 A common twist we see in British and American furniture turning is the
barley form. This generally takes a single or double twist format and is
very distinctive. It lends itself well to any straight or slightly tapered section of a spindle turning.
To lay out a single barley twist, turn your spindle profile and leave it
slightly proud over diameter - the extra will sand off during your
finishing process. Design your turning with a cove or V-cut at either
end of the spiral section to allow for easier finish cuts on the ends.
Using your calipers, transfer the diameter of the spindle as a segment
length to the area or section you wish to spiral. Repeat this process
along the entire length to be carved. If it's a tapered section of the
spindle, reset the calipers for each segment. You should wind up with a
spindle that has segments marked the length of the proposed spiral.
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It all starts with layout. You can't make the progressive cuts shown at left without drawing the spiral first. For the single twist above
you'll need a 1:1 pitch. Use the diameter of the stock as your first
dividing lines (blue). Divide those segments again in half (red), then
mark two horizontal (green) lines exactly 180° opposed from one another.
Now you can draw the spiral (black). |
The Pitch
Pitch is one of the variables we can play with on a spiral. To run a
single twist, we'll set the pitch (ratio of length to rotation) at 1:1.
This means there will be one diameter's worth of length for each full
rotation of the spiral. To set the pitch, divide each diameter segment
you have laid out in half by running a pencil on the turning. You now
have two segments for each diameter of length.
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With stock between centers, lay out and mark your spiral. Here the
author uses a black marker to create a 1:1, single twist ratio. |
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The barley twist is started by using a dovetail saw with a depth stop
clamped in place. Rotate the stock toward you by hand. |
Once you have the segments marked out, use your tool-rest to mark out
two lateral lines 180° apart (on opposite sides) along the length of
what will be the spiral. (See the photo at right.) If your lathe lacks
indexing, you can use two opposite drive center spurs as indicators for
where to draw your lines, or use your calipers set to just touch the
O.D. (the touch points will be 180° apart).
Starting The Spiral
You should now have rectangular sections marked along the length of the
work. To draw your single spiral, simply choose one set of these boxes
and run a diagonal line from corner to corner on each successive box.
Note: this is also where you decide if your spiral is to be left- or
right-hand. If you lay it out away from you starting at the tailstock
(right) end, it will be right-hand. If you mark your layout away from
you starting at the headstock (left) end, it will be left-hand.
Next, use a dovetail or tenon saw with a depth stop clamped to the blade to cut the line of the spiral down to depth.
For a single barley twist I recommend 1/3 the total diameter of the
turning. Cut along the line to the depth of the stop, rotating the
spindle by hand as you go. Keep your saw vertical, and cut on the top of
the spindle to keep your angle consistent. You will wind up with a
spiral cut the width of the saw's kerf that makes one complete circuit
of the turning for each diameter of length it travels.
Carving
I use several very sharp carvers' chisels to pare the waste quickly from
the spiral cut's edges. You can even rest the chisel on the tool-rest
and rotate the turning carefully by hand to speed removal. I use a flat
chisel to "break the cut open," and then switch to a sweep (concave)
chisel. I invert this chisel to achieve the rounded shoulders of the
barley twist. For fluted (concave) spirals you can also use rasps to
remove waste. Be careful to make your chisel cuts emerge from the wood's
grain rather than digging into it. The latter mistake will cause torn
grain and possibly even flake off a section of the spiral. (Hint: any
major "oops" here can usually be fixed with CA glue).
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Once the spiral or twist has been incised with the dovetail saw,
break
the cut open with a flat chisel. The author uses a variety of carving
chisels and gouges to pare the waste from the twist. |
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After a sufficient quantity of stock has been pared away, switch to a
sweep or concave chisel. Invert it and continue to remove wood. It
begins to shape the rounded upper edge of the spiral. |
Sanding
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For fluted spirals, you can also use a rasp to remove wood and shape the
bottom of the cut. |
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As with most woodworking endeavors,
sanding is one of the final steps
before finishing.
Strips of sanding belts can be folded
and used for
this purpose.
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If your lathe will run at low speeds, you can sand the spiral under
power. Start with 80-grit or so to remove chisel marks, but be careful
not to oversand and ruin your form. (Remember that extra dimension you
left? Here's where it disappears.) Roll or fold your paper (old belt
material works well) and allow the abrasive to follow the spiral under
power. Reverse the lathe as well if possible. Work through the grits
down to 220 or so, both under power and stationary. Keep at it to get
all saw marks and torn grain. With care, the result will be a good, even
barley twist. A little practice, and it will become a quick job.
Once you get the idea, keep experimenting. There are no end of
variations on the spiral concept: open, fluted, multiple starts, you
name it. Balusters and newels, furniture, or small craft items can all
be spiralled. If you would like a graduate course in the process, try
Stuart Mortimer's book on the subject: Techniques of Spiral Work.
Steve Blenk is a Washington state professional woodturner.
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