Is your frame tough enough for FIRST?

[vivek16]

Originally Posted by Billfred

For the good of the order (since I can't think of any such cases), what are those limited exceptions where acrylic is used? (1618 used it as side panels its rookie year, but wised up quickly following that.)

We used acrylic last year to cover up our electrical board. Lexan would probably have been better. The plexiglass cracked due to improper hole drilling. It worked though. If you saw last year's robot you would understand.

-Vivek

EDIT: Our frame has always been plenty strong for us. I don't care what anyone says, the kitbot frame is a beast.

[ComradeNikolai]

We used the kitbot frame this year and it held up well. The frame suffered virtually no damage, but our bumpers sure got ripped up at the Kettering Rookie Competition (the judges at Buckeye were very surprised by how much damage we had from it; it was brutal, and we were tipped a few times with no penalty called).

However, I know it can withstand a good blow without bumpers since I was test driving it after we/I got the drive code running, and I went in full reverse . . . into a metal column in our school lobby. The battery casement came off (secured with one screw at that time, but that was fixed), but the pole suffered a chip and the frame had no damage.

[Doctorwho]

On 467 we used a unibody design this season that used the skin to support the internal components without a frame. it worked pretty well as it was light weight and durable. It took the force of being flipped twice at the Connecticut
regional without any dents or damage, our bot was so light that we had to bolt
a 14.1 pound steel plate to the bottom to stabilize it.

Frame, pre-construction:

http://www.team467.org/gallery/main...._itemId=512177

Final Bot:
http://www.team467.org/gallery/main...._itemId=512365

[SlaminSwimster]

Originally Posted by artdutra04

Was the "plexi" acrylic or polycabonate (Lexan)?

The reason I ask is that while they look similar, acrylic can shatter like glass, whereas polycarbonate is much stronger and normally it should never shatter (unless you spill Loctite on it). The only "downside" to polycarbonate is that it is more expensive than acrylic.

On both the teams that I mentor, acrylic is almost never used on a FIRST robot with only a few very limited exceptions, as polycarbonate is the preferred "plexi" material.

I'm pretty sure it was polycarbonate but i'm not sure. It didn't shatter exactly but it cracked apart.

[vivek16]

Good way to distinguish between polycarbonate and plexiglass:

Place a corner of it on the end of a table, clamp down the other side, and have a good whack at it with a hammer (hard). If it didn't break, it was polycarbonate.

-Vivek

[R.C.]

Or try to cut it with a jig saw and if it cracks then its plexi

[AndyB]

Originally Posted by vivek16

Good way to distinguish between polycarbonate and plexiglass:

Place a corner of it on the end of a table, clamp down the other side, and have a good whack at it with a hammer (hard). If it didn't break, it was polycarbonate.

-Vivek

Haha. Real efficient Vivek... I like it.

We used acryllic as our electrical panel. We have a laser on campus that we can use to cut acrylic which takes the error out of drilling holes. We can model it up exactly as we want the board in CAD and then send it straight to the laser. We can even do etching with it if we want.

[artdutra04]

Originally Posted by Billfred

For the good of the order (since I can't think of any such cases), what are those limited exceptions where acrylic is used? (1618 used it as side panels its rookie year, but wised up quickly following that.)

190 used an acrylic tube for the inside of its custom built high power slip ring, because we needed a plastic tube with an ID equal to the OD of the aluminum tube used for the elevator. This piece of acrylic was merely to mount the copper rings on and to act as an insulator.

[AndyB]

Originally Posted by Billfred

For the good of the order (since I can't think of any such cases), what are those limited exceptions where acrylic is used? (1618 used it as side panels its rookie year, but wised up quickly following that.)

Low impact areas where cost is a factor. Electrical panels, covers, etc... are great uses for acrylic.

[vivek16]

I would assume acrylic is a lot more common for rookie and some of the less better off teams because of the inexpensiveness and availability as compared to acrylic.

Heck, I hadn't even heard of the goodness that is polycarb until this year and we have yet to use it outside of the toughboxes on our bot.

-Vivek

[fuzzy1718]

Everyone is talking about aluminum and plexiglas, does anyone use an all steel frame other than us?

[Doctorwho]

Steel, while being very durable and relatively inexpensive is heavier than aluminum and polycarb. Most teams prefer these alternative materials because it gives the a larger weight allowance for other parts of the robot such as the drive train or the manipulator

[AdamHeard]

Originally Posted by fuzzy1718

Everyone is talking about aluminum and plexiglas, does anyone use an all steel frame other than us?

I believe both 269 and 1501 have used welded thinwalled (.035" sounds about right iirc?) chromoly tubing for frames before. \

The thing is, to get steel tubing to be light enough, it has to be very thin. This makes it a lot harder to work with in general.

[R.C.]

Originally Posted by AdamHeard

I believe both 269 and 1501 have used welded thinwalled (.035" sounds about right iirc?) chromoly tubing for frames before. \

The thing is, to get steel tubing to be light enough, it has to be very thin. This makes it a lot harder to work with in general.

Yeah i prefer to use aluminum tubing instead of steel.

[ComradeNikolai]

I believe we had a significant amount of steel on our superstructure... someone on our team decided it was a good idea. Next year I'll be pushing for a lighter material: we barely came in at 119.2 after lightening, but it was 119.9 before elimination rounds.