A couple days ago, I posted a thread BaneBot Wheels Run off CIM Motor. Since then, I came across another thread where someone said the urethane wheels from mcmaster-carr work better. So I have the same question - how do you attach cims/miniCims to them?
Machine a hub that press-fits into the wheel, bore out an 8mm hole in the center, and broach a 2mm keyway into the hole.
Is that the easier way to do it? What about for teams with less machining capability?
I don’t know if we are talking about the same urethane wheels but the one commonly used is McMaster 2477k36 (seen on 1114, 973, 2056 and 254 at champs amongst many other teams). We used them on a suggestion from 973’s Adam Heard and found them to be great.
So that McMaster number in 60A is what we and they used.
The hub really is the easiest way IMO. You only need a lathe.
We machined said hub to interface with 1/2" keyed shaft. The hub was just a piece of 6061 round stock turned to press fit into the wheels bore. I took a look at 1114s hubs and they knurled them to make the press fit better. We didn’t have the resources to do so but were fine through all of champs.
Use different wheels.
If you want I think we have a left over hub or two we might be able to send you. PM me for details.
You need some sort of hub to transfer torque to the rim of the wheel, and something to transfer torque from the motor to the hub. The first requires a lathe, and the second some sort of key, hex, or spline broach. If neither of these is doable, then this is not the wheel for you.
You can use a trantorque style OD/ID expanding/clamping hub and just clamp onto ANY round shaft.
You may have to browse several brands to get the ID you desire. They do make bore adapters to get the ID correct.
This is actually how they are intended to be me mounted. The only downside is a hub is $20-60.
We chose to machine hubs just like the above teams, and were happy with that result. It’s actually a pretty easy part for a lathe (especially if you use plastic as your OD tolerance is pretty loose as it’ll deform when you press pretty easily). Our plastic hubs were like .015" large.
Very helpful. Thanks for your input.
Does anybody know if any team had a working 3D printed hub, or any reason why a 3D printed hub would not work? (We have a friend with a printer.)
I doubt a 3d printed hub would have comparable concentricity.
My other question, why broach for a key instead of just broaching hex?
If you guys don’t have a lathe in-house, this might be a good opportunity to find some local machining sponsors! PM me if you want some one-on-one help finding them.
PS- I’ve taken the liberty of searching around your school for possible sponsors, and you’ve got quite a few solid options to look into. Shoot me a message if you’d like to check them out!
A) Because the OP was asking how to interface these wheels directly with a CIM/Mini-CIM.
B) Because not everyone uses hex shaft
Broaching hex would require a sleeve from AndyMark and a .5" broach. Considering that a 2mm keyway broach is much cheaper, if you don’t use hex elsewhere, it’s a lot easier to broach directly for the CIM output shaft.
Has anyone attempted to use these 4" urethane wheels as drive wheels? At $30 each it would be an expensive setup, but they appear to be similar to Colsons but with a higher CoF.
They stretch a lot. You might have to mold your own urethane tread around an aluminum or plastic rim that doesn’t buckle. (I think 118 does this? Not sure.)
Yep. They actually do a custom wheel mold too.
Just tread a wheel or buy one. Its much easier, and the wheels that are out there are already great solutions for drivetrains.
Colson makes a lot of wheels in addition to the “Performa” line sold cheaply at RobotMarketplace.
Colson has a line of polyurethane-tread wheels molded over aluminum, polyolefin, and cast iron cores. You can see the specs for these wheels here:
I found some 6" polyurethane on polyolefin wheels on eBay for about $10 apiece.
I can’t comment on the construction and concentricity of these wheels as I haven’t received them yet, but if you ask me again in a few weeks I should have an answer for you.
There’s a lot more that goes into whether or not a wheel is good for frisbee shooting than “does it use polyurethane”? Polyurethane varies widely in durometer (hardness), thickness, etc. The blue McMaster polyurethane wheels used by many teams this year have a very thick polyurethane layer (seemingly over an inch of polyurethane) bonded to a metal hub / core. Many wheels (Colsons I believe) have a much thinner polyurethane tread molded over a plastic core. Your mileage may vary.
While Gregor’s suggestion was somewhat snide, if you do not have the machining capability to make a simple press-fit hub, these wheels really aren’t the best option for your team. Investing in several of the Blue Banebots rubber “poverty” wheels would probably be more beneficial. Do note that despite being the same durometer, the Banebots wheels have drastically different wear characteristics than the McMaster wheels, and they need to be changed out over time.
Unless price is a huge driving factor (and it being so late in season, concerns over wear become smaller) the mcmaster urethane wheels are mounted incredibly easy with the style hub I recommended.
If you’re trying to be cheap and fast, can’t argue with the poverty wheels for a single offseason event if you’re not going to practice much going into it.