Banjo mandolin repair advice

[philipkarlberg]

Hi,

I am renovating an old banjo mandolin, unknown brand. I am not sure of the right term, but the "body" that surrounds the skin, has now got an oval shape instead of a round, which makes the neck tilt upwards with higher action as result.

So my question is, is it possible to heat and steam the wood of an old instrument like this, and bend back the "body" to it's original shape?

The sides are glued together at the saddle and where the neck joins the body. Here are some pictures (I currently sanding it):





Thanks

Philip, Sweden

[Big Joe]

Heating or steaming may not do anything, but at best could provide a very temporary solution. However, if it does allow some movement, it should hold better once you get the head and tension hoop back on. It is not uncommon for the rims to get out of shape if they do not have something to hold them in shape. You also want to check the tension hoop to ensure it is not warped as well. That happens as well. Anyway, it looks like a fun project. I have seen worse and we have been able to get them to work. Have fun!

[Jim Garber]

That is an unusual design, I am guessing either British made or German-made on a British design? Most American MBs have separate resonators if any and the neck is attached to the rim.

[philipkarlberg]

Hi. The resonator has two screws at the saddle and then neck, to prevent the wood to go out of shape. Unfortunately, they have not been used very much. Once I have got it back in shape, I could tighten these screws to hold it in shape.

So, you don't think there is a risk to use hot steam? If the glue would start to loose up I mean.

Here is an earlier thread with some images before I took i apart:

http://www.mandolincafe.com/forum/sh...-this-banjolin

/ Philip

[philipkarlberg]

Ok, I have just finished an attempt with steam / heating the wood to get in in shape. I took a frying pan with boiling water, and put some bbq stick on top of it, and then the wood body on top of that. Then some aluminium foil to close in all the steam.

I made a simple "clamp" with a bolt that I gradually unscrewed to a round shape. So far it worked very well. The question is, how much will it go back when I loosen the clamp? Here are some pics:

[Paul Hostetter]

The ovaling of the body is normal and to be expected. Your tool for pressing it back round would have worked without the steam and so on, which I consider rather risky.

In any case, you could fabricate an adapted Gibson-style coordinator rod and just leave it in permanently. This would work well with a typical zither banjo, and would resist the compression of the string tension and allow the assembly that holds the skin to remain at rest with regards to the string compression. You only need one, aligned with and as close to the head assembly as possible.



This is the full set in a Gibson:

[philipkarlberg]

Thanks Paul,

That is a great idea. I will certainly look into that. I will get back to you next week when I am finished with the coating.

Philip