Steam bending

[peter flavell]

I have been thinking about setting up to steam bend some chair parts and have found some simple steam boxes using grey drainage plastic pipes. I have contacted OSMA suppliers

of plastic pipe who tell me that their pipes will only withstand 60 degrees . Has anyone tried this? I realise that a box can be constructed relatively easily but using the plastic pipes

would be simple ,quick and very steam tight so even if the tube lasted just a few steams it may well be a simple solution . Any ideas would appreciated.

 

[marcros]

they probably will state this, but I have seen steam mending on youtube using soil pipe. You need plenty of supports so that when it sags, which it will, then it cant go far.

Osma will say 60 degrees because beyond that temperature it will deform and bend/sag.

There was a very good guide by Veritas about steam bending, let me see if I can find it for you.

 

[marcros]

here you go http://www.leevalley.com/us/html/05F1501ie.pdf

 

[NazNomad]

Did it once for steam-bending some guitar parts, the plastic pipe drooped & sagged like mad.

Then I used a steel pipe, which wasn't very effective as the cold pipe caused the steam to condense quickly.

.. made a simple wooden steam box and it's been fine.

 

[NazNomad]

Before and after ...

 

[Bm101]

What about some old ducting/flue liner if you can get it. Might be worth a look on Gumtree or give your scrappy a bell?

2 sugars please Naz!

 

[NazNomad]

BM, see my edited post above about a metal pipe.

 

[Racers]

Mine is made from OSB and plywood, its not had much serious work but its looking just as rough as it did when I made it.

Pete

 

[Sheffield Tony]

I have been using a length of aluminium pipe. Wrapping it in an old blanket solves the heat loss problem. I would not use iron or steel - I can only imagine the black stains you would get.

I have seen offcuts of Kingspan held together with gaffa tape working quite well.

 

[shed9]

I'm in the middle of building one using two connected 55 gallon drums and a pair of these http://www.screwfix.com/p/titan-ttb419s ... pper/48764

I'm aware that metal enclosures will cool quicker however they will be heavily insulated to take advantage of the thermal properties of the drums. Will be watching this thread with interest.

 

[monkeybiter]

What are typical steaming durations, and what might you regard as a max. viable thickness for steam bending?

 

[Sgian Dubh]

What are typical steaming durations, and what might you regard as a max. viable thickness for steam bending?

About an hour per inch of thickness once the wood has reached temperature. As to a maximum viable thickness that can be steam bent, much depends on how well you're set up to take on the more challenging tasks, i.e., the complexity of the desired end result, and/or the thickness of wood you're dealing with, and in both those cases, speed of getting the hot pliable wood into its desired bent form is critical. Certainly, it's possible to steam bend wood that's 3" or 4" thick, but you need powerful and swift means of clamping up using a really solid bending form - you'd probably be looking at engineered metal for the former and hydraulic clamps.

The general guidance for the best moisture content compromise is wood that's air dried to somewhere between 20% and 30%, which is therefore not too soft through being too wet, nor too brittle through being kilned to below 10%. Slainte.

 

[RobO]

I've tried used plastic draining pipe for steaming it goes completely floppy, probably okay for one off use. A steam box made from celotex is much better, but generally i just use layflat polythene tubing (500 gauge). This has the advantage that you can keep it in the polythene whilst actually bending and clamping the wood. Whilst steaming I cover the polythene layflat tube with silver bubblewrap insulation stuff, just take the insulation off before you bend, and keep the wood in the polythene with the steam on. Gives you 5 - 10 mins to get the bend right and the clamps on, a lot less stressful than the usual 60 seconds.

 

[RobO]

Some info on steam bending here: http://www.danenbergboatworks.com/steam_bending.htm

 

[blackrodd]

Even loads more here, several in fact, on utube, interesting stuff!
Regards Rodders

https://www.youtube.com/watch?v=e4CoTNeoa98

 

[NazNomad]

Some info on steam bending here: http://www.danenbergboatworks.com/steam_bending.htm

They could save an awful lot of time if they bought their timber from Jewson and just nailed it onto the boat.

 

[shed9]

I found this video very interesting and intend to give it a go one day;

https://www.youtube.com/watch?v=--iPQIwSEJM

 

[HowardM]

Does it have to be steamed..?
Is it not the heat which is needed to get the cellulose soft.?
I am just thinking of how a wet part would have to be dried out before glueing.

 

[shed9]

Does it have to be steamed..?
Is it not the heat which is needed to get the cellulose soft.?
I am just thinking of how a wet part would have to be dried out before glueing.

Yes, it needs the wet heat to soften and reform the lignin within the wood.

 

[RobO]

Yes, it's the heat that softens the cells. I think the steam helps conduct the heat into the wood. The temperature in the steam box needs to be kept at 100 degrees. I think a metal tube would make it difficult to main temperature without some sort of insulation. Wetness on steamed wood tends to evaporates very quickly.