This is a simplified model of our previous year’s chassis, without lightening holes or bumper mounts. The CAD model is parametric, so you can enter the desired chassis dimensions, hit rebuild, and the pieces will resize and the tabs will (hopefully) align themselves.
The 2014 competition chassis had some serious issues with loose chains falling off, but we built a new chassis in the offseason that solved those problems. Unfortunately, it’s at school, so you’ll have to wait until Monday for pictures.
I remember being blown away when I saw your robot at Champs 2013 (I believe). Glad to see you guys are still doing crazy cool things with plywood and a laser cutter!
As someone who’s been spending a lot of time designing plywood robots, I have a few questions:
-About how much does this chassis weigh?
-What thickness of plywood are you using?
-Why are you using such big wheels?
-How are your gearboxes mounted? Do you have prior experience mounting gearboxes like that?
-Why is the chassis glued rather than bolted? How will you repair it if you can’t remove individual pieces of wood?
-Next to the gearboxes, it looks like the frame rail is covered by another set of plates that extend to the end. Why is that?
-Does the belly pan extend to the outer frame rails? It would give the chassis a lot of strength if it did, although it might make access to the wheels and chains harder. It might also make sense to cut out the belly pan below the gearboxes so they are accessible from the bottom.
Edit 2: Just saw the description. The whole parametric thing is really cool. We did a very similar thing on our offseason drivetrain. Why did the 2014 chassis have problems with chains? We’ve found this construction method extremely stiff.
-They are only 6 inch wheels. Our team has always used 6 and 8 inch wheels, but it is very easy to change the height of the axles to suit 4 inch wheels.
-The inside piece of wood has a cutout for the gearbox shape, and bolts go through the outside piece of wood to the mounting holes on the face of the gearbox. We mounted them like this in 2014 and did not have any problems with it.
-Wood glue is stronger than bolts, because the joint is continuous, rather than stress concentrating around the bolts. This chassis is plenty strong to stand up to abuse. In 2014 we did not need to make any repairs. In 2013, we made two repairs using more wood as a patch, with five minute epoxy.
-I have a picture below that will hopefully it clearer how the chassis goes together. We glue individual pieces into beams first, and then glue those assembled beams together.
-The belly pan is only in the middle area. The chassis is rigid enough there is no point in extending the bellypan, and it is impractical because it would have to pass through the inside beams. There is nothing worth accessing underneath the gearboxes, so I didn’t leave any holes.
-They are only 6 inch wheels. Our team has always used 6 and 8 inch wheels, but it is very easy to change the height of the axles to suit 4 inch wheels.
-The inside piece of wood has a cutout for the gearbox shape, and bolts go through the outside piece of wood to the mounting holes on the face of the gearbox. We mounted them like this in 2014 and did not have any problems with it.
-Wood glue is stronger than bolts, because the joint is continuous, rather than stress concentrating around the bolts. This chassis is plenty strong to stand up to abuse. In 2014 we did not need to make any repairs. In 2013, we made two repairs using more wood as a patch, with five minute epoxy.
-I have a picture below that will hopefully it clearer how the chassis goes together. We glue individual pieces into beams first, and then glue those assembled beams together.
-The belly pan is only in the middle area. The chassis is rigid enough there is no point in extending the bellypan, and it is impractical because it would have to pass through the inside beams. There is nothing worth accessing underneath the gearboxes, so I didn’t leave any holes.
-The chassis was intended to be used with polycord, but we had problems with slipping so we had to switch to chains in the middle of our first district competition. However, the center-center distance between wheels was not set with chains in mind, and was at the worst possible distance, where the chains would fall off with some driving, but there was not enough slack to remove a link. Now, the axles rest in removable blocks, which can be replaced with new blocks that have the hole drilled in a different location, making it easy to change the wheel spacing.
Cool I believe I am the one driving the Generator to Glacier Peak and the Forklift driver for that event as well as probably being a Robot inspector there. So I’ll look for your team.
