Chassis Connections

[548swimmer]

Our team uses bolts. What we have is a "modular" system of cross supports and drive "modules."

http://www.chiefdelphi.com/forums/sh...ad.php?t=85712

Each of the side plates is .188 aluminum (6061 T6 I believe) despite my best efforts to use .125...

The round spacers between the side plates are half inch aluminum round stock tapped with 1/4-20 on each end and secured with 3/4 inch panheads.

The square tubes run from outside plate to outside plate and are 1/8 wall (I keep pushing for 1/16...) with 2 inch long inserts tapped one inch deep 1/4-20 and secured with 3/4 inch panheads.

We have found this system to be fairly lightweight, especially if you use your spacers for axles. In addition to weight, the outermost module can be quickly detached from the rest of the chassis by removing the bolts in square tubes. For wheel/chain repairs, you can simply remove the outermost side plate.

[Hawiian Cadder]

we have always used the pancake design with aluminum plate. typically this takes around 150 metal screws. however when designing the robot this year we didn't really do the math and ended up with around 1400 holes. the box of screws, (2000 8-32 5/8 long button head) weighed almost 10 LBS. lock tight application for the whole robot took 5 people around 10 hours.

due to this, we are going for angle gussets with 1 inch box tube this year, hopefully it will be easier.

[JamesCH95]

Originally Posted by Hawiian Cadder

we have always used the pancake design with aluminum plate. typically this takes around 150 metal screws. however when designing the robot this year we didn't really do the math and ended up with around 1400 holes. the box of screws, (2000 8-32 5/8 long button head) weighed almost 10 LBS. lock tight application for the whole robot took 5 people around 10 hours.

due to this, we are going for angle gussets with 1 inch box tube this year, hopefully it will be easier.

I'd love to see a picture of this "pancake design" that used 10lbs of fasteners...

[rahilm]

This year, we used lots and lots of bolts. Our whole robot was basically various sizes of aluminum angle, so we just had angle inside angle bolted together with at least 2 bolts.

In the past, we have welded (only drivetrains), used gussets and rivets, and used 80/20 extrusion.

[PAR_WIG1350]

1350 uses bolts and nyloc nuts everywhere. It makes prototyping easy since we can easily build, test, and rebuild any part (easy until you find you built an integral structural or functional component directly over the bolt head you need to get to which can't be moved since EVERYTHING is bolted onto it, but thats OK, it builds dexterity). The real issue comes when everyone is fighting to use one drill bit or wrench that is the only one of its size and happens to be the correct one for EVERY bolt on the robot.

We also like zip-ties, but not so much for the chassis.

[s_forbes]

Through the years, we have built a bolted chassis, a riveted chassis, a glued and nailed chassis, and a welded chassis. All have held up to the stress of 2+ regionals without issues.

You can build a chassis that is strong and light in countless ways if you put enough design work into it. The thing you need to ask yourself is how you can best utilize your resources to build a strong/light chassis as quickly as possible. The faster you can finish fabricating it during the build season, the better.

I would also encourage you to take a look at the big picture when you are designing your chassis. Robot functions change drastically from year to year and greatly influence the design of the drivetrain (hence why we have gone through so many different forms). Remember that you are designing and building a complete robot; the chassis and manipulators are not always independent systems.

[Jeffy]

We have welded our chassis all of our years as a team. For a while our rookie year we were going to use the kit chassis, so we bolted it together, welded, then removed all the bolts. I don't remember the specific weight of the bolts and supports, but it was well over 5 lbs. We ran into trouble with the kit frame warping during the welding, so we made our own, and have done so every year so far.
If you are trying to decide what to do, I would definitely weld to save some weight. The next best option (imho) are aluminum rivets. I don't know enough about them or have enough experience to give a big recomendation, but I have seen them work very well.