The Bowsaw Chair - Popular Woodworking Magazine

The Bowsaw Chair

 In Feature Articles, Shop Blog

bowsaw chair

The Bowsaw Chair.

Inspired by early saws and a midcentury classic, the bowsaw chair is just six pieces of wood.

When human civilization ventured out of Egypt, one of the first technological advances made by the Romans or Greeks (depends on who you ask) was the frame saw, what we now call a bowsaw.

The saw blade is held in tension in its frame with a wound string and a toggle, and when you need to go on a trip, the saw breaks down to just a few sticks. This chair works on the same principle. The leather backrest is tensioned by twine and a toggle. The sling seat is held in place by the backside of the sitter.

This style of chair was made popular in the 1960s by Ole Gjerløv-Knudsen (1930-2009), a Danish designer who also produced a line of daybeds that work on the same idea as this chair. Gjerløv-Knudsen’s chair was designed for mass-production and featured turned components. Many of the extant examples use canvas upholstery, though some use leather, as I have here.

This maple version eliminates the turning, substituting octagons for the round parts so you can easily build this chair without a lathe. It took seven prototypes of this chair for me to get everything working correctly for the modern American frame, but once I had the design figured out, I could build a chair in an afternoon, including the leatherwork.

No Glue, Just Tension

Here’s how the chair works: The two uprights are separated by a stretcher below the seat. You sleeve the leather backrest over the uprights, then use a toggle to wind some twine between the uprights, below the stretcher. This tensions the backrest.

The legs slide through the leather seat and through angled mortises in the uprights. Then you have a seat. It really is simple to build and assemble. Even the leather bits are easy to make with copper rivets and a hammer.

The Uprights

The uprights are easy to make once you build a jig for your drill press (or simply tilt the table; my table doesn’t tilt). The jig is a cradle that holds an upright at 17° off horizontal. It’s easily cobbled together using scraps and screws. After making a bunch of chairs, this jig will get chewed up, so don’t go to too much trouble.

The 134” diameter mortise through the leg is a bit tricky to bore if you want a clean hole. Use the drawings to mark the location of the hole on your uprights. Try to remember that these uprights are mirror images of one another.

The bit extends beyond the edge of the upright, which looks a tad scary. I recommend you clamp a scrap to the upright at this location to make the operation safer and cleaner.

drill press clean hole

A big and tricky hole. To prevent splintering, clamp a scrap to the upright where the bit leaves the leg. This makes for a clean hole.

After you bore the through-mortises, bore a 1″ diameter mortise in each upright for the stretcher. Its location is shown in the drawings. This mortise is shallow; only 18” deep.

The last operation on the uprights is to cut stop-chamfers on the four long edges of the uprights. These chamfers should be about 38” wide. A chamfer bit in a router table is ideal for this operation. Use the drawings to mark where the chamfers should end and use a stop block to make this operation foolproof.

octagon

Easy octagons. Set your table saw’s blade for 45° and rip the four corners to make an octagon.

chamfer uprights

Lighten the corners. The stopped chamfers allow the uprights to rotate a little when inside the leather backrest, which then allows them to tension evenly.

Make the Legs

The two legs are octagons. They start out at 112” x 112” x 40″ sticks that you rip or plane to an octagonal shape. When making a lot of something (I made eight of these chairs), I opt for the table saw. To get all four facets the same size I sneaked up on the correct fence setting and checked my work with a ruler. Then I ripped the legs to shape.

Remove any machine marks with a handplane and use a fine file to chamfer the ends of the octagons. The ends of the legs will be touched by the sitter, so you want them to be hand-friendly.

The Stretcher & Toggle

Use the same setup on your table saw to make the octagonal stretcher. Then you can turn the short 1″ diameter x 18” long tenon on each end. If you don’t have a lathe, this is quick work with a knife.

The toggle is just a stout stick. Decorate it however you like – I cut 38” radius curves on both ends and made little notches in the toggle for the string. But honestly, a stick from your yard will do the trick.

Remove all the machine marks from the wooden parts. I finished all the wood with a blend of linseed oil and beeswax, though any clear finish will do.

stretcher tenon

A quick turn. If you have a lathe, turn the tenons on the stretchers. Make them a little undersized so they slip easily into the mortises in the uprights.

Leatherwork

Working with leather is easy with sharp tools and a hammer. I did all this with a utility knife, hammer, nail snips, a leather punch and a rivet setter. For this chair, I’m using No. 9 x 12” copper rivets and a No. 9 rivet setter. The leather is about 10 ounces.

I make patterns for the leather parts using cheap hardboard (which then gets recycled into other parts for jigs). Cutting the leather with a pattern instead of a ruler will ensure your ruler doesn’t slip and ruin the expensive leather.

Make your patterns, cut your leather and lay out the holes for the rivets using the drawings as a guide. I usually use masking tape to mark where the rivets should go, then I confirm things are correct by wrapping the leather around the wooden part to make sure I haven’t made a mistake.

clam and cut leather

You are the clamp. My body weight keeps the pattern in place on the leather. Score the leather with a light cut at first. Then come back for a full-depth cut.

tape as guide

Tape is your guide. Lay out the locations of all your rivets using tape and confirm everything works before punching your holes.

Once I’ve confirmed the location of the rivets, I punch the holes on 114” centers, which makes a strong seat and backrest. Fold the leather onto itself to produce the pockets for the legs and uprights. Now push each rivet through its two holes and place the burr on the end of the rivet. Set the burr with a rivet-setting tool.

Snip off the excess copper with nail snips and peen the post over the burr with a hammer. Repeat…a lot. Finish the edges of the leather if you like. You can burnish it with a piece of hard wood and add a little wax.

snip rivets

A strong joint. Traditional copper rivets take a little longer to install than “rapid rivets,” but they are far stronger.

Assemble & Sit

Assemble the uprights, stretcher and backrest first. Use some stout 14” rope to tension the uprights and backrest. I attached one end of the rope to one upright with a hangman’s noose. Then I wrapped the rope around both uprights and attached the other end of the rope to the opposite upright with the same knot.

Use the toggle to tension the assembly. Don’t worry too much about over-tensioning the rope. The rope should break before the wood.

Put the leather seat in place between the uprights. Thread the legs through the seat and the mortises in the uprights. Put the chair on the floor and have a seat. It’s a low, lounging position, and you’ve earned it. PWM

 

Bowsaw Chair Cutlist

2 Uprights 21⁄2″ 21⁄2″ 40″
2 Legs 11⁄2″ 11⁄2″ 40″
1 Stretcher 11⁄2″ 11⁄2″ 25″*
1 Toggle 3⁄4″ 7⁄8″ 81⁄2″

*1⁄8″ tenon on both ends

Leather: Tandy Leather – Copper rivets, leather and leather tools.

For more on setting rivets, see “Build A Campaign Chair with Christopher Schwarz.”

This article appeared in the August 2018 issue of Popular Woodworking Magazine.


build a campaign chair

Build a portable chair that will be passed down as a family heirloom! Designed in the 19th century, this chair collapses to a small bundle (like the inexpensive soccer chair in your trunk), but is both durable and beautiful enough to fit in with your living room furniture.

Get your download of“Build A Campaign Chair with Christopher Schwarz”  by visiting our store.

 

Recommended Posts
Showing 2 comments
  • jeremymcon

    Hey Chris! I started making this chair with my little brother recently, and make the uprights at 2.5″. Making the chair from white oak because that’s what I have around, and those uprights are *heavy*. You mentioned that you beefed up the design to accommodate American-sized rears – what are the dimensions on the original Danish version? I’m thinking about taking 1/4″ to 3/8″ off the uprights to lighten them up (visually and remove some physical weight). Bad idea?

  • Danpope1

    I’m having trouble assembling the backrest onto the uprights. Very tight fit that just won’t go on. Uprights are 2 1/2” square per plan and rivets 9 1/4” apart as per plan. Any suggestions?
    Also plan of seat rivets is confusing with no dimensions so I used same dimensions as backrest.
    Thanks
    Dan Pope

Leave a Comment

Start typing and press Enter to search