Picture of Ratchet Strap Chair
closeup strap 3.jpg

This chair is made from a 1/2 sheet of plywood, uses no glue or fasteners, and is held together by a single ratchet strap. I made this chair because I was interested in the forces at play to make a chair stand up: the different parts in tension and compression that make up the structure. It's also part of a broader study I'm up to experimenting with ergonomics- trying variations on the dimensions and posture of Mies van der Rohe's Barcelona Pavillion Chair (1929).

Step 1: 3D Model

Picture of 3D Model

I designed this chair in Fusion 360 (it's recently become my go-to modeling program). The file is attached here, please download it and tweak it yourself! Fusion 360 is free for "enthusiasts", and it's on both Mac and PC.

Shawn Stanford11 months ago

So, here's the thing: I'm a Soldier and I deployed to both Iraq (in '04) and Afghanistan (in '08). Among the egregious incidents of poor planning and spending is the fact that the military will actually haul huge, heavy, expensive pieces of civilian-style office and barracks furniture into war zones. But, we also take enormous amounts of plywood for construction of shelters (barracks, offices, etc.). A suite of simple furniture designs (bunks, desks, shelves, etc.) cut from 3/4" plywood, slot-and-tab assembled, and held together with ratchet straps would be invaluable!

JON-A-TRON (author)  Shawn Stanford11 months ago

That's a great idea. People have been making flatpack furniture for long-term camping trips (burning man, etc.) for a while- it's a great way to make sturdy, comfortable furniture without having to ship all that volume. I think the dead-simple design of this project is probably even better for this kind of use: http://www.treehugger.com/sustainable-product-desi...

All the zoomy lines and fussy details of mine require more time to cut out by hand, not so efficient.

This is another awesome flat-pack project, housing for disaster areas: http://www.wired.com/2013/11/a-disaster-relief-she...

The idea is that you show up with a CNC machine and a ton of 3/4" plywood, and you've got all the buildings you need.

jmwells1 year ago
Update on my comment. Did the cardboard thing. Worked after a fashion. Until a 350lb friend decided to plop down in it. Legs folded.
JON-A-TRON (author)  jmwells1 year ago

Pictures please!

I was preparing to shoot some when Carl crushed it. The legs were still too pointy and thin. I'm going to put on another layer, or two at the bottom of the legs. Perhaps feet too. I used contact cement between layers, the bond didn't break. The paper did. I went five layers of cardboard, for a thickness of about 3/4". The seat and back held up fairly well. We used it for a bonfire starter. Next time I'm thinking seven layers, 1"+,-. If the prototype holds up I'll spray the pieces with an epoxy paint for durability and water resistance. Got other projects right now, will update in a few months.
JON-A-TRON (author)  User11 year ago

So true. Posture is everything when it comes to furniture, and it's been pretty well figured out by the 20th century masters. The Ratchet Strap Chair is based on the Barcelona Pavillion Chair by Mies van der Rohe.

This project, by one of our AIRs, is based on the Eames LCW chair and is also very comfortable without any padding: http://www.instructables.com/id/P9L-Lounge-Chair-made-with-CNC-Router/

do you have pdfs of the pieces rather than fusion 360 format?

JON-A-TRON (author)  PetersPJones1 year ago

Just uploaded a full size PDF to Step 2. If you ever need to convert a DWG file to PDF, just do it on this site for free: http://www.zamzar.com/convert/dwg-to-pdf/

lensman8881 year ago

Great for moving day and you already have the strap to tie up the pieces!

JON-A-TRON (author)  lensman8881 year ago

Hadn't thought of that! I cut the strap so that I wouldn't have to figure out what to do with the excess, but it makes sense to come up with some kind of attractive clip solution so you can still use the strap for other purposes.

fred36551 year ago
Now for the ratchet strap table and foot rest! This awesome, can't wait to make one.
JON-A-TRON (author)  fred36551 year ago

That's the plan! Can't wait to see what you come up with.

great project!

That thing is freaking cool!

travderose1 year ago

This is rad! Great job

JON-A-TRON (author)  travderose1 year ago

Thank you!

CobyUnger1 year ago
Cool dood!
JON-A-TRON (author)  CobyUnger1 year ago

Thanks Man!

rimar20001 year ago

Interesting design.

JON-A-TRON (author)  rimar20001 year ago

Thanks! I'm hoping it's the first of many ratchet strap furniture pieces. I got the idea from this project: http://dornob.com/no-nails-sans-screws-ratchet-strap-wood-furniture-series/#axzz39A6fNK66

howtobasic1 year ago
So ratchet ?
jmwells1 year ago
Think I'm gonna try cardboard, laminate it with alternating internal fibers, and make the legs less pointy. Looks great for a picnic chair. Easy to pack and move.
JON-A-TRON (author)  jmwells1 year ago

Cardboard's a great idea. I would recommend laminating so that they're at least 1" thick when you're done.

You're so right about the pointy back legs! They're on a 1/2" radius, they should be more like a 2" radius like the front legs are.

I agree, this is best suited for outdoor use. But that means I'll need to finish it (everyone's least favorite part).

mcep5f20091 year ago

Pretty cool!

crank_girl1 year ago
Rather neat! B)
JON-A-TRON (author)  crank_girl1 year ago


pretty pics!

lebowski1 year ago

Nicely done!