pic: West coast drive design

[Hawiian Cadder]

Originally Posted by AdamHeard

Crushing from impact (and to a lesser extent parallelogramming) are really a result of poor design in this era of mandatory bumpers.

We've never crushed in our 1/16" wall with some brutal impacts while using bumpers. Without bumpers, the exposed corners often get smashed badly, but just the corner and it's purely a cosmetic issue. If we ran without bumpers, we'd beef it up. However, we know we're using bumpers and take advantage of it.

I was thinking more about the bearing for the middle wheel and gearbox.
if you are using flange bearings (which you have to with walls that thing) and take a hard side hit, have you ever had problems with the flange punching into the tube wall?

adding a bearing block, with holes rather than slots, could help to minimize the risk of this happening.

[42!]

Originally Posted by Hawiian Cadder

I was thinking more about the bearing for the middle wheel and gearbox.
if you are using flange bearings (which you have to with walls that thing) and take a hard side hit, have you ever had problems with the flange punching into the tube wall?

adding a bearing block, with holes rather than slots, could help to minimize the risk of this happening.

Excellent point, I hadn't considered that. And yes the bearing are flanged 1/2 inch hex bearings from Andymark, on a different note the gearboxes as they are shown in this have no protective covering around the gears, I've seen a couple teams do this (notably 254) and it saves some weight on the gearbox, Does anyone know any of the advantages or disadvantages this has?

[Chris is me]

Can we not make claims about robot strength or material thickness based purely on guesswork please? Seriously, if you have no experience with the material, there's no shame in just not posting.

[AdamHeard]

Originally Posted by Chris is me

Can we not make claims about robot strength or material thickness based purely on guesswork please? Seriously, if you have no experience with the material, there's no shame in just not posting.

He's got a valid point, it just took him a few posts to get around to it.

Yes, we avoid 1/16" wall on our rails for drive that have bearing blocks, etc...

We're pretty sure it'd work, but for a base that's already around 30 lbs with motors, we take the few extra pounds that just two rails of 1/8" represent.

[Hawiian Cadder]

Originally Posted by AdamHeard

He's got a valid point, it just took him a few posts to get around to it.

Yes, we avoid 1/16" wall on our rails for drive that have bearing blocks, etc...

We're pretty sure it'd work, but for a base that's already around 30 lbs with motors, we take the few extra pounds that just two rails of 1/8" represent.

I was never suggesting making the cross-members 1/8, but 1/16 tends to bend around where you attach other stuff to it that will experience a lot of force. My fault, I should be more clear.

Originally Posted by Chris is me

Can we not make claims about robot strength or material thickness based purely on guesswork please? Seriously, if you have no experience with the material, there's no shame in just not posting.

If I don't have experience with what is being discussed in a thread I don't post anything. We used 1/16 and 1/8 tube this year on various parts of our robot, and the 1/8 turned out to be overkill on the members that did not have axles or the tower bolted on. In the members with axles or the tower bolts, we should have used more washers to prevent the tubes bending. The 1/16 was about perfect where we used it.