Iam in the process of building a steam bending set up. I have the burner and the steam kettle like this web site shows.
But I had thought I’d make the box from wood not pipe. Anyone out there with there own? What’s been your experiences bending and your projects.
I have been laminating and form bending parts for my rockers but I’ve been thinking about steam bending the backs from full 4/4 stock.
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Replies
Boxes will work about as well as pipes, maybe even better for some sizes of boards.
You'll need to design the box so that it collects the condensate and drains it off somehow. And you'll need to have supports that hold the workpiece up out of the condensate.
The first issue can be handled by simply tipping the box toward one end, and having a small hole for the water to run out.
The second can be as elaborate as expanded metal grating, or a simple as long nails poking through from the outside, making a sort of interior shelf from the points.
And don't forget that you'll need a source of wood that has not been kiln dried.
Vast projects should not be founded on half vast ideas.
I've been pondering the condensate going to a return tube to the kettle. This way reclaiming some of the water and extending the time before more water is needed during long steamings.
As to kiln dry wood, I've read this and understand why but others have said they can do this anyway. I suspect if I still ripped thin strips of kiln dried and steamed them I might be ok and it would just make the pressing a bit easier.
Some have said to pre soak the wood a day before steaming. Not sure that would help some denser woods like purple heart or paduke. Most of my steaming will be quarter sawn white oak and experimenting with bamboo.
Edited 8/12/2008 4:13 pm by jagwah
jagwah
a while back when I was bending cedar shingles I showed my set up.. doesn't have to be fancy.. In my case I included the bending form as ppart of the box but you don't have to do that.. One point I did was line it in plastic & put a slight tilt to it. That way as moisture condensed it ran into a corner and drained back into the kettle (in this case an old gas can) 94041.5 should have a picture of my set up.
Edited 8/12/2008 6:15 pm ET by frenchy
Thanks
I should have used the search engine, lots of info there.
Hey, jagwah,I made a rig a lot like Dunbar's about 30 years ago. Brand new metal gas can with its flex metal spout drilled into a chunk of 2x4 which had been cut to plug a length of aluminum downspout. Lots of heat loss with the aluminum, but it was fast, and worked great. If you do a lot -- building boats, etc, a rectangular wood box is best. Less heat loss, and more space for more sticks on multiple through-drilled dowel supports. But if it's 8:30 am, and you want that one piece installed this afternoon, go with plastic pipe. And I did just fine with kiln-dried lumber. I have never done a side-by-side test to compare kiln-dried to air-dried, so who knows.But before I forget, here's to the Coleman stove! What would we do without it?AitchKay
my first one was out of 4" pvc pipe and it couldn't handle the heat and bowed really bad so i built one out of 1x 12 pine works great.
I have made several steam box's. It really doesn't need to be
that elaborate.
A couple of things I don't like about that set up.
First off, the steam is entering in the middle. Actually in the middle
on the side. Your better of having the steam enter the bottom from
the end (typically the end opposite the door). By pitching the chamber
up towards the door, and having the steam enter from the low end, it
naturally flows up through the stock.
The chamber is very small. You need to work fast when it's time to remove the stock, but you want to get as much as possible done in
each "firing".
As far as reclaiming the water. Sure, but not important. I have
an almost identical can and hose set up. It holds plenty of water
for several "firings".
My current box is made from pine, it holds the heat better then
PVC.
Another thought-
What?
Well I'm gonna tell you anyway.
You can bend kiln dried wood, but not very well. That 4/4
stock will be difficult. Worth the effort to round up
some green wood.
One problem with bending wide stock is that it will often belly and not stay flat. Parts like slats can be forced in the jig but something like the top crest rail in your picture will present problems. You need to generate lots of hot billowy steam. The wood looses it's elasticity very quickly after you remove it from the box. You need to move fast. Parts may change after they come out of the jig, plan on some failures and make extra parts. Select your stock with the straightest grain possible.
My box is just a piece of PVC pipe. It bends and warps when it gets hot, so what? When it melts beyond use I'll make another one. I can throw it anywhere for storage. I have a length of aluminum soffit vent in the pipe to keep the lumber elevated out of the condensation water. I pre-heat my replacement water in electric tea pots. Scavenged a burner off a discarded BBQ and used a piece of radiator hose for connecting from the boiling can. I bored a single 3/8" hole in the pipe to relieve the pressure. Otherwise you blow the caps off. Steam can burn you fast and badly, wear gloves and keep your face clear.
Beat it to fit / Paint it to match
Great looking rig. Thanks for the photo
Do you use wielding gloves?
Just a heads up-
Pressure can be dangerous. Plus you don't need it. The
steam is a medium to heat the wood. Pressurizing the chamber
can and often will slow the transfer of heat from pot to
wood.
Cut a one inch hole on the top opposite where the steam enters.
You want a robust flow through the chamber.
The worst exposure to the steam is when you first open the cap and reach for your piece. Typically, I put on one glove. I always have some deerskin gloves that fit well and allow some dexterity. The wood isn't that hot and cools immediately. I start bending as soon as I get hold of the piece, get it in the jig quickly and leave it clamped over night. Most of what I've bent lately were small but long moldings. A 4" pipe limits what you can fit in the box. I use steam for some bends and laminate others. It depends on the size of the stock and the application.Beat it to fit / Paint it to match
I successfully steam bent all kinds of kiln dried wood before I was told it couldn't be done. Green might be better, but comes with it's own problems.
Cabinetmaker/college woodworking instructor. Cape Breton, Nova Scotia.
Me too... matter of fact, everything I've steam bent has been kiln dried... this is the first I've heard not to<G>Our rig is simple. Hot plate, tea kettle, hose and 6" PVC w/ end caps. Relief valve is scotch cork. PVC has holes drilled for wire to support the stock. The holes are siliconed, so the cork is probably unnecessary, but it makes the scotch a business expense. Now you see this one-eyed midget
Shouting the word "NOW"
And you say, "For what reason?"
And he says, "How?"
And you say, "What does this mean?"
And he screams back, "You're a cow
Give me some milk
Or else go home"
Me too -- I've only steam bent kiln dried wood. I can see where you might get an advantage out of green, especially if it's riven as opposed to cut, but never had any special problems with kiln dried. (Never tried bending anything much over 1/2" thick, tho'.)
Mike HennessyPittsburgh, PA
What problems?
Shrinkage, I suppose.
I tried to resist the green thing , but for
tight curves your gonna need it. Unless your working very thin.
Tho a strap helps a lot.
Timely thread for me. Need to bend some oak gunnels for an 18' canoe.
Oak is the easiest for me to get here.
Did the outside ones some years ago with no problem , now I have to replace both inside and outside. (inside ones are original circa 1950)
Last steamer was a 18'length of 5" "K" style gutter with 2" water in it sitting over a 2 burner camp stove, used gutter spikes to rack the wood over the water and covered the whole thing with a couple pieces of plywood scraps. One question I have is glued joints and steam bent wood. I can't get oak long enough for the entire length of gunnel(I would need a 20' 1x2 stick red oak) so I have to scarf joint it. Last time I cut the joint then bent the pieces and then glued the joint up. Still had the joint break open. I finally got it to hold by reinforcing the scarf with small dowels perpendicular to the gunnel scarf joint but it was a major PITA Any ideas?
They can't get your Goat if you don't tell them where it is hidden.
Scarf @60° or so, resorcinol, dowel or rivet, lash and re-resorcinol?.Depending on the shape of the gunnel, maybe put the scarf in a low bending stress section.Got pics of the canoe? Now you see this one-eyed midget
Shouting the word "NOW"
And you say, "For what reason?"
And he says, "How?"
And you say, "What does this mean?"
And he screams back, "You're a cow
Give me some milk
Or else go home"
Scarf was actually at more than 60 deg., the cut measured aprox. 6" long across the 3/4 dimension.
Used resorcinal 2 part glue.
Edit: Not the same as the old plywood glue, newer less potent stuff. Could use a source of the old stuff if anybody knows of one. Boat shops perhaps?
On another canoe just recently I tried the same joint using Titebond 3, it broke open with days.
Should have mentioned the type glue to start with. I will have to take a pic for you. The canoe is a "Chestnut" , based on the Old town 18' but made in Canada for the salmon fishing trade, it has 1/2 again more ribs than the Old Town of the same size and shape. Originally canvas skin that I fiberglass in the late 70's when I bought it . Canvas was torn to shreds on it when I got it.
Edited 8/14/2008 3:24 pm by dovetail97128
Sorry for the delay, had lent my camera out . Here is the old girl. Outside gunnels removed and getting ready to remove seats, thwarts and inside gunnels . I glassed it in the mid eighties so that I didn't have to worry so much about abuse when the kids learned to use . I haven't had it out for years because it is simply too big for one person to load and unload without straining so it has sat outside under various tarps for years now while I used it's much smaller, cheaper and lighter cousin.
They can't get your Goat if you don't tell them where it is hidden.
Cool fixer upper.
IIRC when I was making a Sharpie Skiff, it had the lapstrakes scarfed at a 1:8 ratio or greater. I had to scarf the Okume marine ply ( and really exp. stuff at that) carfully with a block plane.
All glue was West systems, Mahog for transom and gunnels and seat beams.
I'd epoxie the scarf and seal that Red Oak with the same, remember , epox HAS to be painted or varnished ( with spar) because UV will attack it.Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
Man, that is one heavy looking mother, bet it's a comfortable ride. So, did the glue fail on the gunnel? If that's not a break, scarf looks pretty steep... I'm just guessing, but could you pin the scarf with angled dowels? Now you see this one-eyed midget
Shouting the word "NOW"
And you say, "For what reason?"
And he says, "How?"
And you say, "What does this mean?"
And he screams back, "You're a cow
Give me some milk
Or else go home"
Yes it is.
Weighs in at about 95lbs. Glassing it actually didn't change the original weight by more than a couple of pounds. Will carry about 650-700 lbs . IIRC 18' long, 38" wide ans 13" deep. Extremely stable boat and a beautiful ride. One thing I always loved about it was how quiet it was, no racket from water slapping the sides etc. Yes that is a scarf joint, that one is original (or at least was on the canoe when I bought it as I never changed the inside gunnel)
I will be replacing all the gunnels so I will replicate that glue joint although I may move the joint location a bit away from the thwart location when I repair it. I have been locating sources for real waterproof resorcinal as well as some of the marine epoxies. I think they may do the job if I pre-bend the gunnels and then do the glue up this time with one of those glues. Pinning with angled dowels is what I tried on the smaller canoe I just worked on , that failed, but I think I didn't have enough steam bend in the wood and that produced to much stress , tighter form and bend on the smaller canoe as well.
They can't get your Goat if you don't tell them where it is hidden.
After steaming, can you clamp it to a bit smaller form? Big copper rivets may add a mechanical fastening that would help the glue under stress.Good luck, looks like something worthy of keeping afloat... I've picked up some sail boats that I never could get back together<G> Now you see this one-eyed midget
Shouting the word "NOW"
And you say, "For what reason?"
And he says, "How?"
And you say, "What does this mean?"
And he screams back, "You're a cow
Give me some milk
Or else go home"
dovetail
If that had been white oak most likely it wouldn't have rotted.. red oak doesn't have any decay resistant properties.
Second visit a sawmill. I can easily get 19 foot long whatever and have on occasion gotten 20'+ by having the guys cheat the carriage and hand splitting the last foot.. The added advantage is that it will be green and thus easy to steam bend..
Don't expect to get that size, you'll have to rip it out of maybe a six inch board.. Plan on visiting the sawmill well in advance of when you will actually need the board. They have to have one of their loggers cut the bole longer than normal inorder to get your 20 feet.
Frenchy, I happen to know the owners one of the only oak mills her in this area. he couldn't get me the length I needed so I am stuck with the red oak form the LY. I will confess to not caring for the canoe as I should have, too busy the last 6-7 years or too sick to do it.
They can't get your Goat if you don't tell them where it is hidden.
jagwah,
i have done 1/4 sawn white oak with a steam kettle and a pvc pipe.
even bought the "special kettle' from Lee Valley or somewhere( i forget where)
don't think4/4 white oak is gonna bend well though.
i HAVe bent thinner rips that were kiln dried into pretty tight radiuses though
best of luck it's a lot of fun,
stephen
I appreciate everyones input. Besides the normal reasons to bend wood I'm interested in steaming bamboo. Sounds tasty.
But there are a few oddball ideas I want to explore. I'm gathering parts and hope to have the steamer up and running by the end of the month. I'll snap a few shots of the equipment and pics of the bamboo effort.