Plywood - talk to us about how you use plywood

[Foster]

Back in the 70's everything I owned would fit in the back of a VW Micro bus. A Combination of being a hippy (I had Wildstang shirts before there was a Wildstang) and building things that were minimal in design. For example, the stereo rack of turntable, receiver, 8 track (you get a smack for laughing) and dual cassette player was tensioned 2*2" between the floor and ceiling supported by 1" birch rods. Gave the hovering in mid air look. Psychedelic

Other items was made out of birch plywood. Yes think IKEA, but nice plywood not particle board. All my stuff came apart, stacked flat, fit in the VW microbus.

Fast forward to today. Lots of books / sites about plywood construction. I need to build some things, but want to learn the state of the art, I'm not into using my Japanese micro cutting saw.

The teams that build with plywood help me with:

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

-- 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.

-- 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?

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

-- 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

-- 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"

Thanks for your help!

Just as an aside, if you can't answer the question, but you build robots that are 51% wood, post that you use wood.

[DonRotolo]

I can only competently answer a few of these:

S2S (Sanded two sides) is the term for very smooth on both sides.

Aircraft Plywood is one term for high-ply material, 'hardwood plywood' is the term for what used to be available only in Birch (but now in oak, maple and cherry for example).

Both are available at my local Lowe's, and the really thin aircraft stuff is available at Michael's and A C Moore (craft store chains here in NJ).

Lasers leave a charred edge, most saws don't. Straight cuts are superior on a table saw, curves and complex shapes are trivial for a laser. But thick material (3/4") isn't easy on some lasers.

[Ian Curtis]

We have not used that much of it in the past, but our pit neighbors in Seattle did. 1899 had a gorgeous plywood robot, and we plan on borrowing some of their construction techniques this season.

I've attached a few pictures I took at Seattle this year. For robot building they had cycled through a bunch of different kinds, but ultimately settled on this 5mm sanded ply, which is actually slightly thinner than 5mm. It is super cheap (under $15 for a 4x8 sheet). They sealed it as sheets, and then just put it in the laser cutter and got out puzzle pieces. In cutting the joints they didn't consider the kerf of the laser and the joints were definitely plenty tight.

Because the wood is so cheap, they built multiple iterations of their frame. I forget the exact number but it was at least five. Due to the puzzle-piece nature they also had some fun figuring out the best order to put it together. To hold it together they buy wood glue in 5 gallon buckets, and spent a sizable amount of money on Harbor Freight clamps. Anyone who went to their pit can attest that they had a lot of clamps.

If someone from 1899 is around feel free to correct me or send me a PM, because I've actually got a few more questions.

[fb39ca4]

Originally Posted by Ian Curtis

We have not used that much of it in the past, but our pit neighbors in Seattle did. 1899 had a gorgeous plywood robot, and we plan on borrowing some of their construction techniques this season.

I've attached a few pictures I took at Seattle this year. For robot building they had cycled through a bunch of different kinds, but ultimately settled on this 5mm sanded ply, which is actually slightly thinner than 5mm. It is super cheap (under $15 for a 4x8 sheet). They sealed it as sheets, and then just put it in the laser cutter and got out puzzle pieces. In cutting the joints they didn't consider the kerf of the laser and the joints were definitely plenty tight.

Because the wood is so cheap, they built multiple iterations of their frame. I forget the exact number but it was at least five. Due to the puzzle-piece nature they also had some fun figuring out the best order to put it together. To hold it together they buy wood glue in 5 gallon buckets, and spent a sizable amount of money on Harbor Freight clamps. Anyone who went to their pit can attest that they had a lot of clamps.

If someone from 1899 is around feel free to correct me or send me a PM, because I've actually got a few more questions.

1899 member here. You got most of that correct, except the plywood we used was slightly over 5mm-5.2 to be exact. We originally used wood that was 5.1mm thick, but it had issues with voids and the filler used in them not being cut all the way through, while the final wood we ended up using did not have that problem. However, our CAD model still had slots for 5.1mm wood in many areas, and we never got around to changing them after switching to the 5.2mm wood, which is why the joints were tight. Also, I believe we built eight chassis, including the competition one, and a backup chassis we bagged with the robot in case the main one was irreparably damaged.

[s_forbes]

One of the best robots I got to help design was made of plywood. Our chassis design used various thicknesses of baltic birch plywood (1/2, 3/4) depending on the load seen by each frame member. Some lower quality 1/4" plywood was used to brace the frame members. All were held together with good wood glue and long staples. We were fortunate enough to have a shop with good saws to get all the pieces cut precisely, and a pneumatic staple gun. 2009 was a year with low loads on the drivetrain, so this was a great material.

http://www.chiefdelphi.com/media/photos/32671

To my knowledge this is the only robot built with 2x4s and plumbing supplies to win a quality award. Krylon paint works wonders!

[fb39ca4]

Originally Posted by s_forbes

To my knowledge this is the only robot built with 2x4s and plumbing supplies to win a quality award. Krylon paint works wonders!

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

[donkehote]

We used layered plywood to make prototypes, such as our shooter this year.
Other than that, we dont really use much plywood.

A bandsaw is great for making curved cuts when you don't have a laser. smaller cuts may require thinner, wood specific blades, but other than that, bandsaw, table saw, and jigsaw are all the tools you need to make just about anything out of plywood.

My favorite for assembled/disassembled are dowels and screws. I made a locker organizer that was assembled in situ, and disassembled when you had to swap lockers. Just used dowels with some #8 screws to hold it all together. I could easily stand on the shelves in place (3/4 marine ply ftw) and it all came apart in about 5 minutes.

[Jay H 237]

We've never used much plywood, In the past we used 1/4" to fasten and support the electronic components since it made it easy to mount them but now we have been using a lighter corrugated plastic the past few years.

[avanboekel]

In the past 4 years I've been on the team, we haven't had any plywood on our bot (besides bumpers). We try not to use it in prototypes with high speed applications (our shooter this year for example). It causes far too much binding. Even in other prototypes, we rarely use it. We just find it easier and quicker to use other materials such as 80-20

[AdamHeard]

Originally Posted by avanboekel

In the past 4 years I've been on the team, we haven't had any plywood on our bot (besides bumpers). We try not to use it in prototypes with high speed applications (our shooter this year for example). It causes far too much binding. Even in other prototypes, we rarely use it. We just find it easier and quicker to use other materials such as 80-20

It causes too much binding? I think that's a design issue and not a material issue.

We've run multiple shooters (both this season and last), along with many other systems out of plywood.

Wood is good.

We primarily use 6mm baltic birch ply that we get local in 5x5 sheets and we usually router it. We have used some 12mm for thicker items.

It's a great material, VERY STIFF. This stiffness if often very useful. Cutting it at .25" depth 300 ipm is nice too!

[avanboekel]

Originally Posted by AdamHeard

It causes too much binding? I think that's a design issue and not a material issue.

We've run multiple shooters (both this season and last), along with many other systems out of plywood.

Wood is good.

We primarily use 6mm baltic birch ply that we get local in 5x5 sheets and we usually router it. We have used some 12mm for thicker items.

It's a great material, VERY STIFF. This stiffness if often very useful. Cutting it at .25" depth 300 ipm is nice too!

I'm sure if you took your time in planning and designing to build with wood, it would be fine. But whenever we use it, it ends off being off just enough to where it isn't running at the efficiency that it should. Then you have to re-drill holes, and it becomes a pain. Where as with aluminum extrusion such as 80-20, if you are off by a bit, you loosen the bolts on the sliders, move it to where it needs to be, and you're done. Now,
with the competition not, we waterjet all parts that require that amount of precision. If something is off there, then its most likely a CAD problem, not a machining problem.

Again, I'm not saying that wood is bad, especially in the right application, its quite good. We just don't have the time and precision to use it.

BTW, we don't have access to a router in house. Any machining we do on wood is with a cordless drill and a chop saw.

[AdamHeard]

Originally Posted by avanboekel

I'm sure if you took your time in planning and designing to build with wood, it would be fine. But whenever we use it, it ends off being off just enough to where it isn't running at the efficiency that it should. Then you have to re-drill holes, and it becomes a pain. Where as with aluminum extrusion such as 80-20, if you are off by a bit, you loosen the bolts on the sliders, move it to where it needs to be, and you're done. Now,
with the competition not, we waterjet all parts that require that amount of precision. If something is off there, then its most likely a CAD problem, not a machining problem.

Again, I'm not saying that wood is bad, especially in the right application, its quite good. We just don't have the time and precision to use it.

BTW, we don't have access to a router in house. Any machining we do on wood is with a cordless drill and a chop saw.

'

to clarify, I wasn't criticizing you. I was just making sure impressionable students who crawl all over chief weren't interpreting information the wrong way.

[jvriezen]

We've used 5'x5' 9-ply baltic birch on our last three bots, two of which did very well at competition, includes finalist at regionals and two time champion at off season events. The last two years our frame was also plywood. In 2011, our telescoping elevator tower was plywood--many thought it was aluminum until getting a closer look. 2012, our frame and ball path and shooter assembly was plywood with an aluminum gearbox for shooter wheels.

We've done all the cutting on basic wood shop tools, including hole saw for weight reduction, until 2013, where the parts were cut on a CNC router.

[daniel_dsouza]

Wood is a friendly material. It's cheap, easy to machine, and "easy" to assemble.

There has always been wood on our robots (in recent years anyway). 2013 had a wooden shooter, 2012 had a wooden shooter, 2011 had wooden panels, etc.

When buying, we just find plywood that is as stiff or as flexible as the application demands. "Machining" is done with a table saw, jigsaw, and rotozip combination. Wood is material that we do not worry about tolerances. Engraving can be done with a laser engraver.

Good luck on your endeavors!

[Gdeaver]

Wood is useful for prototyping. Our main use for plywood is for a core material. We use 4mm, 1/4" or 6mm Baltic Birch ply and put a layer of 5.7 oz plain weave carbon fiber on it using vacuum bagging method. In 2013 our shooter platform and electronics boards were done this way. Could we use other materials, yes, But it's a good intro to composites lesson. I'm being pushed to try honeycomb or foam core materials for 2014. You can't beat plywood in availability, price and performance in this app.