Custom wheel hubs with ball bearings and metal U-joints

[Krzychups]

Hi everyone!

I'd like to show you my idea for custom wheel hubs with metal U-joints and ball bearings. These hubs are designed for 12 mm hex rc wheels (I can change to 17 mm if needed), they're not compatible with LEGO Technic wheels. The great thing about it is that it won't come off, and there are lots more tyre and rim options. My idea was to create wheel hubs with ball bearings and metal U-joints to prevent issues like broken U-joints and wheels falling off. They're based on the wheel hubs which @Daniel-99 has. I haven't finished them yet, but I hope they'll live up to my expectations!

So far, I've made these versions. While I was writing this post I realised that my front wheel hub for live axle suspenion has a design problem. But it looks similar to Daniel's ones.

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Image from Daniel's bricksafe.

Rear wheel hub:

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There are two versions:

Needed parts:

• 18 mm lenght 2 mm diameter rod,
• metal U-joint with 2 mm hole (2 versions are available on the market, you can use one of them),
• ball bearing (21x15x4 mm),
• M5 nut and washer,
• M5 threaded rod with drilled 2 mm hole,
• 3D printed parts to attach it to LEGO Technic bricks.

This is the hardest part to do. You need to drill M5 thread in U-joint and 2 mm hole. If all goes well, I will get the parts made on CNC (I have an acquaintance with one person). 

I recommend to print wheel hubs using 0,2 mm diameter nozzle. I'll use nylon, I am curious to see how PLA+ would work out. I've ordered Garolite G10 sheet, so finally I can avoid problems with first layer adhesion!

I want to make another front wheel hub, also modelled on Daniel's ones. It has 0,5 stud kingpin inclination, is it useful?

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Image from Daniel's bricksafe.

I've also ordered HSP 02038 parts, I can use them replacing LEGO ball joint pins.

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What do you think about this? Let me know!

[Ryokeen]

@Krzychups Nice done there, looking forward to it.

Side note. I have those HSP parts here, they do fit, but are a bit higher than Lego pins, means the ballcup won't be exactly one stud above like with lego towball pins

And they do hold, but not as much as lego parts, so you need to connec the lower and upper arms, which can be a problem as they might be 1/4 stud more apart than they should be

Edited December 14, 2024 by Ryokeen

[Aurorasaurus]

This looks super promising. I've also been working on this topic, only trying to connect lego wheels instead of rc wheels. Funnily, I'm also using a 21mm OD 15mm ID 4mm bearing! But I have put my project down for a bit, so I'm glad someone else is doing it too. Cant wait to see how this turns out.

[Krzychups]

9 hours ago, Ryokeen said:

And they do hold, but not as much as lego parts, so you need to connec the lower and upper arms, which can be a problem as they might be 1/4 stud more apart than they should be

Yes, I know about this. I can make corrections in 3D models. I can't use it everywhere, but it'll work in some places. 

9 hours ago, Aurorasaurus said:

I've also been working on this topic, only trying to connect lego wheels instead of rc wheels.

Can you share your project with us?

Edited December 14, 2024 by Krzychups

[Aurorasaurus]

17 minutes ago, Krzychups said:

Can you share your project with us?

Sure thing:
 

Front wheel hub:

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Rear wheel hub:

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Actual photos:

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And finally, a video of a prototype working:

I originally made these out of PETG, attached metal U joints with a hole drilled in one side with glue and a cut up screw, and glued both pieces to either side of the bearing. PETG turns out to be a terrible material for this application, so it broke. The newer ones were from PLA, but I kinda gave up half way through because the brushless motor is just too much power for the lego differentials. I ordered diffs from zene, so I'll pick the wheel hub project up again in a month when those arrive.

STL files are on bricksafe: https://bricksafe.com/pages/Aurorasaurus/brushless/wheel-hubs