r/robotics • u/ArnauAguilar • 1d ago

Mechanical Custom made 3d printed BLDC motor with internal cycloidal actuator V0.1

Enable HLS to view with audio, or disable this notification

For the past months I've been working on my own BLDC motors for a future robotics project. The motor is 3.8cm(1.5 in) deep and has a 9.4cm(3.7in) diameter. All parts except bearings are 3d printed! I coiled the stator myself, the motor has 43 turns per slot with 36 slots wound with single enameled wire of .4mm. The rotor has 40 poles arranged in a hallback array. My tests estimate the motor (wothout the actuator) to be about 20kv and make about 3Nmeters of force, but I'm building a better testing setup to get better numbers. The actuator in the center of the stator is a cycloidal reducer with 2 disks to counter each other's vibrant. It has a reduction of 1/7 while fitting inside the stator!

There is lots of work to be done still, but I'm very happy with my progress. I'm now working on it's cooling system and taking better measurements, I'll update as soon as I have more info!

Any suggestions are welcomed I'm not an engineer at all and I'm learning along the way.

66 Upvotes

100% Upvoted

9 comments sorted by

2

u/adibhat007 Industry 10h ago

This is awesome! I just built an actuator as well (for exactly the same reasons). But I went the planetary route. What winding pattern did you use for the stator?

2

u/ArnauAguilar 3h ago

I'm using this for my winding calculations. In a Y configuration. https://www.bavaria-direct.co.za/scheme/calculator/

Nice, how are the gears holding up? Are they 3d printed? I went cycloidal because I was worried planetary would wear out because of the few contact points between gears.

1

u/adibhat007 Industry 2h ago edited 2h ago

Ah, nice. I am using delta windings (used motorcad to simulate). I actually went ahead and bought gears from KHK. I thought that might be a better choice than 3d printing (mostly for friction heat and longevity). Dealing with grease was a bit messy, but so far, I’m happy. I guess your actuator is more compact as it fits entirely within the motor. I like that!

2

u/ToThePetercopter 3h ago

What material did you use for the printed parts?

1

u/ArnauAguilar 3h ago

For now, it's just cheap sunlu PLA. I'll choose more premium materials based on thermals, I guess, since strength has been good enough while prototyping

2

u/ToThePetercopter 3h ago

plastic gears are often nylon because its low friction so could be an option for some of the parts, bit more challenging to print though

2

u/young-money4L 19h ago

why did you choose to make instead of buy it?? also, how much did parts cost?

6

u/ArnauAguilar 12h ago

Hi! It's still not finished, so I'm not entirely sure about the cost, but the stator was like 28€, bearings amount to another 30, and plastic and copper are veeery cheap. I don't think I can find any motor of these specs for anything close to that price.

But honestly, it was not only cost, If I use commercial, the actuator needs to go attached to the output asking the thing a lot bulkier. I want to build a quadrupled robot, that means at least 3 motors per leg with 4 legs. I need them to be as cheap and as small as possible.

Lastly, the biggest reason is that i find it cool as hell, hahahaha. I'm so impressed by being able to buy raw inert materials and building something that moves, and i can interface from a computer 🤯🤯🤯

4

u/lego_batman 19h ago

Don't think you can buy one with an internal cycloidal at this stage.