Posted on June 16, 2023 by admin
Over the past week I built a lil 1lb melty for a low-key local plastic ant competition. I have tried several times before to build melty brain robots, but never had the greatest luck. Now armed with many more years of breaking stuff robot experience, it was time to try again. I’ve always found the biggest problem with melty brain robots to be keeping the rapidly spinning robot synchronized to the rest of the world. Most melty brains have used an IMU sensing centrifugal acceleration to calculate velocity, and then integrated velocity to get position. This works ok, but because
Posted on November 4, 2022 by admin
For the past few years I have been building motor controllers with generally good success. In the past year, for the first time I have delved into making custom motors as well. For the project mentioned in this article, I used the laminations from an air conditioner, but for my latest motor (the 250lb RIPperoni motor, to be discussed in a future blog post) I designed a fully custom rotor in FEMM, and had the resulting lamination/magnet combo manufactured overseas. This is a lot of effort, but the performance achievable is far superior to anything else on the market. A
Posted on January 23, 2022 by admin
Ain’t nuthin better than getting a hunk o’ junk on Ebay and turning it on, and even better: making it do something useful. The original plan for the Big Dyno was to use a Prius inductor– based buck converter. However, the good ole Prius inductor proved just barely not quite up for the task, with a saturation current of around 175A. Practically, this means it is only good for about 150A of boosting, and I was really hoping for the full 200A (although I will use that quite rarely, it is a nice-to-have for sure). I was able to find
Posted on December 16, 2021 by admin
Big life update: I bought a camera. I’ve wanted to buy a nice DSLR for literally 5 years or so, but only now with some side consulting could I justify shelling out the cash. Turns out, my great grandfather was a professional photographer. So, camera time… I knew I would be using this camera for product photography on a near-daily basis, so I decided to go for a nice camera right off the block rather than putzing around with an APS-C with the plan to upgrade. All of my friends have Nikon’s so I chose to stick with them so
Posted on December 15, 2021 by admin
The good ole’ 2nd gen Prius boost inductor. Extra large, extra cheap. I was unable to find a measurement of the saturation current of this inductor on the internet, so I set out to measure it myself. This inductor is one of the beefiest I’ve ever set my eyes upon, at about 400uH, and I estimated it had a saturation current somewhere between 150 and 200 amps. I measured the line-to-line resistance at 19 milliohms. At 150 amps, this equates to over 400W of resistive losses alone. I plan on using this inductor for the big dyno, where it will
Posted on December 9, 2021 by admin
The land of motor ratings is pretty dubious. All too often, people say, “yes, this motor has a stall torque of 11.8 Nm and a no-load speed of 16krpm- therefore this motor produces TWENTY THOUSAND WATTS.” Alright then… But did you actually measure that? How do we even measure power of a motor in the first place? What even is power? Let’s get into the physics… An electric motor is a device which converts electrical power into mechanical power, usually through a magnetic field. The same device is also a generator, when the flow of power is reversed and the
Posted on October 31, 2021 by admin
The successor to the small dyno: the big dyno. This dyno should be good for around 30 Nm continuous up to 8-10K RPM, and then around 20-30kW from there. It is a lot of dyno.. should be excellent. This size of dyno was inspired by Ben and Bayley’s big dyno. Finding myself in need of a more powerful dyno to test ever larger motors, it was time to build my own. Here is the CAD as it stands. The dyno is largely based around an altermotter paired with an HBM 100Nm 20,000 RPM digital output torque sensor. Interestingly enough, the
Posted on October 9, 2021 by admin
Over the past four years, automotive hybrid air conditioners have been a wonderful source for rotors and stators. All the automotive components are automotive quality, yet purchasable at junkyard prices. So far, all the air conditioners we’ve dissasembled have been of the IPM variety. We’re not exactly sure why, but we believe this is because the magnets can be straight instead of curved, reducing magnet costs. Additionally, the rotor can be constructed using less magnet per unit torque, again reducing cost. Either way, IPMs are cool, so let’s get started. So far, I’ve disassembled four different air conditioner units, all
Posted on December 2, 2020 by admin
Today I laid out a board in record time: 2.5 hours! And, its even a motor drive! However, I did cheat a bit and use a daughter board. My work was throwing out several DRV8305 evaluation boards, which are more or less the same as the lovely DRV8323RS TI motor driver we’ve all come to love. The “throwing out several” part is important, because if I blow up the power stage, I can simply swap my daughter board with minimal effort.. The evaluation board in question: My daughter board design: At the heart of the design is the new STM32G431
Posted on November 30, 2020 by admin
Not much in this post, but its definitely worth mentioning if any readers care to make dollys for their machine tools. A core tenet of the austinshop final plan is to have the surface grinder on wheels such that it can be wheeled outside to use, to protect the shop from being covered in grinding dust. To do this I need some way of wheeling it. And the surface grinder isn’t light, so it needs to be extremely strong. I started with the door bits because they are nice, strong wood about the right size (read later post to see
