So now we’ve got everything back in stock once again!
Welcome to the newest mjbots.com product, the mj5208:
This is a high quality 5208 sized 330Kv wound brushless motor with short pigtails intended to connect to moteus controllers. All the moteus devkits as of last week are shipping using this motor instead of the previous “semi-random” motor.
- Peak torque: 1.7 Nm
- Mass (with wires): 193g
- Peak power: 600W
- Kv: 330
- Dimensions: 63x25mm
There are two bolt patterns on the output, a 3x M3 17mm diameter one, and a 2x M3 pattern spaced at 12mm. The stator side has a 4x M3 pattern spaced at 25mm radially and a 3x M2.5 spaced at 32mm. The axle protrudes a few mm from the stator, making it easy to adhere the diametric magnets needed for moteus.
The moteus controller is capable of a lot of instantaneous power. However, to fully make use of that power, you’ll need to keep the mosfets cool on the board. moteus has two mechanisms for that:
- A heatsink can be mounted to the bottom side of the PCB between the board and the motor. This is most useful when integrated into a servo motor, and the servo housing can be used as a heatsink.
- Mounted to the top of the board, attaching to the MOSFETS directly.
In addition to the MOSFETs, the gate driver chip, the DRV8323 can produce large amounts of heat, especially when the controller is run at a higher voltage, like the 44V that the moteus r4.5 supports.
Getting the heat out of all those irregularly spaced components on the top can be tricky, thus mjbots.com now has the moteus heat spreader:
This precision machined and stylish black anodized aluminum piece fits over the top of the PCB and mounts flush against both the MOSFETs and the DRV8323 to ensure optimal heat dissipation from all components. It can be used as-is, or with an additional heat sink fixed to the flat upper surface.
Don’t hesitate to ask any questions in the mjbots discord!
In the spirit of “most of your users are yet to come”, I’ve gone through a moderate re-organization of some of the mjbots github repositories to make them more usable and sensible.
The biggest change is that mjbots/moteus has had a history rewrite and a directory structure re-organization. The current development (and default branch) is now “main”. The biggest changes:
- Proprietary pdfs have been removed
- All hardware which isn’t related to the moteus PCB has been removed
- The firmware source has moved from “
moteus/” to “
- The client side utilities
tviewhave moved to the “
- There is now a “
lib/” directory which houses client side libraries
Second, mjbots/power_dist is a new public repository that houses the power_dist board firmware and software.
Third, the hardware and software for the quad A1 is now located at mjbots/quad. This repository is rewritten to remove all things that are not quad related, and also to remove proprietary pdfs.
If you have questions about where things are, don’t hesitate to ask in the mjbots discord!
In my quest to create a more dynamic quadruped, I’ve started accumulating a lot of parts from bulk buys that could be reasonably useful to other hobbyists and experimenters. To maybe make life easier for everyone, I’ve started up what may be the worlds ugliest online shop where you can buy some of these components. For now, I have some bearings and custom gears that are useful when building servos for dynamic robots.
Check it out! https://shop.mjbots.com
Unfortunately US shipping only for now, email me or DM on discord to arrange something internationally.
Some samples of what I have online now:
M0.5 100 Tooth Steel Ring Gear
M0.5 20 Tooth Sun Gear
6708-2RS ABEC-1 Bearing 40x50x6mm
Over the last couple of months, I’ve had an increasing number of people looking for help with self-built moteus controllers which is great! However, until today there hasn’t been a great way to get help. Blog comments fall off the front page quickly, and there is no real other mechanism.
Thus, I’ve created a discord server:
There you can chat about the moteus controller, servo, or the quada0 and get feedback and help in closer to real time. Thanks for collaborating!