Need some help with using the neck-jig....

[Mike Kolb]

I've been staring at my StewMac neck jig in the corner of the shop for about 7years now, never actually needing it, as most fret-level jobs and refrets have gone pretty smoothly ... just lots of dumb luck.  Someone mentioned on a recent discussion that "doing a Les Paul without a neck-jig is like...(fill-in the blank, meaning it's pretty necessary).

So here I sit with a Les Paul on the bench with a thin, floppy neck... in dire need of a really good and accurate fret-dress. My standard procedures aren't cutting this one. Not having a spare Plek machine handy, I'm thinking it's probably time to break-out the neck-jig and make it earn it's keep. I've read all the directions, watched the accompanying video (VHS!) 'til I'm blue in the face, but still don't have a crystal-clear idea of how to put the thing to it's best use. I dropped an e-mail to StewMac for some guidance, but got back a pretty fuzzy response about how the jig is "an indispensable tool that produces accurate neck & fret readings". Umm, I s'pose it does, but...?

See if this sounds about right: you strap the guitar on the jig... strung to pitch with normal relief, you set the metal dowels against the neck and set the dial-indicators to zero. You remove the strings, the neck and dial-indicators go wonky; you strap the neck down and adjust it back until the indicators return to zero. At this point, if you level the frets, aren't you leveling against the existing relief in the neck?  Shouldn't there be zero relief if you want level frets, introducing the relief later?  Never mind the "ramping-down"" above the 14th fret... I just want to get the basics of this beast under control.

It's clear that I'm really missing something here. Anyone who's used and mastered the neck-jig will be my hero if you can explain where I'm dropping the ball.  Thanks.

[Mike Kolb]

Wow...thanks for the responses, and now I need a day or two to digest all of this. But, so far, what I'm reading is, basically, "get the neck straight, by any means necessary, and dress the frets".

OK, so what does the neck-jig do that the truss rod can't? The truss rod will (in most instances) get the neck straight and away we go... which is what I've been doing for years. Why go through all the steps to strung-up the guitar in the neck-jig, manipulate some dials and rods, only to unstring it, straighten the neck and get to work? Why not just get the neck flat and get to work?

And if that's the case, my original question remains.... what the heck is the neck-jig good for?! Maybe something clicked in my basic intuition, and that's why it's been sitting in the corner for 7 years:)

PS: Grahame, I only *wish* the money was so good that "I don't know what to buy next". Truth is, I had more disposable income 7 years ago and decided to invest in what I could at the time. The neck-jig seemed like a good idea... but now, maybe not so much. I'm not giving-up yet, but it doesn't look as promising these days as it once did.

[Ned Knepp]

I don't have this jig and I haven't tried to use one but reading what has been written here, it seem to me that the point of the jig is to be able to recreate the strung up neck geometry without the strings. Once that is done the repair person will have access to the fingerboard as it is under string pressure complete with all of the problems that may be present when the guitar is played but without the strings. Now any corrections the technician makes are made to the guitar as it will be played.

In other words, any problems with the guitar happen when it is strung but the repairs can't be made in that condition. Removing the strings changes the geometry of the neck so the jig is designed to replicate this condition in a way that allows a tech to work directly on the problems that are present in playing condition without worrying about the strings or truss rod.

If I understand this correctly, it doesn't really matter what shape the neck has with the strings off because that is not how the instrument is used. If you setup the guitar on the jig and make all the adjustments to the fingerboard shape that may be needed, the neck can take any shape is wants when it is removed from the jig but still unstrung because stringing it and tuning it to pitch should return it to the final shape made on the jig.

IF this is the case, I don't understand how making the neck straight on the jig BEFORE reworking the fingerboard will correct and issues with the strung guitar.

Course, I could be blowing hot air too.


Ned.

[Murray MacLeod]

The nub of the matter is that the "straightness" of the neck when adjusted "straight" by tightening the trussrod while under string tension is, in all cases, a different "straightness" from the "straightness" obtained by removing the strings and then adjusting the neck straight by loosening the trussrod.

This can easily be verified experimentally with a straight edge, three identical gauge blocks and a set of feeler gauges.

[Ned Knepp]

Maybe we define "straight" differently. As far as I can see there is only one state that could be called "straight" and it shouldn't matter how it was made that way.

I though the idea was to simulate string tension on the jig without truss rod tension, make the neck straight by reshaping the fingerboard, (which should make the neck straight when the strings are on the instrument) then using the truss rod to induce whatever relief may be desired. It's always been my understanding that the truss rod's job was not to straighten the neck, it is to reinforce the neck and induce relief. Do I have this wrong?

BTW, I hope I am not speaking out of turn. I didn't start this thread and I don't have the jig but I really want to understand what being said here. If I'm out of turn or a highjacker, say so and I will bow out.

[Pierre-Antoine Roiron]

Paul, redressing or re-fretting is depending on the size of the bumps you can measure on the strung neck, I agree, no problem here.
Thanks for your very detailed answers, both of you, this thread is very interesting!

I use a stewmac like neck jig only when the neck has a S shape. From my experience, I can tell that I have far better results when using the neck jig for his particular problem. And what makes the difference to me is that I can tighten the trussrod and keep the neck close to the shape I want (especially using the headstock stressing turnbuckle) : for a S-shaped neck, the amount of trussrod tightening is essential, because if you don't crank it just a little bit, the S shape doesn't appear. Mike, it's the difference I see between the trussrod and the neck jig.
In fact it's related to the old trussrod technology, the ones using a anchored rod in a curved channel, because these put a lot of compression on the neck, and too much compression can sometimes lead to this S-shape. Gotoh and double-acting trussrods don't have these problems, because they compress the steel rod or the aluminium U channel they're made of, not the neck.
For now I didn't succeed in sanding this particular problem in another way, because you have to make it appear so you can sand it out.
By the way, if any part of my message seems strange, it's just I don't always succeed in describing such technical things in English. Sorry for that!

[Mark Wallace]

My understanding of the neck jig is to simulate the string tension of a guitar held in the playing position. My process goes as follows: strap guitar into the jig, rotate to playing position, tune to pitch, adjust truss rod to straighten neck, set dial indicators and support rods, rotate jig back, and remove strings. At this point I use the pegead jack and strap to place the neck back into the postion where the indicators were zeroed. Once you've done this it is easy to see how much movement typically occurs at the peghead end of the neck by just simply laying a guitar on its back. I purchased my neck jig (from Dan Erlewine) over ten years ago when Stew Mac had a booth set up at an Ohio guitar show. They were not in the catalog yet and mine had some earlier features that have since been changed. I use the jig in a vice mounted on a shop stand. The vice allows the jig to rotates 90 degrees for playing position.

[Murray MacLeod]

" held in the playing position" is indeed the line that Stewmac take with their instructions, but I personally don't buy it.

Any perceived difference in the neck between the guitar held in playing position on the jig and the guitar laid flat is totally negated in practice by the pressure exerted at the peghead end once your average heavy metal rocker gets his left hand wrapped round the neck.

I should really declare an interest here, as I am the designer and manufacturer of the TECHNOFRET range of fretting and set-up accessories, and am to a degree in competition with Stewmac.

Last year we designed and sold on Ebay a neck jig which was radically different from the Stewmac design and which did a more precise job of getting the neck "straight". We discontinued this jig because although it was great for fret dressing, it could not handle fretboard levelling. This issue is being addressed with the Mark II neck jig which will be available shortly. (Feel free to edit out if this is considered spam, Frank)

The reason why I always use quotation marks when referring to "straightness " in a guitar neck is that (unless they have undergone treatment) no neck is ever "straight" in the strict sense that every point on the surface of the fretboard lies in a straight line. As I stated in my post above, this can easily be verified experimentally if you have a toolroom quality straight edge and a set of gauge blocks.

Over the years, I have come to regard "straight" (in fretboard terms) as being best defined as the condition in which, when three identical gauge blocks are placed on the fret board between the D and G strings , (while the instrument is strung up to pitch) , one block in front of the first fret, one block in front of the seventh fret, and one block in front of the fourteenth fret, then a straight edge makes contact with all three blocks.

Obviously, in normal playing condition, there will be a gap between the straight edge and the block at the seventh fret, the size of gap depending upon how much relief the player wants. For set up purposes however it is necessary to get all blocks contiguous with the straight edge by adjusting the truss rod. Remember, this is all done with the instrument strung up to pitch.

Once you have achieved this "straightness" then it's off with the strings and into the jig. Adjust the jig until the above conditions have been replicated and you are good to go. (sanding the frets level, or the fretboard, if fretboard levelling was the objective)

As an aside, I would recommend that if you intend to level the fretboard as opposed to the frets, then ideally you should initially adjust the trussrod to give a small amount of backbow, and then replicate that when the guitar is in the jig. This will give more room for manouevre once the instrument has been refretted and restrung.

In my experience, the topic of neck jigs is a bit like the topic of nut compensation. Some people see it straight away, others take some time to grasp the concept, and others never quite get it.

[Ted Kritikos]

There's a 3 page discussion that touches on some of these points:

http://fretsnet.ning.com/forum/topics/are-neck-jigs-necessary

[Mike Kolb]

Wonderful comments and lots of divergent thoughts.... it's forced my thinking process, and that''s a good thing! Murray offers a great theoretical view of "straightness" as applied to a guitar neck, and it's a view that's worth referring-to. Mark Wallace uses this tool "in the trenches" and explains his process well, and that's that I'm going to attempt to emulate with this sacrificial Les Paul. I'm given to understand now that "playing position" straight may differ substantially from "flat-bench straight", particularly on guitars with flop-prone thin necks.

Does Dan Erlewine read or contribute to the forum? It'd be pretty cool to have him ingest all the info here and respond with his two-cents, seeing that he's the proud papa of this tool in the first place.

PS: Pierre, your English is just fine, sir.... guaranteed to be a whole better than my French,:)

[Jeffrey L. Suits]

I'd suggest reading Don Teeters' books, too. He's another pioneer in the string-tension simulation landscape.

[Pierre-Antoine Roiron]

Thanks! If I can can be of any help for a french test... I'll let you cheat on me.

[Paul Breen]

Murry states:

The reason why I always use quotation marks when referring to "straightness " in a guitar neck is that (unless they have undergone treatment) no neck is ever "straight" in the strict sense that every point on the surface of the fretboard lies in a straight line. As I stated in my post above, this can easily be verified experimentally if you have a toolroom quality straight edge and a set of gauge blocks.

Over the years, I have come to regard "straight" (in fretboard terms) as being best defined as the condition in which, when three identical gauge blocks are placed on the fret board between the D and G strings , (while the instrument is strung up to pitch) , one block in front of the first fret, one block in front of the seventh fret, and one block in front of the fourteenth fret, then a straight edge makes contact with all three blocks.

Obviously, in normal playing condition, there will be a gap between the straight edge and the block at the seventh fret, the size of gap depending upon how much relief the player wants. For set up purposes however it is necessary to get all blocks contiguous with the straight edge by adjusting the truss rod. Remember, this is all done with the instrument strung up to pitch.

Once you have achieved this "straightness" then it's off with the strings and into the jig. Adjust the jig until the above conditions have been replicated and you are good to go. (sanding the frets level, or the fretboard, if fretboard levelling was the objective)

Murry, other than eliminating the tops of most of the frets to set the flatness of the finger board, how does this differ any from just using the tops of the frets? I use the truss rod while the guitar is strung up and I use it when the guitar goes in the jig. I do not just count on bending a flaccid neck with no truss rod tension over the rods.

Ted thanks for the link, there is a picture of my neck jig there.

Mike, the jig at the very least is a safe way to hold a guitar while doing the fret work. Also in the link Ted posted, I show another use for the jig employed as a very useful holding fixture. It shows a guitar strapped in face down and a routing fixture attached to the beam of the jig to spline someone else's botched and failing headstock repair. There are other applications possible when just considering the jig as a stable holding fixture.

Any more, the majority of fret leveling I do is without using the jig at all. Experience has been my guide as to when I need it and when I don't. Possibly, experience is also the reason I feel that I get the same results going through all of the steps of stringing to pitch and then strapping in and making the adjustment again as opposed to just strapping in with no strings and making the adjustments. Either way, I will have already gone over the instrument, strung to pitch checking truss rod range of adjustment and the state of the frets with straight edges.

Nathan, I'm sorry but I type seek and peck with two fingers. It would require more effort than I am willing to spend the time it would require me to type out my whole process.

I suspect that all who have posted in this thread, do fine fret work. Approach and style to fret work is not all that much different than an individuals playing style, just a different way to a same end.