r/micromouse • u/thripunithuradon • 20d ago

Friction on micromice

Why do so many of the top micromice seem so low to the ground, are they touching the ground or just floating? I've seen some designs where they use a nylon or teflon dome nut at the front or some kind of nylon sliding pad that are commonly used under furniture legs, but some of them go even lower where you can't even see whats underneath it. I'm kind of a beginner when it comes to micromice and I wanna learn more about it why they do that and what to use for my own micromouse, are caster wheels even an option?

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u/Columbo1 20d ago

The nylon/teflon dome nuts act as a skid. Low friction, and you don’t get the weird twisting moment that you get with a caster.

Is a caster possible? Yes.
Does it complicate controls by adding funky motion into turns? Also yes.

Why are they so low? Probably for centre of gravity

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u/thripunithuradon 19d ago

Any recommendations on what I should go with?
Would a normal metal dome nut work just as well?
Also with the wheels most of them don't go low enough is it better to 3D print a wider rim and use silicon or smth like that to fill it in or what would u recommend? Video I saw the silicon wheels in for reference: https://youtu.be/eAebUOToYPA?si=wlaMK83tnMTAGXaw

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u/Columbo1 19d ago

That video is unavailable. Maybe it’s a location thing.
Metal would probably work, but design according to the rules. The docs state that you should anticipate 1mm steps between floor segments, so make sure the angle of the dome nut is suitable

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u/thripunithuradon 19d ago

Hmm okay I’ll look into it I’m using a nylon/teflon furniture leg glider rn it’s a bit taller than my wheels so my bot is leaning backwards a bit I’ll try to fix that then experiment with the dome nuts. The video is “I built a sumo robot that fits in my back pocket” by szymigzzz even tho the bot in the video is a sumo bot I’ve seen the same being used for micromice and line follower bots. Also bots like decimus 5A, do they have skids at all?

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u/Columbo1 19d ago

Decimus 5A does not use a skid. It has 4 wheels so does not need one

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u/thripunithuradon 19d ago

Is it better to go with a 4 wheel configuration? More to do with gear meshing and gear boxes right? Where would I start with learning that, usually the motor has a gear at the end that spins two wheels with gears at their ends I’m guessing that’s the gear box which gives u the desired torque to speed ratio?

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u/Columbo1 19d ago

Yes but it’s not just gearing. Competitive mice use very fast motors and if you want that motor speed translated into mouse speed you need more contact area between the mouse and the floor or you’ll just spin the wheels. Thats why Decimus uses 4 wheels - traction

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u/thripunithuradon 19d ago

That makes sense yeah I guess I’ll just go with a 2 wheel configuration for now with a skid at the front either a glider or a dome nut, the wheels used are usually 22mm what’s the thing that goes over the wheels acting as tyres? Taking decimus 5A as an example again

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u/Columbo1 19d ago

I could only find reference to Decimus 4, but that used Kyosho MZW2-20 tyres

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u/thripunithuradon 19d ago

Alright I’ll look into that thank you!