31-07-2014 12:56

M. Mellott

Re: pic: Ultralight Spoked Wheel

It would be doable if the the spokes were solid, but I don't see how you could machine the pockets of the X's into the spokes, no matter what kind of machining resources you had.

Nice render though...

31-07-2014 13:04

RKazmer

Re: pic: Ultralight Spoked Wheel

3D printing the part might work for the 8-spoke. Not sure about the 12.

31-07-2014 13:09

Lil' Lavery

Re: pic: Ultralight Spoked Wheel

They could be cast, potentially. Making the mold would still be a challenge.

31-07-2014 13:13

magnets

Re: pic: Ultralight Spoked Wheel

Under what conditions did you perform FEA? Wheel "strength" can be measured in different ways.

You can measure how much weight it can hold. For an aluminum wheel like this, that's not going to be a problem for just carrying around a robot.

You will have to worry about shock loading, as a rocking/tipping robot can come crashing down quickly. If the wheel is used for a long time fatigue can come into play too.

You could also measure how much torque it can withstand before either the hex strips out or the spokes snap off.

You also have to worry about what happens if you suddenly run the wheel into a wall at high speeds getting pushed by a robot. If there's a step in the field (like in 04), you can really destroy a wheel this way.

There also the issue of side loads. Imagine holding the wheel's axle still, the pushing on the rim on the wheel, parallel to the shaft, to try to rotate the wheel on an axis that isn't its axis of rotation.

As for machining, you could either 3d print aluminum with laser sintering (extremely expensive) or you could manufacture each of the spoke plates and weld it into place.

I agree, it's not practical (a VersaWheel weighs less), but it is a cool looking part.

On the topic of cool wheels, 118's 2012 wheel was very cool looking too.

31-07-2014 13:24

AdamHeard

Re: pic: Ultralight Spoked Wheel

Andymark designs their wheels to be heavier because they need to be robust. They need to account for teams doing odd and out of spec things with them.

Assuming this is nominally a 4x1" wheel, this isn't an un-achievable weight with traditional machining methods.

Our 4x1" wheels we ran on "Black Knight" (Downloadable in sig) were about .25 lbs and could've been pocketed more. I know 254 runs wheels in this ballpark or lighter.

31-07-2014 15:13

JamesCH95

Re: pic: Ultralight Spoked Wheel

Pics of FEA tests or ban!

31-07-2014 18:25

evanperryg

Re: pic: Ultralight Spoked Wheel

The goal really wasn't for this thing to be "logical" or "practical," It was an idea that popped into my mind, largely inspired by spoked car wheels. They might never see competition, but they certainly would be a cool demonstration of what a multi-axis mill (or whatever else you could use to make these) is capable of.

31-07-2014 18:38

kevincrispie

Re: pic: Ultralight Spoked Wheel

As far as I know, these wheels aren't make from a multi-axis mill. From the Truespoke website, where the picture you linked is from, it seems as if these particular wheels are put together by hand. The spokes, rim, and hub would all be separate parts. Regardless, these wheels are excellent craftsmanship and it can certainly be a good CAD project to create a design inspired off of these.

I am curious about the cost evaluation on the part. When you say that the 8 spoke design is significantly cheaper, did you get somebody to do an evaluation, or is this your own estimate?

19-08-2014 14:21

ToddF

Re: pic: Ultralight Spoked Wheel

Hmmm. Looks a lot like this one. Impractical for conventional machining techniques. Great for 3D printing. Mine has the spokes arranged more in the classic spoked wheel pattern, which relies on spokes in tension for torsional rigidity. The design in the OP relies strictly on the bending stiffness of the spokes for torsional strength.



Note that this one has the same internal structure, but adds fairings that protect the spokes.



So, all you folks with 3D printers, print some up, test them out, and let us know the results.