Prevent drive train axles from sanding out aluminum holes?

I have had problems in the past where the drive train axles wear down the aluminum 2 wide C-bar (with bearing flats) on our drive train over time. I was using 2 C-bars on both sides of the base with bearing flats, everywhere the axle contacts metal. Wherever the axle went through the metal it expanded the square hole after a lot of use.
I am curious how you all prevent this from happening.
Thanks!
Past version robot base pictures:
Old_Robot_Base Old_Robot_Base2

well, if you’re using bearings this really shouldn’t happen that much. Maybe send us a picture of your drive so we can see if there’s any clear reason this happens?

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Making sure your bearings are properly aligned can help prevent this.

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Make sure that your bearings are tight. I had this happen on a flywheel once, but it really should not be happening on a drive.

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Yes, check bearings. My guess is that vibrations from your chassis shake the nuts loose a little and then the bearings pop out of their alignment tabs.

You can solve that problem by simply tightening the screws more, maintaining their tightness by checking them periodically, using nylocks, or using loctite. Nylocks are, in my opinion, the easiest solution.

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What’s the front rubber band contration for?

Grab a drill and drill out larger holes for the metal in every hole an axle goes through. I do this every time and I would suggest doing this instead of constantly worrying about the extra maintnence of making sure metal on metal rub doesn’t happen.

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But would’t that no longer allow screws to be inserted into the hole?

I guess that it an intake of some sorts.

If you mean by upon a rebuild you wont be able to place a screw through that hole because its too large? Yes, but the chances of you using that hole is so slim, plus its a worthy investment if it means that your drivetrain can consistently travel in a straight line.

Good idea - thanks for the tip!

This happens when a bearing comes loose. I had this happen to my drive because the flywheel produced small vibrations and over time ended up loosening the motor directly underneath it (which was mounted on a bearing). The result was that the torque exerted from the motor would push the axle up and down and ware down the metal holding it in place which “sanded” out the aluminum holes.

The solution I came up with was to use nylocks on the motor screws as they would secure the screws in place firmly. The motor would no longer be able to come loose and in turn, the holes would not have a torque force from the motor applied against them. Good build quality in general should be practiced, don’t take short cuts and make sure everything is firmly held down. This will help you avoid problems like this way down the line.

Also, try loctite.

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Yep, it was part of our intake last year.

Could you expand on this - i’m struggling to picture it

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I usually use locktite screws and tighten the heck out of a screw with a torx driver, but I did notice that the V5 motors are extremely frail and I found that the golden screw threading breaks and even the plastic housing itself can break too. That is a really smart idea!

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so I’m picturing you have screw, metal, nylock, then motor correct? doesn’t think mean that the motor can no longer nest into the holes?

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Yes. My setup was sort of like this: motor - screw with nylock - flat bearing- c channel - screw head. The screw head and nylock would sandwich the metal (note you need to leave wiggle room between the nylock and c - channel so that you can thread the screw through the motor, then you tighten the nylock all the way).

but, then doesn’t the motor not stay perfectly oriented on the c channel, without the ends of the motor mounts nesting in any holes? also could the nylock pressing against the fragile thread bits that stick out of the motor mounts damage them?

You need to put the motor screws through a flat bearing to get perfect alignment. The screws would go through the bearing. Note, the bearings themselves have notches to perfectly align with the holes in the aluminum. If the screws are tightened as much as possible, then in turn, the motor will be perfectly aligned.

As for the nylock pressing against the thread bits, this might happen but it might happen with any flat surface in general. If anything, the rubber on the nylock might protect the frail bits.

I think the frail pieces are made out of brass, meaning that the screw itself is likely to damage it more than the surface it rests against because the material screws are made out of are a harder material than the brass bits. This is problematic because the screw is constantly being threaded up and against the brass. Just my take though.

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oh ok that makes sense.
Yes I despise the fragility of the motor threads. I’ve already partially broken 4 threads just from screwing into them.