Electric Cigar Box Mandolin

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:

http://www.cigarboxnation.com/photo/albums/my-1st-build-step-by-step

Instead of a floating bridge, I want to use something like this:

https://www.mgbguitars.com/guitar-parts-bridges-4string-roller-chrome-p/20413.htm

And maybe a pickup like this:

https://www.mgbguitars.com/guitar-parts-electronics-pickups-4string-vtj-p/20600.htm

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.

Replies

Ken Vickerson May 8, 2018 at 6:55pm

Thanks Hans I have a better understanding of this now. I also appreciate the link to the angle calculator I will definitely use this for my build. I've already put a curved interior reinforcement inside the box under the bridge so I'm hoping this will counteract some of the string tension. I have a link to a paper on mandolin bridges provided by Thomas so I'll try to find one to suit my purpose and plug it into the calculator. Watch my my page for progress on my build. Thanks for taking the time to respond and spread the knowledge.
Ken Vickerson May 7, 2018 at 8:31pm

Hey Hans your advice is useful to me as I am constructing an acoustic version but I'm wondering about the back angle in relation to the bridge height. As I'm building on flat topped cigar box I'm thinking a lower bridge would be better. Tell me more about back angle,string pressure and tone. Thanks Ken
- Hans > Ken Vickerson May 8, 2018 at 9:34am
  There are lots of people here on CBN who could explain this much better, actually understand the physics of a guitar, and know what they're doing, Ken, but I'll tell you what I know:
  
  Angling the neck back by a few degrees has two major effects:
  
  It makes it much easier to achieve a nice low action because the course of the strings is more parallel to the fret board.
  
  It allows for a steeper angle of the strings at the bridge (and for a higher bridge) which results in higher tension and more downward pressure from the strings onto the soundboard. And a soundboard that vibrates more produces more sound. The volume gain can be pretty spectacular in my experience. (This also has a downside, of course, because more downward pressure makes it more likely that your soundboard collapses - so if you're working with a flimsy box lid you should aim for a low bridge and/or brace it...)
  
  I first angled a neck by a few degrees when I built a mandolin a while ago. I didn’t plan to do it, but then it turned out that I couldn’t fit a mandolin bridge under the strings without getting an unplayable action. So I put some shims under the neck to angle the neck back about 3 degrees and, lo and behold, not only could I use a mandolin bridge and have a good action but the mandolin also got a lot louder. Ever since then I angle the necks on all my instruments.
  
  There’s even an online calculator to find the perfect neck angle:
  
  http://www.tundraman.com/Guitars/NeckAngle/index.php
  - Ken Vickerson > Hans May 19, 2018 at 2:42pm
    
    Hey Hans I tried out the neck angle calculator, have a look at the screen shot. The suggested angle is a bit over 6 degrees, that seems quite a lot. Do you think this is correct? My finger board is a bit under a quarter inch thick, scale length 13 5/8 inches and my bridge is just under three quarters. I plan to use the disc sander to put the angle into the heel and use threaded inserts to bolt the neck to the box. I made the maple bridge according to plans on the Murphy method sight Thomas linked me to. Any advice welcome.
Thomas McGuigan May 6, 2018 at 9:23pm

Well, I'm making progress (and lots of mistakes!!!). I have basically shaped my neck and fit it to the box. I still need to cut it down so the box closes, and fit a cross piece where the bridge will go. The cross will go in the space I cut from the neck inside the box. I have a pre-slotted fretboard from LMI, so after I finish getting the neck situatated, I'll glue that on and fret it.
- Hans > Thomas McGuigan May 7, 2018 at 2:17pm
  
  Nice!
  
  I would consider angling back the neck by a few degrees. In my experience this is even more important with short scale instruments like mandolins. Otherwise you'll have a real problem using a decent mandolin bridge and still having a playable action. Plus an angled neck puts more down pressure on the bridge which results in more volume and better sounding strings...
  - Thomas McGuigan > Hans May 7, 2018 at 4:20pm
    
    It's an electric, and doesn't have a floating bridge.
    - Hans > Thomas McGuigan May 7, 2018 at 5:18pm
      
      Sorry, Thomas, I should have read through the thread before babbling something about string pressure on the bridge... A back angle in the neck also helps with getting a nice low action on electric instruments though. Ever since I started putting a 2 or 3 degree angle on my necks I don't have problems with high action at the high frets anymore. And it's easy to do.
- Ken Vickerson > Thomas McGuigan May 7, 2018 at 8:20am
  
  Nice! Thomas, I like your headstock design.
  - Thomas McGuigan > Ken Vickerson May 7, 2018 at 12:39pm
    
    Thanks! I pretty much wanted to stay within the dimensions of the 2x2 piece of wood I had, but couldn't get it to look right. So I ended up adding a small non-structural wing to get a decent shape. I'm a CAD designer, so having AutoCad to use helped a lot.

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