Calculating the length of my rod

Hi all. I'm planning on building a miniature bass not unlike the 'minibass' thread which was on here a little while ago and I'm wondering what length of rod to use on the neck. The scale length I was planning on was about 18-20'' depending on what length rods I can get.
using the Stewmac fret combobulator it tells me that, if my scale length is 18'' then a 22 fret neck would have a fretboard length about 13''.
I can get a classical guitar rod which is about 12 1/4'' which doesn't seem far off.
I'll obviously be getting some more accurate measurements before I get anything but this post is really just to give you a picture of what I'm trying to do and to see if anyone's got any thoughts on what I should be thinking about when deciding on scale length/rod length/neck length etc.
I'm assuming there's a bit of leeway with the length of rod you can use since, for example, Fender and Gibson's scale lengths are different but you could presumably stick the same rod in either, so does anyone have any of your usual helpfil and very valued advice?
Thanks.

This thread will be worth watching just for the jokes alone! I hope you can get a "straight" answer from these guys.

Getting hard numbers will be tough. Let's see how long it will take for this member's thread to get sacked.

Ok...I'm done.

When you decide what length you need, LMI will makes rods to whatever length you want. I would simply cross multiply to get a simple ratio to determine your truss rod length.

(Truss Rod Length/Scale Length)=(Truss Rod Length/Scale Length)

(18" Truss Rod/ 25.5" Scale) = ( Unknown Truss Rod Length(X)/18" Scale)

(18" Truss Rod * 18" Scale) = ( 25.5" Scale * X)

(324 TRSc) = 25.5ScX

(324TRSc/25.5Sc) = X

X = 12.71TR

I don't see any reason a 12.25" rod wouldn't work.

12.25" ? That is a monster rod.

Don't forget that for a given diameter, stiffness is proportional to length :wink:

I'm sorry, I know it's sad but I can't stop laughing at the title of this post.

As an aside, I thought for sure I had been using a 10" rod but my wife swears it's only 5 1/4".

Keep in mind that you'll get different readings depending on the current temperature. Colder temps often result in shrinkage and you won't get a true measurement.

Keep in mind that you'll get different readings depending on the current temperature. Colder temps often result in shrinkage and you won't get a true measurement.

:lol:

Measure from the pubic bone, not the perineum.

For honest math, we can get most done with this:

Measure from the pubic bone, not the perineum.

There's circumnavigating something. Then there's Fezz :lol:

Now should the rod stand proud while measuring?
Seriously, go with Colt's advice

http://images.celebritysmug.com/4f145ff18b4ae2.46485189-thumb.jpg

.....
I'm assuming there's a bit of leeway with the length of rod you can use since, for example, Fender and Gibson's scale lengths are different but you could presumably stick the same rod in either....

Yes, but if you stick your Fender rod in a Gibson, you risk loosing your Fender.

Has anyone ever asked the mods to remove one of their own threads: )
Thanks for the good advice everyone (particularly Colt).
Now I just need to decide whether to insert it from the front or the back...:mrgreen:

Has anyone ever asked the mods to remove one of their own threads: )
Thanks for the good advice everyone (particularly Colt).
Now I just need to decide whether to insert it from the front or the back...:mrgreen:

I kept my cool on this thread till I read that. Then I about spit milk out my nose.

Seriously, I just built a short scale bass - 30" scale. the neck was too short for a bass TR and a little long for a guitar TR. I wanted to use a 2 way TR from Stew-Mac, so I just bought the 18" and installed it with the adjustment at the heel. It may be shorter than it should be, but it works very well. I tend to overthink things, but for this one I played the ignorance card.

Keep in mind that you'll get different readings depending on the current temperature. Colder temps often result in shrinkage and you won't get a true measurement.

1cUNNKzj_Nc

For honest math, we can get most done with this:

Just remember, the big ones are inches :mrgreen:

why can't I stop laughing here???...uuugh, it hurts! lol

I use a standard rod measuring rule that reads 1,3,6,12...Ron Jeremy.

Sorry, I couldn't help myself.:twisted:

Don't worry about it. Its not the size of the boat, but the motion of the ocean.

You should be able to work it out from the angle of the sun, and the length of the shadow!

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It's also helpful to keep in mind that the amount of tension you apply to your rod is proportional to the degree of relief you'll experience.

i just popped by telehomedepot to see what was new and in the first 20 unread posts, someone is asking about rod length, another is asking about getting hard and surprise! someone else is having trouble with their nuts.

i just popped by telehomedepot to see what was new and in the first 20 unread posts, someone is asking about rod length, another is asking about getting hard and surprise! someone else is having trouble with their nuts.

I came to TDPRI from Strat Talk for finishing and building advice..........I'm staying for the quality of the innuendo. :grin:

I don't know the complete formula, but if you used this to solve for the angle, then you could use trig to calculate the hypotenuse (thats assuming your rod is the longest).

(Angle of the Dangle) x (Heat of the Meat) = (Mass of the Donkey)

In the schoolyards of Minnesota years ago it was the 'square of the hair x the angle of the dangle'. I can't remember if we knew what we were talking about or not - probably not...

I'm sorry, I know it's sad but I can't stop laughing at the title of this post.

As an aside, I thought for sure I had been using a 10" rod but my wife swears it's only 5 1/4".

I can relate to this.

What is somewhat disconcerting is the need to 'calculate', not 'measure' :shock:

What the heck have you go going on down there?!