Convert acoustic guitar to mandocello

[AndyPanda]

I've got a decent old spruce top Yamaha folk guitar I don't/can't play. I'm just not a guitar player for reasons I cannot understand - I can manage four strings/courses (four fretting fingers) but I just cannot make sense of 5 or 6 string instruments and cannot get used to that B string throwing all my scale patterns off. Thinking I'd like to convert it to a mandocello. It's a 25" scale and 1.7" at the nut (too wide? I could narrow the neck if needed).

I used the D'Addario string calculator and came up with this set of strings to give about the same tension as a med set of guitar strings (if I calculated correctly). Should give me about 202.5 lbs total tension which is slightly less tension as a Medium set of D'Addario EJ42 guitar strings.

Do you think this would work?

BALL END PHOSPHOR BRONZE GUITAR STRINGS:
A .020 25.02 lbs
D .030 25.67 lbs
G .045 25.00 lbs
C .070 25.56 lbs
202.5 lbs total tension

[JimY]

try robert fripp's "new standard tuning"- single courses CGDAEG, all fifths except EG, just like a mandocello on the bottom four.

[AndyPanda]

Thanks ... I think I will give that a try. I hadn't heard of it before. How does this look? Or I guess I could/should go heavier since these are not double course.

G 0.0110 in. 27.76 lbs
E 0.0135 in. 29.57 lbs
A 0.0210 in. 28.91 lbs
D 0.0320 in. 29.93 lbs
G 0.0480 in. 29.43 lbs
C 0.0760 in. 31.00 lbs

Maybe:
G 0.0115 in. 30.34 lbs
E 0.0140 in. 31.80 lbs
A 0.0230 in. 35.15 lbs
D 0.0320 in. 35.87 lbs
G 0.0520 in. 34.26 lbs
C 0.0800 in. 34.17 lbs

[fox]

All those tensions sound very high to me, I always thought a standard 6 string set was around 160 - 175lb ?

[AndyPanda]

All those tensions sound very high to me, I always thought a standard 6 string set was around 160 - 175lb ?

You may well be right - I'm not a guitar player so I'm eager to learn before I make a mistake. Here is a chart from D'addario showing total tension for their sets (and the guitar I was planing to use is only 25" instead of 25.6" so tensions should be a bit lower than indicated in this chart). I was guessing that since some sets labeled as "medium" go up just over 200lbs I should be able to get away with it - but I've been wrong before

[fox]

Hi Andy, I think most guitar players use medium string sets (11s or 12s) I would aim for a max of 180lb (or lower for finger playing).
However I also think most guitars are overbuilt so you might find 200lb is ok?
Personally I can't imagine useing such high tension strings would be very comfortable to play with?

You can look here http://www.mandolincafe.com/forum/fo...ay.php?50-CBOM on this forum to find quite a few guitar conversions (including a few of mine) or perhaps the best way would be to google 'guitar conversion mandolins cafe' that should get you lots of info.

[AndyPanda]

I'm not sure, but looking at the tensions of the actual Mandocello string sets - it would seem that a real Mandocello has about 239lbs tension total.... at least that's how it calculates using the D'addario calculator.

I was actually going with smaller gauges than the pre-packaged mandocello sets specifically to reduce the stress on the guitar.

[fox]

Ok in that case you must experiment yourself to see what works for you!
You may find this useful, I use the light set on my conversions as others do but, I also narrow the neck and you might prefer to test the heavys ... good luck. http://emando.com/shop/strings_cello.htm

[AndyPanda]

I just took a quick look at the link - thanks for sharing it. Is it a typo that the light set has heavier D strings (34) than the normal set (32)? Other than the C strings, the gauges I came up with are about the same as the light set at that link. (my set is 20 30 45 70)

I also plan to narrow the neck - even toying with the idea of laminating a little extra down the center so I can give it more of a V shape

[Mark Gunter]

That sounds like a very interesting project. I've been working on something similar. It started life as a cheap parlor guitar, and I'm converting to a resonator OM. The scale length on mine is 24". I narrowed the neck, bound it with cherry, and widened the peghead a bit. I'm interest in how you plan to laminate a little extra down the center to make more of a v-neck.

[AndyPanda]

Well ... I haven't thought it all the way through yet - and I may not be able to do it. The guitar I planned to use has a mahogany neck and I would prefer a maple neck (I may pick a different guitar for the project). I picked this guitar because it is 25" scale and most other acoustics are a bit longer. But as I read through the archives I see people liking longer scales for the better C voice - but I was afraid of the longer reach so I wanted to stay close to the 24.75" that Gibson used.

Anyway .. I figured I would get a 1"x.5" strip of maple or ebony (so there is a color contrast with the mahogany) and then just plane a flat spot on the rounded back of the neck about 1" wide and glue the strip on. Then when I am reshaping to narrow to 1.5" at the nut I will also reshape the profile. Anyway that is as far as I've thought it through --- I'm pretty sure I can plan that much of a flat spot without hitting the truss rod, but I've been surprised once (many, many years ago) when I broke through into the truss channel. I suppose it wouldn't really matter since I'm gluing on a wood strip anyway.

Then again, maybe we don't want a deep V neck on a m'cello? this is all new to me so I'm just playing with ideas at this point.

Here's a crude drawing of what I was thinking:

[Mark Gunter]

Then again, maybe we don't want a deep V neck on a m'cello? this is all new to me so I'm just playing with ideas at this point

It's new to me too, Andy, I'm new to eight-stringed instruments and I'm not a builder, so can't help you with any of that. I was interested in what you're doing. So far, I've just piddled around with lutherie enough to mess some things up and learn a little bit. One thing I would say just as a woodworker, though, if you scab a piece on like that you should plane a flat onto the back in parallel to the fretboard - both for a good joint's sake, and for aesthetics if you plan to use contrasting wood and make it a decorative feature. You'll want a true, straight line on either side, and you'll want it to be as easy as possible arriving at that. You probably already know this.

Looking forward to seeing what you come up with.

[soliver]

I have an ancient hand me down classical guitar that was my mom's as a teenager. I'm curious if this is doable with that ancient wreckage... any thoughts?

[AndyPanda]

I believe classical guitars are only built to have about 80-95lbs total tension (nylon strings not nearly as high tension as steel).

[soliver]

I was kinda thinking that... thanks

[fox]

Classical guitars are great for tenor guitar conversions, 20lb per steel string works perfect for GDAE.

[soliver]

Classical guitars are great for tenor guitar conversions, 20lb per steel string works perfect for GDAE.

Is that a relatively easy conversion to do?

[fox]

I guess it might be for some people, if you have all the right tools and a workshop, for me it is quite a challenge!
To start wth if the guitar in question has a full width neck and full lenth scale it might be easier to make a new neck!
If you just want a 'mess around guitar' with four strings, that sounds great but looks a bit rough, then yes it is relitivly easy compared to building one from scratch.
So the easy way would be to simply cut down the neck either side and retain the bridge plate and just use the the fitted tuners.
That would give you a 25.5 inch scale, four steel string guitar.
The best way I have found to cut down the neck is by making up a template to fit on top of the fretboard and running a hand held 4" grinder with a 2mm carbon disc fitted, down the length! This is not actually that differcult to do and only takes a few miniutes but then cleaning up around the headstock and the guitar body can take a lot longer.
The last few I have converted I did by removed the neck and re fitting a new neck but even then you will still have cosmetic issues around the neck body joint.

Here is a thread I made a few years back... http://www.mandolincafe.com/forum/sh...Big-body-tenor

[soliver]

If I were interested in beefing it up to be able to withstand the tensions of a mandocello, what would that take?

[fox]

Truss rod, new thicker, tapered, fret board. New floating bridge and tail piece should do it!