Stringing – how to bend 1/16 stringing
larrmartin | Posted in General Discussion on
I’m teaching myself stringing to be used on a federal-style walnut side table. I’ve followed the instructions in Michael Dunbar’s book on federal furniture where he used 1/16 birch stringing and “pre-formed” the arched portion of the stringing by rubbing and bending the stringing around a chisel handle. I tried that on a chisel handle and on a wider diameter hose nozzle but the 1/16 and 3/64 stringing always cracked. I finally got it to bend successfully when I reducded the stock to 1/32 and scratched a matching groove which looks quite nice. I’ve used maple, birch and pine stringing with same results.
How do you bend 1/16 stock without cracking it?
Replies
Larry, boil it in water for a few minutes. Make a chamber (steam box) with an escape vent and steam it using a kettle of some sort with a pipe to transfer the steam from the kettle to the steam box. Heat up a cast iron pipe with a blow torch and rub the piece of stringing backwards and forwards across the pipe until you get the wood all warm and it'll suddenly start bending. I've never tried this one, but whack it in the microwave for a minute.
All these efforts to heat the wood will result in warming and softening the lignin, the 'glue' that holds all the stringy fibres together. Once the lignin is warm it softens and allows the fibres to rearrange themselves, i.e., they can be bent around a curve, after which the lignin will cool and lock them all together in their new shape.
The bends need to be held in their new shape for a while afterwards-- overnight or 24 hrs is good, allowing the shape to become set. Clamp the bend up-- in your case masking tape might do. Upon release of the clamps the wood will usually spring back1 some, and you make adjustments to the bend tightness of the former you used for your test bending.
In your case most likely the easiest solution to hand is a big pot of water on the ring of the cooker. Once the stringing is soft and pliable you'll get just seconds to bend it and clamp it in place. There's much more crap on bending wood in my head that I haven't touched on here, but this should get your job done.
1 I occasionally see the rarer spring in after bending. Slainte.
Larry, I should have mentioned that when steaming wood for bending you should heat the wood thoroughly with steam in the steam box at atmospheric pressure to 100ºC and maintain that temperature for ~2 minutes per mm of thickness (not the woods width) or ~45 minutes per inch of the woods thickness.
For boiling and heating over a pipe, etc., make adjustments to your times according to your experience.
I noticed that in response to another question you posted in this forum someone recommended you purchase Joyce. I second that, and the full title is Ernest Joyce, The Technique (US Dictionary I think) of Furniture Making. Slainte.
I've never tried steaming, etc. before so this is as good a time as any to follow your suggestions. Thanks.
You can also soak it in water and just bend it without steam or use a curling iron after the wood has been wetted.
J.P.
Doesn't the soaking cause the wood to swell? With only a 1/16 or a 3/64 groove, seems like the stringing easily could swell and prevent a fit.
No, the string is so narrow that any swelling is not any consequence as far as I have experienced. I think that sometimes you just need to experiment to see what works for you in your particular situation with the type of material that you have on hand. I think that is what makes this type of work so much fun and interesting. Good luck.
J.P.
I finished the stringing and it looks pretty good. I made scratch stock 1/32, cut the stringing 1/32, and it fitted well and bent nicely without breaking.
Excellent, did it work on the first try?
J.P.
Yes, the 1/32 stringing bent fairly easily because I bdegann rubbing it around the circumference of a larger nozzle pieces and then gradually rubbed and moved the stringing down to a narrower circumference so that it was gradually shaped to the size I needed.
The hardest part was figuring out how long to cut the stringing to fit the half-circle groove I had scratched into the table leg. I just estimated, then fitted, chiseled off a small piece a number of times until it finally fit.
I'd love to see pictures if you have any.
J.P.
Here's a photo of the leg and apron. It's the first time I'm sending a photo so I don't know about proper sizing, etc. Hope it works.
Can't see it on the screen but I can picture it in my mind's eye...Beautiful!
J.P.
I've tried again but for some reason the photo will not upload to Knots. Sorry.
Larry,
I do a lot of federal furniture, which of course has stringing. I found out pretty quickly that factory made stringing is nearly impossible to bend without fracturing. I cut my own stringing from solid stock, and sand it to thickness on a jig on my drill press ( see attached photo). Some radiuses can be done just by working the inlay around the curve with your fingers. For those that can't be done this way, I soak them in water for a few minutes. Then I bend them around a hot pipe or bar with a radius equal to, or smaller than the desired radius, backing the stringing with a piece of thin (.002") stainless steel shim stock, but any thin shim stock would work. This backing prevents the fibers from breaking out. As long as the stringing fits the groove while dry, any expansion from the soaking won't matter. The only real thing to watch is to not get the pipe or bar too hot and burn the stringing.
Rob Millard
Larry,
It may sound silly, but consider a $15.00 investment for the Woodwright's Shop video called:
2304 Inlay With Steve Latta
Steve's process is interesting and, as always, a picture paints a thousand words. This was one of the more useful episodes, in my opinion. Scratch stocks, cutting stringing, etc....
Cheers,
Greg
http://www.megspace.com/lifestyles/njmarine/Steam.html
try making a steam box. i did and love it.....just wish i had more things to bend
hopefully this web site is helpful...
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