Eastman Truss Rods

[George Henry]

I came close to purchasing a used MD-404 today, but backed out of the deal because of concern over neck straightness. The neck had excess relief overall, especially on the bass side. We took the mando to the store tech, who attempted to adjust the neck with a correct wrench, but ran out of thread before straightness was achieved. He was afraid to tighten any further. I walked away reluctantly, because the mando was in otherwise pristine shape and sounded great to boot.

I am afraid this is not an isolated problem with these mandolins. I had an MD-504 with an identical issue, and as a store tech worked on a MD-615 and a MD-515. I actually stripped the brass nut when I applied excessive pressure on the 515.

I need some ideas from other repair persons on how to address this truss rod issue. I've clamped a bar to the fretboard to apply back pressure when adjusting. I've added small washers to expose more thread on the rod. I've even replaced the brass nut with a stainless steel one to achieve more pressure, but I know that brass is used for a reason. I've even pulled the frets and sanded the fretboard and refretted.

Any idea?. I'd still like that MD-404 if I could straighten that neck.

[rcc56]

I have not heard of this problem on Eastmans before.

If you've tried washers, cheating the neck into a back bow, and a plane and refret, you have pretty much exhausted all the standard external options that I am familiar with.

The cause might be what is sometimes referred to as a "rubber neck," which means that the neck is not strong enough for the truss rod to adequately counter string tension, or it might be a truss rod that was not correctly installed. Soft necks are easy enough to detect, just apply pressure to the head and see how much it moves. But diagnosing and repairing the root of the problem requires disassembly.

To me, pulling a board and reinforcing a neck and/or replacing a truss rod is not practical on anything but a high grade instrument. On an Eastman, it might actually be more practical to replace a neck than to repair one. But I don't know what kind of glue is used on Eastmans, and I don't know if the glue joints can easily be broken.

And it is harder to take an instrument apart than it is to put one together. That is one of the major things that separates the craft of repair from the craft of construction.

[Folkmusician.com]

Eastman was having a few random neck issues up until around 2012. It wasn't widespread but I do recall dealing with a few. Actually it was usually back-bow. I never encountered rubber necks on these myself.

Around 2011, Eastman Contacted their larger dealers and talked to them about what could be improved on the mandolins. I talked to them and I am sure the other specialist dealers did as well. Shortly after, 2012, there was an overall improvement in the mandolins. One of the main things is that neck issues pretty much disappeared (there are probably a few out there). It has never been publicized, but I have noticed constant small changes in the mandolins. A year or two back, the necks became just a little larger in girth.

Now an MD-404 would have been among the new generation of Eastman's, so I am not sure what is going on there.

The only fix for a bow that can not be taken out if pulling the frets and leveling the board, or compression fretting (works well). If a neck tends to pull too much relief, you can plane a slight back-bow into it. This can also be caused if the fret tang is not a tight enough fit. I have seen some other brands (never on an Eastman), where the fret slots were taper. My guess would be a wobbly saw blade (circular saw), so when the saw first hits it is going side to side and cuts a wide slot, as it gets into the board it stabilizes. End result is a slot that is much wider on the bass side. Over time, this allows the neck to bow on the bass side. It can be addressed by filling and recutting the fret slots or some creativity with the fret tangs.

[George Henry]

Thanks for the responses. The reason I have seen more than my share of these issues is that I am a repairman and people bring their issues to me. I don't get to see all the good ones!

I think I was wise to turn my back on the 404. It was a great price, but not when I factor in my hours of repair!

[B381]

Where did you see it at, we're there others to compare to?

[George Henry]

I saw it at the Asheville GC. Priced at $350 case included. Now off website, so it must be gone.

I took both my Flatiron Performer A and my Lafferty (Schneider) LA-2 to compare. The Eastman was quite loud but not as refined as the other two.

[B381]

Reading Roberts post above some dates were quoted, do you remember the date on the mandolin?

[Br1ck]

So true about repair guys only seeing the problems.

There are a few techs around here salvaging old Yamahas and Takamines from the seventies that need neck resets. They just slice the necks off at the body and route for a bolt on neck instead of the dovetail. I wonder if anyone has ever reset or replaced a mandolin neck this way. I would think a lot of Eastman level instruments use pretty industrial glues figuring folks would buy a new one rather than invest in a reset. Anyway, the slice off neck method has saved quite a few nice old pac rim guitars. They call it a bolt on conversion.

[rcc56]

If anyone can figure out how to bolt the neck on an F-hole mandolin, I'd be interested to hear about it.
I did bolt the neck on an old Octofone, but that's a round hole instrument.

So, before we close this out, does anybody know what kind of glue Eastman is using for neck and fingerboard joints?
It's always nice to know these things before an instrument lands on my workbench, so I can give an owner some idea of what it will take to repair it.

[pops1]

I would mention that removing the fingerboard and flattening the neck then regluing is another option. I did have a Gibson that removing the board didn't help, had to remove it again and dig out the truss rod and lower it into the heel for it to work properly. Works great now and nice flat neck.

[multidon]

Weber has recently changed to dovetails I heard but for most of the last 20 years they had a glued mortise and tenon with bolt reinforcement. Breedlove mandolins had a straightforward bolt on neck. My understanding is, on an f hole instrument, you use bolts that take an Allen wrench and use a very long one to tighten the bolts through the endpin hole.

[rcc56]

I would mention that removing the fingerboard and flattening the neck then regluing is another option. I did have a Gibson that removing the board didn't help, had to remove it again and dig out the truss rod and lower it into the heel for it to work properly. Works great now and nice flat neck.

I've done this too, usually with good results. I prefer hot hide glue for that kind of repair [it doesn't creep]. If it's an old Martin without an adjustable rod, I'll add a few thousandths of back bow to compensate for string tension.

Many years ago, I worked at a shop that was a Gibson dealer and repair outlet. We had a 6 month old J-200 come in with a really flexible "rubber neck." No fix was going to work on that one. We sent it back to Gibson under warranty. They agreed that the neck was no good, and we waited. First, they had changed colors and didn't have what they needed to get a finish match [so they said]. Next, they had changed their neck joint and didn't have a blank that would fit. 7 or 8 months later, they finally replaced the guitar. Needless to say, the guitar's owner will never buy another new Gibson. We discontinued the dealership shortly after that.

[rcc56]

My understanding is, on an f hole instrument, you use bolts that take an Allen wrench and use a very long one to tighten the bolts through the endpin hole.

A tool easily available at any hardware store.
Sounds like lots of fun guiding that bolt into position when you're ready to reassemble . . .

[pops1]

I've done this too, usually with good results. I prefer hot hide glue for that kind of repair [it doesn't creep].

I have only used HHG for more than a decade now. Nothing compares.