Thor – Another nice 3D Printed Robotic Arm

thor has attracted another nice robotic arm project to it’s site.  This is arm is a very nice, open source design that makes clever use of a differential to combine 2 degrees of motion into a single joint.  I also appreciate that he was good enough to go through the inverse kinematic model that defines this arm.  Inverse kinematics is a mathmatical method to figure out arm angles required for the end effector (the gripper in this case) to be in a certain location.  More at this link

Security Enhancements to

I have added some long overdue security enhancements to  First is that the site now supports HTTPS, for those that dont know, this provides for the authentication and encryption of the packets that travel between your browser and our servers to prevent an observer in the middle from seeing your traffic.  For those who are curious, I am using a free certificate from Let’s Encrypt.   Second is that I have added a security question for new sign-ins is likely most cannot be answered without research. While I expect this second one to slow down adoption of this community, ultimately I think those who do choose to sign up will see less spam and enjoy the community more.  If you have any questions, please put them in the comments below.

First Robot Arm

Hi There,

I am here because I just began my journey into robotic arms recently. Although I have a bit of a long history with robotics, specifically last year april 2015 I designed an arm. I dont know much about programming or electronics, but I do know a bit about cad and fabrication.


So this year, on march 2016 I was finally able to afford the cost of waterjet cutting some of the parts as well as buying most of the components I needed. Im not yet ready to start programming since I am still missing about half the arm.

In any case, Id like to start discussing several topics related to my project. Specifically, my main objective is to install a cutting/milling tool on the end of the arm to cut through at least 1/4″ thick aluminum.

One friend of mine commented that in machining there are alot of vibrations and thus the robot arm wont handle it too well. Since Im just starting out I think first I need to finish the arm, then learn to program it, then learn to interface it with cam software, then start cutting, and lastly start improving it.

So yeah, thats my first question, what should I do about programming the arm ?

I have arduino on my laptop, have an uno board with a grbl shield, and 4 steppers. Any advice ?


2DoF Arm Motion

It has been a little while since I have made any progress, but with the summer’s vacations and other activities out of the way, I have a chance to buckle down and get some stuff done.  This is actually the first time I have gotten motion with the arm with the new electronics.  All seems to be working fine, except for a few issues with multistepper (Arduino Library).  Next is getting the pen going.

Note – you will notice the steppers are making a bit too much noise, I just haven’t set them up properly, that will change soon.

2 DoF arm end effector.

The 2 degree of freedom arm end effector is nearly complete.  Here it is controlling a pen up/down motion.  The current design depends on gravity to bring the pen down which is probably ideal for felt tip pens and the like.   It uses a micro servo to drive the pen upward.  The design is 3D Printed and the files will be uploaded to Github shortly.  More coming soon…


YARRM 7 DoF arm from the Hackaday prize

Screen Shot 2016-05-10 at 9.22.12 PM

In the Hackaday Prize competition on, there has been a lot of robotics activity.  This is a pretty clever arm designed to be a 7 DoF (degrees of freedom) arm.  What I appreciate about this arm is that the designer, Jonathan Lussier, used steppers and belts at the shoulder and upper arm and used servos at the extremities.  Assuming he is using cheaper servos, this would provide low cost, high strength to weight fine motion while the coarse motion could be done accurately with the heavy steppers embedded in the base.  The goal of the arm is to be less than $500.  Link here

Open Source Robot Arm Community