legality of bolt and screw heads breaking plane of chassis meeting bumpers

[Jack Jones]

Originally Posted by Al Skierkiewicz

Kika and others,
The bumper design is intended to protect your robot. The GDC looked very hard at the effects on last year's damage and saw that bumpers, as designed, indeed protected our robots. Part of that design is the backup frame structure that prevents the bumpers from damage due to extreme flexing. Robot inspectors will evaluate each bumper implementation to determine if, in their opinion, the bumpers satisfy the rule. If anyone thinks that a 3/4" slab of plywood can absorb the hit of two 150 lb objects by itself should look for a post from Dave Lavery last year on this subject. The bumper system includes the backing frame structure and will be evaluated with that in mind. To that end, the GDC has allowed you to "pocket" the bumper (not drill holes through the material that will weaken the plywood) to allow the bumper to use the backing of the frame to strengthen the system. If you have two bolt heads at each end of the bumper that cause it to be separated from the frame for 35", some failure will occur. If your inspector asks you to make four small pockets, I don't think he/she would be out of line. Please be prepared to remount your bumpers during the inspection process following weigh and size. This step will be needed to evaluate the bumpers, check for height and ball intrusion and kicker extension if any.

If the GDC has looked very hard at the bumper design, then how is it they overlooked the most critical element - the plywood? There's a whole lot of difference between the 13 ply Baltic Birch plywood we use and the 5 ply soft-wood junk they sell at Home Depot. The ruling spends just one word, "plywood", on the most important part, but goes into great detail and updates about trivial air gaps. It just doesn't make sense!

Al - I'll bet you a dollar to a doughnut (no Krispy Kreme please) that a 35" slab of our plywood will take that hit.

[IndySam]

Originally Posted by Jack Jones

If the GDC has looked very hard at the bumper design, then how is it they overlooked the most critical element - the plywood? There's a whole lot of difference between the 13 ply Baltic Birch plywood we use and the 5 ply soft-wood junk they sell at Home Depot. The ruling spends just one word, "plywood", on the most important part, but goes into great detail and updates about trivial air gaps. It just doesn't make sense!

Al - I'll bet you a dollar to a doughnut (no Krispy Kreme please) that a 35" slab of our plywood will take that hit.

In 2007 we had a bumper of high quality plywood unsupported over about 30 inches. It snapped like a twig our first match. We replaced the wood and it happened again so we played the rest of the regional with a broken bumper. At our next regional we replaced it with cheep Lowe's plywood and it lasted almost the entire regional before it broke (it had more spring.)

[Jack Jones]

Originally Posted by IndySam

In 2007 we had a bumper of high quality plywood unsupported over about 30 inches. It snapped like a twig our first match. We replaced the wood and it happened again so we played the rest of the regional with a broken bumper. At our next regional we replaced it with cheep Lowe's plywood and it lasted almost the entire regional before it broke (it had more spring.)

Ah - there's our mistake, we should go to Lowes instead of Home Depot.

[Al Skierkiewicz]

Originally Posted by Jack Jones

Ah - there's our mistake, we should go to Lowes instead of Home Depot.

No comment...
Agreed on plywood type. Most teams are going to opt for the cheapest available or what ever is left over from another construction project. Sam's experience is what the GDC is trying to avoid and what we are trying to inspect.

[IndySam]

Originally Posted by Jack Jones

Ah - there's our mistake, we should go to Lowes instead of Home Depot.

Not that I don't like Home Depot I just cant stand all that orange.

[Rob]

Originally Posted by IndySam

Not that I don't like Home Depot I just cant stand all that orange.

I would rather deal with sickening orange than the terms "FRAME PERIMETER" and "BUMPER ZONE"...

[Daniel_LaFleur]

Originally Posted by Jack Jones

If the GDC has looked very hard at the bumper design, then how is it they overlooked the most critical element - the plywood? There's a whole lot of difference between the 13 ply Baltic Birch plywood we use and the 5 ply soft-wood junk they sell at Home Depot. The ruling spends just one word, "plywood", on the most important part, but goes into great detail and updates about trivial air gaps. It just doesn't make sense!

Al - I'll bet you a dollar to a doughnut (no Krispy Kreme please) that a 35" slab of our plywood will take that hit.

I'll take your bet

In 07 we snapped our front bumper 3 times, including once with 4 pieces if 1/2" angle aluminium. It took less than 30 seconds to snap it and we couldn't move faster than 6'/sec.

* Bumper was unsupported across 35" of frame giving a 1" space behind it.