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methods of work #38: Another test of steambending

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Blog entry by Loren posted 07-01-2014 02:40 AM 756 reads 1 time favorited 8 comments Add to Favorites Watch
« Part 37: Modernist chair - riffing on a vocabulary of shapes Part 38 of methods of work series Part 39: Chinese influenced chair mockup »

Testing limits. This 1” thick by 4” wide board was really difficult for me to pull around. Due to figure this board is probably a less than ideal candidate for steam bending but now I know I can bend this part, so it’s good enough for a prototype I think.

I’m going to make a horizontal back crest for a stool design I had an idea for. The part actually cracked a bit at one end, due to the wild figure perhaps or maybe just because I split the end block at the same spot pulling it around. I don’t need the part that split anyway because I’m going to cut this part off so it’s not really like an armrest, it will just kind of hint at that… we’ll see. I already had the form for another bend in narrower material and didn’t want to make another form just to try out this idea.

-- http://lawoodworking.com



8 comments so far

View Scott R. Turner's profile

Scott R. Turner

260 posts in 1910 days


#1 posted 07-01-2014 08:19 PM

I can’t quite tell from the picture, but is there strapping on the outside? Is this kiln-dried wood?

View Loren's profile

Loren

7809 posts in 2369 days


#2 posted 07-01-2014 09:09 PM

Yes to both. It’s 2 Veritas bending systems bolted together.

I’m in Los Angeles air dried wood is not available. I know
air dried is better but I’m getting acceptable results for my
modest bends using kiln dried.

-- http://lawoodworking.com

View Scott R. Turner's profile

Scott R. Turner

260 posts in 1910 days


#3 posted 07-01-2014 11:06 PM

Yeah, I can’t find air-dried wood either (in Virginia) although I haven’t looked that hard. But I think that’s more than a modest bend! What kind of wood is that? I was bending African Mahogany much more modestly and having some problems, although I wasn’t able to use strapping, which probably contributed to my troubles.

View Loren's profile

Loren

7809 posts in 2369 days


#4 posted 07-01-2014 11:17 PM

Whatever they sell as white oak.

Most exotics don’t bend well. Try oak, ash, walnut,
cherry maybe.

You really need to look at straps and end stops to
bent furniture parts. The set up can take some time
but the results are predictable with low reject rates
with typical bend-friendly woods.

I have bent thin African mahogany on a hot pipe for a guitar.

-- http://lawoodworking.com

View woodshopmike's profile

woodshopmike

175 posts in 385 days


#5 posted 07-02-2014 03:23 PM

Just out of curiosity, how long are you steaming the wood before bending? I’ve never bent anything that thick, but for guitar sides I usually steamed for 15-30 minutes.

Also, I can’t tell from the photo, but I assume you’re using lumber with minimal grain run-out. If not, finding lumber that has the least run-out will pay dividends.

-- www.woodshopmike.com, www.woodshopmikestudio.etsy.com

View Loren's profile

Loren

7809 posts in 2369 days


#6 posted 07-02-2014 03:33 PM

I look at runout of course, but in the end for furniture parts
I just bend and see what happens and my reject rate
is a non-issue using the method you see above. This part
was steamed for about 1 hour.

I’m not bending expensive woods for furniture parts. I’ve
mentioned above exotics don’t bend well anyway. Flatsawn
is said to bend best, which puts a more or less quartersawn
view on the edge, so I suppose ideally the edge would
be quartered with no runout. It might happen if you
split the part. I will will sometimes look at the face grain of
a sawn board and it will be at such and awkward angle
I snap a line and bandsaw a taper on the board, joint and
then rip the board so the grain is straighter. This can
be a wasteful practice or it can make for better looking,
more harmonious work, depending on how it used. I
haven’t tried to strap bend a piece with this “defect”
intact I don’t think, but in any piece over 12” long or so,
some runout is likely to be present on one side of the
face or the other, owing to thickness variations in the
growth rings and twisting trees do when they grow.

I never steamed guitar sides. I spritzed as the bend progressed.
I did soak them beforehand a few times but went over to
spritzing later. If over-wet, grain lift-out occurs when
bending without support on the back, as with bending
sides or binding on a hot pipe.

-- http://lawoodworking.com

View woodshopmike's profile

woodshopmike

175 posts in 385 days


#7 posted 07-02-2014 06:42 PM

I hear ya. I guess the thicker stock makes run out not such a huge factor for your furniture work?

Exotics are tough indeed, but I’ve had success with Wenge and Padauk. Those were slow and methodical. I use spring steel on each side of the piece while bending and haven’t had many failures arise with the extra support in place.

-- www.woodshopmike.com, www.woodshopmikestudio.etsy.com

View Loren's profile

Loren

7809 posts in 2369 days


#8 posted 07-02-2014 06:57 PM

I would guess not. I bent some ash chair legs just a bit off the corner
recently and I didn’t have any grain blow out. The strap was only
in contact with a tiny bevel on the corner, so I surmise that it’s
really about the relationships between the end stops when bending
thicker stock. Of course some hidden defect on the outside face
could blow out without the support of a backing strap. I assumed
when I started strap bending that the strap was there in part to
prevent the grain lift-out I had seen when bending thin parts
on a hot pipe, but maybe I’m wrong on that, at least with bendy
woods like oak.

-- http://lawoodworking.com

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