Unibody/Monocoque Construction

[Sam N.]

Does any team have any experience or knowledge concerning unibody construction? Could anybody compare the construction method with welding or other styles of chassis out there?

My team is researching different chassis construction methods and any input concerning the above mentioned technique is appreciated.

Sam N.

[MrForbes]

look up team 1501....

[Colin]

Team 1501 uses monocoque construction in their robots. Search CD media for some pictures of their robots. They always come out with a very sleak and professional looking robot. Sorry already said.

[woody]

Team 33 has used monocoque construction in our last two robots. We use .063 aluminum and are able to make a very rigid frame for roughly 9 pounds. You can contact Jim Zondag for details.

[Goober!!!]

Yea 1501 is all monocoque and if you need any help with learning ask us and you can go to are website www.huntingtonrobotics.org and people their and it gives more info on it to so hope you will go monocoque because its fun and easy to learn and it also comes out with one beautiful bot!!!

[chris31]

Yep, 1501 would be a team to look at. There was a good section on them in "Behind the Design" which I just bought yesterday.

[Chris_Elston]

One of the students made up this page and they did a video. I dunno if that helps or not..

http://www.huntingtonrobotics.org/in...d=1&Itemid =2


Video Link
http://www.huntingtonrobotics.org/in...=1&key=1&hit=1

[Chris_Elston]

No skin pictures of 2005 robot.

[AdamHeard]

Originally Posted by Chris_Elston

One of the students made up this page and they did a video. I dunno if that helps or not..

http://www.huntingtonrobotics.org/in...d=1&Itemid =2


Video Link
http://www.huntingtonrobotics.org/in...=1&key=1&hit=1

The page is pretty impressive and well done for a student.

Just curious, since then have you moved on to designing the parts with the sheet metal features of inventor, or do you still make a 2d sketch and then transfer to plywood? Or was the plywood just a medium to transfer the unfolded sheet metal pattern to sheet metal?

[Chris_Elston]

Originally Posted by AdamHeard

The page is pretty impressive and well done for a student.

Just curious, since then have you moved on to designing the parts with the sheet metal features of inventor, or do you still make a 2d sketch and then transfer to plywood? Or was the plywood just a medium to transfer the unfolded sheet metal pattern to sheet metal?

2005 and 2006 robot are all 2D 1:1 scale plots transferred to plywood, then sheet metal.

2007 robot was drawn in 3D for the first time. I can't remember if they plotted and used the 3D drawings from inventor or not. One of the students was showing me the sheet metal tool in inventor (me personally I don't have a clue how to use the software), and acutally I think it was a student from team 1720 that was showing me ;-)

2007 was different in a way that it was alot of tubing, the same tubing they use in the landing gear on the airplane. Chromoly tubing, then the wings are sheet metal with rib spars. So it was a bit different than the 2005 and 2006 robot but still based on airplane parts. ;-)

[AdamHeard]

Originally Posted by Chris_Elston

2005 and 2006 robot are all 2D 1:1 scale plots transferred to plywood, then sheet metal.

2007 robot was drawn in 3D for the first time. I can't remember if they plotted and used the 3D drawings from inventor or not. One of the students was showing me the sheet metal tool in inventor (me personally I don't have a clue how to use the software), and acutally I think it was a student from team 1720 that was showing me ;-)

2007 was different in a way that it was alot of tubing, the same tubing they use in the landing gear on the airplane. Chromoly tubing, then the wings are sheet metal with rib spars. So it was a bit different than the 2005 and 2006 robot but still based on airplane parts. ;-)

You guys are using Chromoly? wow... that stuff is heavy, I can't really tell from some pics I just looked up, but what size tubing was it and was it worth it compared to a larger piece of aluminum tubing? Is it something worth doing again? I'm not criticizing, I'm just trying become more familiar with construction techniques


Don't put off learning CAD... I did for two years and it was totally not worth it... It seemed intimidating to me, but I just took the tutorials in inventor and fiddled around; Now I've become pretty good at it. If I can do it as I high school student, you should take some time to learn it. Unless you're not a M.E.; in which case, sorry for harassing you.

[Chris_Elston]

Originally Posted by AdamHeard

You guys are using Chromoly? wow... that stuff is heavy, I can't really tell from some pics I just looked up, but what size tubing was it and was it worth it compared to a larger piece of aluminum tubing? Is it something worth doing again? I'm not criticizing, I'm just trying become more familiar with construction techniques


Don't put off learning CAD... I did for two years and it was totally not worth it... It seemed intimidating to me, but I just took the tutorials in inventor and fiddled around; Now I've become pretty good at it. If I can do it as I high school student, you should take some time to learn it. Unless you're not a M.E.; in which case, sorry for harassing you.

It's not as heavy as you think. Our whole tube frame was somewhere around 36 lbs I think. I am not for sure on that. But I was very impressed. The biggest down fall of the tubing was the welding. We had one mentor and two students that could weld it, the process was a bit slower than 10 guys with rivets guns for sure, but I can't complain, the end result was amazing to me.

I am not an M.E. I am a Controls Engineer. About the extend of my cad is AutoCad Electrical 2008 (<<<--use to be VIA, until AutoDesk bought them out) and I like Google Sketchup. I like Sketchup and have been learning the concept of 3-D drawing, maybe that will carry over to Inventor, if I ever have a need to use it. So far, drawings electrical prints in 3D some how doesn't fit into my schedule so far :-)

Although I wonder if the electricans would freak out if I gave them a 3D wiring diagram???? hmmm.....

[robotguy67]

I was the mentor that helped with the welding of the frame last year. Chromoly can be built very light if done properly. That's why it's commonly used in race car chassis, high stress points in air frames, etc... Given our design goal (killer lift bot), a fully monocoque frame was not appropriate last year. The tube frame could be designed much faster than it would have taken to do it fully monocoque. Aluminum tubing could have been used, but we didn't have the capability to weld it in-house and I'm not sure it would have ended up much, if any, lighter keeping the same strength. The total weight of the tube structure was #25, I believe - and this included the 8 big rollers, 16 bearings and 16 pillow blocks for the main lift. In all but a few small tubes, the wall thickness was only 0.035". This kept the weight down and all the tube triangulation made the entire frame and lift very stiff. The main tubes of the center tower are 1" OD. All the other tubes are either 5/8" OD or 3/8" OD. At one time there was a video on youtube of our bot lifting a 300lb guy on one wing without any showing any flex. As the primary designer of the tube structure I would definately use chromoly again if apprpriate for the application.

Mike

[AndyB]

Originally Posted by Chris_Elston

It's not as heavy as you think. Our whole tube frame was somewhere around 36 lbs I think. I am not for sure on that. But I was very impressed. The biggest down fall of the tubing was the welding. We had one mentor and two students that could weld it, the process was a bit slower than 10 guys with rivets guns for sure, but I can't complain, the end result was amazing to me.

I am not an M.E. I am a Controls Engineer. About the extend of my cad is AutoCad Electrical 2008 (<<<--use to be VIA, until AutoDesk bought them out) and I like Google Sketchup. I like Sketchup and have been learning the concept of 3-D drawing, maybe that will carry over to Inventor, if I ever have a need to use it. So far, drawings electrical prints in 3D some how doesn't fit into my schedule so far :-)

Although I wonder if the electricans would freak out if I gave them a 3D wiring diagram???? hmmm.....

For the past 4 years we have used chromoly steel (.035 thick) tubing for our robot frame. It is slightly heavier than aluminum and is 3 times as strong.

Pics:
04: http://www.cooneyrobotics.com/photos/2006/100_0277.JPG
05: http://www.cooneyrobotics.com/photos/2004/2004-7.jpg
06: http://www.chiefdelphi.com/media/photos/23825
07: http://www.chiefdelphi.com/media/photos/28616

Where we buy it:http://www.aircraftspruce.com/catalo...4130square.php
(Correct me if I'm wrong Ricky)

The frame you see for the 07 bot weighs around 12.5lbs