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mikeyb2
01-18-2016, 11:25 PM
It was my intention to add this to the tenor neck on my first build. I am now having second thoughts,after reading some archives about the need to build in some neck relief when using such rods. I'm wondering whether this would overcomplicate my first build, or should I leave it out and allow for some natural relief from string tension? There seems to be some debate as to whether any strengthening of the neck is really necessary on ukes anyway. Thanks Mike

Beau Hannam Ukuleles
01-19-2016, 04:12 AM
use CF in the neck (under the fingerboard) then sand the relief into the fingerboard

mikeyb2
01-19-2016, 04:43 AM
use CF in the neck (under the fingerboard) then sand the relief into the fingerboard
That makes perfect sense, but for a novice I'm not sure how I could achieve an accurate outcome. The only way I can think of is to shim up the fingerboard around the 7 fret slot( before it's glued to the neck) and sand the board flat, and I'm thinking around 10 thou for a shim.
thanks for the input Beau.

Yankulele
01-19-2016, 06:04 AM
I'm a novice too. I used a scraper to taper a dip of about 5 thou from first to twelfth fret. Finger board was unfretted. Scrape, flip, hold it against a flat surface with a good straight edge and measure with feeler guages. Might be overkill, but I made a matching caul out red oak for the glue up. Ten thou sounds like lot to me.

Nelson

Moore Bettah Ukuleles
01-19-2016, 06:32 AM
I take the relief out out the neck, it just makes fabricating the fretboard easier for me. I shoot for .006" at the lowest part of the relief, using a heavy duty scraper to keep everything nice and even. And like Nelson, I too use a matching caul when clamping and gluing the fretboard to the neck. I can't overemphasize the need for a good stiff straightedge (like the StweMac ones) and not a flimsy ruler for doing good setup work.

mikeyb2
01-19-2016, 09:21 AM
I'm a novice too. I used a scraper to taper a dip of about 5 thou from first to twelfth fret. Finger board was unfretted. Scrape, flip, hold it against a flat surface with a good straight edge and measure with feeler guages. Might be overkill, but I made a matching caul out red oak for the glue up. Ten thou sounds like lot to me.

Nelson
can I take it that as well as unfretted, it was also unslotted? And 10 thou was just a figure plucked out of the air , I was thinking somewhere between 5 and 10.

How also does this affect fret levelling? If it was a guitar with a truss rod, the rod would be slackened to straight whilst the levelling was done , then the relief added afterwards with a tweak of the truss rod. But how are frets levelled with a permanent relief in the neck?

Moore Bettah Ukuleles
01-19-2016, 09:50 AM
can I take it that as well as unfretted, it was also unslotted? And 10 thou was just a figure plucked out of the air , I was thinking somewhere between 5 and 10.

How also does this affect fret levelling? If it was a guitar with a truss rod, the rod would be slackened to straight whilst the levelling was done , then the relief added afterwards with a tweak of the truss rod. But how are frets levelled with a permanent relief in the neck?

The frets are only leveled in relationship to each other. Use a shorter tool to level your frets. The 6" diamond whetstone I use to level my frets coincidentally has a very slight bow to it and does the job perfectly.

Yankulele
01-19-2016, 10:37 AM
My fretboard is slotted and bound prior to scraping in the relief. It gets scraped into the bottom of the fretboard. I do put the frets on before gluing the fretboard to the neck, but I seem to have come across a lot of different opinions about the best order for that step.

Nelson

Tigershark
01-19-2016, 03:50 PM
Won't adding frets alter the neck relief?

mikeyb2
01-19-2016, 10:10 PM
thanks for the replies everyone. It seems that nobody so far has suggested that reinforcement isn't necessary, so maybe I'll go with it. Mike.

Yankulele
01-20-2016, 02:46 AM
Well, I thin the fingerboard to establish the relief, then I add the frets. If the frets are milled and installed consistently, the relief shouldn't change when fretted. And the two I have done this way worked nicely. That said, I think Chuck's method probably makes more sense. Incidentally, my caul is notched for the frets.

Nelson

Moore Bettah Ukuleles
01-20-2016, 06:32 AM
thanks for the replies everyone. It seems that nobody so far has suggested that reinforcement isn't necessary, so maybe I'll go with it. Mike.

You are correct in that neck reinforcement probably isn't necessary in an ukulele since as you mentioned most of them develop a little bit of relief in time due to the string string tension. But how much relief will develop? If the neck is too stiff it may remain flat, if it's too weak it may develop too much relief. It's cheap insurance for me to know that if I can the relief set perfectly from the beginning, with the addition of a CF rod, that it's likely to remain that way fro the life time of the uke. Depending upon what type of strings you use, the proper amount of neck relief will allow you to set the action above the 12th fret @ .080" or even lower. But that's too low for many styles of playing (I set my action @ .090"). So unless you are aiming for super low action and your neck is properly built and the uke will not be exposed to harsh environment or treatment, you'll be perfectly fine without reinforcement.

Beau Hannam Ukuleles
01-20-2016, 06:57 AM
you can use ebony strip too, but like chuck said- at $15 a stick - CF is a sure bet.

Moore Bettah Ukuleles
01-20-2016, 07:01 AM
you can use ebony strip too, but like chuck said- at $15 a stick - CF is a sure bet.

Cf is more stable and far stiffer than ebony. If however you are reorienting the grain of the neck when using a hardwood spline, that's not a bad idea.

Beau Hannam Ukuleles
01-20-2016, 08:07 AM
Classical and Flamenco guitars were/are(?) made with an ebony strip but i would have to be very strapped for cash to use ebony over CF these days.

I noticed that Collings use spring steel strips in their guitar necks and stew mac are even selling Titanium rods now. I'd try one if they weren't $30 each.

mikeyb2
01-20-2016, 09:03 AM
Thanks again, decision made and channel routed today ready to glue in the rod.

Michael N.
01-20-2016, 11:08 AM
You have to get the CF rod deep into the back of the neck, otherwise it does very little. Not that it will do any harm. Short neck, relatively low string tension.

sequoia
01-20-2016, 04:32 PM
I don't add any neck reinforcement whatsoever and have not had any issues. Yet. My thinking is that a good straight grained dense mahogany neck does not require reinforcement with the relatively short scale length and force exerted by "nylon" strings (~25 psi?). However, it can't hurt and so why not? I've always thought that CF reinforcement borders on overkill in the ukulele and is a carry-over from guitar building, but I'm just a hobbyist and not a professional luthier. In my experience, more problems relating to action/intonation come from a rotating bridge than a bowed neck. I'm currently deep in the bushes trying to tame bridge angles with angled saddle slots, bridge patches, bracing, etc. etc. Very hard to predict.

Since this is your first uke, I would suggest you concentrate on other things besides neck set and just build the dang thing. You gotta lotta other more important things to think about in my humble opinion. And you know what? It will all turn out pretty good. Now the next ukulele... then you can get into carbon fiber and all that.

Kekani
01-20-2016, 07:35 PM
You have to get the CF rod deep into the back of the neck, otherwise it does very little. Not that it will do any harm. Short neck, relatively low string tension.
I'll have to disagree a little, but not for the reasons you may think.

I leave my cf rod proud of the neck, and route a channel under the fretboard to match. The proud cf rod is the cornerstone of what I call "centerline neck jigs", which is based off my mortise and tenon neck jig, which is mentioned in the out of the box thread (and Luthier's Insights on Shawn's website). Admittedly, this may have been one of those solutions to a problem that didn't exist, but I'm sticking with it.

And yes mikey, add the cf rod. It allowed me to thin out my necks considerably, although recently I've been adjusting the shape a little thicker, but still flat. But that wasn't all. I found it had almost the same effect as a heavier headstock. Good stuff. . .

Michael Smith
01-20-2016, 07:56 PM
Just want to point out to those new at this all carbon fiber rods and not created equal. You can get fairly inexpensive rod from the kite supply place Good Winds but it is not nearly as stiff as the rod LMI sells at the same dimension. I have been using the LMI stuff but it aint cheap If anyone knows of a deal on the better stuff I would appreciate posting it.

Kekani
01-20-2016, 08:26 PM
Just want to point out to those new at this all carbon fiber rods and not created equal. You can get fairly inexpensive rod from the kite supply place Good Winds but it is not nearly as stiff as the rod LMI sells at the same dimension. I have been using the LMI stuff but it aint cheap If anyone knows of a deal on the better stuff I would appreciate posting it.
http://dragonplate.com/ecart/categories.asp?cID=20

Yankulele
01-20-2016, 11:04 PM
McMaster Carr item 2153t27.

Nelson

Michael N.
01-20-2016, 11:50 PM
I'll have to disagree a little, but not for the reasons you may think.

I leave my cf rod proud of the neck, and route a channel under the fretboard to match. The proud cf rod is the cornerstone of what I call "centerline neck jigs", which is based off my mortise and tenon neck jig, which is mentioned in the out of the box thread (and Luthier's Insights on Shawn's website). Admittedly, this may have been one of those solutions to a problem that didn't exist, but I'm sticking with it.

And yes mikey, add the cf rod. It allowed me to thin out my necks considerably, although recently I've been adjusting the shape a little thicker, but still flat. But that wasn't all. I found it had almost the same effect as a heavier headstock. Good stuff. . .

That's contrary to a lot of advice in terms of the CF rod doing it's job. I can only quote Al Carruth, who is much more of a science type than I will ever be:

'Carbon fiber itself has a very high young's modulus. Since it's mostly the tension and compression of the material near the surface that resists bending a rod can be very stiff. However, the epoxy matrix that sticks the fibers together has a much lower Young's modulus, and also has a low shear modulus. A CF rod inlaid under the fret board is pretty much riding on the 'center of moment' of the neck, as was shown by Dave Hurd. At that point there is very little tension or compression; most of the load is shear. Thus most of it is taken up by the epoxy matrix rather than the CF itself. Of course, as the neck flexes up some of the load is taken up by the fibers, and at some point they will take enough of it to keep the neck from flexing further, but that's generally 'way more of a bend than we want to see. Putting the CF deeper in the neck puts more of it into tension, and helps it to resist bending better.'

I've also read of makers stating that they flex for near 0.4 mm's before the fibres kick in and stop the flex. I guess this is the 'epoxy matrix' that Al refers to in the quote above. Of course 0.4 mm of flex is pretty much the maximum relief that one would want to see even on a classical guitar. Even then that usually only applies to the wound bass strings. For the plain strings I (and others) either dial in no relief or dial in a mere fraction to prevent back buzz.
I have no personal experience of using CF rods in necks. I do have experience of veneering the back of necks. It's amazing how much stiffness a mere 0.6 mm veneer can add to a neck just by veneering it. I suspect that it's the position of the veneer (back of the neck) that makes it much more effective.
Veneering necks was traditional in lute making where often the core material of the neck was just made of Spruce and baroque lutes can exert a lot of force on the neck, just by sheer number of strings.

mikeyb2
01-21-2016, 01:44 AM
Just want to point out to those new at this all carbon fiber rods and not created equal. You can get fairly inexpensive rod from the kite supply place Good Winds but it is not nearly as stiff as the rod LMI sells at the same dimension. I have been using the LMI stuff but it aint cheap If anyone knows of a deal on the better stuff I would appreciate posting it.

I watched a youtube video about building necks at Mya Moe. Gordon shows a neck with the channel routed for the rod, which looks quite short, maybe 5 or 6 inches and is placed from the heel end, leaving 3 or 4 inches at the nut end without.
I've adopted this idea and that way I get 3 uke rods from 1 guitar rod, thus making them cheaper.
https://www.youtube.com/watch?v=eZ_7aE0SQzM

RPA_Ukuleles
01-21-2016, 03:13 AM
quite short, maybe 5 or 6 inches and is placed from the heel end"

I saw that and it always seemed to me to be the least effective location to put reinforcement. It "seems" that if you were using a short stiffener, it would be better placed close to the nut end where the neck is much thinner/weaker. :confused:

Kekani
01-21-2016, 05:12 AM
That's contrary to a lot of advice in terms of the CF rod doing it's job. I can only quote Al Carruth, who is much more of a science type than I will ever be:

'Carbon fiber itself has a very high young's modulus. Since it's mostly the tension and compression of the material near the surface that resists bending a rod can be very stiff. However, the epoxy matrix that sticks the fibers together has a much lower Young's modulus, and also has a low shear modulus. A CF rod inlaid under the fret board is pretty much riding on the 'center of moment' of the neck, as was shown by Dave Hurd. At that point there is very little tension or compression; most of the load is shear. Thus most of it is taken up by the epoxy matrix rather than the CF itself. Of course, as the neck flexes up some of the load is taken up by the fibers, and at some point they will take enough of it to keep the neck from flexing further, but that's generally 'way more of a bend than we want to see. Putting the CF deeper in the neck puts more of it into tension, and helps it to resist bending better.'

I've also read of makers stating that they flex for near 0.4 mm's before the fibres kick in and stop the flex. I guess this is the 'epoxy matrix' that Al refers to in the quote above. Of course 0.4 mm of flex is pretty much the maximum relief that one would want to see even on a classical guitar. Even then that usually only applies to the wound bass strings. For the plain strings I (and others) either dial in no relief or dial in a mere fraction to prevent back buzz.
I have no personal experience of using CF rods in necks. I do have experience of veneering the back of necks. It's amazing how much stiffness a mere 0.6 mm veneer can add to a neck just by veneering it. I suspect that it's the position of the veneer (back of the neck) that makes it much more effective.
Veneering necks was traditional in lute making where often the core material of the neck was just made of Spruce and baroque lutes can exert a lot of force on the neck, just by sheer number of strings.
There was recent discussion on the OLF where Alan commented on cf. He goes on to mention too much stiffness causing the truss to work too hard, and even posed the question of necessity.

As stated, I disagreed with the first statement, but not for the obvious reasons.
I went to a deeper cf (3/16") from the one I started with (StewMac 1/4") in alignment with what Alan describes. I just leave about 1/32" out for reasons explained. Again, a problem solver for one that didn't initially exist.

On such a short scale as an ukulele, with nylon strings, not a whole lot of pull involved. So why install cf? Fear. I've seen too many twisted necks, and probably not because of pull from tension, but that's just a guess. Installing cf gives me one less variable, so I guess I could say one reason is to prevent twisting, rather than add stiffness (although that would naturally be the primary).

Not unlike laminating the backs of necks, just a different path in the same direction. BTW, I like laminated necks, and I'm not sure I'd install cf for stiffness if I did one. Note: I'd install it anyway because my process dictates it.

Beau Hannam Ukuleles
01-21-2016, 07:10 AM
I really like Aarons method of protruding the CF 1/32 to align the fingerboard- yep another jig to make...

Luckily, i now have Jake MacLaurie to help !!!! 87586

I have found the goodwinds CF is strong enough but id certainly be interested in a stronger cf if i could buy it-

Moore Bettah Ukuleles
01-21-2016, 11:03 AM
I watched a youtube video about building necks at Mya Moe. Gordon shows a neck with the channel routed for the rod, which looks quite short, maybe 5 or 6 inches and is placed from the heel end, leaving 3 or 4 inches at the nut end without.
I've adopted this idea and that way I get 3 uke rods from 1 guitar rod, thus making them cheaper.
https://www.youtube.com/watch?v=eZ_7aE0SQzM

I'm not saying my way is the best way but here is how I install a CF rod. I see only benefits by extending the rod as fas as I can. Not only does it make the neck stiffer but it also add some strength at the break angle.
BTW, buy from www.goodwinds.com. Choose the 48" lengths and they'll only cost you a few bucks each after you cut them to your length.

lauburu
01-21-2016, 01:08 PM
Veneering necks was traditional in lute making where often the core material of the neck was just made of Spruce and baroque lutes can exert a lot of force on the neck, just by sheer number of strings.

I have also seen Neopolitan mandolins with veneer over a spruce neck. I thought it was just a cheap method of manufacture but obviously there are other benefits
Miguel

Beau Hannam Ukuleles
01-21-2016, 01:52 PM
Thats a good idea chuck- ive been stopping them in the middle of the nut and first fret- your way to follow it all the way in to the headstock makes alot of sense.

Kekani
01-21-2016, 02:24 PM
I'm not saying my way is the best way but here is how I install a CF rod. I see only benefits by extending the rod as fas as I can. Not only does it make the neck stiffer but it also add some strength at the break angle.
BTW, buy from www.goodwinds.com. Choose the 48" lengths and they'll only cost you a few bucks each after you cut them to your length.
Exactly how I used to do it, until I started installing them shallow. Funny, I was JUST thinking about doing it like this again, and I'll still be able to install it proud.

And yes, the extra break angle strength would be the reason.

Beau Hannam Ukuleles
01-22-2016, 09:43 AM
Aaron- doe the slot in the bottom of your fingerboards (to fit the cf) go all the way from end to end or do you leave both ends un slotted??

dkame
01-22-2016, 09:53 AM
I'm not saying my way is the best way but here is how I install a CF rod. I see only benefits by extending the rod as fas as I can. Not only does it make the neck stiffer but it also add some strength at the break angle.
BTW, buy from www.goodwinds.com. Choose the 48" lengths and they'll only cost you a few bucks each after you cut them to your length.

Do you recommend a cross section size? .250 x .200 would work with a 1/4' router bit? Glue in with epoxy?

Kekani
01-22-2016, 10:25 AM
Aaron- doe the slot in the bottom of your fingerboards (to fit the cf) go all the way from end to end or do you leave both ends un slotted??

I just run it all the way through. Binding covers the soundhole end, and the other end os butted against the headstock veneer- remember, the nut resides IN the fretboard.

I guess I could cut it short, but now there's vwry little sqeezout over the body.

Moore Bettah Ukuleles
01-22-2016, 11:10 AM
Do you recommend a cross section size? .250 x .200 would work with a 1/4' router bit? Glue in with epoxy?

Exactly what I do except I install the CF rod tall so 1/4" bit will be too wide. I found a couple of table saw blades stacked together to be a perfect fit for the .200" width.

Kekani
01-22-2016, 11:53 AM
Exactly what I do except I install the CF rod tall so 1/4" bit will be too wide. I found a couple of table saw blades stacked together to be a perfect fit for the .200" width.
The one thing I didn't like about the SMD cf rod was the specific .200" bit.

Michael Smith
01-22-2016, 12:29 PM
The one thing I didn't like about the SMD cf rod was the specific .200" bit.

I make a cut with my table saw blade then add a shim piece of wood against the table saw fence and make another cut. The shim is equal to final width you want less the blade width. I find this method faster than pulling out the dado blades. I usually am only doing one or two necks at a time.

Moore Bettah Ukuleles
01-22-2016, 02:04 PM
The one thing I didn't like about the SMD cf rod was the specific .200" bit.

Two of my Diablo table saws blades when mounted on the motor shaft will give you an exact .200" wide cut. Easy.

Kekani
01-22-2016, 04:46 PM
Of course Mike and Chuck mention that AFTER I've already moved on to 1/8" x 3/16", which I'll stay with. Gives me .075" more gluing surface under the fretboard, over the body :cool:

I think I still have one more .200. . . hmmm. . .

Beau Hannam Ukuleles
01-23-2016, 06:21 AM
The one thing I didn't like about the SMD cf rod was the specific .200" bit.

yer- that is freaking annoying- try finding a 5mm (.200) bit at homedepo....