Neck tension/bowed neck

[Stephanie Reiser]

I built my own mandolin, from stew-mac f-5 kit. I knew nothing about building these, but I managed to get it done and it sounded great. Slowly but surely the neck is bowing, and I am heart-broken. I don't want to break down and buy a store-bought mandolin. I did nothing to the neck rod truss adjustment nut. I only hand-tightened it and put the cover over it. Is it to late to get a wrench and do something to save it?
Stephanie

[ourgang]

What have you got to lose??? Tighten it up. Being it is so loose, that may be the only problem. Only thing is, go a little at a time. 1/4 turn first and then 1/8 turn.

[Jim Rowland]

Hi Amanda:

If the truss rod will not help,what is its purpose? Don't forget,you have hogged considerable wood out of the neck in order to install it,essentially weakening that area. Although you probably should have tightened the rod enough to provide stability to the neck,I see no reason why you shouldn't realize an improvement by tightening it now. If you follow Ourgang's good advice and provided that you haven't accidentally glued the rod firmly into the neck,you can reasonably hope for success. Don't forget to loosen the strings before you start. Good luck!
Jim

[Stephanie Reiser]

Thanks, fellow, for the advice. I reckon I'll have to place an order with S-M for a wrench. I wonder if a music shop would have such an animal.....? Hmmmm...
Thanks again, Stephanie

[Rroyd]

It is best when tightening the truss rod nut that you apply some sort of physical pressure to straighten the neck before tightening the nut.
It is possible to damage the threads trying to straighten the neck with the truss rod alone.
You can put two small blocks of wood across the fingerboard, (one on each end) and then set a sturdy block lengthwise on them above the neck. Then place a padded block on the back of the neck and use a C-clamp to pull the bow out of the neck by carefully tightening it. The c-clamp is squeezing the lengthways block sitting above the fingerboard and the padded block on the back of the neck. Then you can tighten the truss rod nut without having to apply excess pressure. (I have done this without removing the strings or even detuning it by padding the crossways blocks to avoid damaging strings or frets.) A similar jig can be used if you need to heat the fingerboard to straighten the neck. One way or the other, you should be able to get it straight again. It is quite common for a new instrument to need to have the neck straightened after a few months of being strung up.

[Luthier Vandross]

Wrap it in a blanket, except for the neck, then take it out in the sun... then clamp it as described.

How far is it pulled forward?

When the neck is hot, you take all the slack out, right then-n-there.. make sure it's warm... warm-warm, then clamp it..

Stay off the extension. I plug in the heat block for.. hmm... it's warm.

M

[Stephanie Reiser]

I saw something in Roger Siminoff's older book about clamping the neck. I think I will be doing that before I tighten the nut. That idea of warming the neck is a good one too. I wonder if that can be done with a lamp. Also, I didnt know that it was a commone problem with new mandolins. Makes me feel a little better. I was beginning to think that I had green maple. When I tune it up as perfect as I can, then play an E on the 7th fret of the A string it is sharp. Tends to make tunes like Ode To A Butterfly sound terrible.
I'll let you all know how it turns out. Got to get that wrench first.
Thanks again, Stephanie

[Rroyd]

After a new instrument is tuned up, the pressure exerted by the strings may gradually cause a bit of bowing as the instrument "acclimates" itself to that stress. As far as dealing with it goes, you can use a heat lamp, but don't get in a hurry and get it too close. The goal is to warm the wood enough so that the glue will soften enough to "creep" between the fingerboard and the neck as you clamp it straight. Done gradually and carefully, you won't end up with finish damage, or bubbles around the inlays, and that type of thing. (Protect the peghead and body from the heat no matter what method you use to warm it.) Also, it is very possible that the truss rod has an adequate
amount of adjustment to where you could cure the problem without having to resort to heat. The intonation problem you describe could be due to bridge placement, or it could be tipping a bit, changing the scale length. If it is the neck bow, it sounds like it might need to be treated by heating it, as you are increasing the string tension enough to raise its pitch by having to push it down so far to fret it, which would indicate that the neck was fairly severely bowed. Hopefully, that is not the problem with the intonation. (Sometimes old strings will not fret accurately, too) Anyway, if you have the skills to build it in the first place, you shouldn't have any difficulty dealing with this. Good Luck.

[Luthier Vandross]

A heat lamp works ok, but we use a heat block... you plug it in, set a timer... and pull the plug when it goes 'DING!', then it sits heat clamped, overnight. If that doesn't do it all, we do it again.

The point being, I use a lamp to remove fingerboards.. uhh... be careful, and cover the body, completely, with a blanky, and a piece of heavy cardboard... oh, if it's not a sun lamp, don't waste your time.

M