Scale length--Neck swap question

[moku]

Yes. In the real world, it works.

that's interesting. maybe it only works for jacksons? i wish someone would explain why this is so. just want to learn, that's all.

[DalyTek]

matching the holes so the new neck line up does not change the distance of the end of neck pocket to the floyd post....

Exactly. The distance from the end of the neck pocket to the Floyd Rose posts does not change, and does not need to.
Having the neck heel end (and the respective holes in the heel) closer to headstock will shorten the overall scale of the guitar.
Moving the end of the neck heel closer to the end of the fretboard will lengthen the scale, when bolted into the same neck pocket on the same body.

What matters for scale length is not how far the saddles are from the neck pocket, but how far the saddles are from the nut, which can be changed by altering the placement and length of the neck.

[moku]

Having the neck heel end (and the respective holes in the heel) closer to headstock will shorten the overall scale of the guitar.
Moving the end of the neck heel closer to the end of the fretboard will lengthen the scale, when bolted into the same neck pocket on the same body.

i'm sorry but this is not a good way to properly set up a guitar! moving the neck back and forth?! one can't move the neck heel back and forth to match the scale and not have the neck snugly and firmly resting on the neck pocket (instead, say, having the neck held on to the body just by 4 screws not budding against the neck pocket). besides, if i understand what you're saying correctly, i think you have it reversed: having the neck heel end closer to headstock will LENGTHEN the overall scale of the guitar. unless i'm misunderstanding you.

What matters for scale length is not how far the saddles are from the neck pocket, but how far the saddles are from the nut, which can be changed by altering the placement and length of the neck.

of course, i realize that. but guitars are cut and the posts are drilled with scale of the neck in mind. hence there is a discrepancy with the distance of the neck pocket and the posts.

i'm sorry but this conversation is not going anywhere. i'm just going stop and to accept don's words that for jacksons the necks could be swapped and the guitar still intones... even though it shouldn't and no one can explain the physics of why this is.
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[DalyTek]

moku, you're not understanding what I am saying.

I am not saying to move the neck heel around so it is not firmly in the pocket.
Jackson moved the neck heel further up the neck towards the headstock. ie, the neck is shorter, so the heel physically ends in a different place.
When seated fully in the neck pocket like normal, the headstock (and thus, the nut) are closer to the bridge saddles due to the shorter neck length.

[MetalMedal II]

This would be a great place for someone to post some pics of a switch they did as an example!

[DalyTek]

Took the necks off both and it looks like it will work except one thing is troubling me.

The bolts on the Fusion are thicker and longer than the bolts on the Kelly.
How would I swap them to try it while still retaining the ability to swap them back if it doesn't work?

[Newc]

It's a one-shot deal, unfortunately, unless you find an early Kelly XL neck for the Fusion body.

[Newc]

As for the other issue with neck scale that was brought up;
A 22 fret Jackson neck would fit a Fender Strat (ignoring the difference in heel and pocket width). The Dinky came about mainly to accommodate the extra frets and make them accessible without moving the bridge too much toward the center of the body.

[84sups]

I owned 2 Fusions (Jackson Fusion Pro and Charvel Fusion Deluxe) and the distance between the neck pocket and the trem was less than on the 3 dinky's (PS2, PS4 and Dinky reverse) I've owned. I would post some pics but dont own either of the Fusions anymore. But for the ones I owned they would not have intonated.

[ginsambo]

I still remember reading the 1993 Jackson Catalogue from when I was a teenager. I was dead set on a fusion because of the 24.75 scale length (Lighter string tension = Easier bends etc.)...that was the whole point of why it was called a fusion, because it was a rock strat but with a Gibson/BCRich scale.....hence fusion....but then I saw the price tag so I got a Les Paul copy instead.

3/4 of an inch difference in scale length (25.5-24.75) is a hell of a lot to try and make up. What in essence you are doing is sticking a Gibson scale neck on a strat scale body. I guess the only way to do it is to move the neck in the pocket, until you acheive 24.75" from low E bridge saddle to nut.

Logic escapes me, but presuming both body and neck are 22 fret type, then surely you will have to rout out the body of the KE3 to accomodate the shorter distance required between bridge and 22nd fret...unless its a 24 fret body with extended pocket, in which case you might just have enough play and get lucky.

[DalyTek]

ginsambo, both the Fusion and the KE3 are 24-fret guitars. The Fusion's neck is physically shorter than the KE3 neck overall, it's not just a difference in the distance between frets.

If the length of the neck was the same for both scales, just with different fret spacing, then the body would be left to make up the difference for correct overall scale length.

[ginsambo]

So you will have to rout the body or move the bridge closer then. I did think the two frets approximately = 3/4" theory was a bit jammy.

[DalyTek]

I'm seeing things differently than some people. The scale length is the distance from the nut to the bridge.
If the neck is physically shorter, the nut is moved closer to the bridge, thus lowering the overall the scale length.
There is no need to move the neck pocket, move the bridge or do any other modifications to the body.

X=distance from nut to mounting holes on heel heel
Y=distance from mounting holes in pocket to bridge
Scale length is calculated by the sum of these two measurements (L=X+Y)

so if:
X=18.5 and Y=6.25 then the scale length (L) is 24.75
X=19.25 and Y=6.25 then the scale length (L)= 25.5

Both bodies have the same measurement for Y, meaning the pocket and bridge locations are identical.
The scale length is changed solely from the (X) neck measurement.

This is my theory, based on my fairly firm grasp of physics and my loose grasp on math.
If anyone disagrees, please inform me of which part is wrong and why.

(I want to be 100% on this, as it's an irreversible modification and may render both guitars' intonation permanently unsettable...that's why I am looking for good solid facts and not personal opinions.)

[84sups]

Only way to tell is disassemble both guitars and take measurements from the neck pocket to the trem. If thay are the same length then it will work fine, if not then it obviously wont.

[ginsambo]

The short of it is that if you can manage to get a 24.75 scale length from trem saddle point to nut you are in business, if not it won't intonate. Of course the 24.75 neck is shorter than the 25.5, however, with a short scale, the distance between the 24nd fret and the bridge is ALSO shorter than a 25.5" scale.

To the Low E saddle, this measurement is around 6" on a 24.75 scale (Fusion neck) from 24th fret to bridge and around 6 and 3/8" on a 25.5" guitar (KE3). If your trem saddles will move forward 3/8" you are in business, if not you need to look at other options like routing the body, the end of the neck heel, filling and moving the trem posts, or dare I say it, getting a different body or neck. You don't to be in a position where you have maxed out your saddles only to find it won't intonate on some strings.

Given two 24 fret necks of different scale lengths, your 'Y' variable is not a constant with both scales.