Adjusting 60's D18 neck relief

[Alys and Simcha]

I have a 1965 D18 on the bench for the well-known 'Top bulge at the bass side of the bridge' problem, plus minor intonation tweaks and action adjustment.
Firstly, thanks to Frank - I glued back the separated brace under the bulge with marine epoxy, using clamping cauls cut from 3/8 acrylic sheet, as shown on the Frets site. Worked perfectly! And I could see what I was doing, through the plastic cauls. The bulge had been left untreated for several years and needed substantial clamping force to get the outside almost flat again. I didn't want to bruise the shape of the brace underneath, so I laid cling-film over the brace and moulded an exact-fit clamping pad with magic plastic on a hardwood block. This also worked better than I expected - fitted well enough to hold itself in place while I was placing the clamps.
Anyway, back to the neck.... After the usual fine adjustments to saddle and nut, and a thin stepped bit of bone glued to the front edge of the nut to give a little compensation at that end also, it plays easier, and much more sweetly in tune.
The only thing which stops it from playing _even better_ is the Martin non-adjustable neck which currently has about 25 thou relief.. I'd prefer about 5-10 thou . I could file the fairly high frets, but I wondered if there is any established method for making a slight adjustment to neck relief on this era of martin,without doing anything as invasive as skimming the fingerboard. Is this a problem one has to live with or has someone come up with a slick way of making this adjustment appropriate for a fine quality old guitar?

[Ronnie Nichols]

I'll be interested to see what kind of solutions these luthiers have devised for this problem. I have run into the same problem on some old Martins ( and other brands). The last one I remember was a 1941 D-18 which had the wooden truss rod. I finally decided to just leave the excessive relief in this neck because I felt anything I did could hurt the value. I have removed the frets on some old Martins and trued the fingerboard before refretting. I've even simulated the string pressure and trued the fingerboard on some. This will correct the problem but it leaves a thin fingerboard,which is pretty noticable especially since the ends are thinner than the middle. I have installed an adjustable truss rod in some guitars but this involves a pretty detailed repair. In my early years, I tried heating and straightening the neck. It seems to me that this works but I felt it was a temporary fix since the wood seems to have a memory and often will not stay where you leave it. If you ever noticed the old Martin that Earl Scruggs plays on the 3 Pickers Video (and other places through the years) you'll see that some luthier solved this problem on that guitar. It looks funny to see a Martin Guitar with a Gibson Style truss rod cover on the peghead. I'm interested in any ideas others have along this line, myself.
Ronnie Nichols

[Jim Bancroft]

There are only 2 solutions, that I know of, to straighten a bowed non-adjustable Martin neck.
#1 Refret with oversize tang fret wire. The wedging effect will bring the neck back, hopefully.

#2 This is a solution suggested by Stew Mac recently. When the neck is off the guitar to install a carbon graphite bar inside the square hollow tube reinforcement, that is presently in the neck. This will straighten and stiffen the neck.

I have also placed blocks and a heating pad on really badly bowed necks, but they revert back to the originally bowed condition, over time, normally.

Jim

[Alys and Simcha]

Thank you, Jim and Ronnie. Yes' it's my experience that straightening by heating pad or block is unpredictable - over a couple of years, even on nylon string guitars, sometimes it holds partially, and sometimes it goes almost back to where it was. Amongst other factors, it would depend very much on the creep properties on the glue between fingerboard and neck. Feels like a lot of trouble for an unreliable result - and when the job comes back, you _still_ have to find a proper fix - this time, FOC :(

I am very reluctant to skim fingerboards, leaving the head end tapered thinner - that's just asking for the same problem to occur again - and quicker.

Jim, I really like your suggestion of putting carbon fibre inside the existing square steel tube - probably with enough epoxy to fill the gaps, and maybe with the whole neck clamped straight or with a very small reverse relief , while the epoxy cures. Sure, it's a major job to remove the neck, but with care, this can be done and replaced without damage or anything visible on the outside. I guess there would need to be some kind of small pressure relief hole at the head-end, but this could be drilled through under the nut position, and later the nut replaced. Again, nothing visible on the outside after the job is finished.

There is an occasional story going around about minor relief adjustments to this kind of neck using some kind of arbour press and padded blocks. One writer claimed this was sometimes done at the Martin factory. I have no information about whether this has some basis in truth, or whether it's a complete fiction which grew in the retelling.... I can see it might work ( for very small adjustments) but at the cost of some stress to the fingerboard and fretting. Without authentication, I might just be tempted to try it on a $100 clunker with a flat steel bar in the neck, but not on a beautiful sounding D18 like this one....
Frank, have _you_ heard this one? - Simcha

[Alys and Simcha]

Obviously not appropriate for a good martin, but some years ago, I had a little glut of Harmony solid-wood guitars with bad truss rods and un-meltable glue between fingerboard and neck. Almost unplayable with curved necks but sounding too good to throw away. I would take out the frets, use a jig with a router running on rails to rout straight through the fingerboard down to the truss rod. Then take out the rod, replace it with one that worked, and fill the whole slot with aglued-in rosewood strip which colour-matched the original fingerboard. Relatively quick to shave it level with the fingerboard, join up the fret slots with a saw, and refret. Unconventional, but it did the job effectively in a reasonable time, comparable with the value of the guitar, without any need for lacquer touchup, and the only visible sign was a slightly different stripe down the centre of the fingerboard.

[David Reilly]

that's a brilliant innovative solution.
by the way, i'm an american now living in nz and doing guitar repair in auckland. where are you?
cheers,
dr