Brake system

retired1
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Re: Brake system

Postby retired1 » October 18th, 2017, 2:11 pm

Stainless or brass threaded rod are normally of better quality than the big box store galvanized all thread. A fair quality tap and die set can clean up that rod very nicely and the tap portion can smooth out the wing nut. They do not have to be expensive. Harbor freight will work quite nicely and you can find a 25% discount coupon in several places. You can get cheap ones in either SAE or in metric. They also sell a combination set, but it will be a bit more.
Give it to the school when you graduate as it will be useful for years to future teams.
I went light on this years prototype and used 4 mm stainless. The problem with that was finding APPROPRIATE gears. 1/8 or 6 mm or 8 mm would have been a lot simpler.
Hard to beat the efficiency of the wing nut set up fo a low cost unit.

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Re: Brake system

Postby shrewdPanther46 » October 24th, 2017, 7:36 am

How do you guys attach the gear to the threaded rod? Do you sand the rod down in one spot?

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Re: Brake system

Postby antoine_ego » October 24th, 2017, 8:38 am

How do you guys attach the gear to the threaded rod? Do you sand the rod down in one spot?
For consistency, I'd recommend you buy some shaft mounted gears, such as some from Servocity. These utilize a set screw, so you don't have to deal with sanding down the rod to attach it more easily. Make sure you buy gears with the bore diameter you want (usually the width of the threaded rod including threads works fine), and gears with the same pitch to ensure good grip.
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Re: Brake system

Postby cheese » October 24th, 2017, 8:14 pm

My gear is fits almost snug around the threaded rod, so I just sandwich it between some nuts and the crowned portion of the nut centers the gear,
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shrewdPanther46
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Re: Brake system

Postby shrewdPanther46 » October 30th, 2017, 10:44 am

just curious, if anyone is willing to share:

Has anyone tried the rubber band wingnut braking system (when you stretch a rubber band across the wingnut parallel to the drive axle to reduce skid)? Does anyone know any other ways to reduce skid?

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Re: Brake system

Postby rajofin » December 13th, 2017, 1:49 pm

Our motor does not move without giving power to it and the way we built our buggy, wing nut isn't free to move backwards without rotating wheels. Can we have another set of batteries that we could use to move the motor in reverse (essentially making wingnut move backwards)? Will it be allowed or not at the competition. Hope I made my question clear, let me know if it is not.

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Re: Brake system

Postby shrewdPanther46 » December 13th, 2017, 2:04 pm

Our motor does not move without giving power to it and the way we built our buggy, wing nut isn't free to move backwards without rotating wheels. Can we have another set of batteries that we could use to move the motor in reverse (essentially making wingnut move backwards)? Will it be allowed or not at the competition. Hope I made my question clear, let me know if it is not.
Not sure what you mean when you say "without giving power to it"...

I think I understand what you are asking. I would think that would be allowed (my partner and I are also considering this because rotating the wheels slowly can be painful). I think its just a tool and either way, its not really part of the buggy itself, so I see no reason as to why it would not be allowed.

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Re: Brake system

Postby rajofin » December 13th, 2017, 4:07 pm

Thank you for your response. Just to explain myself, I thought the motor shaft would be free to rotate by hand but it does not. It does not move until current is passed through it. So to move the wheels backward, shaft needs to move which does not happen until we move the motor shaft backwards with another set of batteries.

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Re: Brake system

Postby shrewdPanther46 » December 13th, 2017, 4:23 pm

Thank you for your response. Just to explain myself, I thought the motor shaft would be free to rotate by hand but it does not. It does not move until current is passed through it. So to move the wheels backward, shaft needs to move which does not happen until we move the motor shaft backwards with another set of batteries.
Now I'm curious as to what kind of motor you are using. As far as I know, I thought DC motors are all "free to rotate by hand", and in fact, act as DC generators when turned (they produce a current across the armature of the motor). Unless if you are leaving some sort of load after disconnecting power from your motor, there is no reason for a dc motor to resist change from being turned. Could you please explain to me how your circuit is set up:? ? I've never seen anything like that, so I'm super curious as to what motor you are using/how your circuit is set up.

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Re: Brake system

Postby Almandine » December 17th, 2017, 7:53 pm

The braking system that I like to use is a Soft Gamma Repeater 1806-20. It works very well, and causes almost no skidding.
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