Custom Wheels
 

Alrighty CD Community, does your team have/use custom wheels? If so; What is your process in designing/making them?

Re: Custom Wheels
 

Here is a peek at what Team 316 will most likely be using next year.



They are cast urethane plastic.

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Do you have any issues with the material being worn out?

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The tread or the plastic?

The tread, yes. Plastic, no.

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How did you come up with the design for the wheel and do you have the numbers that would show how durable it is?

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For the design, I just used the same outer diameter as the AM performance wheels and the bore will snuggly fit an AM hex hub. The spokes are just a simple pattern I drew up.

Not currently. I am trying to learn to use the stress analysis tool in Inventor. I made a set of urethane wheels that are considerably weaker due to air bubbles and they held up fine in a few off season events.

Any details on how these were made? I assume you had to create some sort of mold, but how was this done?

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I have been seeing a lot of different types of traction this season too.. Which surprises me, then again it is my first year. But I would like to know what other tractions that are available / teams used!

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Justin and I have been toying with carbon wheels (145g) including tread material on a 4 inch wheel.

its cool but soooo hard to do

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Can't speak for 316, but I expect it's very similar to this.

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Yes basically, but we are using a two part mold. I will explain in a bit more detail when I get home.

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We built these wheels after we got tired of re-treading our Vexpro wheels.

The idea is that they split in half off the axel, so the axel doesn't need to be pulled out (We use a 2x1 Aluminum extrusion on both sides of the wheel axel) Then we can easily drill out the pop-rivets and replace the tread. As of now, we have had no issues with the tread bubbling at all.

The hex was broached after this picture was taken, we built 4 of them in house (3 Axis CNC), then a sponsor built the other 4 (5 Axis CNC).

And all the Conversational code to build these wheels was hand written, which is pretty cool!

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Do you just tread each half and attach them with 2 seams in the tread? Pretty clever for those -hard to replace drivetrains

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Did you have any issues with the flat on the top/ bottom of wheels? How exactly do you replace the tread? Is this on a live axle or dead axle?

Wicked cool design BTW.

EDIT: didn't read whole post. Dead axle then.

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Has anyone tried using another material besides wedgetop or roughtop?

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Blue Nitrile. That first picture in this thread shows some, though it's just about indistinguishable from the wheel. Lots of teams use that.

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Interesting, Most wheels tend to wear out from my view. Our team uses custom wheels with Ployurethane and they've got perfect grip and don't tend to wear easily.

Polyurethane is a great material; we did a Cinco de mayo parade with the robot last year on a hot day and walked on the streets and our wheels didn't wear at all. We'll Be doing the parade this year again ( Tomorrow ):D

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I am not going to go into too much detail because I will make a more detailed thread when they are complete.

To make the two part mold I started off by building the clay half way up the master wheel. http://i.imgur.com/Y1UbrUj.jpg After a good coat of mold release I poured half of the silicone in. Those dimples are called keys, they keep the two halves aligned.

After it cured I took the clay and master wheel out, cleaned up the mold, and put the wheel back in. http://i.imgur.com/TyhgwAN.jpg The rest of the silicone was poured in and 20 hours later it was done. This was the finished mold http://i.imgur.com/FmC5ng8.jpg It didn't turn out very well because I rushed through the clay part.

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There is also this stuff http://www.andymark.com/product-p/am-2611.htm

I felt it on 1218's intake roller and it seemed really grippy and soft. I am not sure how well it would hold up on wheels.


I saw these at champs and they were awesome. Here they are with the tread attached. http://i.imgur.com/3W0z2Ik.jpg

Re: Custom Wheels
 

Live-axle version of 971's wheel. Tread is blue nitrile attached with a zip-tie. If your team has the resources to do this, I highly recommend it; not having to use rivets is excellent.

Re: Custom Wheels
 

Actually it's a live axle design, the drive sprockets are mounted on the hex shaft as well, this way we don't have to design a way to attach sprockets to the wheel.

The tread is put on in halfs, so that we can split the wheel off the axle. The tops and bottom of the wheels induce some vibration, but it's not too bad.


If you want a comparison, watch

this video from PNW champs (Before 6wd)

https://www.youtube.com/watch?v=AlG1JUmWnlk

Then this video from CMP where the robot was full 6wd (Note that the mount for the Gopro changed, so there was some more vibration from that as well)

https://www.youtube.com/watch?v=QkKOhDXiRFY

Re: Custom Wheels
 

I was wondering how you put the tread back on. Once the tread is on, the wheel is one piece, right? Do you attach tread while on the axle?

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It looks to me like the second video has you driving a lot more erratically. Is this just the extra vibration I am seeing or is that a result of the change in drivetrain? In the first video you seem to do a much better job of tearing across the field and making blocks and stops.

Re: Custom Wheels
 

The point I was trying to make with the videos was the side to side vibration, which wasn't as obvious before 6wd. As far as how our driver drove the robot, we had just been talked to about High Speed Ramming, so we were likely holding back a bit. The overall strategy was also different between those two matches, at PNW we were playing nearly straight defense except when finishing (which didn't happen due to defense) so the driver had a much clearer picture of what to do. Personally, I thought the PNW match had a lot of missed blocks, whereas at Champs it wasn't as bad.

Tearing across the field was actually better with 6wd, we had more acceleration and better control when turning the robot. The Omni's we had on the back two wheels at PNW were horrible because they would break loose and cause us to skid out of control.

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How much did the entire process cost you?

Re: Custom Wheels
 

From the calculations I made it would be about ~$10.75 Per complete Wheel

about $5.5 Per Rim and ~$5.25 Per thread.


These wheels we've made have been great because they are Durable, long lasting, great on the field, and cost efficient.

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What kind of wheels are they? Machined with molded tread? Do you have a picture?

Re: Custom Wheels
 

Here's a Picture from Last Year's ( 2013 )

This year's wheels we decided to get rid of the Bolt Hole and Just Hold or rims together with Snap rings on the Hex shaft and also drilled a hole on the center of the hex shafts to screw in a bolt with spacers.

I will upload pictures of our 2014 wheels soon.

Re: Custom Wheels
 

How does the material you use work on carpet in relation to the other types of traction material?

Re: Custom Wheels
 

Compared to other material I believe the material we use has great traction on the carpet
One of our mentors who gave us some history of the traction materials said that out of all materials wedgetop and roughtop were great for the carpet but wore out super easy; and while designing the wheel we wanted it to have great traction/grip on the carpet, easy thread replacement, cost efficent and YELLOW.
So far we haven't had to swap out threads our threads from last year are still good they just don't seem to wear out; im assuming these are good as wedge/roughtops/Nitrile but very long lasting

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Do you possibly have a picture on hand that we could see?

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He said "on hand". This one, was not :D

That is really cool. What is it made of/how was it made?

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Dang it! haha. :D

The Thread is Made up of 70A Polyurethane.
We got Polyurethane Tubing of 4" OD x 3"ID 70A Polyurethane and cut it to 1" slices. Then cut the ID to 3.25" and make a .125" wide cut for the Lip of the rim to rest on.

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So it's like a colson tread, but one piece? Sweeeeeet.
We're totally going to try that come summer.

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well there is Variety of Colson threads; the most common ones have a higher durometer which means the thread is pretty hard. We used 70A because it was right in the middle of Soft and hard + Grippy

Great to hear that You'll be trying it out!
Let us know how it goes :)

Re: Custom Wheels
 

That's pretty neat. How is the tread kept from spinning around the wheel? Friction?

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Here is our 2014 version of our 3D printed wheels. We integrated the tread from vex pro.

We were fairly happy with them. They are made on a uprint plus, ABS solid.

We would get two pairs on a print in about 10 hours.
We basically used the same profile from VexPro CAD and built a wheel around that.

http://www.chiefdelphi.com/media/photos/40594?

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The tread is held with friction and compression; We compress the tread slightly onto one rim and then sandwich the other rim on top just like a "sandwich" or "oreo".

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That's really cool; where can you buy this stuff?

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Also, what colors does it come in? :D

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As mentioned by Eric this material is polyurethane 70A. The nice thing about ordering polyurethane is it comes in several colors. One factor that was key to selecting this material is that the material for our wheel had to survive our 2+ mile walk in the parade.

Here's an image of a complete wheel.

Re: Custom Wheels
 

That hub looks heavy. What is the weight of one singular wheel? (including tread)

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How well did it look after the parade?

I like the idea of not having to continuously replace the wheel for demos and such.

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Team841 Purchases it's Polyurethane from Sunray-inc.com
Colors are on their Website

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How much do these things stretch? Can you stretch it enough so that it can be fitted of an andymark performance type of wheel?

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And how well do they turn in place? If i were to put it on a swerve drive would it work well?

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I highly doubt you'll be able to stretch 70a polyurethane over a wheel. I'm pretty sure you need a wheel that comes apart or a removable rim.

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70A polyurethane doesn't stretch much; I don't believe it can be stretched over a rim. In order to place the urethane as R.C. said the rim must be split. So we make our rims Split to place our tread and so they can be easily replaced, but so far we haven't had any need to replace them; they can withstand most terrains without wear

Re: Custom Wheels
 

That is correct!

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If you're still open to questions: How did you do this machining? It seems to me like if you chucked it on a lathe, it would deform from the compression of the jaws, causing an uneven cut. Maybe it's harder than I'm picturing, or maybe I'm missing something...

Thanks in advance