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  #61  
Old 07-24-2015, 12:14 PM
KevinLPederson KevinLPederson is offline
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I was asking John Osthoff in his thread about his titanium truss rod. I think that is a lighter rod. I have an interest in a certain style of compression rod. Its a SINGLE rod, DUAL action (SRDA). I know many builders use a SINGLE rod SINGLE (SRSA) action, like Jim Olson et al. The SRSA is a rod in a curved channel with a spline glued in. The rod does not rotate and there is a nut on the adjusting end. As the nut gets tightened, it compresses the wood behind the nut and the rod wants to straighten. Many people put a little tension on it before they glue the fingerboard on and then plane that flat. So in essence it has some "dual action". This is an EXCELLENT proven way to do this. Its simple and the spline is hogged down on it, no rattle.

The SRDA, is a rod that has a tab at the nut end and a tab at the rear side (heel) end. The nut is welded to the rod. These tabs are reverse threaded...so that when they are immobilized, and the rod is rotated, they push apart; when the rod goes the other way, they would pull together. PRS has a rod like this. I actually took a PRS guitar apart to get at one of these to see how it worked. This type of rod, via its function, really counteracts neck compression and s-type curves. Because its not just "pushing up in the middle of the neck", its actually pushing the nut end away from the heel end - its doing the exact opposite function to what the strings are doing. Its kind of "pushing out the wrinkles" in the neck.

I'm still interested in this type of rod. If there are any others out there that want to chat about this, feel free to add right here in my thread.

The PRS rod has to rotate - it can't be trapped. It still gets a spline, but it can't be "pinched off". And there is no rattle either. Another add here...this PRS rod moved the neck BOTH WAYS more powerfully and further than any other truss rod I've ever encountered. It was deeper in the heel end and it was a slightly curved channel.

This rod manufactured in titanium would be great.

Just some thoughts.

Kevin.
  #62  
Old 07-24-2015, 07:23 PM
printer2 printer2 is offline
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Let me see if I got this straight. The truss rod would be the nut and rod of a double acting truss rod with opposite threads on the ends but rather than having the 'second' rod in a dual truss rod system the two tabs are captured in the neck. And the neck acts as the second rod.

Just found a picture of one end. Seems there is a mahogany strip over the rod.



I am thinking maybe just deconstructing a regular double acting rod would give a starting point for doing something like it without having to buy reverse tap and die to do the far end.
  #63  
Old 07-24-2015, 09:02 PM
KevinLPederson KevinLPederson is offline
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Quote:
Originally Posted by printer2 View Post
Let me see if I got this straight. The truss rod would be the nut and rod of a double acting truss rod with opposite threads on the ends but rather than having the 'second' rod in a dual truss rod system the two tabs are captured in the neck. And the neck acts as the second rod.

Just found a picture of one end. Seems there is a mahogany strip over the rod.


I am thinking maybe just deconstructing a regular double acting rod would give a starting point for doing something like it without having to buy reverse tap and die to do the far end.
Printer2 - Yes, its a SINGLE rod. There are anchor tabs that get captured immobile in the neck. They have reverse threads on each tab. The nut is welded to the rod, the entire rod rotates (just like the others type you mention with the bar on top). When the rod is rotated, those two tabs push away (back bow) or pull together (up bow).

The "two rod" truss rods like stew mac or the dual action with the flat bar on top work the same way because the tabs are reverse threaded but welded to that bar. But mechanically, they are acting to basically bend the bar/rod up or down. If you trap the top STRAP BAR then it will act more to resist the string compression (which I do). But the way they are designed is to "belly the rod up or belly the rod down". The SRDA rod - the trapped tabs are literally pushing apart - pushing apart - opposing the strings compression on the neck.

I know how it works...I just wanted to see the PRS rod because it was so unbelievably effective. Its could make the guitar totally unplayable one way or the other.

This PRS rod also has a huge 5/16 nut on the neck, with a wrench they supply...so there is more leverage to act upon the nut.

To me, this style of rod would be optimal because its a single rod (no rattle; no top strap bar; less weight)...yet it can move the neck either way. Its just intriguing to me.

However, I think a rod of this nature would struggle if there were carbon fiber rods in the neck because they would resist this rod.




Here was my SRDA rod(s).



I might take this proto to this machine shop and see if they can make it. Its just easier. I tapped the tabs and threaded the rod with reverse threads...they can machine it so much quicker.
  #64  
Old 07-24-2015, 09:17 PM
KevinLPederson KevinLPederson is offline
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Ok so here are the dual action rods with the bar strap welded on the tabs...the tabs are reverse threaded. But...unless you TRAP the top bar strap its not really 100% effective in counteracting string/neck compression...its just sitting there, kind of in a sleeve...and when you turn the nut, it bends up or down, but doesn't "push apart" 100% effectively. Because there is nothing for that top bar to push against (technically).

So this little chunk of maple goes right above the adjusting nut...then the spline goes on top of that and the strap bar...now its 100% trapped. I do this. By trapping this bar alone, your multiplied the effective compression resistance of that top strap bar - while the truss rod is in neutral. If you just put a spline over it...its basically in a sleeve...can microscopically move.



Then the maple/hard wood spline is put over the bar and glued to that little tab over the nut...the top bar strap is now trapped in the neck...when the tabs push apart, they will push on that tab OVER the nut and counter the strings compression. You've just multiplied this compression resistance by utilizing this top strap also. And the truss rod now has more of a anti-compression action to it...rather than being in a sleeve and going up or down.

  #65  
Old 07-25-2015, 04:06 PM
KevinLPederson KevinLPederson is offline
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neck setting time


This jig is probably like everybodys opinion, "everyone's got one". But here's mine. I got tired of fighting a straight edge on the bridge/fingerboard...so I just put the fingerboard and fret height at the bottom of this straight edge where the fingerboard is (in a dado slot). Then I epoxied the straight edge in. I can put whatever gap under the bridge I want and "level" the head block accordingly. The gap will depend on what set I want. This is a super handy tool.



Got the top glued on today. More later.

Kevin.
  #66  
Old 07-27-2015, 07:04 PM
KevinLPederson KevinLPederson is offline
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Got the top on, the neck set and then got the back glued on.


Test fitting the back to make sure it goes down on the linings. Glued it on.


Kevin.
  #67  
Old 07-27-2015, 07:23 PM
KevinLPederson KevinLPederson is offline
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Here is another guitar I had in Memphis. This is a 16" lower bout EuphoricMojo. Nice guitar, and available. I still have to get pics of this. I took some pics of the bridge work. My goal is to have it look like its just sitting on top of the finish. This one turned out really nice.





and a nice tight saddle


Kevin.
  #68  
Old 07-31-2015, 11:25 AM
KevinLPederson KevinLPederson is offline
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Here is the back decoration on this sold EVA UM. Neck detail will be in this vein.








Kevin.
  #69  
Old 08-01-2015, 02:30 PM
KevinLPederson KevinLPederson is offline
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Starting the neck

I make most all of my bindings and purflings.


As I've mentioned before, the next couple EVA UM guitars will have consistency in the ingredients. Doing this will really lay down some parameters on how each ingredient contributes to the tone of the guitar. So the neck on these three will be ovangkol/maple/ovangkol, the b/s walnut, the top will be Bear Claw Sitka, I've deflection tension tuned the top/back and bracing, and kept track of weight etc. This will help forge a "signature sound", because I can pretty much "track" how each element affects function and tone. If down the road I want to use a different wood combination, I'll have a baseline from these to make a fair judgement on how any new material affect the sustain/tone and volume etc.

Thanks.

Kevin.
  #70  
Old 08-01-2015, 05:25 PM
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theEdwinson theEdwinson is offline
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Quote:
Originally Posted by KevinLPederson View Post
Starting the neck

I make most all of my bindings and purflings.


As I've mentioned before, the next couple EVA UM guitars will have consistency in the ingredients. Doing this will really lay down some parameters on how each ingredient contributes to the tone of the guitar. So the neck on these three will be ovangkol/maple/ovangkol, the b/s walnut, the top will be Bear Claw Sitka, I've deflection tension tuned the top/back and bracing, and kept track of weight etc. This will help forge a "signature sound", because I can pretty much "track" how each element affects function and tone. If down the road I want to use a different wood combination, I'll have a baseline from these to make a fair judgement on how any new material affect the sustain/tone and volume etc.

Thanks.

Kevin.
Brilliant combination of Art and Science, Kevin. I am thinking seriously of prototyping a brand new model for the same reasons- paying very close attention to ALL the engineering factors and material characteristics to be able to really fine-tune the tone and quality of the sound.

The EVA UM you took to Memphis had EVERYTHING just right. That one is, to my way of thinking, a fully realized guitar, the one from which all others spring. So in taking careful note of all the factors that make that one so fine, I'm sure you are making some legendary instruments here.

By the way, the mosaic inlay work around the sound hole is just over the top! I don't know where to find the superlatives to describe something like that!
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  #71  
Old 08-02-2015, 12:26 PM
KevinLPederson KevinLPederson is offline
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Originally Posted by theEdwinson View Post
Brilliant combination of Art and Science, Kevin. I am thinking seriously of prototyping a brand new model for the same reasons- paying very close attention to ALL the engineering factors and material characteristics to be able to really fine-tune the tone and quality of the sound.

The EVA UM you took to Memphis had EVERYTHING just right. That one is, to my way of thinking, a fully realized guitar, the one from which all others spring. So in taking careful note of all the factors that make that one so fine, I'm sure you are making some legendary instruments here.

By the way, the mosaic inlay work around the sound hole is just over the top! I don't know where to find the superlatives to describe something like that!
Thanks Steve. As I've said before, your compliments are very kind, and your observations of my dialog are astute. Its is a combination of art and science and this is the means to an end - a "signature tone".

You can start where you are at now; just keep track now. Then you'll know for the very next one(s).

Thanks, that mosaic around the sound hole turned out really nice. I have more ideas on this concept to share in the upcoming builds.

Kevin.
  #72  
Old 08-06-2015, 05:37 PM
KevinLPederson KevinLPederson is offline
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Here is the jiggery I've engineered to tackle the bevel bindings.






The arm rest bevel.

the miters come together nicely.

The purflings in, now I can bind it and do the bevels.



Kevin.
  #73  
Old 08-07-2015, 09:37 AM
nashmore nashmore is offline
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Do you use an airbrush to make your edge gradient? It's a nice look. I like the contrast it creates.
  #74  
Old 08-08-2015, 03:15 PM
KevinLPederson KevinLPederson is offline
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Do you use an airbrush to make your edge gradient? It's a nice look. I like the contrast it creates.
Hey Nashmore - yes I do that with a spray burst over the translucent black. Again, lightly to accent the grain. Thanks for commenting.

Kevin.
  #75  
Old 08-08-2015, 03:21 PM
KevinLPederson KevinLPederson is offline
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Got the walnut binding on body...back strip not complete yet...end graft not in yet.




and the cut away bevel is done...its walnut



and the arm rest bevel done...its walnut


going to look like this...I like it !


I'll have the headstock Leopard drafted up tomorrow.

Kevin.
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