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I play fingerstyle on my classical guitar comfortably down to the seventh fret or so without looking at my left hand. I’m honestly really familiar with it’s neck dimensions like you get after years of playing while reading music. I would like to be able to get the banjo sound playing with this familiarity I’ve developed. I bought a six string banjo and tried to get familiar with it. I couldn’t because the strings are so close together. It had a 1-7/8” nut width. I’m certainly not saying I’m anyone you would want to listen to, but I enjoy playing for my own entertainment.
I’m trying to fit a 2-1/8” nut width classical guitar neck to my five string Iida banjo pot. I’ve studied on this a couple of months now. I’ve given up on getting a neck made from scratch and have decided to use a neck from a damaged classical guitar.
The only real problem is a classical guitar neck needs to be about six inches longer if it is fitted to a banjo pot and the 26” scale length is retained. After removing the banjo neck from the pot and making measurements, I’ve decided lengthening the classical guitar neck at the bottom (bridgeward end?) is my best option.
The classical guitar neck is made from Mahogany. It looks really big for a guitar neck, but in reality has only about 1-1/2 square inches of cross section at the twelfth fret where I need to splice in the extension. I’m wondering if simply gluing the neck and extension piece together under clamp pressure would effect a strong enough bond. Should I drill both pieces and use ¼” dowels?
I’m not taking the instrument out in public. I don’t plan to finish the extension piece or fret it because I rarely play below the eighth or ninth fret anyway. I just want the neck extended out solidly and it play dependably. Am I going about this the right way? Should I just fashion a metal fixture from pipe and plate for the extension? I don’t care if the strings are hanging in midair across that extension piece.
No six string banjos are offered with classical guitar neck dimensions. What I’m trying to accomplish is arriving at something where I can evaluate the performance of a nylon strung classical guitar neck banjo before going to the expense of having a neck custom built. If the idea turns out to be a dog, I’ll forget it. If I like the thing, then I’ll be able to justify the expense of having a presentable neck built. I would appreciate anyone’s insight and benefit of their experience. Thanks, Charles Roper

I can’t say I have ever played a banjo with anything near that wide of neck. Even the six string Deering's I have played were less than 1 7/8" nuts Though I could be wrong but I don't think so. I am neither a banjo builder nor really a player so keep that in mind, but I can't imagine a banjo neck requiring anything approaching classical guitar width. The string gauge is so much smaller that this is just not making sense to me.

I will sand some what corrected the Deering six sting and most I have googled have 1 5/8" nuts and I found a Dean with 1 7/8. But I still think 2 1/8 or 54 mm is a bit of over kill

Don't just butt join, it's not a strong joint. You could scarf, dowel, or spline. I gather that aesthetics are not very important, but try for a good fit of your extension to the pot. I don't think you will find a bridge, so you will need to make one. And you will probably have to make or modify the tailpiece.

_________________
Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Thanks to everyone, I’m in a very rural area and there’s like zero of the kind of resourse I’m seeking here.

But MichaelP, I had an Estrada six string with the ‘big’ 1-7/8 nut width. I know they’re cheap banjos, but I found it about impossible to play the way I play my classical. I’ve heard that’s the reason fingerstyle is about universally played on wide classical fingerboards. My reasoning is if I play to my satisfaction on a classical guitar, I should be able to play just as well on an identical neck, no matter whether it is on a guitar bout or banjo pot.

Thanks Howard, I suspicioned that little butt joint might be weak, especially down at the bottom like that. I don’t know scarf or spline, and probably don’t have the resources to perform such a joint, but I can do dowels. I’m thinking knurled ¼” steel dowels epoxyed about an inch into each piece in addition to Elmer’s gluing the contact face. Is this a bad idea?
As for the tailpiece, the existing one has provision for five strings, I’ll try double stringing one of those poles before buying another tailpiece. And I can’t see that bridge being a big engineering project. By the way, what are banjo bridges made of? I didn’t recognize the wood. And the five string one is not solid. It’s got like three pedestals with ¼” or so gaps between where it contacts the banjo head. Are those gaps critical?
Thanks all

Banjo bridges are usually maple with an ebony saddle, although other saddle materials such as bone and plastic may be used. Cutouts and multiple feet are mainly to lighten the weight. There are a variety of styles of feet; some have outriggers to keep the bridge from tipping. I'm far from knowledgeable about banjo setup, so I don't have any good advice about the style of bridge. Probably just stay close to the style of the 5-string. And I think you can double up on one of the tailpiece mounts.

I would dowel with good hardwood dowels (not the cheap ones made from Chinese mystery wood that you find in hardware stores and a lot of lumber yards these days). A good lumberyard, especially a hardwood yard, will have them in oak, birch, maple, or walnut. But metal glued with epoxy will probably work OK. Glue the fretboard to the extension; it will reinforce the joint.

_________________
Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Yeah, thanks Howard,
I think I’m seeing the light at the end of the tunnel now. I won’t try to describe the neck/pot attachment mechanism, but upon removing the neck from the banjo, I found it stunningly simple and easy to duplicate. I probably can’t describe it correctly, but it is basically a 13/32” hole drilled into the base of the neck along the longitudinal axis into which a 3/8” threaded rod is installed with a 5/32” hole drilled in the nutward end of the rod which is held in place by a 1/8” wood screw intersecting the rod hole through a 1/8” hole drilled in the bottom of the neck. Neck attachment is no problem.
As long as I get the spacing right for the dowel holes, I think I will be OK. My extension piece is larger than the neck in all dimensions including length. If it turns out after assembly the extension material interferes with the action, I’ll simply remove extension material with a rasp until acceptable clearance is achieved.
The neck will initially be overly long by about a half inch and I should be able to make the final radial arm saw cut to length to 1/32” tolerance. If I discover problems with angularity on either of the three axis, I see no reason I can’t shim the neck/pot contact point to correct. Iida saw no reason to shim it. The Iida 225 was about a five hundred dollar banjo. But as I’ve been carefully dissecting it, I find remarkably rinky dink assembly features for what passed for a flashy instrument. If effort didn’t show, apparently Iida didn’t make much. But the aluminum pot casting seems to have acceptable integrity.
I hope I’m not overlooking esoteric issues here. I knew the banjo neck had a gentle, consistent radial counterclockwise twist along the length of the neck amounting to ¾ level bubble. I was always unsure if this was a defect, or maybe an intentional manufacturing feature. It didn’t affect the playing of the banjo. When I was making measurements and trying to understand everything as well as I could, I placed the machinist level on my perfectly performing Takamine classical guitar and discovered a corresponding twist. But it was clockwise by half a bubble. Are these necks supposed to be straight longitudinally? I really don’t want to overlook some known stringed instrument feature and screw my little job up.
Thanks again,, Charlie Roper