Durability of KOP with a frame cutout

FIRST General Forum
1

We have a question about the durability of the KOP chassis if were to cut the front rail creating a U shaped chassis.

We would be in the long configuration, with the front cut out leaving 7 inches of frame rail on either side with an approx 13 inch gap. We intend to use an aluminum belly pan which would extend up to the cut out so it would have a hole of approx. 13 x 11.5 inches in it. The “legs” on either side of the U cutout would then be approx 3 inch wide. The standard front churro connecting both sides of the chassis which is normally around 9.75 inches would have to be removed and we would us 1x2 tubing to connect the two sides of the KOP at 11.5 inches from the front.

Because of the high speed collisions that will occur as travel by both alliances must traverse from loading zone to community zone, we are concerned about the durability of the KOP chassis with such a cutout. We envision the possibilty of being t-boned on the corner of the bot and wonder if anyone else has experience with the amount of damage we will likely see the above described configuration.

Second quesion is how hard is it to replace an entire side rail at competition of KOP chassis if damage occurs to an extent the robot is undrivable.

1 Like
2

Have you looked at the AM14U frame cutout kit? It has a cross brace to prevent the kind of damage you’re anticipating.

4 Likes
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We have seen it. our configuration would be very similar with the use of the 1x2 in place of the andymark cross member. Not sure if we can move kit crossmember far enough back. We will check it in CAD.

Still wondering about durability even if we were to use the cut out kit.

I think the collisions this year are going to be violent even before defense.

4

Have you considered an “over the bumper intake” scheme. Search this forum should give you a lot of stuff to read.

Depending on the way you build your bumpers, they may become slightly more complicated. Bumpers are often difficult to get right for inexperienced teams. YMMV.

5

The durability question is part of the debate between over the bumper versus the frame cutout.

Bumpers are a pain regardless. Would love to see changes to the rule and materials allowed as discussed on here during offseason threads.

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It is good that you are considering the whole picture. Good engineering is dependent on making the “best” trade-offs.

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My team has run the KOP with and without cutouts. Generally, we try to find an over-the-bumper solution first, but will use frame cutouts if our strategy goals and machining/design limitations require it. The KOP frame cutout kit is great and we’ve used it a few times. The sheet metal bends, the 3" height, and the hole pattern plus attachment plates make it a great option. I’ve never been in a situation where the KOP with frame cutout required a side rail replacement. I’m sure you could design for accessibility making that possible (i.e. all superstructure bolts to the top of the rails) but I personally probably wouldn’t suggest my team design around that.

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8

I guess if worried about side impacts you could run some reinforcement, basically something like a “u inside the u”.

Changing a whole rail during competition seems like a monumental task.

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