Ground Clearance Vex clamping gearbox

[Kevin Sevcik]

That still looks pretty exciting for my tastes. We CADed up a long chassis with 6" wheels and the clamping gearboxes and realized things would be awfully tight since our gearboxes are fairly centrally located. If we crossed the scoring platform square, we'd still have the gearbox gear scraping the platform for a bit. Someone suggested we just toss a hex bore wheel on the outside of the gear, but when I noted that we'd still high center badly if we strafed sideways into the corner, we switched to 8" wheels instead. That decision seems to have been trading one clearance issue for another, however...

[Lil' Lavery]

What rule were these inspectors citing claiming they would fail you for a low ground clearance? So long as all your leading edges meet R7, I don't see any reason for a low ground clearance to cause an inspection failure.

[AdamHeard]

Originally Posted by Lil' Lavery

What rule were these inspectors citing claiming they would fail you for a low ground clearance? So long as all your leading edges meet R7, I don't see any reason for a low ground clearance to cause an inspection failure.

Overzealous interpretation of R16G? I don't think the actual HDPE platforms will get too damaged though.

[Lil' Lavery]

Originally Posted by AdamHeard

Overzealous interpretation of R16G? I don't think the actual HDPE platforms will get too damaged though.

R16 is about lubricants
The nearest rule I can find with part G is R15G, which is about displaying your robot outside of the bag.
Not sure which rule you're referencing.

[AdamHeard]

Originally Posted by Lil' Lavery

R16 is about lubricants
The nearest rule I can find with part G is R15G, which is about displaying your robot outside of the bag.
Not sure which rule you're referencing.

Ooops. G16G. Thanks.

[Chris is me]

There is no rule or inspection requirement that demands your robot be able to clear the bumps. That would be ridiculous.

That said, this is a clever solution, and thanks for sharing. Rectangular tubing of all shapes and sizes (not just 1x1 and 2x1) can be quite useful in FRC. I'm a fan of 3x1.5 for internal belt runs, 1.5x1 for live axle manipulators that you press bearings directly into, and other random sizes for anything from gearboxes to framing.

[EricH]

Originally Posted by Chris is me

There is no rule or inspection requirement that demands your robot be able to clear the bumps. That would be ridiculous.

Correct. However, as noted, G16G requires robots not to damage the field--and gives the appropriate parties the authority to require robots that do to go get fixed. There are some teams that will note that an otherwise-legal robot damaged the field, and the Head Referee sent them back to the LRI with a message of "Fix This". It happens.

If you can't go over the scoring platforms, that is a design choice you made. If you damage them in an attempt to go over them, that is a rules problem... which can be fixed either by you not attempting to go over the platforms or by fixing the robot.

[Gregor]

Originally Posted by EricH

Correct. However, as noted, G16G requires robots not to damage the field--and gives the appropriate parties the authority to require robots that do to go get fixed. There are some teams that will note that an otherwise-legal robot damaged the field, and the Head Referee sent them back to the LRI with a message of "Fix This". It happens.

If you can't go over the scoring platforms, that is a design choice you made. If you damage them in an attempt to go over them, that is a rules problem... which can be fixed either by you not attempting to go over the platforms or by fixing the robot.

Have you seen a correctly covered scoring platform? If a team manages to damage it I'll give them the creativity award.

[EricH]

Originally Posted by Gregor

Have you seen a correctly covered scoring platform? If a team manages to damage it I'll give them the creativity award.

Not yet.


OTOH, HDPE has been used on field elements before (before your time, I think--03, 04, 06), and had a tendency to get a bit scratched up. Not too bad... but enough to be noticeable.

[Gregor]

Originally Posted by EricH

Not yet.


OTOH, HDPE has been used on field elements before (before your time, I think--03, 04, 06), and had a tendency to get a bit scratched up. Not too bad... but enough to be noticeable.

As a ref I wouldn't ever foul a team for scratching plastic on the ground. Would you?

[EricH]

Originally Posted by Gregor

As a ref I wouldn't ever foul a team for scratching plastic on the ground. Would you?

Nope. Unless the damage was major, AND they'd previously gotten a "fix your robot".

BTW, if the damage done does happen to the HDPE on the field, that robot will be almost certain to get a "Fix your robot". The hardboard was pretty chewed up on that corner--not unplayable by any means, but noticeable. I don't have any photos, but the field build crew was taking photos of the various field damage--all unintentional--the next day and spent some time around that corner.

[FrankJ]

The edges of the scoring platform are taped. The gear could pull up the tape under the right circumstance. But no more than a stalled wheel spinning on the taped seam.

[Kevin Sevcik]

Originally Posted by Gregor

Have you seen a correctly covered scoring platform? If a team manages to damage it I'll give them the creativity award.

I believe I mentioned our robot was all set to high center on the large gear of a clamping gearbox. I think a gear spinning at 900rpm with 50lbs of down force might be bad for the hdpe. Nevermind if said gear hits one of the seams.

[steelerborn]

We only damaged the field in the very first practice match, after that we never hit the platform again and we played probably 17 matches.

But we were told that since our ground clearance was so low that we "could" damage the scoring zones so our frame would not pass inspection. I felt this was odd because you are flagging a robot for what "could" happen in the field, but if the intent was to damage the field I am sure teams could find a way and we would have many more robots not pass inspection.

For teams with low clearance just avoid the zones but probably start brainstorming options to raise your frame just in case.

[Chris is me]

Originally Posted by steelerborn

But we were told that since our ground clearance was so low that we "could" damage the scoring zones so our frame would not pass inspection. I felt this was odd because you are flagging a robot for what "could" happen in the field, but if the intent was to damage the field I am sure teams could find a way and we would have many more robots not pass inspection.

I'd love to talk with the inspector that decides that robots must have a minimum ground clearance to compete. It is odd because it doesn't make any sense at all, and it's never been a rule that you have to have a specific ground clearance. If you don't damage the actual field, you're fine. That's my 2c.