Lace-Up Chair

Intro: Lace-Up Chair

If you want to use CAD software to design complex geometry, you don't have to have expensive CNC machines to make the finished product. With a local copy shop and a little patience, you can produce just about anything you can design in the computer. This instructable shows you how.

The Lace-Up Chair is part of a broader study I'm up to experimenting with ergonomics- trying different materials and construction methods using the dimensions and posture of Mies van der Rohe's Barcelona Pavillion Chair (1929). This one uses two wooden sides with eyelets, dowels separating the sides, and rope laced through the eyelets that create a sitting surface that doubles as the chair's structure. I also took a cue from this awesome instructables project using rubber hose: https://www.instructables.com/id/Rubber-Hose-Chair/

STEP 1: Tools & Materials

Tools

• Drill & drill bits
• Doweling Jig
• Bar Clamps
• Center Finder
• Combination Square
• Rubber Hammer
• Printed full-scale templates
• Jigsaw

Materials

• Wood Glue
• Dowel Pins (3/4" and 1/2")
• 2X6 Wood (12 linear feet). NOTE: I used off-the-shelf douglas fir, I would highly recommend spending a little more money on hardwood. Standard framing lumber is soft and will not last long. Invest in some Walnut or other hardwood and you'll get a much better result.
• Wooden Dowels: 1 1/4" Ø, 3X 26" lengths
• 1/2" rope, 100' length

STEP 2: Design & Templates

SOFTWARE:

This is my first project designed in Fusion 360. The interface takes some getting used to- it feels more like a web page than it does a CAD program, but once you get past the "Home" interface and start working, it's a remarkably simple program that has very advanced capabilities. It's free for students and hobbyists, and there's a ton of educational support on it. If you want to learn to 3D model the kind of work I do, I think this is the best choice on the market. Click the links below to sign up:

Student/Educator

Hobbyist/Startup

When you open the file, you'll notice there are a lot of "sketches" plus the 3D parts. I used multiple sketches to design and alter the parts, then when I was satisfied with the design, I created new sketches derived from the finished parts to make the templates- to do this, you just click "create sketch" and select the face of the 3D part you want to make a template of, and there's your template!

I designed the chair so that no part was wider than 5 1/2", that way I could cut all the pieces out of 2X6 lumber.

WORKSHOP:

Having created my templates with a 5 1/2" wide box around the parts (that's the actual width of a 2X6 member), I had a local copy shop print them for around $5. Then simply cut the templates out and spray-glue them to the lumber.

STEP 3: Cut Out the Pieces

The quickest way to cut the pieces out is with a jigsaw. There are far more accurate ways to do it, especially on the straight cuts where a circular saw would be more reliable, but if you want to do these kinds of projects and don't want to break the bank, a jigsaw should be the first tool you buy.

I added crosshairs at the center of each circle (the eyelets) so that I could easily find the center with the drill bit. The eyelet holes are 3/4" Ø and the center holes for the cross-dowels are 1/2" Ø.

A good trick for cutting tight curves is to add perpendicular cuts to the curve- that way the jigsaw won't bind.

Make sure to go slow and steady with the jigsaw, always keep the base flush on the face of the wood, and be mindful of which side of the line you're trying to cut. With a little practice you can produce good results.

STEP 4: Join & Glue the Parts

Joining:

I decided to use dowel pins to join the parts of the chair because they're easy to find and they don't require a lot of fancy tools. You could also use biscuits with a biscuit joiner, or you could do dovetail joints if you want to get really fancy.

I used a doweling jig to drill the dowel pin holes: this handy tool gives you perfectly centered, perfectly plumb holes every time.

The blue tape you see on the drill bit is my marker for the depth of the hole.

Once the holes are drilled, glue the holes and tap the parts together with a rubber mallet. You can glue the surfaces that touch as well, but remember that end grain doesn't glue structurally. This is why you need dowel pins in the first place.

Gluing

Once your parts are tapped together, use the bar clamps to make sure the parts glue together snugly. I also clamped them to the work table to make sure they were flush in both dimensions.

OPTIONAL: You'll notice in the photos here that all the parts have smooth edges. I used the table router with a 1/4"Ø fillet bit to get nice rounded edges, but you can do this with a more hand-crafted result with a palm sander.

STEP 5: Cross-Dowels

The structure of this chair basically has two parts:

1. A rope in tension.

2. Three Cross-Dowels in compression.

The 1/2" holes are placed on the sides of the chair so that the 1 1/4" dowels will be held in place while the rope is laced up. Just like in the other parts, it's important to make sure the dowel holes are centered and plumb. Here's how I did that:

Use the Center Finder to get the exact center line of the 1 1/4" dowel. Next, use the Doweling Jig and line it up with the center line you just marked. You can't go wrong!

As before, glue the hole and tap in the Dowel Pin. Then tap the sides of the chair together using a rubber mallet as before. I didn't glue the holes on the sides of the chair in case I want to break the whole thing down later and pack it up.

STEP 6: Lace It Up

As I mentioned, the rope creates the opposing tension that holds the chair together. To get the rope tight without using a turnbuckle or some other kind of hardware, use a Trucker's Hitch. This diagram clearly shows how to tie one.

First, tie a knot in the end of the 100' rope. Then starting from the top, lace the rope through each eyelet from side to side. It's basically like straight-lacing a tennis shoe.

The last eyelet gets a short loop with a knot at the end, taking the place of the "anchor eye bolt" in the Trucker's Hitch diagram. Tie a loop in the end of the 100' rope as close as you can to the last eyelet. Pull the end through the end loop and the loop in the rope- this gives you the leverage you need to get the rope tight.

At this point, you're fine tuning the rope:

1. Sit in the chair, let the ropes stretch a bit.

2. Tighten the rope by hand.

3. Tighten the trucker's hitch.

4. Repeat until comfortably tight.

Once the ropes have a comfortable resting tightness, neatly tie the end of the rope at the trucker's hitch and trim it to get it out of the way.

STEP 7: Sit Down

It's a comfortable posture for a lounge chair, and the ropes make for a nice sitting surface. The dowel at the seat back digs into your back though- definitely consider placing that further down or further back in your version.

It didn't last long because of my poor choice of wood- it finally failed at the eyelets on the seat. With harder wood (or plywood for that matter), this will make for a nice chair.

Comments

[Ken RCC]

Hi Jon,

I have made the chair out of the pitch pine it looked really well but unfortunately it failed on the same joint three times. There seems to be a great deal of strain on the back leg and the pine is quit brittle due to its age. I made the top back rail curved and lowered it slightly and used 50mm mop stick hand rail instead of the dowel. My second attempt has changed the design a bit I have used 18mm OSB board and glued three pieces together to form each side.Instead of sharp angles I have swept radius between the legs and the back. I have taken some photos but I need the help of the younger generation to send them. I'll send them when one of the kids come home.

[mdib]

can you send me picture of th end result ? are you using a cnc machine ?

[JON-A-TRON]

I can't wait to see the pictures! That joint at the back leg is really tricky, I'd love to see how you resolved it. The quality of the wood is a big part of the integrity of the chair, especially with this design.

[T0BY]

That's impressive! What a great idea!

[JON-A-TRON]

It looks awesome- the mortise joints were a smart move. My advice with the rope is to use the trucker's hitch knot I demonstrated in the instructable. It's kind of like tuning a guitar- you have to do it multiple times before everything is stretched to its limit.

[Ken RCC]

I lowered. the dowel down to about the 6th hole and the back is wider than the initial drawings. I think what does help is keeping a good tension on the rope i used mole grips to hold the rope tight on each loop. I haven't used the truckers hitch to secure the rope end i am going to drill another hole and use a bulldog clamp to finish on the inside of the frame.For the finish I applied a couple of coats of light pine stain and clear satin varnish. I've got enough rope left on the coil to make at least another three probably try a few different designs and other materials will post some pictures when they are done. Thanks again Ken.

[Ken RCC]

Hi Jon,

I have attached a couple of photos I am really pleased with it and the people who have seen it and sat on it are well impressed. Thanks for the idea hope you like it.

Ken

[JON-A-TRON]

Very nice! Can you feel the dowel on your back? That was the one problem with the one I made. What did you finish it with?

[Ken RCC]

[Ken RCC]

Hi I am going to have a go have a go at making this chair I have managed to get hold of some reclaimed pitch pine 3 no 14 foot 7x4 and bought a coil of 12 mm hemp. Do I need to factor in the additional eyelets you mentioned you added to the back of the chair on to the 100 foot of rope? Once it's completed I will post some photos.

Thanks Ken

[JON-A-TRON]

Hi Ken,

You could probably get away with the same number holes as shown in the templates. The main thing is that in the design I used, you can feel the dowel on the back- I would suggest doing either a curved piece of wood back there to give you room for your back or moving the dowel lower.

Also, I've be concerned about the hardness with Pitch Pine. It's about the same as the pine I used. I would suggest drilling the holes as small as possible (13mm Ø) while still fitting the rope though, and centering the holes further from the edge of the wood to avoid splitting.

[david.poole.56679]

Hi. I love this and would love to have a go at making it. I dont use computers a lot so please forgive a stupid question. If i down load the pdf how big do i need to enlarge it to get it printed out. Thank you.

[JON-A-TRON]

Not a stupid question at all! The PDFs will need to be printed at full scale to work at templates. Essentially this means that there is no scaling of the file, it will be printed at 100%. Any print shop that does large format printing can do this with no trouble. Remember to use hard wood, and please post pictures of what you make!

[david.poole.56679]

Brilliant. Ive sorted the pdf. Now got to source the wood. Hard wood is really expencive here. what would you recommend instead?

[JON-A-TRON]

Yeah, it's hard to find cheap hardwood anywhere (unless you live in the tropics maybe). If you can't find any hardwood in your price range, I would suggest getting some finish grade plywood and doubling up the sheets (two sheets at 3/4" gives you 1 1/2" thick members). With two sheets glued together, you should have enough stability at the holes, which is where my chair failed using soft wood. The tricky part will be joining the edges of the sides- you'll want to use biscuits for that instead of dowels as I've shown I think. Hope this helps!

[david.poole.56679]

When you say failed what happened? I managed to some soft wood today. Im making this for my wife and shes tiny. I was also thinking about using 200 ft 550lb paracord. What do you think?

[JON-A-TRON]

I would strongly advise against using soft wood. I didn't think to take pictures of the failure, but here's a screenshot showing where it broke. Essentially, the weight of a person combined with the tension on the ropes that's necessary to hold the chair together made the solid parts between the holes break down the center. The weight of the person sitting on the chair might make a slight difference, but if you use my templates with soft wood, it's going to break eventually, take my word for it.

There may be a solution though- 550 LB paracord is 5/32" Ø (I used 1/2"Ø rope). In order to make this comfortable, you're going to need a lot more holes (at least twice as many). If you use my template as a guide and double the holes with a smaller diameter hole (I would use 3/16" to make it easy to lace the rope through), you might spread the load of the ropes out sufficiently to keep it together. Keep in mind though, it seems just as likely to me that doubling the number of holes and decreasing the spacing between them by half might give you the same structural integrity that I had with the 1/2" rope and less frequent, larger holes. I think soft wood is still probably a bad choice.

If you plan to go ahead with the soft wood, I would also recommend using biscuits instead of dowels as I did if you've got a biscuit joiner. You get more surface area glued together that way, they're easier to assemble, and you'll probably get a sturdier chair when you're done.

Best of luck, I hope it works out better than mine did!

[a_touny]

So nice you did .

[JON-A-TRON]

Thank you!

[sjean3]

What did you cut the 2x6x12feet wood down to before shaping the legs and base and such? Cause 2x6x12 wood for hardwood is hard to come by. and I'd like to have it cut down some before running it across my work bench.