Official Luthiers Forum!
http://www.luthiersforum.com/forum/

Side bending question
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=28783		 Page 1 of 1
Author:  murrmac [ Thu Aug 26, 2010 12:59 pm ]
Post subject:  Side bending question
I am about to start building my first acoustic, and would like to solicit opinions about side bending possibilities.

I can cobble up a bending iron no problem, I would prefer not to fork out for a heating blanket, what I would really like to do is to stick the sides in a steam chamber for ten minutes (or whatever) and then whip them out and clamp them in an unheated former. I reckon I could have each side out of the steam chamber and fully shaped in like 15 seconds max, and leave them to take their set.

I have read many times in forums that you can't steam sides. I just wondered how many builders had actually tried it and found out that it couldn't be done, and what the reason was.

In all modesty, I consider myself greased lightning at machining wood, and I cannot believe that the cooling off period of a steam heated side is outwith my handling capabilities.

I do know that there is an issue with some timbers regarding loss of colour in the steaming process, but since I will be bending black walnut, I don't think that is an issue here, it's not like all the resins are going to leach out, like what might happen with cocobolo for example.

There are very probably some issues involved of which I am unaware, so I would be extremely grateful if anybody with experience of steam bending thin wood could offer some suggestions/advice, either positive or negative.
Author:  Corky Long [ Thu Aug 26, 2010 3:57 pm ]
Post subject:  Re: Side bending question
I don't have enough experience with steam chambers to tell you why it won't work, but I have some suspicions.
1) 212 fahreneit isn't as hot as what is attained with a blanket, or on a pipe. Perhaps you could get a steam chamber hotter? (physics question) At any rate, youre' bending right when the wood is cooling - and you'll try to force it by bending it before it cools.... "crack".
2) Others have commented that using too much water will cause their sides to tear if there's any figure at all, when bending on a pipe. This would certainly be the case if you've got your sides in a steamer.

Why not use a bending pipe? It was good enough for a hundred years before someone figured out that a side bender was easier and more uniform (was Charles Fox the first? I dont know) No need to invest in a blanket on the first build. Bending on a pipe (simple large gauge plumbers pipe with 90 degree angle mounted in a vice, with a torch stuck inside it is how I do it) is pretty straightforward, and fun, in a masochistic sort of way.

Takes a bit of practice to get the bends looking symmetrical, and I've never succeeded in avoiding springback, but once it's bent, then I clamp it in the mold, and leave it that way for several days, to reduce springback.

My 2 cents
Author:  Laurent Brondel [ Thu Aug 26, 2010 4:08 pm ]
Post subject:  Re: Side bending question
Steaming works well for thick timber, as in building a boat. However at the thickness your sides will be at (.065" to .080) they will invariably warp and cup. Bending sides with a hot iron or with form and blankets is easy and time proven.
Author:  alan stassforth [ Thu Aug 26, 2010 7:38 pm ]
Post subject:  Re: Side bending question
funny thing, i built an archtop git back in the 80's?, when all i had was the sloane book on classic guitar building.
so he said to build a trough, steam the wood for 1 1/2 hrs, then bend them on the jig.
i did that, (man, what a long wait!), and stated bending from the bottom of the guitar.
yep, when i got to the waist, crack! so i figured i'd start at the waist (doah!) and it worked.
rad quilted maple too.
wood was darker after that, and didn't match the back perfectly.
3" sides.
Author:  bluescreek [ Thu Aug 26, 2010 8:07 pm ]
Post subject:  Re: Side bending question
steaming can be an issue as it you can get too much water into the wood. It is more a thing that is per species but as a whole steam isn't the best method .
Author:  JJ Donohue [ Fri Aug 27, 2010 8:33 am ]
Post subject:  Re: Side bending question
I'm using far less spritzing these days than I ever have and getting better results. The less water we use, the less cupping and leveling will be required once the body is all glued up. I'm not sure at what lower level of moisture will cause cracking but I'm probably close to finding out. At this point, I'm lightly misting the craft paper one-half squeeze from about 3' away...hardly even damp.

And yet there are great builders (Wayne Henderson) who totally immerse their sides in water for a considerable period of time before bending and get flawless results...go figure! idunno
Author:  Alain Desforges [ Fri Aug 27, 2010 12:38 pm ]
Post subject:  Re: Side bending question
I too have found that too much water isn't a good thing.

JJ, in my new bender, I tried some Zebrawood test pieces, totally dry. I deliberately tried cranking my bender as fast as I could. I actually wanted to see if I could break the sides. True that the ratio/action on my bender crank is rather high (think of Gotoh Delta 501's LOL) so it doesn't close with the greatest of speeds, and it supports the side for its entire length. Still... No cracking whatsoever. The side came out perfect in every aspect.

Maybe that's the secret; irreverence... Now where is that African Blackwood set...
Author:  murrmac [ Sun Sep 12, 2010 5:15 pm ]
Post subject:  Re: Side bending question
OK, I accept that steam bending is not the way to go, so will go the Omega heating blanket route.

So which thickness of stainless steel is recommended for "backing up " the bend ?

I am thinking maybe 0.5mm would be about right, or is that too thick ?
Author:  JohnAbercrombie [ Sun Sep 12, 2010 6:01 pm ]
Post subject:  Re: Side bending question
alan stassforth wrote:
........... all i had was the sloane book on classic guitar building.
so he said to build a trough, steam the wood for 1 1/2 hrs, then bend them on the jig.


Ah, memories....
The Sloane book actually directed the builder to steep (totally immerse in gently boiling water) the sides for 90 min., using a 'boiling trough'.

Cheers
John
Author:  JohnAbercrombie [ Sun Sep 12, 2010 6:07 pm ]
Post subject:  Re: Side bending question
There's an interesting thread over at delcamp on bending:

http://www.delcamp.us/viewtopic.php?f=11&t=52548&start=15#p570882

For those who haven't yet 'converted' to the dry bending school, there's some good info there.

Cheers
John
Author:  Bob Shanklin [ Sun Sep 12, 2010 8:43 pm ]
Post subject:  Re: Side bending question
murrmac wrote:
OK, I accept that steam bending is not the way to go, so will go the Omega heating blanket route.

So which thickness of stainless steel is recommended for "backing up " the bend ?

I am thinking maybe 0.5mm would be about right, or is that too thick ?



Murray

Use .010" Shim in a Can http://catalog.daemar.com/category/shim-in-a-can .

Bob
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/