Getting the Facts about Ski Jumps

[Bubble]

Well there's good justification to keep using 40 - 95 strings. VEERY light on tension , easier on the fingers, frets and neck. But a little weak on the deep bass, sustain, and better with ceramic pups for the volume boost. They are also slippery in the string bend directions, it takes some precision fingering because sloppy fingering will get you off notes. Come to think of it they slightly sound of how my short scale Mustang Bass was.
I'm also compromising with 45 - 100's on two basses, they are in the middle balance between 40 - 95's and the big fat strings. The 40 - 95's are factory setup for my dear old Washburn Lyon LB-40. That bass is so nice and easy on the fingers. It's a relief to play awhile when my fatter strings are tiring my hands.

 

[walterw]

OK this thread as taken a turn towards the fantastic since i've seen it last, @Turnaround the pic essay on the "shim fallacy" is on point!

i can report that i just recently heat-treated a couple older fender USA deluxe basses, the ones with the extra fret, both with textbook neck kinks.

i've taken to using a small clothes iron sitting on top of a chunk of 1/2" thick aluminum a little bit bigger than the iron itself sitting on top of the kinked area (to even out the heat hopefully). this seems to get heat through the neck shaft without cooking the fretboard like the heat lamps i was using before can.

one cooperated nicely, i was able to make the kink go away and get good action without any real fretwork after, while the other one took some convincing, requiring several sessions with the heat-pressing process followed by a full fret leveling.

in fact, the second more obstinate neck ended up with a distinct fallaway when i was done, the opposite of a kink! i have a feeling that having been coerced so far the other way, that neck is probably never going to revert all the way back to an upward kink.

 

[walterw]

*has

(wow, we can't edit posts after only one day?)

 

[byacey]

As mentioned in my last post, I intend to answer specific questions that have been raised. And this is one.

A ski jump is caused by the tension of the strings. Typically it takes some time to develop, and it becomes "set" - i.e. when string tension is removed it is still there. If you level the frets or the fretboard it doesn't immediately form a ski jump when the string tension is reapplied.

But your question brings up another item of interest - that of levelling without string tension. With a decent quality neck you can reasonably count on a satisfactory result when levelling when a neck which is not under string tension. You start by getting the neck as straight as possible, then level the frets. Then when the neck is installed it will bow under string tension which you control with the truss rod to give the desired amount of relief.

BUT - there are three gotchas when using this approach. When I say "start by getting the neck as straight as possible" you would do that by tweaking the truss rod. Under ideal conditions you won't need any tension on the truss rod at all to get the neck flat (that's the was it was manufactured). But if it takes a little tension on the rod it's probably OK. But if it takes a fair bit of tension on the truss rod to get the neck flat you are starting with a significantly compromised neck and the results will likely be similarly compromised - perhaps very seriously.

The second gotcha bass to do with the quality of the neck wood. An ideal neck is stiff and resists bending. There are a few brands of mass-produced instruments that seem to use far less than ideal wood and you cannot count on them behaving at all well under string tension. This lack of quality is usually reflected in their price. Not always though.

The third thing has to do with how a specific neck behaves under string tension. Ideally the neck would bow evenly giving just the right amount of relief. But wood in not a homogenous material, and it does not always bend in a nice even curve. So if we level a neck without string tension, there is no guarantee that it will form a nice even curve when under tension. One of the ways to deal with that is to put the neck under tension when it is levelled. There are tensioning jigs that will do that. They are not a perfect solution, because you put the neck under simulated string tension, then get it as straight as possible, then level the frets. Hopefully the neck under tension will form just the right curve when the strings are re-installed and the trussrod relaxed a hair to induce relief. It's a pretty good bet that it will be near ideal, but it is possible that the relaxed trussrod will induce an uneven curve - actually highly unlikely.

A variation on using a neck tensioning jig is to level the frets under real string tension. You leave the strings on the instrument, tuned up, and use a special beam that rides under the strings. You need to raise the strings up a bit at the nut to provide clearance, but this method works well.

I hope this answers the question.

I believe that when planing out a ski jump, the wood will eventully reach a point of equilibrium and resist further bending under tension, unless the neck is unusually weak.

Is this a good reason for using quarter sawn wood with the annular rings near vertical for the up / down cross section of the neck blank? That would yield the stiffest neck, compared to some of the slab cuts I see on cheap basses, and having considerable grain run-out too, making matters worse.

 

[Turnaround]

I believe that when planing out a ski jump, the wood will eventully reach a point of equilibrium and resist further bending under tension, unless the neck is unusually weak.

Is this a good reason for using quarter sawn wood with the annular rings near vertical for the up / down cross section of the neck blank? That would yield the stiffest neck, compared to some of the slab cuts I see on cheap basses, and having considerable grain run-out too, making matters worse.

Quarter sawn wood resists bending no better than flat sawn. Generally, the straighter the grain and the closer the growth rings the more rigid the wood will be.

Though a piece of wood might reach a point where it will not continue to bend, planing some thickness off it will reduce its rigidity and it may bend again. I would say if a neck is bendy it needs reinforcement.

 

[_Obra_]

Quarter sawn wood resists bending no better than flat sawn. Generally, the straighter the grain and the closer the growth rings the more rigid the wood will be.

Though a piece of wood might reach a point where it will not continue to bend, planing some thickness off it will reduce its rigidity and it may bend again. I would say if a neck is bendy it needs reinforcement.

I hear what You are saying and believe that's true, it's just not what Fender says on their web site.

Invalid Link Removed

I quote one part:''Quartersawn wood is less susceptible to wear, shrinking, swelling in width, twisting, warping and splitting''.

I suppose it must be written in commercial purposes.

 

[Turnaround]

I hear what You are saying and believe that's true, it's just not what Fender says on their web site.

Sizing up a Neck - quality evaluation

I quote one part:''Quartersawn wood is less susceptible to wear, shrinking, swelling in width, twisting, warping and splitting''.

I suppose it must be written in commercial purposes.

It's common to see manufacturers hype the benefits of certain things that they think might give them a competitive advantage. According to a 38-year-long scientific study published by the Ministry of Resources and Development, Forest Products Laboratory Division there is no consistent difference in bending under load. My own demonstration showed the same -
Sizing up a Neck - quality evaluation
Post #46

There is an often-overlooked detail about construction with quarter-sawn vs flat sawn necks and fingerboards -the two should not be mixed. To quote the study above "never glue a plain-sawn member to a quarter-sawn one , as such a procedure will probably cause failure at the joint". Some modern-day adhesives may be strong enough to avoid the stress fracture, and if they are it's because they are stronger than the wood. Which means that the wood forms micro fractures rather than having the glue fracture. Those micro fractures of course weaken the wood.

I just had a brief look at the Fender blurb. It's full of inaccuracies. But consider that it was written by the marketers based on a modicum of understanding of wood properties. Makes a good bit of advertising copy.

 

[TomB]

It's common to see manufacturers hype the benefits of certain things that they think might give them a competitive advantage. According to a 38-year-long scientific study published by the Ministry of Resources and Development, Forest Products Laboratory Division there is no consistent difference in bending under load. My own demonstration showed the same -
Sizing up a Neck - quality evaluation
Post #46

There is an often-overlooked detail about construction with quarter-sawn vs flat sawn necks and fingerboards -the two should not be mixed. To quote the study above "never glue a plain-sawn member to a quarter-sawn one , as such a procedure will probably cause failure at the joint". Some modern-day adhesives may be strong enough to avoid the stress fracture, and if they are it's because they are stronger than the wood. Which means that the wood forms micro fractures rather than having the glue fracture. Those micro fractures of course weaken the wood.

I just had a brief look at the Fender blurb. It's full of inaccuracies. But consider that it was written by the marketers based on a modicum of understanding of wood properties. Makes a good bit of advertising copy.

Great info! It begs the question: in your opinion, is there any advantage to a quarter sawn neck blank over one that's flat-sawn?

 

[Turnaround]

Great info! It begs the question: in your opinion, is there any advantage to a quarter sawn neck blank over one that's flat-sawn?

There are a couple of advantages. First is that quartersawn wood reacts to humidity differences by expanding and contracting principally in thickness, not width. So fret sprout is less common/severe.
Second is that quartersawn wood tends to be more precisely cut than flatsawn. More wood is wasted in quarter cutting, and thus it is more expensive. And if it's more expensive, the sawyer is more likely to take extra care in it's cutting - a poorly cut piece on the quarter is of little more value than a piece of flatsawn. And only the better logs are quarter cut - for the same reason. So you are more likely to get a better piece of wood if it's quarter cut. No guarantee though.
It is far more important that the wood is of good quality and well cut than whether it was cut on the quarter or on the flat. Runout on a piece of quarter cut wood is not so obvious, but runout is runout regardless of its orientation and though moderate runout is not a concern, more severe runout is.
But

 

[Pilgrim]

Though a piece of wood might reach a point where it will not continue to bend, planing some thickness off it will reduce its rigidity and it may bend again. I would say if a neck is bendy it needs reinforcement.

I find it hard to find logic in an argument that reducing the size and mass of a piece of wood could increase its rigidity and resistance to bending.

The backwards logic reminds me of a favorite accurate saying of my dad, who did a lot of woodwork: "No matter how many times you cut it off, it's still too short."

 

[Gilmourisgod]

Great info! It begs the question: in your opinion, is there any advantage to a quarter sawn neck blank over one that's flat-sawn?

I work for an Architectural firm that does high-end residential work on Cape Cod, and unless the Owners don't like the look, we spec Quarter Sawn White Oak for floors almost exclusively. It just doesn't move much seasonally compared to other woods, particularly red oak. White oak was used for barrel staves and ships hull planks for centuries because it's reasonably impervious to water coming through it, which always made me think it would be a great neck wood. It's heavy, a little hard to work, and not the most beautiful unfinished, which I guess is why you don't see it much.

 

[TomB]

There are a couple of advantages. First is that quartersawn wood reacts to humidity differences by expanding and contracting principally in thickness, not width. So fret sprout is less common/severe.
Second is that quartersawn wood tends to be more precisely cut than flatsawn. More wood is wasted in quarter cutting, and thus it is more expensive. And if it's more expensive, the sawyer is more likely to take extra care in it's cutting - a poorly cut piece on the quarter is of little more value than a piece of flatsawn. And only the better logs are quarter cut - for the same reason. So you are more likely to get a better piece of wood if it's quarter cut. No guarantee though.
It is far more important that the wood is of good quality and well cut than whether it was cut on the quarter or on the flat. Runout on a piece of quarter cut wood is not so obvious, but runout is runout regardless of its orientation and though moderate runout is not a concern, more severe runout is.
But

Thank you for the very clear explanation. One more question if you don’t mind. Unless I missed it, not sure if I understand what “run-out” is? I can guess but I’d rather ask .

 

[Turnaround]

Thank you for the very clear explanation. One more question if you don’t mind. Unless I missed it, not sure if I understand what “run-out” is? I can guess but I’d rather ask .

Have a look at this thread - it's explained there as well as some other facts about necks that you might find useful.

Sizing up a Neck - quality evaluation

 

[Lancillotto]

Hi Guys, how could I mitigate the effect of the sky junp on my instrument without a heavy repair? Is there a setup which may accomplish this goal?

 

[Turnaround]

Hi Guys, how could I mitigate the effect of the sky junp on my instrument without a heavy repair? Is there a setup which may accomplish this goal?

Read post #284.

 

[Lancillotto]

Thank you so much!

 

[yankeeblues]

Thank you to the pros for sharing all these observations. I love thin fender jazz necks but I have noticed that adjusting the truss rod does not address the relief (or kink) above the 12th fret, leading me to this thread.

It makes me extra appreciative of my Modulus flea bass with a truss rod, as its the only bass I own that I feel I can get ultra low action with no fret buzz anywhere up or down the neck. Luckily I found mine about 10 years ago when they were much more reasonably priced on the used market. On the other hand, I still find wood neck instruments have a more pleasant and versatile tone, and I don't need ultra low action for most things.

From reading this whole thread, it seems like theres no way of predicting if a small kink will keep bending or if it will stop while the kink is still slight and can be worked around with fret leveling and truss rod adjustments. It certainly makes me question my love of fender style basses, and gives me a bit of anxiety that they will just keep bending forever and ever...

 

[Turnaround]

Because of the angles of stress, if you keep low action and keep the neck adjusted so it never has excessive relief, you stand a better chance of avoiding the 12th fret kink than if you let the relief get out of hand and have high action.

 

[yankeeblues]

Because of the angles of stress, if you keep low action and keep the neck adjusted so it never has excessive relief, you stand a better chance of avoiding the 12th fret kink than if you let the relief get out of hand and have high action.

Given that advice (I understand its not an absolute), I would love to see how a heat treated neck holds up after 10, 20, 30 years. If the initial kink developed due to neglect and time, It stands to reason that a heat treated and straightened neck may stay straight for decades with proper maintenance.

In your opinion, have any of the big name fender style builders addressed this issue and solved or mitigated it better than the rest? I'm thinking Lakland, Sadowsky, Ernie Ball, Nash etc. Thanks.

 

[Turnaround]

I don't recall running into any that have specifically addressed the problem. Bruce Johnson may know better - perhaps he will chime in.