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creating spiral rope design in columns12/30/12
I have 10 fir logs, 12 foot long, to be used for pergola columns. I wish to create the "rope" spiral design I have seen here in New Mexico on these logs. Those who do this work will not share their secrets. Is there anybody on this site who knows precisely how to create these spiral , rope like, designs?
I have made many spiral turnings on a special lathe. The machine would be too small to use on your columns. Historically, these were always carved by hand. As such, they were the highest expression of a carver's art, whether in stone or wood.
Layout is done with a long roll of paper, wrapping the shaft in a spiral fashion and marking the shaft with the resulting spiral.
Carving a cove, or a v-groove or a deep u shape will result in cove, rope or Barley twists. Set up a shaft horizontally at the correct height, layout the spiral you like (determined by width of paper roll, cut on a bandsaw), and try a few basic cuts. The Rope is the easiest.
I assume you have basic carving skills and tools so you can visualize from there....
Thanks for this advice which gives me some very basic ideas as to the layout of the spiral patterns. This is a start, and I do not have the tools or skills, YET!
Check out the video from Legacy Machines. Google may have more.
Too small for logs, but the machine operation is the same for large or small.
Get in there and start cutting, just realize it will all be hand tools. I hope you are working green Pine....
Precise instructions in a few paragraphs and you without tools, machinery or skills?
OK here goes...
Logs are first sent to a sawmill where they are cut into square timbers or a log-lathe to be turned round. Square timbers are then turned round on a lathe. (Without benefit of a lathe you'll need to "hew" them round as shipwrights have done more than 500 years ago.)
Round or tapered/round shafts are then laid-out with grid lines taken from the plan (ring and longitudinal lines). The intersection of these lines establish points along the spirals. Small nails are driven into these points and a chalk-line is wrapped round the shaft and snapped as you go (either that or a bendable straight-edge).
With all the spiral lines on the shaft, a hand or skill saw is used to make the initial cuts. These are made to depth along the spiral lines. (This is done on the lathe or between centers while the shaft is rotated.) Further cuts can be made to leave a spiral "V" notch. A hand saw can be fixed with a depth gauge or an antique stair saw could be used.
Now you're ready to carve, rasp and sand the loops of the rope. This is also done on the lathe. The shaft is rotated as you work but must also be solidly fixed as you carve. This is time consuming but not difficult. All the carving is done "downhill" of the grain. You'll need to work from opposite sides of the lathe, or left/right hand positions.
I don't know what you're seeing in New Mexico but twist turnings are classified by style: rope, barley, Jacobean, open, etc. These all require different layouts but the execution of the work is the same.
Today twist turning are done on special CNC lathes like the Hapo 7000. Home-built lathes can be set-up like the old (Sears) router-crafter toy.
I use the Legacy mill to make rope columns, but anything over 8' long has to be segmented. The diameter is limited, too. I think mine will only do about 12" in diameter.
You might want to look into finding someone with a CNC lathe with a large enough capacity to process the logs.