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Thread: Steam bending Oz timbers
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18th July 2016, 06:34 PM #1SENIOR MEMBER
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Steam bending Oz timbers
Most of the info I've read about steam bending timber refers to overseas timbers, where the steaming time equates to 1 hour of steaming to 1 inch of timber thickness. Is this relevant to Australian hardwoods or do you need to add time to the steaming process? I understand that some timbers lend themselves better to steaming than others.
I should mention that I'm in the process of making a couple of pairs of Ojibwa snowshoes, and I'm starting out trying Alpine ash (vic), needless to say an abject failure first time round. Hence the question. Thinking about stringy bark next time
As an aside, I'm using a shavinghorse, drawknife, spokeshave and blockplane as my weapons of choice, pity the rest of the world didn't use those a weapons.
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18th July 2016, 07:32 PM #2SENIOR MEMBER
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I'm in the process of coopering a bucket, pretty much mimicking Reudi Kohler's video(if your familiar with it?), I'm just about to bend the hoops for it, however I made a poor choice of timbers and am using Atlantic Cedar, unfortunately sawn not split and maybe not best suited for this type of work. I haven't played with bending Aussie hardwoods but imagine most will bend, depends on thickness and radius of the curve of course, but have read Tas Oak (air dried) and nice straight grain will bend well
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18th July 2016, 08:23 PM #3
Forests NSW published a booklet on bending wood with particular reference to Australian species. Since it is very hard to find, I will attach a copy
Cheers
Jeremy
If it were done when 'tis done, then 'twere well it were done quickly
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18th July 2016, 09:27 PM #4GOLD MEMBER
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Air dried is a must. My understanding is that it simply does not work with KD timber.
I haven't done it but it's an interest of mine. I believe a modest hardness, a high modulus of rupture, and straight, medium, continuous grain is what you want to look for.
I wouldn't expect Eucalypts to be the best choice. I would look more at something like rainforest timbers (QLD Maple, Crow's Ash).
But that's literally all speculation based on general knowledge. No experience speaking whatsoever.
Good luck,
Luke
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18th July 2016, 11:46 PM #5
In the 1970's we were still building 16' skiffs using diagonal veneer hulls with steam bent laminated ribs / frames etc. My steam bending experience is limited to 2mm up to about 8mm or so strips from air dried FNQ rainforest timbers, particularly Red Cedar and Silver Ash. Steam bend strips is far easier and far more reliable than solid wood. Selecting suitable timber is also paramount as grain direction plays a signifcant role in the "bendability" of steamed timber. The link above covers most of the info you require, and remember to pay particular attention to what the timber comes into contact with while it is being steamed and bent, timbers like Alpine Ash will stain badly if it comes into contact with a "tanin" or bare steel etc.
Mobyturns
In An Instant Your Life CanChange Forever
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19th July 2016, 02:39 PM #6
Steam bending information is fairly widespread. I have an extensive previous post about what to look for. Ideal stock should be green, freshly cut. Next on the list is naturally seasoned, but you can still steam bend kiln dried stock too. The only difference between these three options, is the percentage of breakage you can expect, with kiln dried causing the most and green the least. Some species just don't like to be bent, but with persuasion and diligence, these too can be forced to comply, though expect a higher breakage percentage.
If you bend more than a few sticks, you're going to break one. It happens and is the nature of the game. What makes wood bend is heat and steam is a good way to apply it, but not the only way. I've bent many a piece with just a heat gun. Grain runout is another major concern. I can look at a piece and know where it'll break and more importantly, which way it should be placed on the bending jig. You'll have to break a few pieces to learn all the things to look for, but most should be obvious. Naturally straight grain stock is prefered, but if you have a bending jig, you can often convince a piece to take the bend, by backing it up with some sheet metal. The metal helps keep the fibers from bursting out, on the outside of the bend.
One tool I value is a floor cleaner, the other half use to own. It was designed to clean grout lines in tile floors with steam and it came with a several tools for the wand. It's now a shop tool and it applies steam at pressure, directly to a surface. It heats up in a few minutes and stays running for over a half hour. I just drag the tool over the piece several times, flip it over and do the same again and most thin stock is ready to bend. It beats the hell out of steam box that's for sure.
If the wood is really dry or kiln dried, soaking it in water for a day or two, prior to steaming is a good idea. Adding a drop or two of dishwashing liquid is helpful too. You can also simply soak some bath towels with boiling water and drape these over a piece that needs bending. I do this often when on a site, where I don't have every tool in my collection available. I repaired some battens on a batten seam powerboat this way a few months back. I scarfed on the replacement stock, but had to bend them around the hull, which this stock wouldn't have liked much, so 15 minutes under boiling water soaked towels, convinced the heart pine to bend around nicely.
All woods will bend, regardless where it's from. Some like it better than others. Alcohol can be used for bending too, though this requires some care as it can catch fire, if you're not careful. In the end, it's all about a good heat soak with a reasonable moisture content, so the wood's cellular structure can soften and deform, without collapsing. Moisture in the wood cells prevents the walls from caving in and the heat makes things pliable.
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19th July 2016, 05:27 PM #7SENIOR MEMBER
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Thankyou folks, for your advice. I've just cut down some stringybark and some bluegum which I'll turn into smaller sticks tomorrow morning, then I'll trim them down to 3/4" x3/4" ready for steaming.
I wont be giving up on the alpine ash though, I'll just cut some larger diameter logs hopefully giving me more timber to pick and choose from.
Just another aside, alpine ash was used to make Australia's first snow skis (which has a lovely spoon bow to help prevent too many face plants). And spotted gum and blue gum were especially important in boat building(steam bent frames).
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20th July 2016, 12:25 AM #8
Having been through a similar grief.....
CHAIR DESIGN 101
..... I can confirm that Australian hardwoods do not seem to comply with (particularly) Northern hemisphere 'truisms' and experiences of steam bending. My grandfather steam bent wheels from green and riven spotted gum with ridiculous ease so that might be a good one for you to try?
Of course, there is always your namesake ..... Huon pine steam bends BEEEEAUTIFULLY!
flettya rock is an obsolete tool ......... until you don’t have a hammer!
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20th July 2016, 04:42 PM #9SENIOR MEMBER
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Thanks fletty, I suppose I was leaning towards the eucalypts/corymbia species. Especially blue gum and spotted gum because of strength and interlocking grain (does interl ocking grain help with steambending ?). I'm not sure I want to use my huon pine on snowshoes, I'd rather keep it for boat restorations.
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20th July 2016, 06:27 PM #10Senior Member
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I've steam bent kiln-dried Surian cedar, just to throw a spanner in your theory. Apparently straight-grained radiata (yup, bloody radiata) is pretty good too, although I haven't tried it.
...and straight, medium, continuous grain is what you want to look for.
I wouldn't expect Eucalypts to be the best choice. I would look more at something like rainforest timbers (QLD Maple, Crow's Ash).
But that's literally all speculation based on general knowledge. No experience speaking whatsoever.
Good luck,
LukeYou know you're making progress when there's sawdust in your coffee.
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20th July 2016, 07:29 PM #11SENIOR MEMBER
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Cheers Sumbloak, I assume you're talking about pinus radiata. I should mention that one of my concerns is strength. what I mean by this is that when I'm out in the middle of nowhere, I don't want my snowshoe to go crrraaaaaackkk, especially when I have a 20 plus kilo pack on my back.
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20th July 2016, 08:55 PM #12Senior Member
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Silver ash (Flindersia schottiana, or F. bourjotiana) is supposed to be one of the best native timbers for bending. You can get it from sustainable sources if you look around.
No doubt there are several other timbers that would do the job well.You know you're making progress when there's sawdust in your coffee.
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21st July 2016, 11:08 AM #13SENIOR MEMBER
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Hmmm, didn't know about that one. Wonder if you can get it green? Sumbloak, do you know of any sustainable sources or an online list of those sources?
Cheers.
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21st July 2016, 11:14 AM #14SENIOR MEMBER
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I tried splitting the timber yesterday, no problems with the stringybark (using wedges and froe) but a different story with the bluegum. The wedges just bounced off. Might have to rip it down the guts with the chainsaw, then use the bandsaw.
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21st July 2016, 12:15 PM #15SENIOR MEMBER
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Thanks Jeremy, I've just downloaded the information that you mentioned
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