The Thrifty Bot: 2" Vectored Intake Wheel Product Updates

1323 used a similar mecanum back in 2017 and had to put surgical tubing over the rollers for the balls. The wheel didn’t work well and we haven’t went back to it but the 125 wheel this year looked promising.

3 Likes

I’d love to see video of these on different types of game pieces; if it looks good, we’ll probably order a few.

Definitely looks cool and will fit in nicer into many designs than the 4" wheels we’ve had to use in the past!

Alright Ryan, you get my money

2 Likes

As others have alluded to, I wonder how hard it would be to reduce the diameter of the nylon rollers a bit, and stretch surgical tubing (or something similar) over them to provide a bit more grip. Also wondering what performance differences this would make to them (if any).

1 Like

They are just black Nylon spacers with a chamfer. They work on the 2019 and 2016 game pieces, should have some video in the next few days with them in action.

These wheels do come apart by removing two 6-32 countersunk bolts. So if the need arises to create a tacky wheel roller, it would be possible to create a roller kit and not have to purchase all new wheels. Or to create your own, modify the existing ones, etc.

9 Likes

Look great, like a lot of your products! Love how quickly you are introducing new products, agile.

What is the weight of them?

.07 lbs per wheel

And thanks! Appreciate the feedback.

1 Like

You can’t print the CAD model that was posted. To quote Nick responding to a question about that on the FRC discord:

“It’s a single body model and some of the specific dimensions are missing. The CAD gives the overall appearance that the wheel actually has, and enough info that a dedicated person could figure out how to get it the rest of the way there if they really wanted to.”

The posted CAD model is representative enough to design with, but intentionally not ready to print. It’s disingenuous to claim otherwise. I would not make the assumption that you will be able to run off a batch of these to test with unless they’re willing to send you the actual STL files.

4 Likes

Agilé

It must be Italian.

2 Likes

I should clarify. I am not trying to make an argument that printable files for this wheel or any other product should be available. Besides, with the nylon rollers it is not clear that this would be straightforward for someone else to “just print” anyway.

My comment was meant only to make it clear that the STEP files uploaded on the product page are for design, not printing on your own. Earlier comments in this thread were ambiguous in that sense, and at least one person seemed to have the idea that the model could be printed by anyone who downloaded the files. That is not the case, and I think it should be said explicitly before people start trying.

2 Likes

Have you guys tried to print these with 3 or 4 perimeter wall passes instead of the two that are shown? It’s easily configurable in markforged Eiger and could reduce the tendency for the hex shaft to damage the bore under high loading conditions.

Single Body Model? am I missing something?

Your drawing has a potential error. It calls out the Overall Wheel Diameter to be 2", but it doesn’t look like you have properly crowned the rollers (hence why this isn’t for a drive-train). The overall wheel diameter should be shown as going to the corners of the wheels. If someone were to design for these with a tight clearance, they would have issues give the 2" specification.

I recommend leaving the 2" number on the drawing but relabeling the dimension to be “Wheel Root Diameter”

1 Like

From a few posts above in the thread

It’s really close, just depends where you measure since the rollers are flat -

3 Likes

Here is the dimension as theoretically measured in CAD. It may be slightly more accurate than using a pair of calipers.

The Blue Circle is tangent to the Projected Green Curves. The green curves are the projection of the outer chamfer of the rollers.

image

5 Likes

I think nominally it’s close enough. Keep in mind many wheels sold by other vendors are not exactly the dimensions labeled, i.e. in our experience an 8” pneumatic wheel isn’t actually 8”. It also seems to match in CAD, so most teams designing for tight tolerances should be fine.

11 Likes

I get tight tolerances. But if you’re designing a mechanism that requires 1/16" of clearance for a moving part, I’ve got bad news for you… after getting banged around for a couple of matches, you’re going to have problems.

23 Likes

I totally agree,

That said, I know its happened. I’m not too proud to admit that I did it once…

1 Like

Add to this the fact that most game pieces have some amount of conformity. Precision dimensioning of intake wheels is … not necessary. As long as they are all identical, it will be fine.

3 Likes