Re: Who makes their own wheels?
 

While we're on the discussion (and since I have one hanging on my wall)-

195 made a custom shooter wheel for 2013.

The wheel was ~12" in diameter, weighed 4.5lbs and was direct driven by a CIM.

It started as a 14"x14" block of aluminum that was Wire EDM'd to have a spoke profile.

The block was then placed on a CNC mill and the 'wheel' was milled out using a .5" end mill. This left the 14"x14" block with a 13" hole cut out of it.

The rim of the wheel was then sandblasted to allow for the urethane to hold while at speed.

The outside of the block was used as the mold for the urethane cast. The wheel was replaced back inside the block and a .5" dowel pin was used to make sure the wheel was centered in the block. 60A durometer urethane was poured into the mold and was let to sit.

The overall process was a lot of work, but it worked well as a flywheel.

Mountain Dew can for scale.

Re: Who makes their own wheels?
 

In 2012 Skunkworks made a flywheel using a method similar to what you are proposing. We cut an aluminum hub that was .25" thick and of 6" diameter iirc. We added .25" steel rings with matching OD and 5.75" ID, sandwiching the aluminum hub. The assembly had considerable mass, but the mass was where we wanted it to maximize moment of inertia. We covered the wheel with a section of inner-tube from a motorcycle tire to give it a more desirable surface.

I would consider constructing a custom flywheel a worthwhile endeavor, but in my experience an accurate shooter has much more to do with proper control than superior mechanical design.

Re: Who makes their own wheels?
 

We 3D printed and then cast hubs for urethane tube to use as intake wheels in 2015.https://scontent-yyz1-1.xx.fbcdn.net...048631_o.j pg

Re: Who makes their own wheels?
 

Uploaded a video of another flywheel I build for a physics project with the method I outlined previously. Might help make sense of my garbled description.

https://youtu.be/XKjixa894uU

Re: Who makes their own wheels?
 

I don't think one aspect is more critical than the other. You need both, period. 469's shooter in 2012 was not the best mechanically (double axle, very low MOI, low compression), and as hard as we tried, no amount of code was going to make up for that.

Re: Who makes their own wheels?
 

I'll concede to that in general, perhaps I was being a bit shortsighted. I appreciate your response.

Re: Who makes their own wheels?
 

I didn't mean to dismiss anything. I will argue to my dying breath, that every part (bolt, cotter pin, wheel, rivet, screw, etc) is critical to a successful system. Just like a chain is only as strong as its weakest link, a system is only as good as its worst part. Selecting the best part for an application, only comes through luck or knowing what your doing.

Yes we are building robots right now, but my students have higher aspirations.

Re: Who makes their own wheels?
 

I think what people are objecting to is the idea floated in this thread that buying a wheel is inherently a decision that is against the interest of teaching students. There are educational things about buying subsystems, and most of the skills and principles taught in designing and machining a drive wheel could be taught with designing and machining a manipulator part, for example. To each their own and all that.

Re: Who makes their own wheels?
 

+1 There is no need to reinvent the wheel (insert groan). There are plenty of other parts that do not have such a strong COTS variety that are both educational and productive to make.

Re: Who makes their own wheels?
 

We were having a normal discussion about a simple offseason project, when the trolls show up with "WW2056D" and then we get told that for 99.99% of teams it is a waste of time.

Constructive criticism is one thing, but dang.

I have been on investigations into a number of mishaps, many times we found the reason for a multi-million dollar loss of aircraft and/or life came back to a faulty "trivial" part of the system or the improper installation of a "trivial" part.

Many times the "trivial" part failed because someone substituted an inferior part for the one that was called for. Which is why everyone working on a system has to understand at the very least the specifications for the correct part.

Yes it can be taught many ways, this is one way I selected.

Re: Who makes their own wheels?
 

You guys are also missing my point about collaborating with academic teachers.

Getting normal teachers to step outside of their comfort zones is not easy, getting a physics teacher involved with wheel design isn't that far out of his normal classroom teachings.

Re: Who makes their own wheels?
 

They're looking at the problem from a different paradigm than you are. Many mentors on this forum are trying to find the perfect intersection of teaching students, inspiring the team, and maximizing competitive success. You're clearly more interested in the specific lessons that can be taught about locomotion from wheel design in addition to manufacturing, etc. So while their advice isn't really relevant to you, it's useful for other people to learn why teams that prioritize optimization of resources / competitiveness don't machine wheels in the regular season. You've got plenty of valid reasons to do what you're doing; rock on.


And I don't think people are objecting to that, really, they're objecting to when you asserted that everyone who doesn't make that decision is opting not to teach their students!

Re: Who makes their own wheels?
 

Chris, I was asking clarifying questions to the troll post of

See my post below

I know that 2056 and all of the top teams teach their students the how and why, they have too. You can't pick the right COTS part without understanding how it works.

The implication I took from the troll post was "don't worry about design and copy what 2056 does."

Re: Who makes their own wheels?
 

Well, if I = (1/2)mr^2 for a cylinder, just attach some weights to a banebots wheel. :p

Re: Who makes their own wheels?
 

How is that a troll post? The poster is simply referencing another thread on pretty much the exact same topic.