Hi all! I'm setting out to build my first cigar box instrument. I'm a mandolin player, and want to build a four string electric.
I am thinking I will use this basic design:
Instead of a floating bridge, I want to use something like this:
And maybe a pickup like this:
The cigar boxes I have are fairly thick and sturdy (see pics). I have limited experience with luthiery, but can set up an instrument, have made my own compensated floating mandolin bridges, and have refret an old mandolin banjo. I want to give it probably 20 frets, with the 15th at the neck/body intersection and a small fretboard extension. Does anyone have experience with the specific parts I mentioned? Would you recommend anything different? I would appreciate advice on the design, and any other help.
Hey Maximo post some photos of your mandolins. I'm particularly interested in the home built from the 30s. If you have any suggestions on my build I'd love to hear them. Ken
Hi Ken, there normally is a rod in a mandolin neck. The neck angle creates a high bridge so string pressure/tension is pretty high, and its not a very thick neck, you will have trouble at some time.
I have built many mandolins and have used adjustable rods as well as steel bar in the necks. Many of the old mandolins and banjos that I see with bowed necks have no reinforcement in them. I saw one of my old mandolins recently, 30 years old in fact, still strung up and played regually, and it's perfect. It has a steel bar in the neck.
But it's up to you.
Thanks Taffy that's good advice, putting a steel rod in seems doable. What is the advantage of the high bridge and back angle? It seems I'm missing a basic concept. Does the back angle increase string pressure on the high bridge and does this improve the quality of the sound? Are these concepts applicable to a cigar box mandolin? Also the neck tapers to the top is there a purpose in terms of playing...tuning? I appreciate the advice.
Hi Ken, glad to be helping. Crap this is a bit long winded!
The reinforcement in the neck I mentioned was a bar, higher than it is wide, for strength. A rod would just bend with the timber unless fitted in a certain way and threaded with a nut to allow tensioning against the pull of the strings.
Regarding the bridge, its a bit of an involved answer so I'll try to be as basic as possible.
There are many different recommended bridge heights due to the many different heights of a carved top above the height of the rims. As in the violin, its this shape of the "belly" that gives the top its strength, along with a few braces, as well as it's tone and volume.
To enable the strings clear this "bellying" of the top and to provide suitable downward string pressure [loading of the top] through the bridge it is designed to a height that works best for that instruments design. These are the Bluegrass carved top style of instruments, Gibson "F" style.
The other type of mandolin, a more simpler design is the flat top mandolin. Martin "A" style would be an example. Although called "flat top" they can have a radius and an area of the top that slants back from the bridge to the tail, giving the bridge a elevated position. As the bridge is normally lower off the surface of the top, this I would imagine allow for a greater break angle.
Fingerboard tapering.... Just my thoughts on the matter.
It looks more pleasing/balanced to my eye.
The fingerboard/strings would have to be as wide at the nut as it is at the saddle
With the wider fret spacing at the nut end it may make for more difficult fingering to also have the strings spaced that wide.
Likewise further down the neck where the frets are closer and the strings wider apart than normal.
Building these CBG's is all about learning what works and what doesn't, but I still base what I do on sound known practice and theory. Then bend it a bit. Better men than me have worked this all out years ago.
What's that about re-inventing the wheel?
Thanks Taff that explains a lot, I appreciate you taking time to educate me. I've cut a strip of 1/8" x 5/16" steel to reinforce the neck. I will probably go with a lower bridge as I don't need to clear the rounded top.
I liked your responses to the tapered neck question, they made sense to me and I'm going to try it. It appears there will still be some serious string loading and I am going to consult with my luthier friend tomorrow regarding whether a scarf jointed head stock will stand up to it and best design for the bridge and saddle. That goes for reinforcing the box.
I will also need to reconsider the anchor block for the neck and a dovetail joint is looking more solid than some of the other possibilities. If you have any ideas on that I'd love to hear them.
I think it's less about reinventing the wheel than adapting it to fit on your moon buggy. Thanks for spreading the knowledge...otherwise it gets lost. K
Check this out for bridge ideas:
I made one like this for a mandolin banjo.
Cool!!! I'll be looking for a low one for a flat top. Thanks
Hi Ken, in the recent post "rod slot without power tools" I show photos of me in laying a carbon fibre bar into a violin neck. The bar was the same size as what you have.
Thanks Taff I watched the video, I dont have a laminate trimmer so I will cut a recess for my truss bar with the table saw, nice approach though. I visited my luthier friend and got further education on the mysteries of mandolins. He showed me a scarf joint that will probably work. I have adapted it to my available lumber source (Home Depot) as you will see in the attached drawings. I also picked up a set of Gotoh mandolin tuners which needed a redesign of the headstock. Phil, my friend, also showed me how to insert a curved bridge reinforcement inside the box where the bridge will go to counteract some of the string load. My headstock is a bit of a comprimise due to my access to lumber or milling but I'm keen to try it. I’ve decided to go with a combination of an insert bolt and a laminated heel that will be screwed to the box. Any advice is welcome. Here are some pics. K Headstock.jpeg. Tuners.jpeg. Template.jpeg. Neck anchor.jpeg
When I made this paired string dulcimer(to sound like a mando) I did not use a truss rod It has six strings and has not showed any signs of bowing in 3 years, not that it won't.It has a flat top and a murphy style bridge. What I did do was use good hard maple with proper grain orientation. I glued two 1x2 together and selected lumber that was flat sawen so that when glued together the grain was perpendicular to the fret board.
I attached the neck the using 2 hanger bolts( a lag screw on one end and threaded 1/4-20 on the other).
I only have one on this one but you get the idea.I think you'd get a truer mando sound using a regular mandolin tail piece and two of those pickups offset to cover four paired strings. Good luck and I can't wait to see it done.
Thanks Frank! I'm not after a true mando sound. I used to have a four string electric Mandobird, and regret selling it. I eventually want to make a nice solid body four string too. I got all the parts in the mail the other day, just need to find the time to put it all together.