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IndySam
12-23-2010, 10:04 AM
We have hooked up with a local company that makes large dies for cutting corrugate.

The will supply us material for free and laser cut whatever we want.

The plywood they use is high grade maple in 3/8" 1/2" and 5/8" thicknesses.

Looks like we will be building a wood robot :)


Anyone have any helpful tips and tricks for this kind of construction they would like to share?

craigboez
12-23-2010, 10:53 AM
Team 2471 has made a few robots that have been predominantly plywood. They may be able to offer some insight.

Rosiebotboss
12-23-2010, 10:53 AM
A couple of things come to immediately-

gusset, gusset, gusset everything.

RAGE, Team 173 is known for their wood drive bases. PM me and I'll send along contact info for their mentors.

Also, a few years ago I saw a team from Maine that built their complete robot from very high end plywood, I think it was 7 or 9 ply baltic plywood. I cannot remember the team number....anyone else??

SteveGPage
12-23-2010, 10:58 AM
A couple of things come to immediately-

gusset, gusset, gusset everything.

RAGE, Team 173 is known for their wood drive bases. PM me and I'll send along contact info for their mentors.

Also, a few years ago I saw a team from Maine that built their complete robot from very high end plywood, I think it was 7 or 9 ply baltic plywood. I cannot remember the team number....anyone else??

That would be the Riot Crew, FRC 58, from South Portland, ME. http://www.riotcrew.org/

Steve

JamesCH95
12-23-2010, 11:31 AM
95 has made many wood chassis robots. We found the most robust way to attach the panels together was with bolts and 90deg angle aluminum. The angle brackets can be drilled on a drill press, clamped in place on the plywood, then just match-drilled through. Our recipe was 1/2" plywood with 1"x1"x1/8" angle brackets and 1/4-20 fasteners, CNSK heads on the outside for a nice smooth finish, and hex-heads with washers everywhere else. 3"-4" of space between each bolt, FWIW.

Have fun!

Edit: we also used the 7-layer baltic plywood, it is good stuff.

ebarker
12-23-2010, 12:18 PM
If you are doing a plywood robot - "heck yea" on using baltic birch !!

JB987
12-23-2010, 12:56 PM
Check with Jim, Team 1726...they make great wooden bots.

TestEngr571
12-23-2010, 01:18 PM
Team Paragon 571 has been thinking "inside the wooden box" for 10 years !!!

Jeffy
12-23-2010, 01:42 PM
Team 1771 created an excellent wood chassis.
http://www.chiefdelphi.com/media/photos/34907

Chris is me
12-23-2010, 01:51 PM
1726 frames are awesome and a great inspiration to anyone making wood frames.

If you don't like cantilevering wheels, 1771 also makes fantastic rigid frames. I saw that thing in Atlanta and it was solid as a rock. Maybe a little heavy but with so much material the frame could take anything.

Baltic Birch!!!

MrForbes
12-23-2010, 02:10 PM
We only made one mostly wood robot, it worked well. We glued/stapled the main chassis structure, taking time to figure out how to make the thickness of the different parts so they'd be strong where needed, and light where we could get away with it, and also be able to attach the parts together--for example using thicker wood where staples needed to go into the edge.

Also baltic birch is strong, but it's kind of heavy, you might find that there are places in the robot where it would be better to use a less dense, thicker piece of plywood.

1771's construction method is really neat, with the interlocking tabs. Like an R/C airplane fuselage...

DonRotolo
12-23-2010, 04:20 PM
I second the interlocking tabs.

My father (nor 92) owned a company that did die-cutting of cardboard. Back then, it was all hand-cut, but some of those dies are amazing.

For those unfamiliar, you first cut a thin line through plywood, then fill the space with a strip of razor steel "rule". Squish the finished die onto a piece of cardboard, and viola', you get cutouts. Think jigsaw puzzle. They used to get something like $10 an inch, decades ago. A typical 22 x 34 die might have 1000 inches of rule...

Consider using thin plywood with a fiberglass/epoxy coating where strength and low weight are a consideration. Do the math correctly, and wood can be pocketed like metal for weight savings without strength loss.

MrForbes
12-23-2010, 05:34 PM
For those unfamiliar, you first cut a thin line through plywood, then fill the space with a strip of razor steel "rule". Squish the finished die onto a piece of cardboard, and viola', you get cutouts. Think jigsaw puzzle.

So that's how it works....I always pondered that while gazing at jigsaw puzzles. I was on the right track, but had never figured it all out, and never remembered to look it up when there wasn't a puzzle in front of me.

Bertman
12-23-2010, 06:00 PM
418 has done lots of work with wooden chassis and wheels. I personally have some experience with lightweight wooden boat construction. PM me if I can help in any way. a couple of years back we made a wooden chassis out of red oak (7 lbs) that is still knocking about as out promotion robot (should still be on CD someplace) and has had zero structural failures after many crash tests.

JaneYoung
12-23-2010, 06:04 PM
a couple of years back we made a wooden chassis out of red oak (7 lbs) that is still knocking about as out promotion robot (should still be on CD someplace) and has had zero structural failures after many crash tests.

Is this (http://www.chiefdelphi.com/media/photos/32054) it, Tony? I think this was the one made on a dare with members of the team, discussing the strength of wood.

Jane

sdcantrell56
12-23-2010, 07:00 PM
As far as I know we (1771) are the only team to do laser cut plywood construction so far. I will be happy to share all that we have learned as well as alternative woods and joining methods. You can without a doubt build a solid, light f4ame from plywood that requires nothing more than wood glue for assembly. Send me a pmwith your contact info and I will b happy to get in touch with y'all after christmas to talk through the design and construction aspects. In the mean time look at our pictures on here on here and also my pictures on picasa. My username on there is seanc56.

Karthik
12-23-2010, 08:05 PM
Team 1346 has done some great work with wood robots over the years. Jason Brett (dtengineering on CD) should be able to provide lots of details. Search his posts and I'm sure something will turn up. Here's a picture accompanied by a detailed explanation:

http://www.chiefdelphi.com/media/photos/35536

czeke
12-23-2010, 09:37 PM
Team 1091, this season, is planning on using bamboo for our chassis and mechanism. It's very strong and light weight.

Chris is me
12-23-2010, 09:50 PM
Team 1091, this season, is planning on using bamboo for our chassis and mechanism. It's very strong and light weight.

What's your COTS bamboo source?

DonRotolo
12-24-2010, 01:17 PM
Can things you grow yourself be COTS? Makes me wonder.

Dick Linn
12-24-2010, 01:26 PM
Team 975's first robot was wood - cheap plywood for the most part (low budget). The drive wheels were made from glued-up 1 x 4 pine. There were a lot of material restrictions back then.

czeke
12-25-2010, 10:06 PM
Chris, having been in Wisconsin, you'll know that there aren't very many bamboo stores available, much less at this time of year. We managed to locate , on the internet, a business called Bamboo Habitat, which sold us about 10 pieces each, of 3/4", 1", and 1 1/4" diameter, by 8' long Tonkin bamboo. We're currently experimenting with it, to determine what kind of joint connectioning, we're going to use. We aren't even certain, if FIRST will allow to use lashing, at the corners.