Introduction: Ramified Armchair - Bending Plywood

I always wanted to make a bent plywood chair so I went ahead and made this prototype. I used compression mold to curve the plywood and a water based resin glue to put the bendy ply together.

I decided to make a simple design that would be broken down into 7 different pieces:
• Front leg (x2)
• Back Leg (x2)
• Arm rest -connecting front and back leg- (x2)
• Seat

The seat is elegantly supported from the edges of the branching legs creating a bridge between the front and the back legs. The ramification of the legs not only split in two directions with the same angle to each side generating a consistent flow in the legs but also creating the armrest. The biggest design challenge was creating the partition in the legs that become part of the armchair and seat. The front legs start thick from the ground and bend forward to become the seat and also backwards to become the armrests which then come down as the back legs. The ramification was the whole concept around the project, which made it an interesting detail.


Material: Poplar bendy ply and red oak veneer
Molds: Random scrap plywood
Strip of plastic (x2) for quick and clean unmold
DAP® Weldwood® Plastic Resin Glue
Biscuit Joints
to put the 7 pieces together

Step 1: Testing Ergonomics

Making a full size prototype is helpful to check dimensions and proportions.

Testing the ergonomics to verify if the angles and lengths are comfortable.

Step 2: Testing Material

I tested the flexibility of the bendy-ply to know exactly the minimum radius I could bend the wood.  After deciding the minimum radius was 3.2 inches I then went back to the CAD drawing and did some adjustments in the design so I could manufacture the prototype.

The total material for my chair was 2 sheets 8x4 ft. of poplar bendy-ply of 3 mm and 1 sheet 8x4 ft. of red oak paper backed veneer. I got all of my material at Macbeath in San Jose for less than $100.

Step 3: Mold and First Bend

I started doing the male mold for the front leg. I decided not to use a female mold because I was going to be short on time and had to do 7 pieces in total.  I decided to clamp the pieces down with just pieces of wood that spread fairly even the pressure of the clamps.

Making the first bend:
In total I used 5 strips of the 3 mm bendy-ply and used regular wood glue and left it for 24 hours to dry. It was an easy and short bend of 90 degrees. As a tip: I put a thin piece of plastic over the mold for two important reasons, first, to make a smooth surface to bend, and second, to make it easier to unmold.  Also as it was my first bend I used 13 clamps but after that I realized I could have probably used 8 clamps.
As I was told that regular wood glue will tend to open up after a few months I decided to use a great wood water resin glue called: DAP® Weldwood® Plastic Resin Glue. It is basically a powder that you mix with water and creates a super strong glue. You don’t have too much time to play around (probably 30 minutes) so you need to make the bends and clamp them down fast.

Step 4: Second Bend

Bending the armrest was way harder than what I had expected because it took triple the time than the front leg. Of course, doing the mold was also more complicated. I believe this is due the 2 bends on the single piece.  In addition, having long pieces to bend makes the setup and handling of the material more difficult. After I took the piece out from the mold I discovered that the bendy-ply wasn’t very structural for longer pieces.  It flexed more than what I wanted and got worried that the whole chair wasn’t going to resist a person.

The Third bend was probably the easiest one. You can check out the last picture.

Step 5: Clamping

Molds need to have parallel surfaces so that you can place the clamps. Clamping really tight is very important. The orange clamps worked better than the rest. Warning: don’t do so much pressure with the same hand because you can get blood blisters in the palm of your hand.

Step 6: Mold: Seat

Making the mold of the seat was definitely harder. I cut some strips of wood over the curve and then put some wood puddy and sand it down smoothly.  As a female mold was going to be complicated I kerfed a piece of ¾ fine plywood (only the part of the radius) up to the very last layer, spacing them evenly 7 mm away from each other.  This created a flexible piece of plywood that I could easily use as a female mold.  To clamp the seat to the mold I had to ask my wife for some help gluing the surfaces of the wood and also clamping it from the other end.

Step 7: Cutting the Pieces and Veneering:

One the pieces were bent I sanded the edges and cut it 2 mm from each side so that it was squared and even.  I then put some contact cement on the wood and on the veneer, waited for 20 minutes, and then stick them together. At first I clamped them down but I realized this was not totally necessary. Contact cement is really strong and will stick together and make it almost impossible to remove once it is done. Something tricky but everyone should be aware of. The veneer was cut slightly bigger than the piece and I later cut it with a knife.

Step 8: Prior to Assembly

After I had my 2 sets of legs I aligned them with some clamps and measured it with a 1:1 plan to cut it exactly where I had to cut the legs. I glued the legs together with 6 biscuits and let them dry for 24 hours. Finally I squared the 2 sets of legs so that they were identical.

Step 9: Assembling

One of the key parts of the process was the assembly.  I had the two set of legs and had to glue them together with the seat. I measured where I wanted to put the biscuits and did the 3 holes in the back and 1 hole in the front of the legs. It was easy to glue using some parallel woods that helped me keep everything straight.

Step 10: Finishing

I decided to use oil and wax as a surface finish. I heated Boiled Linseed Oil to 140 degrees and then applied it with a brush. I let it dry for a few hours and then remove it with a cloth. Then I added 3 layers of wax to have a nice and protected surface. If you want you can smooth the surface with a 600 sandpaper.

Step 11: Enjoy Your New Chair

Although Bendy Ply is not super strong to make a commercial chair it worked OK for this prototype.

Comments

author
charlesp4 (author)2016-01-26

A very good design, cheap, but looks like an expensive chair from the furniture store. Needs a lot of work, but I'm very sure you are very satisfied with your perfect job. I like it.

author
charlesp4 (author)2016-01-26

A very good design, cheap, but looks like an expensive chair from the furniture store. Needs a lot of work, but I'm very sure you are very satisfied with your perfect job. I like it.

author
charlesp4 (author)2016-01-26

A very good design, cheap, but looks like an expensive chair from the furniture store. Needs a lot of work, but I'm very sure you are very satisfied with your perfect job. I like it.

author
charlesp4 (author)2016-01-26

A very good design, cheap, but looks like an expensive chair from the furniture store. Needs a lot of work, but I'm very sure you are very satisfied with your perfect job. I like it.

author
Lucas.Mas (author)2015-03-02

Exelente trabajo, me gustaria aprender más sobre las tecnicas para curvar que se pueden hacer, hay algun libro o web donde pueda mirar? Un saludo y enhorabuena.

author
alepalan (author)Lucas.Mas2015-03-02

Muchas gracias. Hay mucha informacion y videos en instructables o en youtube. Un libro que recomiendo: http://www.amazon.com/The-Complete-Manual-Wood-Ben...

Saludos!

author
unlearny (author)2014-08-12

really amazing. the chair is lovely and looks more elegant, and more comfortable than an Eames plywood guest chair. so your $100 beat the $1,000 competition.

author
sbrown9578 (author)2014-03-17

nice carpentry skills!

author
malepalan (author)2013-11-26

I want one Ale!!!

author
windrian (author)2013-10-18

this is really a beautifull design with low cost....thanks for sharing this post

author
meblozo (author)2013-10-08

This is beautiful!

author
JohnMeng (author)2013-09-21

Beautifully done. Thanks for the very clear step-by-steps. Were I to try something similar - which I'm certain would be worth it all, with thanks to you - I'd consider a few changes:
1. To have the front and back legs bent from the same pieces of ply as the back and seat. The grains would be continuous that way adding harmony and congruity. Yes it will complicate the molding quite a bit but that, frequently, is the self-imposed challenge of an artist.
2. To have the back high enough to serve as a rest for both the shoulders and the head.
3. To give longer legs to the chair. It would be more comfortable for me that way.

Thanks for your enthusiasm and ingenuity. It is a beautiful accomplishment!

author
technosasquatch (author)2013-09-20

best thing i've seen on here in a long time!

author
finton (author)2013-09-20

Others have said this already, but: beautiful object, well written 'ible, great photography! Very keen to see more Instructables from you.

author
ezgnann (author)2013-09-20

Can you give some insight as to how you made the forms? The lamination does not look to difficult, but I want to know how the forms are built.

author
67spyder (author)2013-09-20

My wife wants 2 please!

author
alepalan (author)67spyder2013-09-20

:) thanks!

author
Edgar (author)2013-09-20

Went to this Blog:
http://faz-voce-mesmo.blogspot.pt/2013/09/cadeiras-camaras-digitais-e-vigilancia.html

author
badvaquero (author)2013-09-20

exelente trabajo, exelente diseño, exelente "instructable". felicidades y gracias por compartir.

author
alepalan (author)badvaquero2013-09-20

Gracias vaquero!

author
EnergyHandyman (author)2013-09-20

Totally Rad!
I need more clamps!

author
alepalan (author)EnergyHandyman2013-09-20

Thanks! Check out one of the comments bellow, it might be interesting to explore this option and use less clamps : http://3.bp.blogspot.com/_5cm4MO0-Udk/SnHTPmfVFWI/AAAAAAAAAHA/yQXP-FHSzbI/s1600-h/003.JPG

author
Dr_Stupid (author)2013-09-20

Very nice piece

author
alepalan (author)Dr_Stupid2013-09-20

Thanks!

author
Cheese Queen (author)2013-09-20

fabulous inst. wow, a $500 chair . although it looks like a fortune in clamps, but if you make enough, that amortizes out. these should sell like hot cakes to up scale decorators.

author
alepalan (author)Cheese Queen2013-09-20

Thanks! It would be pretty cool to get a manufacturer excited to make these!

author
Miro_B (author)2013-09-19

beautiful

author
alepalan (author)Miro_B2013-09-20

Thanks!

author
bricobart (author)2013-09-19

What to say!? Whaoow!!! Excellent work, thanx for sharing, I'll start this day a bit less stupid!
To make an IKEA-version you could integrate bolts (those long ones) into the seat and screw it all together.

author
alepalan (author)bricobart2013-09-20

Thanks. Anyone has contacts with the IKEA design team?? :)

author
macrumpton (author)2013-09-19

Very interesting design. I thnk it might look a little better about 4" taller on the back.
I wonder if a lazy mans version where you cut kerfs (for the curves) into regular plywood would work?

author
alepalan (author)macrumpton2013-09-20

Thanks. I don't know if will work (the kerfing). I tried kerfing on a few projects and it usually breaks after some use.

author
mrmkurtz (author)2013-09-19

Gorgeous! This brought back a lot of memories of a bent plywood chair project I had in design school. Although I will be honest and say your results were far more elegant than mine :¬D) The other thing I like about this approach is that you can play with different wood veneers and colours on each side of the pieces. Great job!

author
alepalan (author)mrmkurtz2013-09-20

Thanks! Great advice, could look really sexy with different veneers and colours.

author
CraigRJess (author)2013-09-19

Nice work and great design! I like the huge spacious shop you get to work in. Awesome.

author
alepalan (author)CraigRJess2013-09-20

Thanks!

author
DeeRilee (author)2013-09-19

I wonder if Min-Wax Wood Hardener would give added strength to the BendyPly?

author
alepalan (author)DeeRilee2013-09-20

I've never heard about the hardener. I might give it a try for another project and will let you know.

author
twall2 (author)2013-09-19

Great work! Great design! One note, A metal strap will save you a ton of time on future projects :)

http://3.bp.blogspot.com/_5cm4MO0-Udk/SnHTPmfVFWI/AAAAAAAAAHA/yQXP-FHSzbI/s1600-h/003.JPG

author
alepalan (author)twall22013-09-20

Nice! I heard about it. That picture is beautiful! Thanks for sharing.

author
hawkluvbeer (author)2013-09-18

What are biscuits?

author
badideasrus (author)hawkluvbeer2013-09-18

i've not actualy gotten tto the point where they mention them, but in wood working, a biscuit is a small piece of wood taht you fit into a slot cut into two pieces of wood. you then glue them in. they're usually ovalish and long, thin. it adds strength to a joint and helps line up pieces where you want them.

author
alepalan (author)badideasrus2013-09-19

Yes. They come in 3 sizes and they are really easy to use. Check out on youtube some videos (for example: http://www.youtube.com/watch?v=kJt5NRZH7_U)

RX-DK-DIY064016_glue-biscuit_s4x3_lg.jpg
author
stephenf (author)2013-09-19

Wickedly Beautiful!
I [currently] weigh 290 - think it would support that kind of weight?

author
alepalan (author)stephenf2013-09-19

I used bendy-ply for the prototype and I guess it won't hold 290 pounds. If you use single plywood it should definitely work.

author
strooom (author)2013-09-19

Well done!
Nice & professional product pictures as well. Quality is clearly one of your core values.
I want to make a chaise longue and this instructable helps me forward to that project.

author
alepalan (author)strooom2013-09-19

Thanks! Good luck with your chaise longue, hope to see some pictures soon!

author
bob3030 (author)2013-09-19

Very cool, beautiful chair. Thanks for showing all of the work to produce the chair. Thanks for posting.

author
alepalan (author)bob30302013-09-19

Thanks!

author
jjdebenedictis (author)2013-09-18

Beautiful! And I'm amazed at how cheap the basic supplies were for such an elegant final result.

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Bio: Alejandro is an industrial designer who focuses on creating impact through his designs. He has a broad background having worked at a graphic design agency ... More »
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