Axel Diameters

[Booger]

Hey guys, I need some help.

I need to find out the width (diameter) of a standard Robot axle.

The kind that go with these wheels:
http://www.ifirobotics.com/robot-traction-wheels.shtml

3/8" Bearing
or
1/2" Bearing
???


Thanks!

[Ben Piecuch]

As listed in the middle of that webpage, you can order either a 3/8" or 1/2" diameter bearing. Therefore, your shaft would be either 3/8" or 1/2".

There are many teams that utilize 3/8" shafts. There are equally as many teams that utilize 1/2" shafts. As a point of reference, the kit chassis is designed to work with 3/8" shafts (or bolts...)

BEN

[Booger]

thanks homie

[AndyB]

We use 3/8"

[M4 Sherman]

If you use Grade 8 bolts, 3/8" works fine.

[Billfred]

1293's used 3/8" threaded rod for two seasons with no complaints at all. (After some personal experience with my omnidrive project, however, I'd be inclined to make the switch to bolts.)

[Alex Cormier]

I prefer 1/2" shaft, it is smaller and saves that precious weight.

[Billfred]

Originally Posted by Alex Cormier

I prefer 1/2" shaft, it is smaller and saves that precious weight.

Isn't 3/8 less than 1/2?

[Alex Cormier]

Originally Posted by Billfred

Isn't 3/8 less than 1/2?

minor details.

[AndyB]

Originally Posted by Billfred

Isn't 3/8 less than 1/2?

Only in metric...

[Ken Streeter]

Originally Posted by M4 Sherman

If you use Grade 8 bolts, 3/8" works fine.

As another point of reference, 1519 used standard (grade 3) bolts on their 2005 robot for the non-drive wheels and had problems with the axles becoming bent. (We never did get around to switching the grade 3 bolts out for grade 8 bolts, primarily because we had added about 0.75" of thread by hand and didn't want to do that on grade 8 bolts!)

I would think that 3/8" grade 8 bolts would work fine for most FRC robot drive axles.

[Booger]

Originally Posted by Billfred

Isn't 3/8 less than 1/2?

hahhaha thats what i was thinking

[Raul]

If you use 3/8, make sure it is steel.
If you go to 1/2, you can use aluminum - this is our typical shaft size and material.

[ConKbot of Doom]

3/8" shaft must be supported on both sides, you can probably do without the extra support with 1/2". In 2005 we used 3/8" shaft with the skyway wheels, and slowly the axles bent upwards. They would be fine if it was just our robot driving around on the flat surface, but it had to content with other robots weight some of the times, and being leaned back onto 2 wheels for getting it up onto the cart, etc... Luckily, we just had to undo some bolts, take off some shaft-locks, and slide out the old axles, put new ones in, put wheel and shaft locks on, tension up the chain, and tighten the bolts back up.

[Gdeaver]

I highly recommend using 3/8" grade 8 bolts with the KOP frame and Skyway wheels.