Any way to flatten a maple fingerboard

[Frank Capo]

I am doing a neck with stick reset on a 1928 National wood bodied Triolian.  This guitar came to me with a previously stripped finish and missing tailpiece. Otherwise in structurally sound condition however with very high action though no obvious sign of structural deformation. It occurred to me that this round neck guitar may have been set for lap playing at the factory, though unlikely and I was unable to determine that if any as such were ever produced.  There was no significant neck warping to explain the high action. To make this usable to me, I decided to remove the glued-in neck and stick assembly, which was was quite painless, and do a reset. Although I did not plan to remove the fingerboard, it came off without any struggle or damage as I was considering epoxy rod installation. Upon further inspection, the beefy neck without fingerboard seems quite straight/flat. However the removed maple fingerboard has a slight upward bow and twist at the body end. It will flatten out with slight pressure, and it seems unlikely to me that the slight fingerboard bow could bow the neck when reinstalled, but I still would prefer to flatten perfectly if possible. So, my question is, are there any heating or steaming techniques that can be used to perfectly flatten out this board? Thanks

[Greg Mirken]

I think the distinct kink at the heel region explains your high action. Don't worry about the board. If you glue a rod of some sort in the neck and reset the neck to body the fretboard will be fine. Those are indeed beefy necks...

[Frank Capo]

Thanks for your reply. After seeing how flat the neck without fretboard appears, was hoping to avoid installing a rod. But a rod does make sense at this stage. But, looking at the fingerboard, the tab is pulling upward, which may be exerting an upward pull on the top...so the rod may not have an effect on that force...though there is no obvious distortion in the top under the tab...

[Greg Mirken]

I thought you were considering adding a rod. The neck has rotated relative to the body rather than bowing itself. It would probably be fine without added stiffness, but I would add a CF rod anyway. Your idea of the physics is wrong, I think. String tension has let the neck rotate forward, resulting in high action. The fingerboard extension is being restrained by the soundboard, which is why the bend at the body edge. With the neck angle reset, all should be flat.

[Frank Capo]

Greg. Thanks. Installing rod was considered but seems to be unnecessary. The neck and neck stick perfectly undistorted as the body so no obvious explanation. I can’t see any obvious way it could have shifted as dovetail joint could. I have the fingerboard cooling down will see if I made any progress in flattening.

[Greg Mirken]

Dovetail joints don’t shift; flattop guitar neck resets are necessary because of body deformation allowing the neck to rotate forward. It’s just that the best way we currently have to deal with the issue is to take the joint apart and re-fit the joint so the neck is at the original orientation to the body.

[Frank Capo]

OK. Thanks.  I accept and understand that explanation re dovetail joints. I also have come to believe that one component of neck set failure in resonator guitars is the failure of the joint between the neck and the stick. So getting back to my National, the neck stick is perfect, body and neck everything is square and level (assuming thats the way it should be)...built like a tank...the only glue seam failures were a lower portion of the sound well ring, and the lower rim of the top...while the back looks flat...so not obvious if the top creeped down. There was a raised nut when I acquired it but the frets do seem to show wear...so it could be an original neck set problem...who knows... I guess the good news for me is I was able to put a backbow in the fingerboard and should be able to trim the heel and stick to make it fully playable spanish style as I believe it should. I would think it will need a wedge under the fingerboard tab. Generally it seems to me in reading about neck resets, there is not much discussion about dealing with the fingerboard following the reset...

[onewent]

Hi Frank, I agree with Greg's take on the issue here .. neck angle needs adjusted for correct angle, which in this guitar is a combo of stick and heel.  The top on these wood-bodied Nationals are ply and are quite stiff, I've never seen them deform.

I've dealt with lots of bowed fingerboards in the type of guitars I repair, and I've found success in wetting the back of the board with hot or warm water, laying a moist paper towel on top and clamping to a flat surface.  One or two treatments usually gives you a straight board again.

Also, another issue is 'cupping' of the board due to shrinkage, especially if the board is celluloid covered.  It's near impossible to get that cupping out.  In this pic I've wetted the cupped end, and clamped it as flat as I could get it.  If it's not better after two attempts, I'll just have to plane it flatter and deal with what I have at that point.  The cupping is usually not a playability issue at the extension end (yours looks a bit cupped in the photo) but the one in the photo is actually in first position, bass side, so I'll see how it works out.

Sounds like you're well on your way to getting this one sorted out!

Tom

[Frank Capo]

Thanks. Yes as posted above was able to flatten the fingerboard by wetting and heating/cooling clamped in vise. Trimmed the heel and stick and got it pretty good without having to wedge the tab. Still a bit high beyond the 9 fret or thereabout but good compromise for freting and slide. I did not glue it back so the next geezer doing a reset will have it easy