15 lb. hollow drum bot??

Hello!

I am new to these forums, and I am currently in the design process for my second robot for my team. The one we used this year was thrown together real quick with a 2.25 in. diameter solid aluminum drum with bolt heads as teeth. I'm going for a 3 inch drum this time now that I have more time to think, but I still want to have mobility be a high priority (we placed 5th out of 35 with a robot designed basically in two weeks, but we had a fast drive system so we did pretty well).

Basically I was wondering for weight purposes how I would construct a durable hollow drum 3 inches in diameter? Thanks!

Tubing

Right, but how would i put it together so that the drum won't come apart?

JohnnyGTR34 wrote:

Right, but how would i put it together so that the drum won't come apart?

out of flat stock aluminum make up end caps
also you want to use 3/16 or 1/4 thickness tubing

Generally, the challenging part is to install teeth of some kind in a way that can deliver more damage than they take.
I do not have (somewhat asinine) perfunctory way to tell you how to do this.
(Sorry for the snarky way I replied earlier.)

To be honest, our team really has not developed a great way to install teeth in a tubing drum yet. We have tried S7 teeth that are bolted into threaded holes in the aluminum. We have also tried installing them into a milled groove in addition to the bolts. We have made teeth that stick out through openings all the way through the tubing. We once even had aluminum teeth milled out of a much thicker tube, then added steel teeth in front of them.

All eventually have broken--either the teeth or the drum.

His Senior year, Will Bales paid a small fortune to have a hollow one-piece S7 drum, with integrated teeth, manufactured out of a solid 6 inch cylindrical slug. It hasn't broken, but it also hasn't seen much combat, because he moved up to120lb that year and hasn't ever really gone back to it. His little brother is trying to revive it, so maybe by the end of the month we will have some idea if this works.

We use 3.5 dia .5 thick 6061 tube about 5" long, milled grooves and installed two pieces of s7 tool steel for teeth, run the bolts through the tube and add washers and nuts. Have used it for about 10 to 12 battles. replaced the teeth a couple of times, other than that not a problem with it. weight's 3.5 lbs

Thanks guys!

That sounds like a good idea. We were also considering having a solid drum like before except with bigger bolt heads attached. But I will definitely try S7 teeth with bolts running through and nuts on the end.

you also can't go wrong with grade 3 or 5 ti at about 32 to 38 rockwell, cuts back a little on weight and as strong if not stronger than steel