martin D12-20 72 or 73 truss rod reinforcement

[peter meyer]

howdy all,

I'm about to do a neck reset on this Martin  12 string, and while in in there I'm planning to reinforce the truss rod w/ graphite rod Ala Dan Erlewine ,,,seems like a niffy idea. Have any of you tried this approach or have other tried and true approaches you'd like to share ,, thanks

Posted on May 31, 2015 at 8:35am Edit Post  

[Ned Knepp]

Does it actually need to be reinforced? 

[peter meyer]

yes,, the neck doesn't give proper relief ,, so the thought is to create a straighter neck thru use of the 1/4 in. graphite rod placed in the center of the steel tube truss rod ,, of course i could remove the fretboard and install and adjustable rod but i'm trying to keep the price down for the customer ,,yet be effective

[Demetry Merkuloff]

Is it actually the neck relif or the action at high frets?These two may come together.

So you've removed the neck? What about the neck angle, shouldn't it be corrected before going on to the neck relief itself? As for the truss rod, does the neck stay bowed without the string tension? If so, reinforsing the steel tube seems useless...

[peter meyer]

perhaps,, i haven't  been clear,, this guitar needs a neck reset to change the neck angle .the truss on this guitar is nonadjustable, ." martins square hollow tube" of that era which is not doing its job .so while i have the neck off i wanted to strengthen the rod so it will allow proper relief // and the idea of the 1/4 in graphite rod glued into the steel tube (stu mac idea )seem like a good fix . i was wondering if anyone else has tryed this  fix  PS. this is a guitar i'm getting ready to work on

[Andrew]

Yes, if both the relief and the neck angle are out of whack, the relief should be dealt with before the neck goes back on in this case if inserting a cf rod is the plan - if you can avoid having to remove the fingerboard and get a good result then its worth trying as the neck would already be off. I dont see why that wouldnt at least help to reduce the relief, although Ive never done this myself... Presumably epoxying the rod in place inside the square tube would increase the advantage of the rod.. But I could be wrong.

Thomas' suggestion of compression fretting is also a good idea.

[Thomas James]

Haven't done this, but if it still has too much relief after jigging it straight and inserting the carbon rod, you could try compression fretting.

[Ian Davlin]

 I haven't added graphite, but I have added steel key stock with really excellent results. The technique was fairly straight forward. Jam the key stock down the hole with some West Systems.

One guitar I did had perma bow from string tension over the years. When I reinforced the rod, I clamped the neck straight for the epoxy cure. The reinforcement and epoxy brought the neck into compliance.

There is the weight of steel vs graphite and I might worry about neck balance on a six string, but with a twelve string and the weight of the tuners, I think the guitar actually balanced better. 

[peter meyer]

thanks for your reply,your approach is the same as i,m trying sans graphite for steel i,ve got the graphite ready the 12 string is the next thing in line.. ill let you know how it goes

[Russell Vance]

Hello Peter,

We use a lot of poltruded graphite which is stronger than the retail graphite usually supplied and one thing which I am sure of is that graphite is fine used to reinforce necks relative to the wood you remove to install it but it is not very effective in applying force to straighten a "bend" or pretension in a neck. There are two different physical equations in play here - one is reinforcement by binding a surface area and one is a force lever (which in this case is minimal).  

If the neck is bowed with the fixed rod it will probably not respond to hammering a minimal cross section graphite core into it for any length of time. Thomas gives some advice which is pertinent here.

However, if you do proceed follow Ian's advice and pretension the neck straight or into slight back-bow before or during  gluing and curing the insert.  Obviously, the glue you use is critical as any creep will have unhappy endings and remember to score/abrade the rod to get a good key with the epoxy (West System or better).

Regards,

Rusty.

[Hesh Breakstone]

My first thought was the same as Ned's.

If proper relief is the goal messing with modifying the construction of the instrument seems over kill to me AND if there is a budget to be respected it also sounds like over kill to me.

Instead the fret plane can be shaped to a very large degree as we may need to shape it and correct things such as how much relief, where the relief is, etc. simply by creative fret dressing.  You can even improve the neck angle by concentrating on certain areas and leaving other areas unscathed.

Relief is not difficult to correct, induce, increase or decrease with simple back or forward pressure while leveling after observing and noting where you want the improvements to be.  

No messing with the truss rod or any invasive stuff required, client's budget is respected and you don't have to jump through hoops should something go south with the truss rod augmentation route.  Keep it simple.

[peter meyer]

Hesh,,,

im not sure there is a way out of a neck reset on this guitar,, my plan after reinforcement of the square rod was to address the fingerboard in way that you are suggesting. id love to make this an easier job if i could ,,i will make one more assessment  before i dive in ,,,thanks for your thoughts 

                                                                              peter

[Hesh Breakstone]

OK, got-it Peter and thanks for the information that the thing needs a reset.  

It's standard fare in our shop to dress the frets after a reset since things tend to move and/or it's likely  that prior to the reset the fret plane could have been improved anyway.

I do want to suggest again though that for instruments that are on the cusp of needing that reset and when the client has no budget for a reset we have been able to improve the neck angle at times by dressing the frets concentrating on the nut end and avoiding the body joint end.  If you do the math, measure the current fret height, etc. it's possible to gain up to .020" of correction to a neck angle making this an economical alternative when this fix is appropriate for the instrument and the client's budget.

Although not a fan of shaving down bridges.... often the addition of string ramps milled into the pin holes (to improve break angle with a low saddle) in conjunction with a lower saddle and that creative fret dressing can get an ax back to f*ctory specs for no more coin than a quality fret dress.  

It's just a good club to have in the bag and can keep a client with limited budget happy for some years to come.