1930-31 National Duolian with neck issues

[Jeff Mando]

[QUOTE=Ginridge;1901766] This is a fairly early guitar (1930 I believe) so National might have been trying different things but I'd be curious to hear if anyone else has come across this./QUOTE]

Agree probably a 29 or 30. 12 frets to body and flat (non-rolled) f holes indicate that. There should be a number stamped into the wood on the very top end of the peghead. I usually call Marc Schoenberger, he has a lot of knowledge about the details of these instruments and may be of some help. His number is available online. (National guitar repair)

[Ginridge]

Thanks, Jeff! Yes, the headstock number is C 230.

Marc Schoenberger proved to be an excellent suggestion. I found Marc's website and gave him a call. He clearly knows his stuff and had some great info!

He told me that being a '31, the fingerboard is NOT dyed wood. In 31, National was experimenting with phenolic fingerboards, a composite material, for fingerboards (shades of the bakelite neck!). It failed because it shrank over time causing the necks to warp. I think I read somewhere that over 1500 guitars were returned because of warped necks! Marc agreed with previous comments that that the fingerboard will need to be replaced since it has shrunk and curled and will continue to do so. That certainly explains the very odd nature of the material and the extreme neck warp.

Marc was not surprised to hear about the glue in the neck joint and thinks I'll need to do a full removal of the neck to properly work on it. Re-setting the neck angle apparently is more complicated than on a standard guitar.

As I thanked him for taking the time to talk, he wished me luck and told me he was glad this wasn't in his shop!

[pops1]

Those early Nationals are very thin metal compared to later ones. If you need to reset the neck there is a special technique for the National. I have reset the neck on one of the same vintage as the one you are working on. The thinner metal gives a wonderful sound, but is not as stable as the later guitars.

[Ginridge]

Thanks Pops1! I'd love to know more about that process. Could you share details of the neck re-set process here or pm me if you prefer? I'm hoping to avoid having to disassemble and re-set the neck if I can, but I expect knowing the correct process is something I'll need, if not for this one, certainly for one down the road!

Marc mentioned that the way the necks are set on these guitars, the neck angle has to match the angle of the top of the guitar between the cone and the neck. This angle is different than the angle of the rest of the body to the neck. So far, it does appear that if I can straighten the neck, I may be able get away with not have to disassemble the neck from the body (which I am afraid may damage the metal above the neck rod and will certainly involve destroying the shim that's holding everything in place). If that doesn't work out, I'll definitely have to remove the neck and I know from what Marc said, that will be a very different thing than re-setting a dovetail neck!

[pops1]

If you look at the dowel stick on the National, it is thicker toward the neck than under the cone. Right where it goes from thick to thin you make a diagonal cut PART of the way thru the dowel stick. The cut will run from joint toward the front into the thicker part of the dowel stick. I wish I knew how to draw on a computer, alas I don't. In that cut you place a wedge to tip the neck back. The wedge is glued and screwed in place. With the metal on the early being so thin I doubt you will have to cut the heel. Somewhere there is a tutorial about this, but that was long ago, before the internet for me, and I can't remember where.

[Ginridge]

That sounds similar to what Marc was talking about. I'll keep searching and see if I find that tutorial.

[Ginridge]

rcc66 mentioned "If you're going to pull the board anyway, the amount of extra labor incurred by installing a replacement would be limited to shaving it to size and installing a few position markers. The extra materials cost would be maybe $50 for a CNC slotted board plus $10 for the position dots."

I'm back in off the road (SERFA conference) and looking into replacing the fingerboard as suggested with a new ebony one. The owner wants it to be a radiused fingerboard and I was talking to LMI about having them slot and radius a new board for me. They mentioned, though, that they don't do position dot cut outs. I'd prefer to have that done during manufacture if at all possible since I don't have access to a drill press and I want to make sure I get the holes for the screws in the fingerboard exyension exactly right. Is there a fingerboard supplier that does include the dot cut outs?

[rcc56]

You're overthinking/over-worrying.
A drill press is nice for drilling for dots, but not at all essential.

Clamp the fingerboard to your bench [if you wish]. Drill a small pilot hole. Stand up your drill with the dot sized bit in the pilot hole. Rest your elbows on the bench to hold it steady and look at it from several angles until it's as plum as you can get. Pull the trigger. It will be close enough.

Measure twice [carefully], mark carefully, and cut once. Use reasonably fresh bits.

[Ginridge]

OK... You talked me into it! I'll let you know how it goes.

[rcc56]

If you have any doubts, find a piece of hardwood scrap and practice. That will also tell you whether your bit will work on hard wood without tearing it up.