Plywood - talk to us about how you use plywood

[dtengineering]

-- Plys seem to be thinner and they are doing more and more cross ply work. Is there a common way to ask for this?

Baltic Birch is my "grade" of choice, however my local plywood shop also introduced me to "Russian Birch" plywood, which they said was less expensive because the glues were less water-resistant. You can also take a look at radio control modelling shops (or even airplane shops) for a range of plywoods. My main concern, rather than the number of plys, was always that they be relatively void-free. http://www.aircraftspruce.com/menus/wp/plywood.html

-- Final surfaces are now coming into play, used to be birch only, now more wood types. Plus double sided finished sides are available for a reasonable cost. Where do you go for these items? whats the right way to ask for nice surfaces.

S2S has already been mentioned, I believe you may also see it as "G2S", short for "Good 2 Sides". My experience is that most of the high-end, low-void plywoods might have one side that is slightly better than the other, but both sides are usable.

-- Laser cut is the art - +/- a 64th. So tight fit is possible. Who cuts this for you? Is it very expensive? What CAD do I need to supply?

Laser cutters are becoming more and more affordable. Ones that would be useful for FRC chassis sized pieces are starting to come down around $10k or so... more than a team might spend, perhaps, but a local hackerspace or similar community might have them. Commercial providers are also seeing the potential in this business http://www.umake.ca/ but your best bet, of course is to find a local college or woodworking business with a laser cutter and an interest in sponsoring your team. The cool thing about laser cutters is that the cost of operation is essentially zero. Photons come pretty cheap.

-- Other cuts -- I have a carbon tipped 1/64" blade to make clean and smooth cuts. Is the laser cuts as good ?

The advantage of the laser cut is the CNC speed and precision. We didn't use a laser for our machines, but rather a CNC router. (I do, however, bow to 1899 and their laser-cut awesomeness.) Mechanical cuts will likely be slightly cleaner, and in thicker pieces where the laser focus comes into play, may be slightly more square and will be free of the "burnt edge" finish, which you can see as either a "feature" or a "bug", depending on whether the burnt edge looks good in your final product.

-- Assembly -- Fine miters and dados with some screws worked. Now there is lots of camber bolts/lock devices. What do you use to keep things from coming apart. I'd like to take this apart, so "glue" isn't a primary option. I'm good with 'biscuits" for support, but don't want to glue them, unless I'm building a larger surface. I've been surfing the Blum catalog, lots of choices there

There are so many choices... and so much of the choice depends upon design. For a simple and robust design in 2010 (our last FRC bot) we just ran a piece of 2x2 on the inside corner joints and screwed the machine together. Key structural pieces that we weren't going to disassemble were glued up with white glue. It was more than enough to smash the aluminum bots around pretty good. http://www.chiefdelphi.com/media/photos/34972 (and, just for the record... most of the cuts on the machine in that link were done using table saws and drill presses... only a few crucial connections were made using a CNC router... no laser was used in the design.)

-- Finish -- I'm a master at raw edge finish with glue and veneer. I see the T plastic and some T wood edging available. Do you finish the raw edges or go "its a robot that kicked you in points, deal with the edges"

Baltic Birch offers up some nice edges, especially as the low void content allows you to router half-round and quarter-round edges, but the key thing to building with plywood is to make it look nice. Well, make it work does come first, but then make it look nice. The key detail is to stain and seal the wood before it has a chance to get dirty. Unlike metals, wood is porous and will absorb oil and grease at the first opportunity. My experience is that a nice clear coat finish (stains and dyes can help achieve team colours while letting the wood grain show through) and good sanding job will catch the judges eyes every time. We have received at least three engineering awards over the years that specifically recognized our use of wood. When I had to give up mentoring and took up volunteering instead, I spoke with one of the judges and he told me, "Oh... you're from the team that always used wood. Lots of teams build with plywood, but you guys made it look NICE."

So let your woodworking aesthetic come through, and remember that wood comes in many more forms than just plywood! http://www.chiefdelphi.com/media/photos/22924

Jason

[Clem1640]

We have access to laser cutting via a sponsor (Edgetech). Results are extremely accurate (based on CAD file), but edges are scorched. We've used laser cutting sucessfully for plywood, polypropylene and steel. I love the results when cutting complex shapes and patterns and multiple pieces.

We would only use laser for complex patterns. For most of our plywood cutting, we use saws.

[HumblePie]

If you don't have access to a CNC router, but do have access to a 3D printer, here's a technique we've used.

Print a template of the part you'd like to (accurately) produce, at least 4mm thick (and in multiple interlocking pieces if the piece is larger than your printer envelope). Fasten the template to a rough cut piece of plywood using screws or double sided tape, and run the sandwich across a router table with a pattern trim bit installed (A team member with woodworking experience is a plus for this part). The resultant part is accurate and has a nice clean, smooth edge.

We used this technique for making our shooter rail (2 pieces of 3/4" oak plywood laminated together), and a support ring for the feeder bucket.

[JamesCH95]

Team 95 has used plywood chassis numerous times in the past. Some pictures:

http://www.frcteam95.org/wp/picasa2/...aszetaArchives

http://www.frcteam95.org/wp/picasa2/?album=Archives

Very simple implementation: plywood sheets cut to size usually with a combination of table, circular, and jig saws, and then bolted together with 1x1x0.125 angle aluminum and 1/4-20 bolts. Countersunk bolt heads on outside surfaces of the robot.

Probably not the lightest assembly method ever, but every robot built this way survived quite nicely in the days before bumpers. It is also very cheap and easy to assemble and build with only basic hand tools (circular saw, jig saw, and a drill will get you there) and doesn't require a ton of precision to work well.

9-layer baltic birch is what we've used in basically every instance. Easily available at Home Depot and other hardware stores, very strong, and comes with a good finish.

[GBK]

We have used plywood for something for the last 4 years. In Logomotion we used 3/4 in plywood for fins to line up to the tower to deploy the mini bot. Worked great until we got to MSC and broke 5 of them, all on the same side. I almost felt bad for the student that spent almost an entire day at MSC making replacements. We of course did not bring enough plywood to make all the replacements, but were able to scrounge enough. I remember team 141 was ready to tear apart the pier awards they made to hand out so we could have wood to make replacements. (thankfully we did not have to go to that extreme) The student ended up making one out of 1/2 in plywood framed with aluminum angle. Somehow we never broke that one. Bent the heck out of the bracket that mounted it to the frame though.

[bbradf44]

We usually use wood for our electrical board in case something gets overlooked, crossed, done wrong by a freshy it won't effect the metal components of the robot. And its cheap

[Jaxom]

Originally Posted by fb39ca4

Speaking of plumbing supplies, there was a team at Championships this year that had a PVC pipe chassis. Anyone remember which team that was?

1810 from Mill Valley HS in Shawnee KS was in Curie. They've been using PVC as a primary building material for years. Pretty much a fixture here in the Kansas City region.