Steam Bending, an Addendum

[stevem]

just a few words of caution

i have to steam bend 4 more pieces for the chairs im working on and i ran into an unforeseen problem
i've been using a piece of 3 inch abs pipe as a steam chamber, seemed easy, wrap it in fibreglass, fittings easily available etc etc

but the 5 foot piece of pipe sagged about 2 inches during the last steambending session, preventing the stock from fitting in, a disaster in the making!!

so just a caution, support the pipe well, not just at the ends like i did, and watch out for that steam!! it'll burn you in seconds

steam bending is a good process for many things, but heat and water create a real hazard in the shop, from fire hazards from the hotplate, steam burns etc etc, it seems pretty benign, to steam a piece of wood for an hour, but it can be very dangerous

protective clothing is a must, spilled boiling water on yourclothes are a real hazard, i wear rain type gear for sailors, believe me you wont be able to get jeans off fast enough if you spill boiling water

support the steam chamber well, dont rely on the kettle for support, when its empty, it will fall over, my setup fell over the first time i used it and it wasnt pretty

and remember, water ie steam has a very high specific heat or in general terms contains a huge amount of energy and it will burn you in seconds or even less

all in all the process is pretty cheap and easy, just needs some real precautions

i'll post more details of my steam bending setup if there's interest, let me know

[big mac]

Uhhhh ----Steve--Lee Valley has an excellent book on steam bending Just pulling your chain You are exactly right on all points--it is a cheap process but there can be some real pitfalls. Needless to say you will probably be able to write a how-to when you finish this job. Glad you didn't suffer any real injuries Getting the jeans off reminds me of an incident in my brother-laws shop many years ago.

He was just getting into wood work and all that goes with it---planers-jointers etc and a spray booth. He was using a pressure pot rather than a gun with a small container under it. For the fellas that don't know --on large jobs you can fill the pot or put an open 1 gallon container inside and lock the top down. Two hoses go to the gun. One air and the other fluid. This one day after spraying he decided it was time to clean up everything.

So he proceeded to fill the pot with industrial strength thinner and first blow out the gun and the fluid line OK that worked great --now he went to the pot---compressor still on---started to swish the pot back and forth to wash the lacquer off. He was crouched over with the pot between his legs when the relief valve let go and sprayed the whole of his inner thighs and the "nether region" with thinner. By the time he realized what had happened--the insides of his thighs and everything else felt like they were on fire! He quickly stripped down--grabbed a jar of hand cleaner and was in the process of lathering himself down-----when in walked the wife of the couple he was doing the job for Wish I had been there

We will never let him forget that one

[stevem]

thats hilarious!!
but i cant negate the seriousness of steam burns
my dearly beloved is a nurse, at one time an er nurse
she says steam burns are nasty, like really nasty because of the high specific heat of water and relatively low temperature
so precautions?
water proof pants at least and boots
fire extinguisher bigger the better
a big bucket of cold water
steam is a very useful tool, but just as dangerous as a router out of control or a tablesaw kickback and it happens in a second or less
so if you want to try steam bending(its easy and cheap) think about the consequences of a serious burn and act accordingly

[David in Mississauga]

Steve,
I've been meaning to ask you...what is the MC of the wood before you steam it? I've read that it should be between 20 and 30 percent MC but am curious to know if you just used KD wood.

Regards,

[stevem]

david, im not sure of the moisture content but its seems very dry, but not kiln dried
when i picked up the lumber in september it was wrapped in plastic and a dehumidifier under the wrap had been gonig for two months or more, before that the lumber had been air drying for two years, thickness was around 6/4
based on the joinery ive done so far ie the table top, its dry
i heard that air dried lumber is much better than kiln dried for bending, so thats the route i took, after all a dehum. doesnt heat the wood like a kiln
i have steam bent the 3/4 stock from HD with very poor results(it is kiln dried), so my air dried white oak should been fine as it is so far

[stevem]

steam bending is easy, the prep is time consuming
first a form must be made, only a test run or two will get the right shape, some spring back is expected
a decent steam generator is paramount, my set up was the bare minimum, just a kettle on a hotplate
the kettle must have a spout that fits a standard pipe fitting, mine is the same diameter as a bathroom vanity sink tailpiece
i used a piece of 3 inch abs drainpipe for my steamchamber and it worked flawlessly until it sagged requiring support in a t least 3 places (in 5 feet)
the kettle to steam chamber connection requires a really tight joint, my 3 inch abs chamber has a wye fitting with 1 1/2 on the side and a fernco type coupling to the kettle(rubber with hose clamps) a regular compression fitting witha white plastic ferrule melted
the steam chamber can be sealed on both ends with an orange test cap
the whole setup cost maybe 50 bucks, including a hotplate, kettle and plumbing fittings
it takes an hour or less to reach temperature and maintains 210 plus as long as the kettle has water in itwhich lasts 2 hours, refilling the kettle on the go doesnt seem to affect chamber temperature
but please please pay attention to my safety stuff in the previous posts, steam burns are serious ****, really serious

[big mac]

Hey fellas--that's why in an earlier thread I said "if anyone has ever worked with good air dried wood" they will notice the difference. Kiln drying seems to "case harden" wood----you can really tell the difference esp. when on a lathe--or if your jointing. Even if you are jointing in the right direction--the wood seems to make a snapping sound

Your right Steve---maybe I should have put that somewhere else---I really didn't want to make light of accidents with steam-----it can be really dangerous

[J.P. Rap]

When I was a teenager I lifted a pot of water off the stove and the handle broke. The hot water spilled down my chest and belly (but no further thankfully). I was luck as the water wasn't scalding hot yet. I got a minor burn but it could have been much worse.
I have suffered second degree burns and I don't even want to think about third degree.
If you have never been burned, believe me, you don't ever want to be. It's a pain you will never forget.I have often heard burns are the most painful of all types of injuries and I believe it. Even after the back problems I had.

[Backflush]

protective clothing is a must, spilled boiling water on yourclothes are a real hazard, i wear rain type gear for sailors, believe me you wont be able to get jeans off fast enough if you spill boiling water

Excellent advise. I can confirm first hand that any absorbant clothing will make burns many times worst as it soaks in and has more contact time with the skin. I once spilled some boiling water on my sock covered foot and ended up with 2nd degree burn the exact size of the area it soaked into.