So we were putting the bellypan on today and realized that our robot isn’t exactly square. We initially blamed it on bad routing and redrilled holes, however when we were putting on our bumper mounts we found that the bumpers didn’t align perfectly. The specified robot drivetrain dimensions was to be 22 inches in width and 29 inches in depth. However, we measured and found that one side of the robot width was 22 inches and the other was about 21.875. Will this be a big issue. We are around the time where the robot is too assembled to completely disassemble and fix. How big of an issue will this be? I foresee possible brown out issues from pulling more amps in our drivetrain but what else?
I can’t quite tell from the pics how out of square it is. The first two look way, way off, but I think it’s the camera angle as you said its only 0.125 inches out of square? The last pic looks more square. That’s not bad at all I don’t think. My teams build many, many non-square robots over the years, only recently actually making them really square, and we’re still likely an 1/8 out somewhere. I’d say if you don’t walk in the room and go “wow, that’s not even close to square” it’s likely fine.
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That right rear wheel is crooked, you might want to look into fixing that. (As for the actual base, I’ll let others say their thoughts)
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Huh, looking closer, you are using versa frame for the ends, that’s the side that is off right? It should be right on with the versa, unless your rivets are too small and allow a lot of play, you drilled new wholes, or the connections in the extrusion on the sides give a lot of play (ie, can tighten them down to one side or the other a bit.) try loosening the extrusion connections and see if you can wiggle it around a bit to square, then tighten it back up? Just a guess.
Rather than disassembling your robot, I recommend that you loosen every screw which holds your frame together (you don’t have to remove them). Manually move the parts within the slop of the screws until the robot is more square. You probably won’t get perfect right angles, but it’ll be straighter than before. When you’re done, tighten all the screws again and see if that’s any better.
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I agree with this advice, but with one small tweak:
Loosen all the screws, then attach the bellypan, then tighten the screws.
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Or even try and put a 1/8th inch shim in to equal that gap as well and it should push it back out.
Get some massive clams and bend it until it’s square
That would only bring the robot into square if the parallel sides were exactly the same length, which isn’t the case unless I misunderstood the OP. You’d need a pretty hefty clamp to compress 2x1 tubing lengthwise, and the tube would probably buckle first anyway.
I can confirm that the drivetrain in the picture is made of 4 versaframe 2x1 extrusion pieces that are CNC’d to exact dimensions. The corner brackets that hold each piece together is what we suspect causes the misalignment, as those were made by hand. It was only after we put the bumper support pieces on the sides that we noticed the chassis wasn’t square.
Ah I see. That makes a lot more sense. Could you possibly create new brackets, either on the CNC machine you used to make the frame rails, or with a drill guide of some sort? From the pictures that were posted, it doesn’t look like replacing the corner brackets would be all that difficult. You could also remove the brackets, attach them to the belly pan, then match drill new brackets through the tubing while it’s fixed in place by the belly pan. Having your chassis out of square by an 1/8th inch definitely isn’t the end of the world, but it could cause some headaches down the line and it would be easy enough to fix now.
Versablocks tend to get crooked when tensioned by a WCP cam since they have no squaring feature. That’s what I believe is one of the main reasons teams use the WCP side bearing blocks or teams like 971 have put tab-slot features into custom versions of their outside bearing blocks.
It might be better to remake the corner brackets as triangles rather than L’s. Even if @Pickleb gets the frame square, it might not stay that way after a few high speed collisions.
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Not sure how bivalve mollusc could help, even a large one, but the loosen/tighten thing is the way to go.
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What’s up with the rear wheel looking so crooked in the first photo?
I was thinking maybe too much tension on from the chain if the hole was too far. But… im just a student eager to learn and i dont know the correct answer
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