26-02-2014 00:49

Adamz_

Re: pic: Team 696 Teaser #3

These have to be some of the nicest wheels ive seen in a long time, and id love to see them implemented.
Great work!

26-02-2014 01:13

DampRobot

Re: pic: Team 696 Teaser #3

Absoutely stunning. Can you give us some more details on how you held the part, especially for machining the tread grove?

26-02-2014 02:05

sanddrag

Re: pic: Team 696 Teaser #3

Thanks for the complements. I should mention you're looking at the backs (insides) of the wheels. The outside is not as deep, and has corner rounding on the spokes.

Last year, I'm pretty sure we did nearly identical wheels in two operations only on the CNC mill. This year, I forgot exactly what I did last year to finish them off, while having only very little left to hold. So, I did them in two operations in the CNC mill, and left a little bit of the groove unmachined, so I could hold them. Them I finished off the groove in the manual lathe. You can see where the surface finish changes.

In the mill, I held them just in some aluminum softjaws, and went around the outside with a really el cheapo junk HSS woodruff keyway cutter. It took much longer than I'd like due to the HSS cutter, but it worked fine. I'd like a bigger carbide T-slot cutter or something like it to do the tread grooves., but they're $$$.

On the manual lathe, it was actually a pain to finish off the groove, because the wheel is so thin and light that it just resonated and chattered like crazy, leading to horrible surface finish there. But, it's under the tread, so you'll never see it.

26-02-2014 07:59

Peter Matteson

Re: pic: Team 696 Teaser #3

They look beautiful.

I would like to know what drives your make buy decision on a part like this?

We switched to just buying wheels a few years ago due to cost and freeing up machines to make other parts, and I'm curious to know other teams rationale for making that type of decision.

26-02-2014 10:22

sanddrag

Re: pic: Team 696 Teaser #3

Good question. We evaluated the same question kickoff day. Here's what we came up with.

• Custom wheels let us do a 7/16" hex, to use 1/2" round bearings. (Primary reason).
• Over 15 wheels between two robots and spares, we were able to save a significant amount of money (about $350) by making our own.
• These are significantly lighter than a wheel such as the AndyMark Performance Wheel. With other wheels, our robot would be overweight.
• The hub on the back of these is set back about 1/8", so the wheel actually encompasses the bearing block. This let's our robot frame be 1/4" wider.
• Since we had the capability to do this ourselves, we figured we might as well. We want to teach our students to be designers and fabricators, not just catalog consumers.

26-02-2014 23:29

S2K JDM

Re: pic: Team 696 Teaser #3

Those wheels are awesome. They kind of look like Volk CE28 rims.

26-02-2014 23:35

Mk.32

Re: pic: Team 696 Teaser #3

You anodized in house?

27-02-2014 03:14

Chowmaster4695

Re: pic: Team 696 Teaser #3

we have used this before, and it works great. Many anodizing shops leave parts in too long, which adds extra weight . By anodizing ourselves, we can control the entire process, and saved 1.7lbs last year. Also we have experimented with adding oils in when anodizing our sprockets. this is one of the reason our mecanums are so fast this year.

27-02-2014 04:00

sanddrag

Re: pic: Team 696 Teaser #3

OK, we did not Anodize in house. Anodizing and powder coating are the two processes we leave to the pros.

27-02-2014 10:30

Cory

Re: pic: Team 696 Teaser #3

Are you thinking of powdercoat? There is no possible way you saw a mass increase through anodize.