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Author Topic: Tension Question for Parker Fly 12-String Hybrid Project  (Read 1969 times)

Offline vjmanzo

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Tension Question for Parker Fly 12-String Hybrid Project
« on: March 26, 2018, 09:32:59 AM »
Hi everyone.

I am looking at the notion of converting a Fly into a "12-string Concert” of sorts; more info on that soon. At this stage, however, I have a question about string tension. I’ve modified the bridge and saddles of a Fly to physically accommodate 12 strings (6 two-string courses), and intend to “fix” the bridge by replacing the tension spring with a wood block.

My question is:
what are the limits on overall tension that a Fly can handle?

I’d like to use D'Addario EJ38 12-String Phosphor Bronze Acoustic Guitar Strings, (10-47), which have the following gauges:
Plain Steel .010/.10, .014/.014, Phosphor Bronze Wound .023/.008, .030/.012, .039/.018, .047/.027

I’ve never used 12s on my Fly, but, in principle, a Fly with a 12 spring could handle the below string tension of about 150 lbs. of tension (with D’Addario EJ21 12s) as follows:

String Note Gauge     Tension
1   E 4   0.0120 in.  23.36 lbs                                                                             
2   B 3   0.0160 in.  23.31 lbs                                                                             
3   G 3   0.0240 in.  28.02 lbs                                                                             
4   D 3   0.0320 in.  27.63 lbs                                                                             
5   A 2   0.0420 in.  25.60 lbs                                                                             
6   E 2   0.0520 in.  21.15 lbs

Total 149.07 lbs. of tension


For the 12-string idea I’m proposing, with a wood block used instead of a spring, the guitar (truss rod, bridge, etc.) would need to support about 250 lbs. of tension in total resulting from a set of 10-gauge 12-strings. D’Addario lists the tension for 12-String 10’s (EJ38 set) as follows:

String Note Gauge       Tension
1   E 4   0.0100 in.   16.22 lbs                                                                             
2   E 4   0.0100 in.   16.22 lbs                                                                             
3   B 3   0.0140 in.   17.85 lbs                                                                             
4   B 3   0.0140 in.   17.85 lbs                                                                             
5   G 3   0.0230 in.   27.90 lbs                                                                             
6   G 4   0.0080 in.   14.68 lbs                                                                             
7   D 3   0.0300 in.   26.71 lbs                                                                             
8   D 4   0.0120 in.   18.54 lbs                                                                             
9   A 2   0.0390 in.   24.66 lbs                                                                             
10   A 3   0.0180 in.   23.41 lbs                                                                             
11   E 2   0.0470 in.   19.91 lbs                                                                             
12   E 3   0.0270 in.   26.91 lbs

Total 250.86 lbs. of tension

I know that the carbon fiber exoskeleton is strong, but I don’t want to push it beyond its limits. I also don’t want the bridge to pull up from where it’s secured. If anyone is knowledgeable about long-terms effects of having this added tension, please let me know. At this stage, I haven’t done any modifications to the guitar itself that are irreversible. Ideally, if successful, I’d like to continue this project and document how this 12-strong mod was executed.

Thanks for the help!
Fly Mojo (2005), Fly Deluxe [w/Sustainiac] (2007), Fly Mojo [w/Sustainiac] (2008), Fly Concert (1997), Fly Classic (2003), Fly Deluxe (1997), Fly Artist (2010), Fly Deluxe [redwood, hardtail] (1993), Fly Bass FB-4 (2003) || More Info

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline ParkerPlayer

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #1 on: March 26, 2018, 11:20:39 AM »
Hi,
this sounds like an ambitious, challenging project !  I like the idea, and if works I bet it will be a very cool guitar indeed.
Though I have not ever heard of anyone doing this before.  My first inclination would be to do this kind of modification on a hard tail version instead of a tremolo version because the hard tail has 3 points of attachment whereas floating bridge has only two.  I have read about some instances where the floating bridge mounts have migrated over time under string tension (AKA the "leaning post issue").  You might want to search the forum to read up on that issue before you continue. 
good luck!
'95 Fly Deluxe, Majik Blue, Hard Tail
'96 Fly Classic, Transparent Red 
'98 Fly Classic, Transparent Red
'99 Fly Supreme, Honey
'09 Fly Artist, Custom Hard Tail

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline vjmanzo

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #2 on: March 26, 2018, 11:39:57 AM »
Thanks for the reply and the information. Yes, I'd considered doing this on a hardtail, and, besides the hardtail models being somewhat rare, my thought was that either bridge (hardtail or floating) might need to be reinforced, so, if that's the case, I might be better off trying this on a non-hardtail Fly since they can be found in abundance. I'm also drawn to the idea that, if these problems can be solved, others with the interest can try it on Flys that are more readily available on the second-hand market.

Thanks again for the info and the thoughts!
Fly Mojo (2005), Fly Deluxe [w/Sustainiac] (2007), Fly Mojo [w/Sustainiac] (2008), Fly Concert (1997), Fly Classic (2003), Fly Deluxe (1997), Fly Artist (2010), Fly Deluxe [redwood, hardtail] (1993), Fly Bass FB-4 (2003) || More Info

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline Patzag

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #3 on: March 26, 2018, 12:08:32 PM »
I believe that your main issue is not going to be the neck but the bridge posts.  @ParkerPlayer is right IMO.  The hardtails are a little more rare but would definitely be more suitable to this project.
Teal Fly Classic 1998 / White Deluxe Hard Tail 1994 /Axe FX II

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline vjmanzo

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #4 on: March 26, 2018, 12:23:43 PM »
Thanks, Patzag. I appreciate the info.

Do you happen to know what kind of reinforcement a hardtail bridge might need (if any) in order to compensate for the added tension? It's unclear to me just how much tension the hardtail bridge (or the floating bridge) can handle.

I believe that your main issue is not going to be the neck but the bridge posts.
Thanks for your thoughts on the neck strength; do you feel the neck (and truss) could handle the added tension as a result of the carbon fiber? If I'm going to focus my attention to reinforcing the bridge, I'd like to be confident that there isn't something I should also be addressing with the neck hence my original question about how much tension (in lbs.) a Fly can handle.


Fly Mojo (2005), Fly Deluxe [w/Sustainiac] (2007), Fly Mojo [w/Sustainiac] (2008), Fly Concert (1997), Fly Classic (2003), Fly Deluxe (1997), Fly Artist (2010), Fly Deluxe [redwood, hardtail] (1993), Fly Bass FB-4 (2003) || More Info

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline Patzag

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #5 on: March 26, 2018, 05:24:27 PM »
I'm no expert on the subject of string tension, but if you look at the construction of the hardtail, the bridge is anchored by 3 ferrules the allow the bridge to be adjusted in height. If the ferrules are solidly anchored in the wood, as they are, you should have no tension issue. I've never heard of a bridge moving on a hardtail.  I have one and it has maintained its position for the last 20 years.  It is well designed and well anchored.
The deluxe however has occasionally suffered from bridge posts that move forward ever so slightly.  The tolerance of the bridge cavity is so tight that any forward motion would cause friction.  There being only two posts anchoring the bridge, any relaxing on either one caused that problem.  It's not widespread and only a few reported the issue out of the many thousands of guitars produced.  But this leads me to believe that that bridge would not be well suited to a near doubling of the tension on it.

As far as the neck, it is very strong.  Much stronger than it appears to be, because of the carbon fiber skin.  But I think the you're going to have to be willing to try and accept any consequences including trashing the guitar if it can't take it.  Maybe some of the very knowledgeable wood workers on the forum will chime in soon.  Give them a couple of days to see the thread.  There are some very smart and able people on this forum.
Teal Fly Classic 1998 / White Deluxe Hard Tail 1994 /Axe FX II

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline Big Swifty

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #6 on: March 26, 2018, 06:02:53 PM »
Wasn't there a change in truss rod design at some point in the Fly evolution, from wire to solid?

At any rate, pre-refined Fly have a piano wire truss rod, and that will only go so far..but no, don't know how far exactly.

And i THINK that it was replaced with a typical solid rod at some point in the refined series.

Might be a different series of Parkers, but worth checking.

And yeah, agree with Patzag... don't know if you're going to get a definitive answer on this one.

Maybe try contacting Ken Parker himself?...

Good luck!

B.S.

(Hey, my 333 post, thats halfway to The Beast!)
« Last Edit: March 26, 2018, 06:04:25 PM by Big Swifty »
94 Fly Deluxe
2010 DF 524
The system can't get you in your dreams.

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline Patzag

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #7 on: March 26, 2018, 06:34:31 PM »

Maybe try contacting Ken Parker himself?...


Brilliant.  Try that!  kensarchtopguitars@gmail.com
Teal Fly Classic 1998 / White Deluxe Hard Tail 1994 /Axe FX II

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline sybersitizen

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #8 on: March 26, 2018, 07:02:50 PM »
It'll be interesting to find out what the definitive answer is.

In the meantime, I became curious about what Gibson did when designing the 12-string part of the EDS-1275. I found a couple of photos that I could manipulate and position in order to compare its necks against the regular 6-string SG neck. Have a look:



Evidence suggests that the Gibson guys did not trust the standard 6-string neck to bear the stress of the extra strings. What they did there was to 'slide' the fretboard deeper into the body, thereby shortening the overall length of the neck, presumably reducing the risk of any issues. You can see that the bridge was correspondingly pushed deeper to maintain the same scale length. In order to maintain consistency between the 12- and 6-string parts of the EDS 1275, the 6-string neck and bridge were restructured as well. A side effect is that the upper frets of the EDS 1275 are harder to reach.

It's well known that the SG neck joint was pretty minimalistic and pushed the limits of reliability. One might call it vulnerable to breakage if mishandled, so caution was probably well justified. This is of course not the same situation with a Fly ... but I guess we shall see.
'01 Fly Deluxe|'69 SG Standard|'69 EB-3|Pignose Strat|Savannah SGO-16CE|Glen Burton GE47|Dean Vendetta 7-String|Loog 3-String|Fishman Aura Spectrum|Roland Amplifiers

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline vjmanzo

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #9 on: March 26, 2018, 08:22:31 PM »
Thanks, sybersitizen. Good information for sure. I’ve been reading what others have written on a variety of guitar forums with regard to converting guitars into 12-strings. The general consensus is to buy a reinforced neck. I guess the SG required similar forethought. I wonder what the Fly neck can handle.

Thanks again for chiming in.
Fly Mojo (2005), Fly Deluxe [w/Sustainiac] (2007), Fly Mojo [w/Sustainiac] (2008), Fly Concert (1997), Fly Classic (2003), Fly Deluxe (1997), Fly Artist (2010), Fly Deluxe [redwood, hardtail] (1993), Fly Bass FB-4 (2003) || More Info

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline vjmanzo

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #10 on: March 26, 2018, 08:51:09 PM »
Thanks Patzag again for the info. Okay, so it looks like hardtail is the way to go. Is there any sense in trying to secure a floating bridge in some way? Adding another anchor point?

Yes Big Swifty, I think I’d have to look for a refined hardtail for this to take advantage of the actual truss rod.

Thanks everyone for the continued input. I mean, I could also just look into other non-Parker electric 12-strings, but where’s he fun in that?! :)
Fly Mojo (2005), Fly Deluxe [w/Sustainiac] (2007), Fly Mojo [w/Sustainiac] (2008), Fly Concert (1997), Fly Classic (2003), Fly Deluxe (1997), Fly Artist (2010), Fly Deluxe [redwood, hardtail] (1993), Fly Bass FB-4 (2003) || More Info

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline Big Swifty

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #11 on: March 27, 2018, 12:02:40 AM »
There's actually a pretty cool and remarkably well made 8 string Fly inspired guitar on the Facebook "Parker guitar owners and lovers" page at the moment.

Worth a look.

B.S.
94 Fly Deluxe
2010 DF 524
The system can't get you in your dreams.

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline vjmanzo

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #12 on: March 27, 2018, 12:17:18 AM »
Very cool indeed! Thanks for pointing that out!
Fly Mojo (2005), Fly Deluxe [w/Sustainiac] (2007), Fly Mojo [w/Sustainiac] (2008), Fly Concert (1997), Fly Classic (2003), Fly Deluxe (1997), Fly Artist (2010), Fly Deluxe [redwood, hardtail] (1993), Fly Bass FB-4 (2003) || More Info

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline billy

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #13 on: March 27, 2018, 12:45:41 PM »
Cool project VJ!

A few thoughts:

1. the posts will be fine.  The leaning post issue, once again, has nothing to do with wood or wood compression or wood failure.  (It is a diameter mismatch between post and bushing- the more the post extends outward from the bushing, the more the post can lean.  Variations in body thickness and action preference determine how far the posts extend out.)  If you have the delrin stabilization rings, you will not have an issue.  A hard tail is probably better for this in most ways, but I also think it will be more prone to binding from added tension when adjusting the bridge height .

2.  The neck should also be fine, though for sure you'll have to tweak the truss rod.  That said, a maple neck is more likely to crack, which is why the SG probably needed reinforcing (though those changes might have as much to do with aesthetics or even getting the guitar to fit into a certain size case/box). 

3.  The truss rod itself should be fine.  However, this is one place where I'd worry about wood compression:  If you have lots of tension on the truss rod (or wire), the points where the anchors contact the wood could become an issue over time.  Given the soft bass wood of most fly necks, wood compression near the anchors is in my mind the greatest risk.  A mojo might be a good choice if possible.  Another potential issue is having enough "adjustment" available in the rod.

4.  The neck joint to the body would be the next risky thing, though I don't think you'll have an issue unless you somehow violently shock the joint under high tension.  A floating bridge could actually help in this regard, imho.   

IMHO the most difficult things functionally are the realtively narrow width at the nut, and getting more tuning machines on the headstock.  You could downtune your new 12 string a full step and lower tension a bit that way too.  Small tradeoff there I think.

Keep us posted, looking forward to seeing your results!
Billy

[always the beautiful answer who asks a more beautiful question.  e. e. cummings]

Re: Tension Question for Parker Fly 12-String Hybrid Project

Offline vjmanzo

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Re: Tension Question for Parker Fly 12-String Hybrid Project
« Reply #14 on: March 27, 2018, 01:41:35 PM »
Thanks, Billy. Excellent info.

Good to know about the leaning post issue--I was worried about that one! I suppose that if I do look for a Mojo for this mod, I can look for a 2005+-ish version that have the delrin rings already installed? Otherwise, "some guy on this forum" wrote a really detailed guide :) Thanks for that! Hardtail Flys seem so rare these days, and I'd really hate to take one out of the second-hand marketplace while so many more (relatively speaking) floating bridge models exist.

I'm open to detuning the guitar at first as I test the waters, great suggestion. I also think I can avoid violently shocking the neck joint; though, nothing makes me emote like a rock god more than playing a 12-string  ;D Good to note a few positives for trying this on a floating bridge versus a fixed.

I'm working on the bridge modification now with some of my students; we'll tackle the nut afterward--good points on that, Billy! For the headstock, here's the concept I'm going to try to pull off (practicing on some spare wood several times first):


Far out right?! The idea would be to try stagger another set of Sperzels in between with holes (gulp) straight through the headstock to allow the string to pass into the locking mechanism. That particular modification, given how permanent it is, will require some intestinal fortitude!

Thanks for the continued help, Billy, and everyone. I'll try to post a picture of the bridge modification soon!



Fly Mojo (2005), Fly Deluxe [w/Sustainiac] (2007), Fly Mojo [w/Sustainiac] (2008), Fly Concert (1997), Fly Classic (2003), Fly Deluxe (1997), Fly Artist (2010), Fly Deluxe [redwood, hardtail] (1993), Fly Bass FB-4 (2003) || More Info