Drivetrain Slop

I built a geared Omni drive for change up. There seems to be a little bit of slop between the 84 tooth gear that is driving the wheel. Is there a way to get rid of this slop?

Well you have lockbars, standoff related methods, and zipties from the wheel to gear. All of these things should be viable. The easiest thing I can think of is ziptying the gear to the wheel.

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How would I install a locker? I tried a standoff but I couldn’t find a way for it to eliminate all of the slop. Zipties are viable but I want to find a more permanent solution.

If I am not mistaken you should be able to do it with just a screw through instead of standoffs. (This will mean you will need to be a bit creative, though, but its probably not hard to figure out)

This solution is actually more durable than you’d imagine. Ziptie each spoke of the wheel to a hole on the gear. The slop will be virtually eliminated.

Standoffs can also be pressed up against the wheel spokes by screwing them directly into the gear. You’ll have to force one of the standoffs to fit which by definition eliminates the slop. The wheel allows you to force the standoff into place because of the deadzone it has before engaging with the axle. At the end of the deadzone, one of the holes for the standoff to be screwed into becomes fully exposed. Not sure how else to explain it.

Alternatively, you can use a smaller size omni wheel (and forcibly a smaller gear) and directly screw the wheel into the gear.


If it helps Michael from Skyline (4411s) used zipties on his TP worlds robot, so you can see it in his video about that robot. (Also that obviously vouches for that method’s viability and durability)

I might try zipties. I tried standoffs in cad and they seem to contact the wheel. I had not considered the deadzone of the wheel. I’ll probably try both at my next meeting. I’m not exactly sure how I would use a screw besides doing the standoff method, which would probably be more effective.

Seems like the solution has been posted while I was double checking the usability of using screws. Will post a second viable option anyways just in case:

I would probably use zipties, but the reason I opted for standoffs was because the zipties interfered with the sides of the chassis. This won’t be a problem if you allocate at least 3-4 mm of clearance but my chassis was super compact. I was able to sand down the screw heads which left enough clearance between the side of the chassis and the screw heads. You could also use shoulder screws but I didn’t have any on hand.

TL;DR zipties work best when you don’t have clearance issues. I’d argue both work equally well, but maybe for a 6m drive or speedy drives (with large changes in acceleration), use standoffs so not to worry about anything snapping over time.


Although I agree, standoffs are not really a viable option with 4” wheels, which is why this thread was created.

Why do you say that?

Freshman year I tried using standoffs for 4” wheels and it was impossible, so I threw the idea out. Unless I am mistaken by some trick that needed to be done, or the wheels were later modified to handle standoffs from a distance of 3 holes, I am pretty sure they do not work.

They fit, you just have to follow the process I explained. The slop in the wheel masks the hole needed for the standoff to be screwed in. By “forcing” the wheel into a slopless position, the hole becomes exposed. To the naked eye, it’d seem as though it’s not possible to screw in, but it very well is.

There is an alternative configuration which I used on one of my robots where two standoffs hug only one of the spokes on the wheel. One of the standoffs gets a spacer added onto it to increase the diameter. The slop is virtually eliminated that way.


Just tested putting standoffs on a gear going through a wheel and it has almost 0 slop


This has virtually 0 slop (the spacing was made so that there was just enough clearance for chain to go through the sprocket without hitting the rollers).
Using the vex delrin spacers worked very well for me because they compress and expand very nicely to create an interference fit


Ohh that probably will reduce how much the standoffs bend making it more consistent over time. Also if you add lock tight screws it will become even more consistent.

Do you know anyways to reduce slip for 3.25 inch Omnis without cutting/drilling holes into a gear/sprocket

Yes you can just attach a lockbar and the gear/sprocket itself by using the mounting holes on the 3.25”

I could only see being able to use standoffs if you cut away some plastic on the wheel as shown in the photo

So maybe if you drill out a little bit of the plastic it would fit but because it’s such a minor amount it probably wouldn’t compromise the strength of the wheel.

Correct me if I am wrong, but that is a 2.75 inch wheel.

This is a 2.75 inch wheel:

This is a 3.25 inch wheel:

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