Asked — Edited

The Birth Of The XR-1 DIY Robot


The XR-1 robot platform at Robots Builder stands out for its user-friendly design, emphasizing accessibility and ease of assembly. Crafted with the idea of making robotics more approachable, the XR-1 has been meticulously engineered to be easily 3D printed and assembled using generic parts like servos and bearings.

User-inserted image

Our commitment to simplifying the building process meansthat enthusiasts and robot hobbyists of all skill levels can engage in constructing their own robot. We've invested time in perfecting the design, ensuring that users can swiftly move on to the exciting aspects of teaching and programming their robots. The XR-1 is highly customizable, featuring a variety of hands and heads to choose from, allowing users to personalize their creations. To foster a collaborative and open community, we're proud to announce that everything about the XR-1 is open source, inviting users to contribute, modify, and share their innovations with the global robotics community. Get ready to embark on a journey of creativity and exploration with the XR-1!

For more information checkout the following link:

As one of the creators of the XR-1 I will be leveraging SYNTHIAM ARC platform for robot control and I hope others here will also decide to join me on developing an ARC project to support an XR-1 robot.  As of today Jan 9th 2024 we have started to post files for the 3d printing, but at the same time we are still developing documentation and the above website so please check back.

My goal is to have a walking, talking, listening and seeing robot the size of a small child using ARC and it's many skills.

As I go down this path I will be posting more about my efforts here.

User-inserted image

I have started building the torso from the hips up as shown in the pictures below.  The shoulder are not fully installed because I am waiting on the correct screws to come in.  Please excuse the messy work bench.:p

User-inserted image

To support the robot I have designed a set of boards that will have ARC firmware loaded on them and connected to the onboard PC will sit in the middle of the chest.

User-inserted image

The above board will be mounted on the backplate between the two shoulder sockets and connected to the USB hub that will be connected to the PC.  Two more usb cables along with servo power will run down to the boards in each hand.   The USB camera and Head board will be connected to the PC's other two USB ports.  ARC will be running headless on the windows 11 Pro PC using RDP to connect to it from other devices.  There is also a MPU connected to the main board that I hope I will be able to leverage with ARC.

I have added the shoulders and arms down to the wrists and the arms seem to be  very strong and capable.

I decided I wanted to make a J5 type head for my build with two cameras in it.  The following is the completed head. I have added 6 more servos to my build for the eye flaps so now we are at 50 servos total. I have added a directional mic array along with an ultrasonic radar. For sound there are two speakers mounted in the head with an audio amp. 

User-inserted image

I have also decided to add an option to the XR1 to support a 5 touch display as seen below. 

User-inserted image

The display will provide more options for operator options using the ARC remote.

I have created both two and three finger claw grippers and also human type hands that can be used on the XR1.


Upgrade to ARC Pro

Join the ARC Pro community and gain access to a wealth of resources and support, ensuring your robot's success.


Pretty cool robot! How tall is it?


@Jeremie,  He is about 105cm or 42 inches tall I think he is currently 44DOF at this point depending what you do in the head it could be more.

The current design will have a very small but powerful Windows 11 Pro PC on board with USB hub connecting an Arduino Nano in the head and Nano in each hand and two Mega Pro's on the back for everything else.  It will also have other sensors.


Very cool. Great work.  I took a look at your BOM, I am glad you used hobby servos and gave links to AliExpress . Every time I go to build a project it’s just buy a dozen of  these $1500 dynamixal servos


Nice work smiller29


Anyway section by section part by part he is being uploaded, we should be at 80% by end of week less the head and hands only.

User-inserted image

The head is very close to being completed. The hands are going to take a bit longer as we are working to make a strong functional set of hands and with the child size they are smaller so it creates a challenge.  We have been working on many concepts but have not decided which one to use at this point.


We have added a link to SYNTHIAM on the website for a software solution for the XR-1 so I hope you get some added traffic to your site.


I am hopeful that the Arduino Mega Firmware is going to work on the Mega Pro Mini without having to change it.

My testing starts today I hope if I find issues I can get some help from DJ to fix things to support these boards because our project is depending on them.


Looks really exciting. Thanks for sharing. Good luck with the roll out.

#9   — Edited

User-inserted image

We have now posted all of the above XR1 parts on the site and the next section to be release is the lower arm and wrist once we have completed testing them.


Very cool! Looks like a fun project:D


Well DJ we need to get your team to build one.  So you can help make stuff for it.


We’d love to! Resources are thin right now as top priority is ARCx. It wouldn’t be until after March that there will be time to do it. By then you’ll be busy adding ARCx functionality to it. What a great robot though! Can’t wait to try it and promote it for you


Well I am looking forward to ARCx I think next month I need to do my subscription again.

It would be nice if you could create firmware ID’s for the Nano I currently am using the UNO firmware and it works but within ARC the image shows the UNO it would be nice if it could show a Nano.

Based on my testing the Mega firmware seems to be working on the Mega Pro Mini so it would also be nice if that had its own ID and picture within ARC.

Maybe this could be something for ARCx.


I see you have a telegram channel.  A lot of robotics folks hang out on Discord. Do you have a discord channel?  The photos and design docs are very professional and look great. Do you have a video of the XR1?


Not fully built.  I had a prototype version but that was not the same as this new design.  We have made many improvements based on testing.   We currently have about 10 people building this new design including myself.

So far the people have said things are going well and they are very happy with the design and fitment of the parts.  Once I get the rest of my stuff to complete the control pack and get ARC setup and start developing scripts we are not going to see any real animated videos.

We are making some videos of some of the joints and sections of the build.  I am sure we will end up posting them on the website at some point.

As far as discord goes we don’t at this point, but we have created a facebook group.  We can’t spread our self’s to thin right now but I am sure discord will happen at some point.


This is a update to let people know we have completed more parts of the XR1 for release.

User-inserted image


Thanks for sharing! I really appreciate a new open source bot out there.


hi averyone

smiller29 very cool design .


remember that the cheap servo's dont have a full range of 1 to 180 degree . its more like 1-5 to 175-180  degree .

#19   — Edited

We are in the process of releasing a new set of legs that will not require leg covers and have better support for cable management.

draft of the design

User-inserted image


Ooooooh that's awesome - i'm glad you're still working on it! Take your time getting the physical components and build to your satisfactory level and it'll be ready by the time ARCx is ready fingers crossed. I keep getting in trouble every time I mention ARCx haha. I know it's a million+ lines of code being re-written and it's a lot of work but I'm eager to get you all using it!


DJ I am depending on ARCx so my fingers are crossed your team continues to have success with it’s development.

We have made a lot of improvements on the XR1. We have also created a feedback main board for using four wire servos for position feedback.

I currently have 51 servos and a bunch of sensors in my build so I have a lot to control and I need ARCx for the job. xD