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Thread: Classical Guitar to Tenor conversion questions

  1. #1
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    Default Classical Guitar to Tenor conversion questions

    I have an old classical guitar that I'm considering converting to a Tenor. The guitar was one of my parents and has no real value and essentially has sit in a closet untouched for years. I have become more interested in Tenor Guitar lately and thought it might be a fun task to restore this old junker as a tenor, not only to satisfy me desire to try out a TG, but also to take a leap into luthiery, which I've been hoping to do for some time now.

    What I foresee doing is:

    1. Slimming down the neck. I'm not sure what the exact nut width is, but I know its fat and I'd like it slimmer.

    2. Replacing the nut, bridge and saddle. the bridge will probably have to be something custom.

    3. Refinish the whole shebang.

    My questions are:

    1. Any recommendations on how to slim down the neck without butchering it completely? Will I need to remove the frets and end up refretting it too? I would consider replacing the neck, but I am under the impression that Classical Guitar necks are not necessarily removable.

    2. What is the best way to remove the old bridge?... I have been watching a lot of YT how to's on making a classical guitar bridge, so I have a good grasp on that (I think).

    3. Recommendations on finish? Someone once told me that Waterlox was a decent finish for instruments and I have a fair amount left over from a recent project... thoughts?

    As stated, this guitar is not of any real value and is probably upwards of 50-60 yrs old, but I thought this might be a fun project. So while I would like it to be successful, failure would only lose me time and minor expense.

    I am in the middle of finishing up a big home improvement project so it may be a little bit yet before I get to this, but I am in the research phase and would appreciate any input you guys have.

    Thanks in advance.
    aka: Spencer
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  2. #2

    Default Re: Classical Guitar to Tenor conversion questions

    Classical guitars are lightly braced. If you proceed with this, you will have to use extra light strings or silk & steel. And if you plan to use it with octave mandolin tuning, that means even more tension. My recommendation is to give the guitar to somebody just starting out - perhaps a school guitar program, and find a modern steel string tenor for yourself, or perhaps find a kit to assemble. You will end up with a much better instrument that way.
    Roger

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    Don MacRostie designed Stuart MacDonald A-style kit I built myself.
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    Default Re: Classical Guitar to Tenor conversion questions

    Thanks for that input Roger. I do plan to use nylon strings, and this will be an experiment. Its not worth donation and honestly, I'm excited to at least give this a try.

    I plan to either tune GDAE or CGDA, whichever will work better.
    aka: Spencer
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    Default Re: Classical Guitar to Tenor conversion questions

    The conversion is more difficult than it sounds. First the scale length of the classic is probably 25 inches. The tenor likes 20-23 inches. The neck is probably glued onto the body of classic. You will have to cut it down while connected to the body.

    I have converted a couple of kid size guitars to tenors. I choose these because the scale length is 22.5 inches and the necks are removable so I can chuck them in my mill.

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    If you want to continue this effort, I would suggest removing the outer two strings and give it a try. You will probably have to replace the remaining strings in order to obtain the tune you want. Can still be fun to play like this.

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    Default Re: Classical Guitar to Tenor conversion questions

    I just measured the scale length and it is 23 3/4" so it's not too terribly big. I'll take the E strings off and play around with it.

    Thanks
    aka: Spencer
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  6. #6

    Default Re: Classical Guitar to Tenor conversion questions

    John Lawlor, arguably the best living tenor guitarist (or for sure the best living jazz tenor guitarist) plays a six-string tenor guitar.
    Work out the string gauges to match, between the four strings, similar tension to the 6 strings previously fitted. I think you should be fine. You can always use the first fret as a zero fret and get a shorter scale length if need be.

    Check out John, playing in Eddie Freeman tuning:


    Probably the best way to do this is to remove the fretboard, slim down the neck, put a new fretboard on because the old one is definitely crap, and then use the existing or a new bridge. Should be a fun, and quite straightforward project.

    Just use shellac for the finish, or shellac over Waterlox.

    Waterlox does make a good instrument finish! Here's one I did in Waterlox. It doesn't hide any imperfections, so your sanding game needs to be dialed in, but you have that under control.

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    Default Re: Classical Guitar to Tenor conversion questions

    Thanks so much Marty!... looking it over this evening, I'm thinking you're probably right about removing the fretboard; it's pretty old and ragged and probably wasn't much count to start with.

    I think it was you that told me Waterlox was a good instrument finish.

    I took off the low E string and replaced the B string with the high E and tuned it GDAE. It actually had a very pleasant tone but it was very fumbley because the neck feels stupid-huge, but I haven't played guitar regularly in years.

    As stated above, it isn't a very big guitar but not quite as small as a parlor guitar. If anyone is interested, it is a Giannini which was my mother's when she was probably 13 which is right around 55 yrs ago (guessing).
    aka: Spencer
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    Default Re: Classical Guitar to Tenor conversion questions

    I couldn't wait to start messing around with it, so I started picking and prying at stuff... I was able to pop the bridge off last night by heating up a very thin putty knife with a plumbers torch, but not without burning the wood some. Hopefully it will sand out. Started on the fretboard, but it was late and I needed to get to bed. Is there a way to use a "hot knife" and not scorch it?

    I'm realizing that it is a laminate top, which is disappointing, but not going to deter me at all.
    aka: Spencer
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    Default Re: Classical Guitar to Tenor conversion questions

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    Just last month I converted a steel string guitar. It was a cheap laminate from the sixties (I guess) but it had the right scale length--23 inches. I pulled the frets and then used a rasp to reshape the neck, matching a tenor I already own. The very cheap fretboard did tend to chip and needed some repair afterwards but has had no ill effect. However, taking off the fret board is probably a good idea. The bridge was pulling off so I removed it, patched the wound with veneer (not trying to hide it), and used a floating bridge and tailpiece. The result has been surprisingly good. In fact, good enough that I'm going to sell my other tenor. I have considered refinishing the top to make it look less like Frankenstein's guitar but I'm getting used to it. Good luck!
    Cary Fagan

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    Default Re: Classical Guitar to Tenor conversion questions

    Thanks Cary,... I considered doing the same with a floating bridge, but thought a tailpiece would likely have to be custom made and be difficult or awkward with the nylon strings. I also thought it may not be wise with the light bracing of a classical guitar.
    aka: Spencer
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    "You can never cross the ocean unless you have the courage
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  13. #11

    Default Re: Classical Guitar to Tenor conversion questions

    You can use a clothes iron on the fretboard to remove it without scorching. Might want to put a couple slightly damp paper towels between the iron and the frets for steam and to protect the iron. More chance of finish damage but you don't care about that. Or get a Goodwill iron for three bucks and save some marital stress.
    Using a heat gun instead of a torch is recommended.

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    Default Re: Classical Guitar to Tenor conversion questions

    Hogwash
    Actually just throwing out my experiences for reference and levity.
    I've done quite a few conversions and I've never pulled the frets or removed the fretboard. I just thin the neck using a sanding drum with monster heavy grit sandpaper or use my spindal sander if the neck is removable. I've found most flat top bridges to be easy to modify in place so why mess with a bridge that is in the right location and already properly glued in place. Just plug the original holes and drill new ones to your preferred spacing.
    A 26" scale length will work just fine for tunings that have a first string E. Totally agree that you should never try steel strings on a classical guitar but a nylon strung tenor will work okay -- just not be very good for four chords or some fast melodic lines.
    Sanding drums make quick work of fret wire -- I havent encountered stainless frets yet.

    I have a Ric 330 style electric guitar with a 24.5" scale that I built years ago and blundered the finish on twice only to strip it down with acetone twice. I'm considering it a candidate to be an 8-string octave mandolin. Its a set neck but I think I can do a fair job of tapering the neck. It'll get a little more wide toward the end of the neck than if I had originally intended it to be an octave mandolin but someone will give it a home eventually. The good thying is that I never drilled the headstock for tuners. I've ordered a pair of very inexpensive blade humbuckers on ebay and they should be here in a couple weeks.

    Part of the same series of electric guitars that I made at the same time, I have my Ric Capri style guitar that was purposefully built as an octave mandolin. It also has a 24.5" scale. Its been a wonderful instrument but then, I'm not a mandolin player.

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    Default Re: Classical Guitar to Tenor conversion questions

    Hey Spencer! I've been buying up and fixing a lot of '50s and '60s guitars lately, and here's something I noticed about a lot of these import "classical" guitars: they are all ladder-braced, exactly like the steel-string models that use tailpieces. Feel around inside yours, but I suspect it's just the same body used on all the imported guitars from that factory with a "through-bridge." Harmony and Kay used through-bridges (classical style) on plenty of steel string guitars.

    Good luck with the fretboard - a clothes iron should take care of that. Watch out if you use your good iron, though: most of these fretboards are dyed poplar or pearwood. The dye can (sometimes) leech out when heated. (Ask me how I know that.)

    Good luck! Looking forward to seeing what you come up with.

    -Matthew

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    Default Re: Classical Guitar to Tenor conversion questions

    Thanks guys,... I've already gotten the bridge off and the fretboard is about 1/2 way pried off. I borrowed a heat gun from work and that is doing the trick. I have a lot of scrap maple from my kitchen counters I plan to use to replace the stuff I'm removing. But of course It looks like I might need to get some tools: Fret Slot Saw, Fret Wire Snips, etc....
    aka: Spencer
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    Default Re: Classical Guitar to Tenor conversion questions

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    It's an ugly job, but someone had to do it.

    The heat gun did the trick. It still took a little work, but it's done.

    Considering scale: if I reduce the scale length by an inch or 2, making it a 21"!or 22" scale, which would be better; to move the nut further down the neck (closer to the body), or to love the bridge and saddle closer to the sound hole?

    I checked the bracing (by feel) and it seems like a fan style bracing with no real extra support or specific place for the bridge.
    aka: Spencer
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  20. #16

    Default Re: Classical Guitar to Tenor conversion questions

    Non-instrument builder here, but with wood/metal experience. A router might help thinning the neck and fretboard in place, especially the overhang on the body. Any decent HSS or carbide bits will not be upset chewing through brass frets, or even harder materials if you slow the speed. Use a clamped-on fence. I’ve been thinking of trying something similar to make an octave mando, with 8 steel strings. The forums show some background for this. As far as the bridge support being weak, I would think that belaying it with a tailpiece and some wire or heavy string might be good, although not reducing the downforce. Since you have a soundhole, a transverse brace could be put in underneath, even screwing it through the top and the bridge.
    Question though: Can one assume that nearly all glues of this vintage, found on factory items, are like hide, thermal softening? What’s used in factories now?

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    Default Re: Classical Guitar to Tenor conversion questions

    Thanks Richard for those ideas, I actually thinned the neck last light with a combination of spoke shave, scraper and block plane.

    A little google-action and I found that an average nut width on most TG's is 1 5/16", I used that with a 22" scale, and with a little bit of experimentation, I found that along with a 2" saddle width, I ended up with an almost exactly consistent thickness to be removed from the neck, and it seems like it will be pretty comfortable to play.

    So that being said all the dims will be:

    Nut width: 1 5/16"
    12th fret: 1 21/32" (ish)
    Saddle: 2"
    Scale: 22

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    It's not perfect, but I'm not necessarily going for absolutely perfect.
    aka: Spencer
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  22. #18

    Default Re: Classical Guitar to Tenor conversion questions

    I'm fairly adventurous but wouldn't use a router near frets. Too much of a risk that a fret could become a projectile.

  23. #19
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    Default Re: Classical Guitar to Tenor conversion questions

    That's looking really good!

    Re: relocating the bridge: I've stiffened up a lot of sagging tops from guitars of this period by adding a bridge strap underneath, with grain running across the grain of the top. Usually something very thin, around 1/16" or less. But your fan braces will be in the way of that. I'd check the tension your strings are going to put on the top (D'addario has a nice online calculator). I seem to remember that you plan to use nylon strings on this, so it'll probably be fine without. You could always go the tailpiece route and do a floating bridge. If you go back to a fixed through saddle/bridge, will you reuse the one you've removed?

    All weekend as I looked at my pile of scrap parts guitars lying around the shop, I kept thinking about your project. You might have inspired me! I'm running out of repairable guitars, so I'll need something to keep me busy... I'm really enjoying watching your progress!

    -M

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    Default Re: Classical Guitar to Tenor conversion questions

    Update:

    I've been pecking away at this a little bit here and there when I can and I've bought some tools and things needed to complete the project (Amazon):

    Frets
    Fret wire cutters
    Fret slot saw
    Nut and saddle
    New (cheap-o) tuners

    I have a nice piece of maple left over from my kitchen counters which I have dimensioned and ready for the fretboard and a piece of walnut ready for the bridge.
    aka: Spencer
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    "You can never cross the ocean unless you have the courage
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    -anonymous

  26. #21

    Default Re: Classical Guitar to Tenor conversion questions

    Looking forward to seeing more progress. I very much like the idea of a nylon strung tenor. I'm on the lookout for a perspective guitar to modify myself.

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    Default Re: Classical Guitar to Tenor conversion questions

    Last night I spent time with the Fret spacing calculator on the Stew Mac website and laid out the fret lines. Tonight I tested my my fret slotting saw and worked on filling in excess space in the tuning machine slots that will no longer be occupied.

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    aka: Spencer
    Silverangel Econo A #429
    Jacobson Nautilus Oval Hole Prototype

    Hand Crafted Mandolin Armrests
    Check them out here

    "You can never cross the ocean unless you have the courage
    to lose sight of the shore, ...and also a boat with no holes in it.
    -anonymous

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  30. #23
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    Default Re: Classical Guitar to Tenor conversion questions

    Futz'd around with the headstock a lot this evening:

    First I cut the "bump" off to make it more Martin shaped;

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    Then worked up a nice veneer with more scrap Ambrosia Maple (very curly stuff) and a little walnut strip down the middle.

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    aka: Spencer
    Silverangel Econo A #429
    Jacobson Nautilus Oval Hole Prototype

    Hand Crafted Mandolin Armrests
    Check them out here

    "You can never cross the ocean unless you have the courage
    to lose sight of the shore, ...and also a boat with no holes in it.
    -anonymous

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    Default Re: Classical Guitar to Tenor conversion questions

    Loving that maple!

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    Default Re: Classical Guitar to Tenor conversion questions

    Got back earlier than usual from the Jam tonight and just had to finish up the headstock. Wiped it down with mineral spirits to get a look at what it would look like all finished ... I am pleased

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    aka: Spencer
    Silverangel Econo A #429
    Jacobson Nautilus Oval Hole Prototype

    Hand Crafted Mandolin Armrests
    Check them out here

    "You can never cross the ocean unless you have the courage
    to lose sight of the shore, ...and also a boat with no holes in it.
    -anonymous

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