Monthly Archives: September 2021

New product: Surplus SpringRC SM-S4303R Continuous Rotation Servo Pair (Two Servos)

via Pololu Blog

SpringRC SM-S4303R Continuous Rotation Servo Pair.

We are now offering a two-pack of Surplus SpringRC SM-S4303R Continuous Rotation Servos. These servos are functionally identical to our stock SM-S4303R servos except for the direction of rotation, which is reversed. We are selling them in pairs to help differentiate them. See the product page for more details and specs.

Video: How to Assemble the 3pi+ 32U4 OLED Robot

via Pololu Blog

In case you missed it, the 3pi+ now comes with a graphical OLED display! Accordingly, we have released an updated version of the 3pi+ assembly video. This video walks you through the steps found in the assembly section of the 3pi+ 32U4 User’s Guide. While our user’s guides aim to be as thorough as possible, some things are a lot easier to understand when you actually see someone doing it (like soldering the leads to the motor tabs!), so we hope you find this video a useful addition to our 3pi+ documentation.

Is there something you would like to see in a future 3pi+ video? Let us know in the comments below!

Performance graphs for our 25D Metal Gearmotors

via Pololu Blog

We have published performance graphs (2MB pdf) for our 25D Metal Gearmotors! Each chart is based on hundreds of individual measurements that reveal how the speed, current, power, and efficiency of that particular gearmotor version depend on the applied load (i.e. torque). Our test methodology is the same as the one we used to make our Micro Metal Gearmotor performance graphs, so you can see our blog post about that for more information.

25D mm metal gearmotor undergoing dynamic performance testing.

These characterizations are yet another way we set our gearmotors apart from the many similar-looking alternatives out there. When you get your gearmotors from us, you know what kind of performance to expect, and you can count on consistency from batch to batch.

If you have any questions or feedback about these graphs or if there is additional information you would like to see available for our motors, please feel free to contact us (or just leave a comment below).

Performance summary table from 25D mm Metal Geamotor datasheet.

Curtis’s laser-cut arcade stick case

via Pololu Blog

Hello, I’m Curtis, an engineering intern at Pololu. I’m studying mechanical engineering at University of California, Irvine. I’ve been playing a lot of Tekken during the pandemic. In fighting games like Tekken a lot of people use arcade sticks to play. So, I wanted to build my own.

I built an arcade joystick case using acrylic parts (3mm and 6mm thickness) that I made with our Custom Laser Cutting Service as well as various M-F standoffs, F-F standoffs and screws and nuts.

I designed the case myself in Solidworks. I decided on a length and width of 8" × 14" because that makes it large enough to be comfortable, while being small enough to fit in a backpack and carry around. The positioning of the buttons and joystick is based on Hori arcade sticks, with some modification to fit my hands. The difficult part was figuring out how to mount all the components. I ended up layering the acrylic pieces to form the top and bottom plates. This let me mount components in between the layers, which hid screws and made the case look better. I was also able to cut holes to position vertical supports, like the front and back walls, to increase the case’s rigidity.

It’s designed to fit:

PCBs from Brook are popular for arcade sticks. They have low latency and are compatible with PC and consoles. Button and joystick choices are based on personal preference, similar to mechanical keyboard switches. Sanwa buttons are popular as well, and pretty standard in a lot of arcade cabinets, so I picked them because I’m used to them. I chose the IST joystick because the joystick tension is stiffer, which I prefer because it makes quick movements easier.

It can be a little tricky to put together. I didn’t realize that the joystick switches had tabs that extended beyond the sides of the joystick, so it couldn’t slide into the case. To get around this, the joystick just has to be taken apart and put back together inside the case.

Overall the case works really well. I was worried that the acrylic wouldn’t be stiff enough, but the case is rigid, and all the components fit.

You can download my CAD files (.DXF and .CDR) for the laser cut parts here (97k zip) to cut out the same case I designed, or as a starting point to design your own.