Continuous Arm Windsor Chair – Part 2
An ultimate woodworker’s challenge – to make a Windsor chair by hand using traditional chairmaking techniques.
In our Feb/Mar 2020 issue Peirce detailed how to make the seat, make and install the legs and how to shape the continuous arm.
The Steam Box
A wallpaper steamer and ABS piping is used to construct a “steam box”, which is used to steam wood for bending.
Tying Off the Arm
The bent arm is tied off on the form and left to dry on the form for two days.
Gluing up Hand Blocks
Blocks are added and clamped to the outer edges of the arm rest that will be shaped into the hand rest.
Splitting Spindle Blanks
Oak is rived to form spindle blanks using a froe.
A draw knife is used to rough out the spindles.
Using a Go Gauge
A “go gauge” is used to measure the spindle diameter.
Spindle Sight Lines
Sighting lines for the spindle mortises are lightly marked on the seat.
Drilling Spindle Mortises
Spindle mortises are drilled with a brace, a #9 spoon bit and a bevel square set at the appropriate angle on the spindle platform.
Aligning Arm Stumps
The arm stumps are aligned using winding sticks and a bevel gauge to ensure they have the same splay and rake. Slight adjustments are made with the tapered reamer until the alignment is correct.
Wedging Arm Stumps
Glue is applied to the arm stump mortise, the tenons are split using a chisel and then wedged in place.
The beading tool is used to cut a 1/8” bead on each side of the front face of the bow.
Drilling Hand Rest Mortises
Mortises for the arm stumps are drilled using a brace and a #7 spoon bit. The hand rests are held in place on scrap wood with hand screws to prevent blow out.
Mounting the Arm
The hand rests are fitted to the arm stumps using a winding stick as a reference to measure from the top of the arm to behind where the arm stump enters the seat platform.
Finding the Bow Center
A spindle is inserted in the center spindle mortise and aligned with the bow to find the “sweet spot” where it appears symmetrically centered in the bow.
Drilling the Center Mortise
The center spindle mortise is drilled in the bow using the platform mortise as the sight line.
Spindle Mortise Sight Line
Looking down through the center spindle mortise provides a view of the imaginary sight line used when drilling.
Drilling Outer Long Spindle Mortises
When drilling mortises, the bit must start at 90º relative to the surface of the bow. The drilling angle is then adjusted gradually until it lines up with the spindle platform mortise.
Aligning Short Spindles
The rear short spindles are placed in their mortises and aligned so they are equidistant from where the arm stump protrudes through the arm.
Adjusting Spindle Ends
The spindle ends are 5/8” thick and the spindle platform mortises are 9/16”. Small grooves are cut with a gouge creating a star shape that will lock the spindles in place.
The spindles are all mounted in the arm and bow prior to mounting the arm.
Driving Spindles Home
Glue is applied to the mortises, the spindles are aligned with them and they are driven “home” with a hammer.
The chair is turned upside down on the corner of the bench and the legs are given a first coat of paint.
Tung Oil Applied to Chair
With the black paint lightly distressed, and the entire surface then sanded smooth, tung oil is hand rubbed into the chair legs
Painted and oiled chair legs showing black on red antiquing.
Steam bending the arm
My steamer is simply a 70” ABS pipe 4” in diameter with a threaded cap attached that is attached to a wallpaper steamer. The outlet drains into a bucket of cold water to cool the steam and prevent condensation in my workshop. I’ve encased it in a wooden box for both insulation and esthetics. The continuous arm bending form is an arc 8-3/4” in radius, which is extended 1-1/4” at each end such that the second bend begins at 10”. The form is mounted on the bench and the radius of the second bend is 3”, which extends 10” below the bench.
To bend the continuous arm, I place it in the steamer for 30 minutes while the wood becomes “plasticized” as the lignin softens. Using insulated gloves, I then quickly transfer it to the bending form, hammer a wedge in the slot to hold it in place and slowly bend the arm to form the arc or bow. Wooden pegs are used to hold the first bend in place while I begin to slowly make the second bend in a downward direction. The arm rests are then tied off to “hitch posts” that are 1-1/2” high. The arm is then left in the form for two days to dry and harden.
I add 1/2”x 1-1/2” x 6” blocks to the end of the arm to create the hand rest. The outer edge of the arm rest and the blocks are joined, and the blocks are glued and clamped to the arm rest overnight to cure. The following day I rough out the shape of the hand rest with a coping saw and then round over and complete the process using a spokeshave.
Wood for the spindles is rived into 1” blanks from a green wood blank 24” long. I use my bench and a froe to facilitate the process, followed by the drawknife to rough out the shape and a spokeshave to fine tune the taper. A total of nine long spindles (23”) and four short (12”) spindles are required. Every chair maker developed their own style of spindles. Mine taper from 5/8” at the thick end to 7/16” at 10” and 3/8” at the end. A “go gauge” is used to measure the 5/8” diameter of the thicker end and the 7/16” diameter along the spindle. The short spindles have the same transition but at 5-1/2”.
Drilling spindle mortises
Spindle mortises are drilled using a brace and a #9 (9/16”) spoon bit. I mark off their positions by “walking” dividers set at 1-5/8” around the spindle platform and mark the mortise centers half way between the platform groove and the edge of the chair. I then lightly draw spindle sight lines on the seat from the center of the spindle mark to the center of the pommel, with the line for each of the eight long spindle mortises on each side of the center spindle being offset progressively by 1/8”. Site lines for the short spindles are drawn from the mortise centers to the center edge at the back of the seat. I then drill the spindle mortises 1-1/4” deep at the following angles: center spindle and the two adjacent ones at 10º; the next two on each side at 12º; the following at 14º; and, the short spindle mortises at 14º and 19º. I drill using my bevel square on the spindle platform set at the appropriate angle.
Mounting the arm stumps
The arm stumps are affixed to the seat with a tapered mortise. Using the sight line that is from the center of the mortise to the back of the chair seat center line, a brace and tapered reamer, I ream the holes, taking care to stay true with the line and at the 24º angle drilled earlier. I use winding sticks and a bevel square to check and align the arm stumps. The tenon should protrude around 1/2″ from the bottom. Once all the spindle holes have been drilled and the arm stumps aligned, I glue the arm stumps in their mortises. I then turn the chair upside down, clamp it on the bench and then glue and wedge the stumps in place.
Completing the arm
Prior to mounting the arm, I finish shaping the hand rest with a spokeshave, scrape the arm and round over the edge with a rounding tool. The bow has a bead on each side of the face that is made using a beading tool. The beading tool consists of a flat head screw mounted 1/2″ from the end of a handle and set so it cuts a 1/8” bead. Holding the handle, and with the bow clamped firmly on the bench, a bead is carved on each side of the bow face up until the transition to the armrest.
Mounting the arm
The arm stump mortises are drilled using a #7 (7/16”) spoon bit 2-1/2” from the end of the hand rest. I clamp the hand rests on a scrap board firmly to the bench using hand screws. I set the bevel square at the same angle as the arm stumps (24º) and use the point of a second bevel square set in line with the center of the bow to create an imaginary sight line. Once drilled, the hand rests are mounted in a bench vise and reamed using the tapered reamer from the bottom towards the top at the same angle. The arm is then mounted on the arm stumps and, using a winding stick as a guide, I measure the height of the arm on each side from behind the seat post to the top of the arm. I continue to widen the mortises with the reamer until the arm sits at 10-1/2” above the spindle platform. I then find the center of the bow by inserting my straightest spindle in its mortise and visually adjusting it until the bow is symmetrical on each side and mark the center.
Drilling spindle mortises in the bow
The centers of the spindle mortises are marked on the arm 2-1/2” apart, with the exception of the outer long spindle mortise, which is 3-1/4” from its predecessor. I use a #11 veiner to dimple the arm at just over 2/3 of distance from the back to the front of the bow. This ensures that when drilling the mortises, the bit does not blow out the back of the bow. I drill the center mortise holding the chair in place by stepping on the center stretcher and bracing the back of the bow against my leg. The spindle mortise sight line is from the dimple to the center of the spindle platform mortise. To help brace the bow while I drill, I take off the bow, insert the spindle in the arm, replace the arm on the stumps and push the center spindle into its seat mortise. I always start to drill at 90° relative to the surface of the bow and then “walk” the bit up until it is aligned with the seat mortise.
The rear short spindles are seated snugly in their mortises and aligned against the arm rest. Taking care that they are equidistant from the top of the arm stumps, I mark the position of the rear short spindle mortises and drill them out. The front mortises are drilled half way between where the arm stump protrudes and the back short spindle mortises.
Preparing the back for assembly
I disassemble the back once more and scrape the arm, paying particular attention to the bottom of the bow as it becomes inaccessible once all the spindles are in place. Following this I scrape and lightly sand all the spindles, taking care to round the ends over. The spindles are 5/8” in diameter at the bottom and the seat mortises were drilled at 9/16”. To lock the spindles in the seat mortises, I shave away small grooves in the outer end using a #3 sweep veiner. I test fit each one in their mortises, and when completed I insert it in the bow until all the spindles are snugly in place. At this stage, it’s important to examine the spindle platform for any marks that need to be addressed before final assembly.
I squirt glue in each of the seat spindle mortises and spread it out using a glue stick. Glue is applied to the end of the arm stump and the arm is mounted on the stumps. I push each spindle into the top of its mortise, use a 16-ounce hammer to drive the spindles home and clean up any glue squeeze-out with a wet rag. Using the hammer, I tap the bow firmly on each side of the center spindle, gradually adjusting the arc until it is symmetrical. I trim all the spindles and the arm stumps with a coping saw so 1/8” remains protruding. The ends are split with a chisel in the direction across the grain of the bow, wedges made with a draw knife, glue applied to them and they are driven home. I start by wedging the arm stumps, followed by the center spindle and the remaining spindles using a symmetrical approach so the bow doesn’t shift. I allow the glue to set overnight before I trim the wedges using a flush cut saw, followed by a #3 sweep veiner. Finally, the bow, arm and hand rests are scraped and sanded lightly, paying particular attention to detail where the spindles and wedges intersect the bow.
Historically speaking, Windsor chairs were usually painted with milk paint and a water repellant top coat was applied to the paint. Antique Windsor chairs have multiple layers of paint, and the colours were dependant on what was popular at the time. Milk paint is porous and requires a sealant. There is considerable debate as to what product is best to use as a top coat, including waxes, natural or synthetic oils, the various lacquers, varnishes, water-based sealants, etc. I personally prefer to seal chairs I make with hand rubbed tung oil.
Surface preparation is critical to the finishing process. I lightly spray the chair down with water to raise the grain and, when it is dry I sand the chair using 150 grit sandpaper. The rougher finish provides a surface that the paint can adhere to well. Once I have finished sanding, I make certain to brush away the all the dust from sanding before I begin to paint.
The final step in finishing the chair is the application of the sealant. At this stage, I rub the first coat of tung oil into the bottom and top components of the chair using a lint free cloth. Care must be taken to saturate the paint and bottom of the chair without leaving any residual puddles or drips. After allowing the oil to penetrate for five minutes, I wipe off the excess oil. Each coat of tung oil is allowed to cure at least 24 hours, following which I lightly sand the surface with 220 grit sandpaper. Before I apply the next coat, I wipe away any dust with a tack cloth dampened with mineral spirits and wait for the chair to dry. This process is repeated until I achieve the desired sheen, which requires a minimum of three coats of tung oil. I am satisfied with the antiquing effect if a slight amount of the first coat of paint will show through, the effect of which is enhanced by the tung oil.
Milk paint powder is mixed in accordance with the manufacturer’s directions. I have found that 1/4 cup (60 ml) of milk paint is sufficient to give a chair a coat of paint. I mix the milk paint thoroughly and allow to rest five minutes. I begin the painting process starting with the chair legs. The chair in this article will have an antiqued look that’s created by using layered colours, and slightly sanding through the second colour to reveal a bit of the first undercoat. I used a red undercoat and a top coat of black.
Like most chair makers, I do not paint under the chair seat, which both saves on paint and leaves the wood bare for my brand. Milk paint takes very little time to dry to the touch. Once the legs have dried sufficiently, I turn the chair over and give the chair back and seat their first coat. I lightly sand the chair using 220 grit sandpaper and brush any paint dust off before the second coat of paint is applied. I repeat the entire process once more giving the chair a top coat of black milk paint. Once the top coat has dried, I lightly sand the chair once more, dust it off and brand the bottom of the seat.