pic: Unobtainium 6wd - Cantilevered, Dead-Axle, Slot-Tensioned Drivetrain

[topgun]

Originally Posted by Joe Johnson

A lot that is cringe worthy as well, but overall, a nice effort.

For those of us that use the various drivetrain designs posted on CD as learning tools, what do you find cringe worthy? And why?

Thanks.

[Joe Johnson]

Originally Posted by topgun

For those of us that use the various drivetrain designs posted on CD as learning tools, what do you find cringe worthy? And why?

Thanks.

Let me start by saying that I am home sick today and probably should not have used the term cringe worthy. I really don't want to pick on the design. There is a lot to like.

Here is the thing. For those who have been doing this for a long time, design is an emotional experience.

I believe that we humans utilize our emotional brains to sort through complex space of possible solutions. Our emotional brains are just really good at searching through complex system interactions.

So... ...When I see something obviously awesome, I often laugh (I recall the first time I looked up in the GA Dome I laughed and laughed as I realized how cleverly the designers used hoop strength and tension members together with compression columns to raise the higher and higher tent poles over that beautifully clear interior). When I see something not so awesome, I feel it in my stomach.

So... ...what do I think is less than awesome in the design?

I think it boils down to two conflicting functions of the 1/4 angle. When I first see it, it seems both not strong enough and too strong at the same time.

It doesn't seem strong enough to be the sole mount for the cantilever axles. While at the same time the 80-20 and 1/4 angle seem pretty heavy for what they are doing.

The thing about emotional brains is that they can be wrong. We educate our emotional brains the best we can but they sometimes point us in the wrong direction.

I would have to do the calculations to know (and I haven't).

So... ...that is probably the numb of what I was getting at (that and the connection between them draws my eye as well).

Let me close by saying I was too harsh. There is a lot to like and a lot that I would change. But a very interesting effort.

Joe J.

[topgun]

Thank you Joe for your comments.

I agree with you about the 1/4" angle. I see teams driving down to thinner and thinner metals so to see something that thick makes me wonder.

Last year we accidentally ran our .090" 5052-H32 sheet metal frame into a cement column at full speed without bumpers. We ended up with a little ding on the flange, but the structural integrity remained. Made me think we could have gone to .080 or maybe even less.

I always like to know the tradeoffs on various drivetrain designs so I can help our students understand the tradeoffs and make decisions according to what we need.

I am also constantly looking for designs that use less precision machining because I see a lot of teams without that capability. That is one thing interesting about this design.