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GTison
Feb-23-2012, 9:59pm
Today I tried to steam the dovetail apart in my old A-O model Gibson. (It is a project mandolin. ) Anyway I got the fretboard off ok, but the Neck joint I couldn't get to budge. I must have steamed if for at least an hour. Anyway, the "riser" piece on the body of the mandolin is made of what looks like maple. With the steaming it got significantly larger. It came off. The problem is now the riser is larger than the sides of the mandolin. Will it shrink back to its original size before steaming? .

sunburst
Feb-23-2012, 10:21pm
Yes. At least, very close to the "original size". Wood is in constant motion, shrinking and swelling in response to changes in moisture content brought on by changes in relative humidity.
Can you describe your method of steaming and steam source? Perhaps we can offer advice on what to do to get the neck loose. And to go back a little farther, why does the neck need to be removed?

Big Joe
Feb-24-2012, 6:36am
The first rule of wood is that it will always try to return to a tree. That does not address your issue, but that is why using heat set to straighten a neck usually does not work. In you case, it will shrink as the wood dries out. It can be fit to the neck if needed when you begin to reassemble. If both parts were equally humidified and allowed to dry equally it should be quite close. However, it is a "living" thing and does what it will do.

GTison
Feb-24-2012, 8:18am
first the story of the mandolin; I bought it about 14 years ago. It was in bad shape; had been wet while in the chipboard case, top was warped and pulled up by the tail piece, back was warped away from the tailpiece, the whole thing had been stripped and PAINTED w/ chocolate brown paint, and the center seam on the back opened up, bad frets and board. I worked on it a while when I got it then got busy and put it away. It became a Project Mandolin, forgotten. One of the things that stopped me was how to take care of the released end block without taking off the neck. I decided some time ago that I would take the neck off and just reassemble the mandolin from scratch. However, yesterday since the neck would not release easily. I thought it might be just as easy to make a form with a neck cut out somehow. I'm not sure how I'll do that either. So, that is a bit of a show stopper. I thought about a different way to glue in the end block. That I may try instead of removing the neck but I think I'll still need a form to get the sides and top back in position. I'll try to post pictures today. I took a few.

GTison
Feb-24-2012, 8:24am
Things done so far:
1. stripped the paint and cleaned as best I could.
2. re-glued the back seam and flattened the warp.
3. glued up a few cracks in the top. not cleated but I will.
4. glued some kerfing back in.
5. glued sides to the head block. (may need redoing since the steaming of the neck)

sunburst
Feb-24-2012, 8:27am
Deleted post.

GTison
Feb-24-2012, 8:31am
delete combined w/ post below

sunburst
Feb-24-2012, 8:33am
You will need a form of some kind, but unless the neck joint is compromised or the neck is badly damaged, you won't have to remove the neck. I'll see if I can find a picture of a jig I made to do a similar job...

Found 'em.
The first pic is two forms, one for mandolin, one for mandola, along with some cut-off scraps from side material. They are padded with sheet cork material. The instrument goes in as in the second picture, and the screws in the jig can be tightened to force the rim into compliance with the shape of the top and back. When alignment is good, clamps can be applied to glue things back together, and the whole thing can be set aside to dry.
Also, check out Frank Ford's ideas at Frets.com.

bmac
Feb-24-2012, 8:35am
'The first rule of wood is that it will always try to return to a tree."

I knew I shouldn't have purchased all that antique bent wood furniture!

Just about as long as people have been around wood has been bent for various uses... ship building being one good example and certainly furniture building is another good example.

I presently play mandolins with steam pressed tops and backs and they are close to 100 years old. In restoration I have steamed both of them apart and they went back together just fine.

Moisture in moderation is the instrument builders best friend. But if you want to use your instrument as a boat, you are on your own.

GTison
Feb-24-2012, 8:38am
I steamed with a hose out of an old pressure cooker. with a ball inflation needle attached on the end. finally I just stuck the hose in w/o the needle. Here's a pic of the iron to loosen the neck. And finally the pic of the riser block loosened & swollen by the steam to a larger size.
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sunburst
Feb-24-2012, 8:38am
deleted post, I combined it with the one above. Who knew there would be two posts while I was typing?!

GTison
Feb-24-2012, 9:23am
I think the neck will hold as it did not come off yesterday. unless it shrinks loose when it dries. I will build a form something like yours. I like those.
Still, what do yall think about the riser block? Should I wait and dry it out? It was real tight before it got so swollen. I wonder if it will return to being tight?
My guess is I should put it in place without glue and see if it will shrink back to its original shape. Then inject hide glue in the joints when it is back to shape. In the mean time I will build forms to correct the end block problem. And then worry about glueing up the top to the repaired rim..