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Tatsu

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Reply with quote  #1 
I've got an idea which is like taking two Chapman Sticks and removing the belthooks, then shaving down the foot of the belt hooks so that the two stick necks can be placed flush back to back, either bolting or clamping them together. Redesigning the belthook so it comes out of the sides is required of course. Any amateur luthiers want to work with me on this? I've already got some good blue prints (better than the ones I posted over on Stickist. Let's do it. I've already been in conversation with the folks over at Handmade Music Clubhouse and the Luthier Forum and know some of the limitations now that I'm working with in regards to neck thickness etc... Looks like it would need either a graphite neck or a graphite reinforced neck with a double truss. Although a really thick passive aluminum truss might work for a prototype.
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bergland

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Reply with quote  #2 
Quote:
Originally Posted by Tatsu
I've got an idea which is like taking two Chapman Sticks and removing the belthooks, then shaving down the foot of the belt hooks so that the two stick necks can be placed flush back to back, either bolting or clamping them together.

Tatsu:

Very interesting idea? Can you explain how you see this being played, or what kinds of creative advantages such a hybrid instrument might produce?

Don

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Tatsu

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Reply with quote  #3 
It allows me to play moving bass line, perhaps not just ostinato but walking WHILE holding a chord and still have another hand available for soloing.

Right now on the stick you can play those horribly voiced 153 chords or 137 chords (and arpeggiate them) in the left hand so there's the illusion of bass and chords while you play solos with the right hand.

But if you want a bass ostinato, you have to transfer the chord to the right hand while your left plays the ostinato bass or walks, so how can you solo?

I can play a major/minor scale over one octave in one position on the back of the neck. If those are bass strings, the left hand can play a 3 note quartal with one finger on the top of the neck/bass side, leaving right hand free to solo. "SO" much better.

People over at Stickist like Greg are saying it only works conceptually not in the real world but I "KNOW" different. I've tried it. I didn't leave it at the conceptual.

Hoping some luthiers will join me in my project. Know any?

If no one joins me I'll make my tapping instrument with zither pins and a passive aluminum or steel truss as a proof of concept.
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Jtmart

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Reply with quote  #4 
I might be interested, I'm in the process of building a "standard" type touchstyle instrument but I'm always interested in innovation.
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Tatsu

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Reply with quote  #5 
That'd be really fun, Jtmart. I'm going to blog here about my thoughts on the construction of this instrument. Everyone can evaluate my ideas for how I think it should be built and provide comments as to why they might not be good and how they could be better.
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Tatsu

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Reply with quote  #6 
Here starts the beginning of my "blog" on a Backside tapping instrument.

I saw where one luthier said the thinnest bass necks he makes are.500. I took that to mean half an inch thick. He also said if he makes them that thin he always uses double truss rods and carbon reinforcement.

Another luthier working at a famous bass company for 20 years said, the normal carbon reinforcement is actually mostly plastic in the bar. It's pulstruded. Only has a little bit of carbon fibers in it. He said it kills the sound of basses putting that much plastic in the neck along with a hollow chamber with a truss flopping around in there. Cutting out that much neck wood also destroys the existing strength of the wood. He said a better solution was to use raw strands of carbon fiber, thin thread called TOW. Use West Systems epoxy to put the carbon fibers up to the 5th fret 1/16"x 1/4" wide, placed behind the truss rod about 1/8" from the back of the neck.
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Tatsu

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Reply with quote  #7 
Here's an image for how truss rods and carbon reinforcement is normally installed. The last option is often used on really thin necks. But the reason bass manufacturers use that is because it's cheap, easy, and a good marketing ploy to say the necks are reinforced, plus it's what customers say they want, not that it's the best solution. It's a bad solution.

Some of the amateur luthiers or people who have a project they don't care to reinforce the modern way may opt for passive aluminum truss rods or steel.

Aluminum expands a lot so not good if you're going to travel much or expose it to temperature extremes. Although it can be O.K. for a short instrument like a banjo or some such.

Another issue is that some people say you need aircraft grade aluminum but that's not entirely true, you can yous 6063 or 6061 aluminum, doubling the thickness from a 2024-T4 alloy and get the same amount of reinforcement with these lower quality commercial grade aluminums.

Other people prefer steel reinforcement. 3/16"x3/8" tempered chrome moly steel passive truss is often used, though weaker than carbon rods. They can be slimmer than carbon rods though because they're stronger in profile than carbon rods are. For folks who like tall thin necks.

Steel is heavier but provides less expansion and greater reinforcement than aluminum. So steel is a good option if you don't mind the weight.

Other solutions for strong but thin necks are necks with a laminated core or polycarbon necks.

I was hoping initially for a neck only 1.1 cm thick so when I place two necks back to back with a 2mm gap between them, I'm only about as thick as a Chapman stick. I don't really know if that's possible. I wish someone experienced would tell me.

Anyway, I think it's possible to have a neck only a little thicker at 1.3cm making a double instrument be 2.8cm.



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jpeg manico.jpg (1013.36 KB, 10 views)

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Tatsu

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Reply with quote  #8 
Other solutions for a really thin neck are to make them from metal like Gittler guitars or by using a mold to create them from a very strong material.

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Tatsu

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Reply with quote  #9 
Let's talk wood.

Upon looking around for hard woods used in bass necks I came up with;

Northern Hard Ash, Eastern Hard Maple, Palisander Rosewood, Walnut, Zebrawood, Bubinga, Ebony, Koa, and Satine. Very knowledgeable luthiers and players don't want the tone of these woods destroyed with all that plastic filler used in carbon reinforcement bars. Even a truss diminishes the tone. Actually, for neck through instruments, the wood used in the body is of little importance when thinking about the tone because all the vibration is in the neck. Choosing which neck wood you're going to use is a VERY important consideration on an instrument like a tapping instrument.

Anyway, long ago there were no truss rod or reinforcement technology and people had basses fixed, bought new necks or replaced the whole instrument when they started to buckled. Some feel if you care about tone that's the only way to make 'em and live with them: without all that crap.
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Tatsu

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Reply with quote  #10 
How to install reinforcement bars if you're going to use them?

I saw one discussion that asked should they be parallel to the truss rod or parallel to the strings.

The answer on one of the luthier forums was that they should be set on edge parallel to the strings not the truss rod which means they will taper toward the neck. This allows you to get as much reinforcement out of them as you can.

One problem with reinforced necks is that it takes a lot of torque from a truss rod adjustment to make reinforced necks move. Also, the reinforcements have to be put in very snug especially on the ends so that sound is transmitted down through the neck and not die on the way through.

This is another reason to avoid them or to be careful and wise about installing them.

You have to keep your truss threads oiled so that you don't have a situation where rust has locked the whole thing up a year later when you try to turn it. Many people will forget of course.

Trusses too should always have the play removed from them and be "engaged" for optimal sound transfer even if the neck was made with a bow already in it.

In the attachment is how NOT to install reinforcement bars. They've gone past the 5th fret and when you turn the truss it won't be able to bend the instrument where it's supposed to.

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png ROD_zpse2a13981.png (77.14 KB, 13 views)

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Tatsu

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Reply with quote  #11 
How about frets?

Stainless Steel frets are hard on tools and even then, they will wear down. Emmett's idea to use anodized aluminum for a tapping instrument is better because the frets of tapping instruments get more abuse than normal guitars and basses. But you will work hard and you're tools will be sorry you chose to cut something like that.

Another issue is that tapped frets will often start to come out after a while. That's why Emmett puts his in from the side so that can never happen.
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Tatsu

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Reply with quote  #12 
btw working with carbon fiber is not friendly to your health. You should always wear gloves since it shatters so easily, if you get splinters (and you will) the tools you try to use to pull them out will just crush them instead of pulling on them.

I don't really understand the difference between polycarbonate, graphite and carbon reinforcement bars. Maybe someone can explain it to me.


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Tatsu

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Reply with quote  #13 
One luthier who used laminated wood for the complete body of his basses said it's very difficult to make something like that from scratch if you care about quality. The wood chips before the tools do. He said he throws out as much stock as he uses in the final instrument because it often happens that the one layer he'd been working on for hours or days finally chipped in the end before he could finish it and that makes it absolutely unusable with the layers he was successful to finish. He said it's very frustrating and makes the instrument expensive but the beauty is worth it.

But the lamination job for a laminated core neck is different from this kind of thing.

Here's a link to how he does it: http://www.ricktoone.com/2007/09/stacked-laminat.html

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jpeg images_laminated_body.jpg (8.49 KB, 7 views)

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Tatsu

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Reply with quote  #14 
Concerning trusses again.

When putting in trusses you have to leave .125" behind the truss, so when you turn it after completing the instrument, it's not pushing up against the back of the wood blocking it from doing it's job.
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Tatsu

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Reply with quote  #15 
Now we're getting to the nitty gritty.

Heastock's usually angle backwards but we've got two instruments back to back with very thin necks. Headstocks should be about 12-15mm thick and my instrument is already down to 13mm per neck. That means the strings won't arch over the nut and need to be pulled sideways, or figure out some way to make the strings pass through their own headstock to the rear headstock and that seems like an innovative idea. [smile]

The problem with pulling the string sideways is that it will be difficult to impossible to have a nut that can accommodate different string sizes for future changes of tuning or string thicknesses making a problem for strings being the correct, homogenous distance apart.

Maybe someone experienced has an easy solution to this they can share here.

Whether pulled back or pulled sideways; the angle should be about 15-17 degrees, otherwise strings have an annoying chime that accompanies them when plucked. We might not care if only tapping but if someone wants to strum open strings on it, this has to be taken into consideration.

Heck, maybe there's a way to pull the strings forward?

By the way, here's an image of tuners that might work if they didn't stick out to the other side of the instrument. I like the knob style on the bottom not the ones on the top.

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jpeg images.jpg (4.83 KB, 12 views)

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