Is your frame tough enough for FIRST?

[JesseK]

Let's see if I can get this in under the radar...

As soon as our prototype frame was completed with all components assembled, I intentionally ran it 10 fps into the concrete wall of the high school with no bumpers. Other than a ding on the outer aluminum frame at the impact points, everything was ok. Then for the production frame, we rearranged some of the 1" aluminum extrusion to allow for an open front. Again, the same quality assurance test was completed, but this time at 12fps and testing was only done on frontal impacts. The result was a small dent in the front exposed tubing, but nothing severe like we had our first year.

During front impacts of the competition season, these aluminum bars became more and more crushed, which leads me to believe they served as a crush zone that made up for the lack of bumpers. In hindsight I'm glad we had them because that meant there was less shock force delivered to the rest of the components. While I don't condone running full speed at a wall to test your frame, I definitely think quality assurance tests are quite helpful. Plus they make for great videos...

[M. Mellott]

Originally Posted by fuzzy1718

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

We used Ultrasteel (thin-wall steel sheet, dimpled for added strength, bent by the manufacturer into 8"-wide C-channel) for our ramps in '07. It allowed us to make ramp panels with a very minimal aluminum frame underneath (strickly for hinge mounting). Worked great, plus it was easy to repair if it got bent--just hammer them out.

We usually use welded aluminum for our base frame. Using steel as a base frame would be too heavy--maybe small pieces to strengthen joints that aren't being welded.

[R.C.]

Any link to the ultrasteel???

[M. Mellott]

Originally Posted by rc_cola1323

Any link to the ultrasteel???

http://www.dietrichindustries.com/ultrasteel/menu.asp

We had always wanted to use a locally-manufactured product on our robot to further gain community interest in our program and FIRST. A parent of one of our students works at Dietrich in Warren, OH and helped us aquire a supply of framing members.

[qnetjoe]

When it come to frames, your number one enemy is impulse (force x time). Even you most violent collision inside of first cam be modeled by

F = (2*(M*∆V))/t + M

So when design a frame you need to consider ways to maximize the time over which the impulse occurs. This reduces the force applied and thus the stress in the element. Bumper are just one method to reduce the total force acting on a frame. Rubber Cushioned Pillow Block are another.

I recommend using iso clipping inside of your cad package to check to see the effect that impulse has on your frame.

[Alex.Norton]

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.)

On our 2007 bot we used acrylic to hold omniwheels laterally in place since we could use a very thin sheet, had a laser cutter for it, and couldn't find any other fender washers that would do the job. Since they were omnis the acrylic never saw and force and we never had a piece shatter, even after we destroyed the wheels that were being held in place.

[R.C.]

Does anyone have pics of their super cool frames???

[Lions for First]

http://www.phxhs.k12.az.us/images/pa..._id=1203612925

this was our frame

[popo308]

Going into the season this year we had a very pretty frame... but now that the season is over its not so pretty. We used 1/16 wall 1x1 tube for our frame. It held up pretty good for us all year. the bottom rails aren't so pretty anymore from robot arms and appendages getting under the bumpers and hitting the frame, also the bumpers were just high enough so if we accidentally hit the dividing wall in hybrid or teleop the bottom supports for the overpass would get under there and beat our frame up pretty bad... Ill have to see if i can get some pics of it tomorrow?!

[artdutra04]

Originally Posted by rc_cola1323

Does anyone have pics of their super cool frames???

Here's a photo of Team 190's 2008 base chassis. I's not a good general all-purpose frame; rather it was highly customized for our design strategy.

http://img142.imageshack.us/img142/7225/1003436io0.jpg

It's four motor (3 CIM, one Globe), 4WD drive (two custom omni, two Colsons). It's designed to allow our robot to drive right up against a wall, then drop the rPOD to scoot sideways into it, in order to position ourselves perfectly for our "unique" trackball strategy.

[samir13k]

our robot's gyro freaked on us, and pushed a 250+ pound table that was not meant to move. It took two adults to just push it back! ... and the other day at the 4-H fair, we built a robot that you can ride on. the only kill switch that worked was on the actual bot itself (in the form of a breaker, the switch on the remote would only make it lose the signal.) We were unpacking our trailor, and i was using the bot to haul around crates (approximately a 100 lb. load ) when the gyro also freaked on us. It ended up taking out 2 and a half boothes. Luckily no one was there due to the fact that it was before the fair started.

I know you are thinking about why the kill switch on the remote did not work. it was because we were using a vex Robot Controller so it was never meant to operate on such a big scale.

[R.C.]

Originally Posted by samir13k

our robot's gyro freaked on us, and pushed a 250+ pound table that was not meant to move. It took two adults to just push it back! ... and the other day at the 4-H fair, we built a robot that you can ride on. the only kill switch that worked was on the actual bot itself (in the form of a breaker, the switch on the remote would only make it lose the signal.) We were unpacking our trailor, and i was using the bot to haul around crates (approximately a 100 lb. load ) when the gyro also freaked on us. It ended up taking out 2 and a half boothes. Luckily no one was there due to the fact that it was before the fair started.

I know you are thinking about why the kill switch on the remote did not work. it was because we were using a vex Robot Controller so it was never meant to operate on such a big scale.

Do you have any pics of the robot itself?

[MrForbes]

Originally Posted by rc_cola1323

Does anyone have pics of their super cool frames???

blue painted pultruded fiberglass channel, with a riveted on sheet aluminum bellypan and corner gussets.

http://photos.project1726.org/thumbnails.php?album=28

[Doctorwho]

Team 467 Unibody Chassis. Although it has no real frame the unibody grants us an extremely light-weight and durable body.

Pics:
Construction:

http://www.team467.org/gallery/main...._itemId=511138
http://www.team467.org/gallery/main...._itemId=511236

Chassis with Skin attached:
http://www.team467.org/gallery/main...._itemId=512219
http://www.team467.org/gallery/main...._itemId=512201
http://www.team467.org/gallery/main...._itemId=512177

Final Product:
http://www.team467.org/gallery/main...._itemId=512353
http://www.team467.org/gallery/main...._itemId=512356
http://www.team467.org/gallery/main...._itemId=512365

[samir13k]

we call this the "Magic Carpet"
we built it in 3 days at the 4H fair using a vex controller. It was the one that took out the boothes. (it had heavy tubs on it at the time)

http://i213.photobucket.com/albums/c...picture048.jpg

And this is our 2008 robot. it was the one that pushed over the heavy table.

http://i213.photobucket.com/albums/c...8c5211e3fe.jpg