Introduction: CNC Scissor Chair (Plywood)

CNC + plywood = furniture. Search instructables and you'll come up with over 47,000 results for "CNC furniture." But for the great majority of CNC machines -- the 2-1/2 axis CNC routers that can move only in X, Y, and Z (no tilting or rotating controllers) -- a very specific condition has come to be part of almost all projects that result: the orthogonal joint. The orthogonal joint, essentially a product of the needs for tightly-fitting "notches" to fit together with friction, is a defining characteristic of furniture made this way.

This project, the "Scissor Chair," takes its design inspiration from the non-orthogonal joint cut on a machine capable of cutting only orthogonal (non-beveled) profiles. The finished chair is as purely a CNC project as I could manage: it requires exactly one sheet of standard 1/2" plywood, no extra parts, no hardware, no glue, and no other tools (except maybe a mallet to show it who's boss).

The Scissor Chair will be one of the first chairs available for purchase through Fabsie, a new website aimed at letting people buy highly designed small-run furniture anywhere in the world by connecting buyers with local fabbers and digital designers from all over. James McBennett, Fabsie's founder, made the world's second scissor chair. He is working to smooth out the fabrication process to open up the design everywhere!

More and larger photos are available on my website, http://www.phil-seaton.com (click "Scissor Chair" once you get there). I will share the DXF files with anyone emailing from an academic email (".edu"); in exchange I ask that you send back photos of your process and finished chair, and tell me about any snags you hit while making it. The goal is to iron out problems people encounter during the making process: if you get the file, that's not license to distribute or sell the file or the finished chair.

Step 1: Scissor Plan

From the top (plan) view, the final chair's design rests on the complex joinery required to allow planar sheets to intersect in this way.

Step 2: Joint Studies

For this orthogonal-but-not orthogonal design, a series of oblique joints with straight cuts served as generative components for the chair. Tight friction-fit joints are maintained oblique parts. The joint on the right side was abandoned later as the design evolved more purely towards the "scissor" plan.

Step 3: Design Considerations

The design assumes a perfect "scissor" plan / top view. Variations of the "tightness" of the scissor joint and the chair's profile serve to produce several design iterations on the same principle.

Step 4: Scale Models

1:4 tests were lasercut to test the structure and design of the chair. The 1/8" thick masonite makes it possible to exactly test the joint's tightness of fit: The files are scaled down to 25%, and the material is exactly 25% the thickness of the final 1/2" ply.

Step 5: Assembly Diagram


Step 6: Cut Sheets

The entire chair is cut from exactly one full 4x8' sheet of 1/2" ply. Details in the final file cut corners wide to allow space for a 1/8" router bit to profile cut without destroying the geometry.

Step 7: On the CNC, and Then, Glue-free Assembly!

Photo and this assembly video courtesy James McBennett of Fabsie (see first page for description). This is chair 2.0, which will become a part of a series of scissor chairs after the same design. Stay posted for more!





Comments

author
amandaghassaei made it!(author)2017-04-05

whoa, I never saw this before, so cool phil!

author
HarrisonFilleul made it!(author)2016-06-21

Do you have these shapes in AutoCad?

I want to make one of these as I have access to a CNC that runs on AutoCad/Microvellum.

Cheers!

author
pseaton made it!(author)2016-06-24

I've been hoping that by limiting this to students (.edu addresses), I'd have more luck getting photos of the finished products people make with the cad files. So far no luck so here's my request: if you use the files for anything, please upload an I Made It !

Here are links to the CAD file, and some notes that I've gotten from feedback along the way:

DXF: https://drive.google.com/file/d/0B6nIu9U60DlGeWZlV...

Fab Notes: https://docs.google.com/document/d/1p6Q_mxhN5HZCWy...

Note that the license for the CAD files is Creative Commons "Attribution-NonCommercial-NoDerivs 2.0 Generic (CC BY-NC-ND 2.0)", not the same as the license for the Instructable. You can't modify, sell, or distribute the files without permission. You must cite the author in any use.

https://creativecommons.org/licenses/by-nc-nd/2.0/

author
HarrisonFilleul made it!(author)2016-06-24

Thank you,

Looking forward to making it!

author
buck2217 made it!(author)2015-06-25

Awesome , does it come in extra wide for the Mrs?

(just kidding Darling, now put down that knife!!!)

author
Dai+HyekH made it!(author)2015-05-20

oh very nice design but we are need the cut sheet dxf and pdf file. pls share the details on reo0823@naver.com

author
sbrown9578 made it!(author)2014-03-20

great a chair that expands when your butt does. lol

author
Samw made it!(author)2013-03-06

Hey this is great. I love the mechanics you use here. Is this an original design?

author
pseaton made it!(author)2013-03-07

It is, thank you! It's possible I'll have the chance to develop it a little further to make a "form family" of related furniture in connection with Fabsie (www.fabsie.com). This depends somewhat on the success of Fabsie's first venture, on kickstarter now -- https://www.instructables.com/id/This-Stool-Rocks/

Thanks again!

author
mganpate made it!(author)2012-07-31

very nice design but we are need the pdf pls share the details on mahesh.gan.143@gmail.com

author
scoochmaroo made it!(author)2012-05-26

Holy guacamole! You should come work for us!

author
angelabchua made it!(author)2012-05-29

hahaha!

author
pseaton made it!(author)2012-05-26

hey now, that's a great idea!

author
cephean made it!(author)2012-05-29

Wow looks very close to my chair design for graphics when i was in grade 10:

author
cephean made it!(author)2012-05-29

Chair_by_cephean.png
author
Val-S made it!(author)2012-05-27

May I ask, how much does it weigh?

author
pseaton made it!(author)2012-05-28

It's not so bad actually... maybe 25-30 pounds? It takes up a whole sheet of ply, but I'm afraid much of it goes up the dust chute.

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dagob made it!(author)2012-05-27

Amazing! I looks great! I luv it!

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poofrabbit made it!(author)2012-05-27

This is just plain wicked cool!!! Nice work!

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biggsfamily2012 made it!(author)2012-05-25

How long did it take you to make...tire actual hours
working on it

author
pseaton made it!(author)2012-05-26

hmmm well quite a few if you count all the testing, design time, failed and rejected options, etc. But the actual construction of the chair isn't so bad. It's probably 2-3 hours of CNC time once you get started, and another 2-3 hours of assembly if all goes well.

author
rimar2000 made it!(author)2012-05-25

Interesting design.

author
pseaton made it!(author)2012-05-26

Thanks!

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Bio: Architect by training, Phil is a designer who codes. He abuses CNCs and industrial robots while building fine furniture, mixing digital fabrication and craftsmanship. He ... More »
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