Part 5 - Necks - Scarf Joints

Replies to This Discussion

Permalink Reply by Wichita Sam on February 3, 2010 at 9:36am

Josh,

Thanks for the series.... a couple questions.... instead of using a block plane, would a table top belt sander work as well.... also how about you choice of glue. I've used all three titebonds, and have no preference between II and III, why are you such a strong propoenent of titebond III?

I really like you glueup clamping scheme.... very practical and workable for the average builder with limited tools...

the best,

Wichita Sam

Permalink Reply by Josh Gayou (SmokehouseGuitars) on February 3, 2010 at 2:02pm

I've done both a block plane and a belt sander several times to compare the two and I'll say that it actually takes more skill and finesse to do this properly with a belt sander than it does to do it with a properly set block plane.

The reason for this is that a belt sander removes A LOT of wood extremely quickly and it is very easy to round over the sides before you even know what happened. This is especially true considering that you will just be holding the work piece by hand instead of being able to ensure that it is square to the belt. As noted, having the surface is critical.

If you have a block plane that is set up properly, meaning that the sole has been lapped, the blade properly sharpened, and the depth set shallow, this process is a lot easier than it sounds. If you have your blade set to whisper (extremely fine shaves from the surface), you'll find that the block plane actually self-levels as it cuts. Add to this the fact that the block plane only removes wood as quickly as you want it to - you will have complete and total control over your cut the entire time. Again, all that assumes that you've set up your plane correctly. Setting up a block plane probably warrants a whole separate discussion, now that I think about it.

I use titebond III exclusively for all my heavy load bearing joints. There are several reasons why this is my brand. First, it is in ready supply and affordable considering some of the other alternatives. I can find this stuff at any decent home improvement store. It's not some ultra secret super rocket fuel that I can only get from luthier ninjas living in the mountains or Paraguay. Second, the III variant is rated as their strongest formula. Since a fully tuned six string guitar will place roughly 105 to 115 lbs of pressure across my joint, I want to lock it down with the strongest stuff I can find. Third, there is also social acceptance. All of the well known (or at least better known than us) luthiers swear by the stuff, and I even watched a few experiments designed to compare the performance characteristics of Titebond III against other alternatives (not carried out by the company that makes the product of course) which showed it to either match or outdo the competition.

In fact, the only glue that I've read about that could possibly outdo Titebond III for our purposes is probably Hide Glue and the reasons are more a matter of taste than they are performance. For one, the curing properties of Hide Glue make it slightly easier to get an invisible glue line than with Titebond because is cools as it cures, therefore it contracts and pulls the pieces together. On the other hand, if you ensure that Titebond is thinly applied and clamped correctly, this is a none issue. The second benefit of hide glue is that you can soften it up and get it to let go pretty easily if you apply sufficient heat to it. Whether or not you actually see this as a benefit is a matter of personal preference. Now, when you consider how cranky hide glue can be when you're trying to apply it, for me at least, it's just easier to use the Titebond.

Wichita Sam said:

Josh,

Thanks for the series.... a couple questions.... instead of using a block plane, would a table top belt sander work as well.... also how about you choice of glue. I've used all three titebonds, and have no preference between II and III, why are you such a strong propoenent of titebond III?

I really like you glueup clamping scheme.... very practical and workable for the average builder with limited tools...

the best,

Wichita Sam

Permalink Reply by Jonathan on April 7, 2010 at 11:07am

so? are scarf joints stronger than if, say, i just cut the whole neck out of a laminated block. and i just cut the angle out.

Permalink Reply by christian pearson on July 11, 2010 at 4:49pm

this is a great thing to read. and the pics are great.

Permalink Reply by c baxter on August 20, 2010 at 3:10am

Simply Thank You..... And if you have anything else as great as that. Please write again and add pictures they really help! No more plain necks on my CBGs.

Permalink Reply by Michael L. Castle on September 7, 2010 at 5:59pm

Josh,
Dumb question, but.....Why is it necessary to completely flatten the cuts before gluing a scarf joint? It seems like I saw somewhere where someone said something to the effect that if you leave 'em rough, the glue will "fill 'em in"
Is this due to the nature of "aliphatic resin glue", or is this true in general? ( Actually, I guess one has only to read the label, where it says "must fit tightly" )
T.I.A.!
Michael

Permalink Reply by Josh Gayou (SmokehouseGuitars) on September 7, 2010 at 6:23pm

The glue is there to joint the wood together, not act as a gap filler :)

There are several reasons to this:

1. Leaving the surfaces jagged creates a lot more gaps than you want, no matter what anyone tells you. This is a huge structural liability and is likely to lead to joint failure. Also, yellow glue, even when it sets up completely, is softer than wood. If you have a tone of that spackled into your joint, it will suck up all the vibrational energy and kill your sustain.

2. The surfaces have to be flat in order to have an invisible glue line. If you don't get them flat you'll have a thick, ugly glue line that'll stick out like a sore thumb.

Michael L. Castle said:

Josh,
Dumb question, but.....Why is it necessary to completely flatten the cuts before gluing a scarf joint? It seems like I saw somewhere where someone said something to the effect that if you leave 'em rough, the glue will "fill 'em in"
Is this due to the nature of "aliphatic resin glue", or is this true in general? ( Actually, I guess one has only to read the label, where it says "must fit tightly" )
T.I.A.!
Michael

Permalink Reply by ledbelly on November 17, 2010 at 2:47pm

i dont haVE A PROBLEM WITH FENDER I ACTUALLY LOVE THEM BUT I DO LIKE THE ANGLED HEAD SO THANX AND JUST SOO YOU KNOW I THINK I'LL BE USING FENDER PUPS IN MINE HEHEHE

Permalink Reply by Slowpaw Steve T on February 23, 2011 at 2:46am

This is the most informative guide i have found on CBG building techniques, also found the fret mounting tips and materials guide very useful, thanks to Josh for making it freely available!

There is very little information out there on CBG's, most Blues guides list Strats, Teles and LP's as the  best Blues guitars, though it seems the traditional Blues sound really comes alive on 1, 2, 3 and 4 stringed  instruments !

 

.

Permalink Reply by Josh Gayou (SmokehouseGuitars) on February 23, 2011 at 10:59am

Cheers, Steve.

Permalink Reply by Wichita Sam on February 23, 2011 at 1:51pm

so... if you like fenders and angled headstock, why don't  you scarf a neck and then cutout a tele headstock profile... I've done it a couple times...  one word..."NO STRING TREES".....

the best,

WS

markholt said:

i dont haVE A PROBLEM WITH FENDER I ACTUALLY LOVE THEM BUT I DO LIKE THE ANGLED HEAD SO THANX AND JUST SOO YOU KNOW I THINK I'LL BE USING FENDER PUPS IN MINE HEHEHE

Permalink Reply by Josh Gayou (SmokehouseGuitars) on February 23, 2011 at 2:27pm

Looks kinda weird though, no?

Wichita Sam said:

so... if you like fenders and angled headstock, why don't  you scarf a neck and then cutout a tele headstock profile... I've done it a couple times...  one word..."NO STRING TREES".....

the best,

WS

markholt said:

i dont haVE A PROBLEM WITH FENDER I ACTUALLY LOVE THEM BUT I DO LIKE THE ANGLED HEAD SO THANX AND JUST SOO YOU KNOW I THINK I'LL BE USING FENDER PUPS IN MINE HEHEHE