pic: 2175 Wheel v2

This is the second iteration of 2175’s wheels to be swapped in when we arrive in st louis

What are the differences of the new version? Different type of plastic?

Yes, the black wheel is made of Altem, a stronger 3D print material. We ran into the problem that after 2 regionals we wore the hex out on the wheels, so we asked our friend to make us some stronger wheels.

Looks like your robot is going to need some re-inspection :smiley:

Did your pneumatic arms ever get approved up in Duluth? I was the inspector that didn’t actually do much because we were waiting on a ruling from the LRI.

Yes, they did get approved, but we decided not to use them… We made passive climbers that were able to be actuated for North Star. A lot simpler and safer.

The new wheels also have a stronger printing pattern around the hub. We did not start noticing wear on the origanal wheels until after a regional and a half. We also are using a much smaller hex shaft then we wanted (3/8) we ended up having to use this size shaft because all of the half inch bearings were out of stock.

Yes we got them approved, but ended up not using them because they would have crushed our new shooter we had installed. We added a passive ten point climber that actuated up for north star and it worked beautifully.

Coming from a team that is planning on 3D printing some wheels next year, what material were you originally using?

Yes, they did get approved, but we decided not to use them… We made passive climbers that were able to be actuated for North Star. A lot simpler and safer.

Glad it was approved, but they seemed a little over-engineered to me for a simple 10-point climb. Glad you guys figured something else out! Congrats on the regional win at North Star and I am looking forward to stopping by your pits at champs!

The original material if memory serves was abs m30, and the new material is Ultem about 2x stronger according to our printer friend

Could you send me a picture of the worn out hubs you’re describing?

Glad to see 3D printed wheels are working for you guys, in at least some extent. I think they’ve got the potential to open up custom wheels for a lot of teams that may have not had that option available before.

I would be VERY careful with those 3/8" drive shafts supporting cantilevered wheels. Have plenty of spares ready and check them every match, and make sure they are a strong material (7075 AL or a nice, strong steel alloy).

Otherwise, neat wheels.

I’d be willing to bet that the 3/8" hex shaft is also a factor in the hub wear as well. Figure a 3/8" hex shaft is transmitting the same amount of torque through a significantly smaller area on the wheel than 1/2" hex, so it should be more prone to stripping the hub out.

Also, for those of you that are curious, ABS M30* has an tensile strength of ~5,200PSI and Ultem* 9085 has a tensile strength of ~10,400 PSI.

*Assuming that these materials are being printed using a Fortus Printer… AFAIK it’s the only machine that uses both of these materials.

Since our season ended, we have been doing some experimentation with 3D printed wheels, too. Here are a couple of our results:

More pics here:

The latest version has the spokes as internal structure, with fairings on the outer surfaces. We’ll print some graphics or lettering on the outer fairing in a contrasting color.

Fun experiments, but we were so happy with our Colsons this year that we’ll probably go that route again, unless there is a compelling reason to switch.

Ill try and find the wheel at the shop tonight and upload it later. we believe the reason for the failure was because of the less then ideal shaft size causing the forces not to be distributed over a large enough area in the wheel. What size shaft do you guys use it looks like 3/4.

Also the 3/8 shaft is steel (not sure the exact alloy) and they have held up through 2 regionals plus practice in the shop, i dont expect to see any failures from them, but we have two spare drive sides that we can scavenge off of if they start to fail.

I view these as a case of someone who has not yet realized the full potential of a 3D printer, my guess is you could use a fair amount less material, resulting in a lighter wheel, and also have it much more aesthetically pleasing.

Let your imagination run wild, I always have to re-jump the hurdle when I cad something I know will only be 3D printed, as past experience has taught me to CAD for whatever machining capabilities I’ve had at hand.
3D printers only recently joined this list, and its been fun.

go crazy, you’re allowed to

Notice the 7 spokes :stuck_out_tongue: But in all seriousness we knew we could do some really cool designs and there were team members that really wanted to, but we decided to play it safe for our first year doing this with such an important robot part. Expect some much cooler wheels in future years if we continue printing wheels which i personally hope we do

We used 1/2" alum this year. I believe we did 7/8" in 2012 and iirc we were rolling 1" hex in 2011. I’m too lazy to embed, but here’s a link to the entire 2013 assembly (4" wheel). The back end of the axle is unfinished in this photo.

Your wheel pictures have been a major source of inspiration for us. Out of curiosity, what is the weight of one of your 2013 wheels with the tread attached? How wide is your tread, and how is the tread holding up?

At some point, we are going to have to make a decision about whether the benefits of printing wheels is worth the time it takes. Right now, we’re just playing, to see what is possible.

Fully assembled, the wheel weighs 130 grams (.286 lbs). We use the 1" wide wedge top tread that Andymark sells. They changed the rubber compound they’re using, and it seems a lot tougher than the kind they sold last year. We did two events on the same set, and they really don’t look any different now than they did on bag day. Granted, we’re only running 4 cims in a drivetrain that wasn’t geared nearly as high as a lot of robots out there.

I’m looking at new options for tread attachment personally. What kind of glue did you guys use for your wheels?

Is that a 3d printed bearing block? How are you tensioning it? Does this save time/weight over an aluminum version? We on 422 are strongly considering a 3d printer for next year, and things like this make us want to take the plunge. Is this printed on something like a makerbot/reprap with ABS or PLA, or is it Ultem with some more commercial printer?

Yep, 3d printed. We print all of our parts at home out of ABS with a uprint from Dimension. It doesn’t save any real time, but it saves man hours which is helpful considering the tiny team we had this year. It might take ten hours to print a couple of wheels, but all those hours are passing while we’re asleep :cool: .

The ABS portion of the bearing block is captured with two long screws between the two plates, and the frame tube is captured between the two plates. Tensioning is accomplished using that cam sitting next to it on the table (the cam is bolted onto the frame tube next to the block, rotating it either pushes the bearing block outwards or allows it space to move inwards).