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wood steaming - Dennis Nicholas - 07-08-2021
Would someone who has done it give me details of steaming some ash for my Nippy. I am asking full details including what materials and dimensions for steam box and time of timber in steam.....how much water to start with etc. Just to save reinventing the wheel. I have some very well seasoned ash.
Also wondering if i could just get away with cutting a curved piece out of solid with my bandsaw or whether it would end up with too short a cross grain at any point.
Last attempted in early 1970s to do boot bodywork failed (more due to chamfer angles and wrong curves) and I made frame from 1/2 inch angle cut and shut to curves..
The job in hand is to make the 2 new 3/4 inch pieces that run between floor and top lip of the cill in a Nippy body.
I have a propane stove that has a 9 inch ring/burner that screws into a dumpy 2Kg gas bottle, also have other smaller cooker/burners.
Dennis
RE: wood steaming - Chris KC - 07-08-2021
Hi Dennis, I have a LITTLE experience and can offer advice correspondingly!
#1 - Don't try and bend bits which were originally sawn on a curve. This may sound obvious but sometimes you have to look very closely at the timber to identify confidently which is the case. If Austin did it by sawing don't get fancy.
#2 - I've had limited success bending (and twisting) ash timbers about 1/2" thick & 2" wide. The steaming was accomplished by slipping them inside a long tube made from P.U. mineral water bottles taped end to end; steam came from an aluminium kettle ("whistling" type, sans whistle!) on a butane camping stove. Use leather gloves and provide a hole at the end for steam to escape. I seem to recall the rule of thumb 1 hour steaming per inch of thickness (so I did mine for 30 mins). When sufficiently steamed, the timber was transferred swiftly to a wooden jig and clamped to it tightly with G-clamps. This was much harder than it sounds! And if you try to bend too tight or without enough steaming it will crack and split in two... Leave it overnight to "set". The jig needs about 15% "over-bend" as the piece will spring back a little once released - will need some trial and error.
#3 My results were "not too bad" and (with a bit of fettling) serviceable. I'm not in a rush to try anything more complicated. One thing I can say is that a bit of well seasoned ash is a fine strong bit of timber, and easily tougher than laminated layers.
For what it's worth, my advice would be to use your covetable supply of ash to cut the easier straight sections, and chat with a pro for the harder bits - I know Martin Prior has been doing woodwork for quite a few Nippies so he must be quite good at it by now!
Best of luck and do keep us posted on how you get on please.
RE: wood steaming - Hugh Barnes - 07-08-2021
I can't add much to Chris' comments except to say that I ad some success using 4" plastic sewer/down pipe as the receptacle for the wood I was bending and used a mains wallpaper stripper to supply the steam.
As Chris also suggests, don't try to rush it...
hth...
RE: wood steaming - Martin Prior - 07-08-2021
The easiest way to do this is to buy the parts from a specialist supplier. Modesty prevents me from naming them!
RE: wood steaming - Bruce Nicholls - 07-08-2021
I have used a boat building method of putting the length of timber in a bag (made of a poly-tarp or similar) with one open end. Push the pipe from the steam generator (kettle, wallpaper stripper or whatever) down the bag to the closed end. Loosely tie up the open end round the pipe and start the steam. the timber can be gradually bent round a former of the correct shape as it softens. When fully bent turn off steam clamp up and allow to cool. The advantage is that the timber is not cooling while taken from steam box to former and it takes the guesswork out of how long to steam.
RE: wood steaming - "Slack Alice" Simon - 07-08-2021
I am reasonably practical, and persistent.
I gave up trying to bend my ash, using steam.
I had (final version) an 15" aluminium pipe, lagged with 2" of felt, fed by two wallpaper strippers until they both ran out of water, a good solid jig to make a 4" radius curve inside and out, loads of G cramps - and, as I say, quite a lot of patience.
I failed to bend 1" x 1" ash to my satisfaction.
So I ran it through a bandsaw and steamed the resultant 1/8" strips, and laminated the curves I needed, using waterproof PVA. That worked.
I concluded that well seasoned ash is probably a bad idea and that, if there ever is a next time, I would use unseasoned or partly seasoned timber.
RE: wood steaming - Martin Prior - 07-08-2021
As Simon says, laminating is a far more satisfactory and reliable method. We always make curved sections this way. Steaming is difficult, messy and unpredictable.
RE: wood steaming - Ray White - 07-08-2021
History shows us that steam bending timber can be a mistake. Not long after the Swallow Coachbuilding Company moved to Coventry, a certain Mr Aylesbury - whose company had patented a method of steam bending timber - convinced William Lyons to purchase some of their machines claiming they would save materials and man hours. To implement the new process, an 'expert', Frank Etches, was employed.
The process completely failed to produce the expected results as the timbers kept unbending; bringing production to a virtual standstill.! The frustrated Mr Etches left one day never to return.!
RE: wood steaming - Dennis Nicholas - 09-08-2021
Thanks all. Have had another look at body and seen floor/cill not as curved as I thought so will go with band sawing slightly wider section to fit the curve.
Currently have body upside down raised up on pallets, with poles between so can stand inside, removing paint from scuttle.
This is etch primer I put on a few years ago when started rebuild. Trying to get all bare metal so can go through full process to apply POR15. I never want to do this again!!!!!!!!
PS someYouTube vids advising how to get round sticking tin lids by drilling 2 holes and plugging with screws!!! then when next need to use just remove screws and pour out........they obviously missed the point that the pigment will have settled to the bottom and the paint should be stirred before use so will end up with rubish paint job that will not stay.
Dennis
RE: wood steaming - dickie65 - 09-08-2021
When I worked in boatbuilding most of the steaming was done with quarter sawn green timber.
The grain has to be aligned properly for bending.
The steam box used several immersion heater elements and the whole lot was lagged in hessian sacking. a health and safety nightmare
( except health and safety did not exist in this particular boatyard )
Laminating and using a decent glue is far more predictable.