How do you implement a non-center drop with omni wheels?

FIRST General Forum
1

We haven’t received our shipment yet, but trying to get ahead of a problem we noticed in the CAD files. Our plans are to run no drop, VEX traction wheels, and VEX omni wheels. When looking at the CAD drawings we noticed the traction wheels are 6.25" instead of 6", and this will give us 1/8" of drop. The Versa Blocks have some adjustment built-in, but not enough for the 1/8" we would need. How are other teams getting around this? Just running a drop? We are trying to keep them as thin as possible, so the Andy Mark wheels and hubs are a no go.

Our shipment will hopefully be in tomorrow or Wednesday, but we’re trying to get an alternative going in the meantime. Thank you for any help!

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2

Use a layout which would normally give a 1/8" drop - then turn it upside down. 1/8" rise, offsetting the drop.

Alternatively, sand the wheels down.

2 Likes
3

I’m wondering if this has changed at all with the revised Versablocks.

4

Use 4 wheels instead. Six would be superfluous in this design.
Just use a smaller center wheel to keep it off the ground normally (if you’re doing a HAB 2 climb), or just belt drive pulleys in the center (if you are doing Lv 1 or 3 HAB).

5

Why is an 1/8in drop a problem?

6

What drive train are you using? Are you using KOP, or custom? We have experimented with different drops on the KOP and you wont notice .125 drop. The middle wheels will wear down and the rolling circumference will get closer as they crush into the carpet more. Unless for some reason that .125 is making a difference, its probably not worth any design changes. We have removed drops, milled wheels down, made custom drives, and often use KOP and have come to the conclusion that anything under .25 is not noticeable for all intents and purposes. Also be aware when assembling the KOP that it can be racked (not on a flat plane). When you rock back the KOP either to the front or back make sure the spacing between the floor and the front or back wheels is equal.

(edit: I assume your doing custom after seeing versa blocks)

7

We go through the process extensively here on our guide video:

You can flip the versablocks appropriately, sand the wheels, or leave no drop and let the traction wheels compensate for the drop center or lack thereof for desired results.

8

1/8" of drop will be perfectly fine, probably even better than no drop.

9

1/8" is the easiest with standard parts too. Just drop everything in the middle down .0625" and if you dont like it with no drop, flip the outside versablocks upside down and you now have 1/8". Just remember the versablocks ALWAYS OFFSET by .0625" from center.