Thread: Steaming big and long bits of wood

Ah ha. A timber box is back on the agenda if it's the better way to go. Why? Because I have those old floor boards that were originally going to become the coaming but which I've now realised aren't up to it

So, PVC pipe (quick and easy) or a wooden box?

Would it be possible to make the box with a removable top to make it easier to lift out such a long plank?

Richard

Richard
Whatever way you design it remember you need to get the wood out as fast as you can..... remember it will be very, very hot ! ..... it doesn't take long to cool and lose the bending ability......

Do the strips need to one piece, or are you able to scarf them together from 2 or 3 pieces. I am asking for 2 reasons, it would make for a smaller, quicker, and more compact steamer, and I suspect that you will find it difficult to impossible to get a 3m+ length into place and sufficiently clamped before it looses te pliability that steaming will give you.

Spent a fair bit of time watching the Queenscliff Maritime Museum build a display Couta boat years ago overseen by some of the professional guys who built originals. They were bending ribs to about 2.8m long in a planked steamer, had about 2 minutes to assess the rib in the steamer, pull when ready, set into keel rebate and clamp, and then form and clamp around the mould. Any thing went wrong to slow the process, and there was a very resounding crack and some swearing.

Ribs were abt 60 x 20 hardwood, with most bending being accross the face. You anticipate larger timbers, and needing to bend on face and edge together.

I would consider doing it as 3 pieces, placing the centre first and then the two outers. Most of the timber boats that I have seen were done is segments about 1.5 -2 m long.

I do wonder if you aren't right Mal, but suspect you're not. The other thing is, if I have to do them in three bits, I don't need steam at all It's all part of the plannng process though.

Aberdeen is just trying to talk me out of it because he knows HE'LL be the poor bugger helping me come the big cook up

Richard

Hello Richard,
I have not steamed anything except SWMBO everytime I come in from the shed in my maingy uggies, but I digress. The current issue of AABB has a great article in it using a ply box that is extendable. Some dowels to hold the wood off the bottom, a hinged door one end and a keg sitting on a gas burner, perfect.

FWIW I think you will have trouble with PVC bending too much with the heat. A sheet of elcheapo 3/4 ply might work out a better bet.

Mike

Richard

do you need to steam bend the whole stick or just a shortish section ?

the latest Aust Wood Review has a article on steam bending the centre of a plank.
could you do the same?
or those parts where the natural whip of the stick is not enough to make the bend?


ian

pm sent

regards,

AD

Originally Posted by ian

Richard

do you need to steam bend the whole stick or just a shortish section ?

the latest Aust Wood Review has a article on steam bending the centre of a plank.
could you do the same?
or those parts where the natural whip of the stick is not enough to make the bend?


ian

The whole board is curved both vertically and horizontally. None of it's particularly severe, just there's a lot off it across a wide board. I reckon it's just as hard to do half the board as all of it. Bung the steam in the middle so that cops the best of the heat and let the ends look after themselves. It's a pity I have to bend from one end (where it fits inside the transom) but by the time the board's cooling, I'll be past the worst of it - as long as the board's heading in the right direction I'll be fine.

I'm leaning towards a wooden steam box (pm sent bloggs )

Richard

The real trick to successful steam bending is the prep, much like a fine paint job.

If you're bending over a jig, then it has to be strong enough to accept the resistance of a hunk of lumber, that may not necessarily want to go willing into position. This jig also needs to have a very secure way of restraining the bent stock. Clamps, wedges and Spanish windlasses are common methods.

If bending on the boat the same is true. Perform a dry run with a piece of cardboard of similar dimensions as the stock you'll bend. You have to have clamps, wedges, tools and literally everything you'll need during the process at the ready, as you'll have no time to find a tool or clamp while the process is "hot".

Working time varies with plank thickness, but generally you've got a solid 2 minutes where you can do anytime you want, then another 2 minutes where you get rapidly diminishing returns from your efforts and lastly the next two minutes, if you're still wrestling with the piece, it's very probable you're going to hear a quite loud crack, usually followed by cursing, heavy drinking and lies about why you need another piece of expensive lumber for you project to the better half.

I can't tell you enough how important having everything just at hand is and how necessary a dry run is. The dry run will find flaws in you technique an show you where the tools need to be.

I've seen PVC steamers, but personally prefer my old section of steel chimney pipe myself. A plywood or solid lumber box will retain the heat much better then PVC or metal (my metal is insulated with 3" of fiberglass batting).

Typical steamers will have one end raised up slightly, say 5 degrees (steam rises) and the steam enters at the lowest point. The higher end of the steam box should be sealed with a loose fitting door, or you can drape several rags over the opening, which will permit pressurized steam to escape, but hold the steam in the box to work it's magic on the wood.

Another trick is to soak the wood for 24 hours (or more) in a bath of water (completely immersed). This is especially helpful on kiln dried or well seasoned stock.

About an hour for each inch thickness, but this is just a very rough guide. Some woods will bend readily with less time, other like to cook for longer. Only experience and many broken bits of lumber will help in this regard.

Wear glove, because the stock will be hotter then a prostitute outside an automobile assembly plant on payday.

Thanks for the help.

Plywood steaming box it is That's the easy bit as it turns out.

The biggie is the steam source. Blogg's unit is a ripper (thanks for the photos mate, they explain a lot) and if I thought I'd be doing a lot of steaming, I'd be building one that way, however, it's a big build for a pair of coamings. Considering these'll be the last bent pieces fitted to the boat, I need to think carefully about how much I want to spend on bits and bobs. Aberdeen's offered to lend me his steam source so if that has the capacity I might be right (it was set up for a smaller job).

The working time will be fine - my wedge clamps work well and go on very quickly once you're set up.

Still lots to think about before giving it a go. Maybe scarfing two or three bits together at odd angles is the way to go though I can't help feeling that'd be a pity, at least without trying to do it one bit first.

Richard

Daddles
The 'old boiler' (no not the missus) is 22.5 litres - that should be enough for any bloke

Have the heat making source also but you might need a gas BBQ bottle ?

Originally Posted by Aberdeen

Daddles
The 'old boiler' (no not the missus) is 22.5 litres - that should be enough for any bloke

Have the heat making source also but you might need a gas BBQ bottle ?

I read that as meaning you've got a burner.

I've got a gas bottle. Hmm, I should probably fill that shouldn't I.

How big's the spout and tube into the box?

Hmm, now my biggest problem is two bits of wood Anyone in Adelaide putting down floorboards and wouldn't notice a couple missing

Richard

Daddles,
If your not in a panic I've got a pack of Studley's hardwood coming soon and there may be some bits that would be suitable.

Anyway give us a yell if you need a hand as I wouldn't mind learning a bit about steaming.

Mike

Thanks for the offer Mike. She's probably got enough hardwood in her now, much to Mik's horror (he doesn't use any hardwood). I'd like to get this going as quickly as practical ... which could mean anything from having a cookup this weekend through to sometime next century

I'm happy to give you a yell when I'm ready to go though. This is one job where a few pairs of hands won't go amiss.

Richard