pic: FRC558's modified VEXpro Drive in a Day

[jwfoss]

loading photo ...

Also you can read more about the robot on beyondinspection.org

[bkahl]

I'll be the first to attest that this drivetrain is a BEAST. For reasons I have yet to figure out, it could manhandle almost any bot on the field... Including 2 speeds.

[AllenGregoryIV]

Looks good, I like the purple.

Why did you opt for 3/8" solid bolts as dead axles instead of using 1/4"-20 bolts going through 1/2" tube axle?

[Knufire]

Originally Posted by AllenGregoryIV

Looks good, I like the purple.

Why did you opt for 3/8" solid bolts as dead axles instead of using 1/4"-20 bolts going through 1/2" tube axle?

The dead axle WCP Colson hubs are already bored out for 3/8" bearings.

[R.C.]

Originally Posted by Knufire

The dead axle WCP Colson hubs are already bored out for 3/8" bearings.

You can use the 1/2" I'D x 7/8" OD bearings as well. Allowing teams to use tube axle.

[Mike Marandola]

Originally Posted by AllenGregoryIV

Looks good, I like the purple.

Why did you opt for 3/8" solid bolts as dead axles instead of using 1/4"-20 bolts going through 1/2" tube axle?

Just curious, what is the benefit of that? To save weight? Smaller holes in the frame?

[BrendanB]

Originally Posted by bkahl

I'll be the first to attest that this drivetrain is a BEAST. For reasons I have yet to figure out, it could manhandle almost any bot on the field... Including 2 speeds.

Truth this setup was a beast.

[Chris is me]

Originally Posted by R.C.

You can use the 1/2" I'D x 7/8" OD bearings as well. Allowing teams to use tube axle.

I'm curious if anybody has run these for a season. My gut would think the smaller balls of these bearings would reduce their load carrying capacity to the point where I'd be concerned about an ill-timed bearing explosion. But I haven't tested it, run numbers, etc. so I'd love to hear some reports of teams having success with this setup.

[AllenGregoryIV]

Originally Posted by Mike Marandola

Just curious, what is the benefit of that? To save weight? Smaller holes in the frame?

The tube axle becomes a frame member and dramatically increases the rigidity of that chassis section. When using the 3/8" bolts you can't tighten the bolts since that would bend the frame. With the tube axle setup you preload the bolts to achieve greater chassis strength.

[AdamHeard]

Did you guys slit the colson wheels at all? Or run them stock?

[Ty Tremblay]

Originally Posted by AdamHeard

Did you guys slit the colson wheels at all? Or run them stock?

Not to steal any thunder, but they ran them stock. 228 is/was the biggest proponent for slitting Colson wheels and I think Art Dutra might have posted numbers somewhere.

Personally, I don't think the cost of implementation is worth the benefit of the added traction. Colsons are already up there in the traction world. They're just under blue nitrile if I remember correctly and slitting them still doesn't get them to nitrile's level. Their wear characteristics far outplay any wheel I've seen in FRC, though.

[Gregor]

Originally Posted by AllenGregoryIV

The tube axle becomes a frame member and dramatically increases the rigidity of that chassis section. When using the 3/8" bolts you can't tighten the bolts since that would bend the frame. With the tube axle setup you preload the bolts to achieve greater chassis strength.

If you were to use proper length spacers with the bolts, couldn't you tighten the bolt too?

[TD78]

Originally Posted by Gregor

If you were to use proper length spacers with the bolts, couldn't you tighten the bolt too?

In my past experience, if the bolts were tightened (to the point of them trying to act as a stiffener) with spacers, the spacers would interfere with the bearings and lock them up, making the dead axle wheel hard to rotate.

Ideally in this configuration, you would use standoffs around the axle to provide stiffness. That adds more parts, more weight, etc. Not hard to do, but you are limited to using the mounting holes provided by the DIAD, chain routing, etc.

Anyone have thoughts on using 3/8" steel rod as dead axles? Tap both ends of the axle and it'd be close to using tube axle/bolt. I wouldn't think a 1/4"-20 bolt would work...not enough thickness left in the rod. Something smaller like a #10 or #8...at which point you would have to drill all 4 holes in the DIAD sideplate, rather than using the pre-punched 1/4" hole for the outer wheels (of the 8wd)...but it could work.

[JesseK]

Originally Posted by TD78

Anyone have thoughts on using 3/8" steel rod as dead axles? Tap both ends of the axle and it'd be close to using tube axle/bolt. I wouldn't think a 1/4"-20 bolt would work...not enough thickness left in the rod. Something smaller like a #10 or #8...at which point you would have to drill all 4 holes in the DIAD sideplate, rather than using the pre-punched 1/4" hole for the outer wheels (of the 8wd)...but it could work.

We had great success with 1/4" steel rod that was put through a die on either end with locknuts in 2007. 2011-2012 we moved to 3/8" steel rod that was supported similarly. It was quite easy to machine - stick the die into a vice, stick the rod in a cordless 18V drill, use lots of tap magic and BAM 30 seconds later you have an axle. Just make sure the mount hole hits the solid rod and not the threads.

As for maintaining proper wheel alignment & spacing - I'd recommend any solid non-deforming material for standoffs. The dark-grey plastic from Andymark works great (it's why it's in the KOP, or was last time I used a KOP).

I agree that the axle itself should NOT be used to stiffen a frame. The only load you want on a wheel axle is normal to the floor so it rides correctly on the balls inside the bearing.

[TD78]

Originally Posted by JesseK

We had great success with 1/4" steel rod that was put through a die on either end with locknuts in 2007. 2011-2012 we moved to 3/8" steel rod that was supported similarly. It was quite easy to machine - stick the die into a vice, stick the rod in a cordless 18V drill, use lots of tap magic and BAM 30 seconds later you have an axle. Just make sure the mount hole hits the solid rod and not the threads.

I should clarify. I was not looking to form 3/8"-16 threads (or similar) using a die...I was thinking about drilling and tapping the ends of the steel rod (using a drill and tap). The rod would become a stiffening dead axle.