything ;)

Happy to help!

I'll send you a replacement STL for outer ring tomorrow morning, in 12 hours or so from now. I have not experienced this problem, I will look into it and solve the issue ASAP.

I can confirm that I found the original ring too loose but the replacement was too tight. I ended up filing down the inside of the ring to get a good fit.

I'm curious to know, mirecta, what length screws you used. I had 25mm which were too short and 35mm which were too long. I suspect that 30mm would be perfect.

Hi guys, there is much work still to be done to get this project where I want it to be, or for it to meet its potential. The issue is I have started a company in another field and we are 14 days in the new warehouse, so I am going to be focused on getting that company up and running until I can hire the right person to give me a day or two off so I can release Iteration 2 of this Arm.
I check my email often and I will always make time to answer your emails so don't be afraid to hit me up!


Can you provide any more info on the number and length of M4 screws are needed?

Same as uarm, here is the assembly guide:

Thanks. I see M2 and M3 in those instructions and I assumed from the ebay it was only M4. All the other non-printed parts are incoming. I'm really looking forward to doing some development of the firmware and adding some limit switches for calibration. Nice work, btw!

Edit: I know you are busy, but I wanted to ask what you did for a flange shaft sleeve?

Could not find what the hell that was I just skipped it. In i2 we will just use 2 bearings as the parts are thicker/more stable.

Thanks! I'm happy that people appreciate the work that went into this :) I'm looking forward to see where this goes.

Hi Armatc! Nice job! I want ask you about the firmware: which firmware you use for move it? I want try it, can youpost it or send me by mail?

The hardware was the easy part. I can't seem to find the uArm shield online yet so using the uArm Arduino code is out for now.
I am learning Arduino, and will start a topic in their forum for code that can generate coordinated X,Y,Z movements for use in 3D printing Gcode, maybe I can use pronterface with it.
So far this is all I got sorry: (note this forum uses code so some details are missing below)
// Testing for Lite Arm Project


Servo servobase;
Servo servoshoulder;
Servo servoforearm;

void setup() {
servobase.attach(9, 1000, 2000); // Set servo to digital pin 9, min, max
servoshoulder.attach(10, 1000, 2000); // Set servo to digital pin 10, min, max
servoforearm.attach(11, 1000, 2000); // Set servo to digital pin 11, min, max

void loop() { // Loop through motion tests
home1(); //go to start pos
delay(1000); // Wait 1000 milliseconds (1 seconds)


void home1() {


void pos1() { //pen to paper


void pos2() { //move forward (draw line)


void pos3() { //move forward (draw line)


Lite Arm_Open Source Robotic Arm (i1)
by Armatec

Hi, I saw that you wanted some help printing parts for these. I put up an ebay auction for the printed parts only.

Let me know if there is a problem. This is some great work!

I sent my friend David your way!

The only thing I would add is don't bother printing #1, it is replaced by "i2 base" which is wider and easier to mount to a table.
Kick ass! Thank you!
It's awesome seeing something you designed printed by someone on the other side of the country, got to love thingiverse for making a place for this!

Ok - I will update the item and only include the i2 base version.

That's great that you made this. I was going to try and make a uArm clone as well. I am going to try and make one of these in the near future!

Have you given any consideration into using stepper motors instead of servos? I was thinking about doing this with me, for greater precision/repeatability.

Absolutely, before I saw uArm I was working on the idea of stepper control for an arm, especially for use in CNC and 3D printing applications. Probably a Nema 17 motor.

Yup I agree, same stepper I was looking at. I would love to rework this for the stepper but I'm a CAD newbie. Might just make the servo version first since you've gotten that all set up here ready to go.

I am hoping to get started on this next week or so!

Cool! I'll see what I can do in the next few months to make a conversion kit for the Nema 17's

@chipheap420 Happy to hear you are printing one BTW! Send me an image:

Actually I am having a problem printing. Its very strange. The problem is in slicing. The resulting gcode looks fine in viewers, but the actual print's height is way off. A 10mm thick part is coming out only a few mm thick. the head is staying at the surface of the print. Its as if the whole thing has been resized in the z axis only. and its only these stl files. other things as well as my own stl files generated from freecad and openscad all print fine with no special concideration when generating the stl. Im baffled. every attempt has resulted in the same thing, parts are perfectr in x/y axis and a couple mm tall.

Which part btw?

just a couple I tried.

I have it narrowed down to some wierdness with my instance on slic3r installed. Nothing has changed on my software so I am at a loss. When I load it up in mattercontrol and use the slic3r that is built in and load the same ini I failed with I get a good print. Can print the parts now but still trying to find the issue with the standalone installations of slic3r.

That is strange, Maybe try Slic3r. I know three people have printed this arm with no problems. Sorry to hear that. Keep me posted.

can we get a part count for each print item? IE how many of each to print? Im waiting on the hardware and want to get the parts printing.

If you look at he images above the 10th one in when you scroll left to right is an exploded diagram, each part has a number, same number as the STL files. Just use that as your guide. Im printing my third arm this weekend and that what I use to guide me. I suggest you use the i2 base its a better design, it replaces part #1. I labeled the parts beginning at the base and worked my way up. I hope this answers your question. I'll be available if you have any further questions. I plan to make a YouTube assembly video soon.

hey, just curious, what's that clear tube connected to your tool head on the printer?

The tube is for an air pump that helps keep the cold end of the extruder cool, I don't like using a fan because it cools the print bed too.

Thx and nice work! Looking forward to building one.

Your welcome!
I have been working on this project for a loooong time. It feels great to finally release iteration 1. My wife is over this project, so she will be happy too haha!

don't see the source files

Oops! I forgot to add them, they are there now. 2 SKP files:
"LiteArmParts7302014.skp" & "Model_LiteArm_i1.skp"