Flat top mandolins

[reb0964]

when bracing a flat top mandolin,,do you x brace the top or run tone bars as in a f style mandolin...I have really gotin intrested in building some of these...are there any books on building just the flat top manolins with flat backs,,,and is there certain thickness that tops and backs need to be to sound good,,,,,,I know it seems simple question but didnt know if any one else on here just builds this type of mandolin. I have serched the net and found some beautiful mandolins like i speak,,,any help would be appreciated....

[Bill Snyder]

X-braces are fairly common in flat top mandolins. Some of the guitar shaped ones have ladder bracing. John Troughton's book The Mandolin Manaul is about constructing flat tops and if memory serves me correctly it has a couple of different bracing patterns shown, neither of which is x-bracing nor tone bars as you would see in an arched top mandolin.

[Rob Grant]

Several years ago I made a nice little flattop mandolin for a local bloke. The top was King Billy Pine from Tassie and the back was one of our rainforest timbers called Queensland Walnut. For its size and simplicity it was a very "punchy" (sound-wise) little mandolin.

I based it around a rough sketched plan (below). The top had two braces. The back had one. One top brace was directly under the bridge. The other top brace was between the headblock and soundhole. I got my rough sketch from an inspection of one of the early Flatiron flattops that were popular back in the late 70s and early 80s.

[MikeEdgerton]

Check out this thread.

[8ch(pl)]

The first flat tops made by Gibson were the Alrite from 1917 and the DY or Army and Navy model. #The Alright had longitudinal tone bars, one on each side of the sound hole. #The Army Navy dropped these for braces (2 I believe) transversing the top.

The Flatiron was a copy of the Army Navy. #Stewart MacDonald's Campfire is similar.

Mid Missouris have X bracing, they have a slightly different body shape with the sides connecting at the neck at less of an angle than the Gibsons used.

I play my Mid Missouri M4 almost every week in the Worship Band at my church. I get a lot of compliments on how it sounds. #I expect some of the modern Flat tops which are using X bracing would render similar service.

[Graham McDonald]

At the risk of blatant self-promotion (well, its not really a risk, it is blatant self-promotion # #), I would point out that my new book on mandolin building, The Mandolin Project, is now available from LMI and Elderly Instruments, and it covers flat-top mandolins amongst others

cheers

graham

[Rob Grant]

"At the risk of blatant self-promotion (well, its not really a risk, it is blatant self-promotion).

Graham puts out an excellent book on "zooks" and citterns. I imagine "The Mandolin Project" would be invaluable to any builder looking for plans, construction hints and new ideas.

[Steevarino]

Flat top mandolins! #What a perfect topic! #I recently started building flat mandolins. #In fact, you can see pictures of a couple that I currently have up for sale in the "New Mandolins For Sale" section of the Cafe classifieds.

The design I am using looks a lot like the sketch Rob posted above. #Similar shape and bracing, anyway. #I did notice the sketch above calls out a neck angle of zero. #I build a bit of neck angle into the instrument, which leaves enough room for a modified version of one of my mandolin bridges. #I (almost) flatten the bottom of a carved-top-style bridge base, and then have a flat mandolin with an adjustable bridge, which I think is a nice feature.

I am also experimenting with various wood species for the back and sides. #My first batch of 10 or so was a split between plain maple, figured maple, birdseye maple, and an absolutely stunning wood called Australian lacewood.

My next batch will include the above woods, with the addition of Honduras mahogany and Claro walnut for the backs and sides. #I have always been interested in the changes in tonal characteristics that various woods have on stringed instruments, so this should be an interesting study.

I am also in the process of experimenting with various body depths. #None of the Big Fatties have come through completion yet, but I am anxious to hear how they sound, compared to the more traditional thickness Alrites, Army/Navies, Flatirons, Red Lines, etc.

Now I guess I should invest in Rob's book, just to make sure I am building these things correctly

Steve Smith
www.CumberlandAcoustic.com
www.RedLineResophonics.com

[David Newton]

Steve.
I saw your new mandos in the classifieds, look great.
As a builder of their twins, I would love to do an A - B with one of yours, maybe someday.
I like the way you've designed yours to accomodate the adjustable bridge, nice feature.
Sell a bunch, lets overwelm the world with flatties!

[Bill Snyder]

...Now I guess I should invest in Rob's book, just to make sure I am building these things correctly

Steve Smith
www.CumberlandAcoustic.com
www.RedLineResophonics.com

Actually it would be Graham's book.

[Steevarino]

See? #I can't even get the author right! #Reminds me of a couple of years ago when I got the bug to make some ukuleles. #I got every book I could get my hands on, read them all, and never got too far on the uke project. #This time, I just jumped in, no books, and voila! #Just about a dozen of these little flatties running around the shop!

Then Dave in Tejas said... #"Sell a bunch, lets overwelm the world with flatties!"

Sounds good to me! #Let's have a Flattie Fest !!!

Steve

[OzMando]

This build might interest you. x-braced top with ladder braced back.

Mando exeriment

Not my own, just stumbled across it and thought you all might be interested.

[Rob Grant]

In regards to the neck angle; I actually put a slight "rake" on the fretboard by gluing a thin wedge under the board. This accomplished the same thing as installing the neck at an angle to the body.

Here's a photo of the installed "wedge" (ebony)...

[Rob Grant]

Here's the complete instrument (all Australian timbers)...

[Rob Grant]

The Queensland "Walnut" back and the three piece neck of Queensland "Maple" with a centre strip of "Red Ebony"...

[Steevarino]

Dang Rob! #She's a beauty! #You have some fine timbers to work with on your side of the globe. #What in the world is "Red Ebony?" #Sure looks nice!

Looks like we are working with about the same neck angles. #I use a similar wedge, but it is only under the extended portion of the fretboard. #It ends when the body ends, if you know what I mean. #I'll try to post a picture when I have a camera, a mandolin, and a computer all in the same general vicinity.

Steve

[Rob Grant]

Steve,

Yeah, we've got some great woods here.

"Red Ebony" isn't an Ebony(Diopyros)at all but rather a member of the Fabaceae family. It's an extremely dense timber with a waxy feel and a beautiful "burnt orange" colour. It glues well without extra preparation (as is necessary with rosewood). It also has excellent wear resistance (better then Ebony).

The reason for the length of my wedge is basically because the neck itself has no angle or "rake." I found that after I mounted the neck I needed a bit of angle to get the action and necessary top pressure. Rather then remove the neck, I pulled the fretboard and laminated a ~5mm piece of black Ebony to the board. I then machined the Ebony to a wedge shape to give me the needed angle and glued the fretboard/wedge back on the neck. The whole exercise gave me a particularly strong, rather attractive neck.

[tumblewead]

Here is the top bracing on a flat top Kalamazoo I recently had apart for repairs. I had to reset the neck, reglue a back brace and cleat a couple of top cracks, but the top was not sinking at all. Wonderful mid range tones on this mando.

[thistle3585]

Rob, Do I understand correctly that the "neck angle" is basically within the plane of the fretboard vs. the actual neck joint?

[Rob Grant]

thistle3585 wrote:
"Do I understand correctly that the "neck angle" is basically within the plane of the fretboard vs. the actual neck joint?"

Yeah, the neck on the pictured flattop mando I built is not installed at an angle to the body. There is no "set" in the neck in relation to the body. The fretboard with its wedge is the key factor in the break angle over the bridge. The next flattop I do will have the neck angled to the same degree as that produced by the wedge. The wedge was the least complicated solution to the break angle problem presented by the way I installed the neck.

I like installing my mando necks in a way that literally makes them part of the headblock (they don't shift, even with time and hard use). It was less complicated for me to remove and change the angle of the fretboard with a laminated wedge then go to all the work of mucking about with the neck joint. So in a sense, my solution was a way of changing a design fault. It worked very well, but I would not recommend this to someone starting from scratch. It would be better to angle your neck to the body and put a short wedge under the part of the fretboard that extends over the body (like "Steevarino").

The bloke that purchased this instrument from me is a professional violinist. A month or so after I sold him the little flattop I got the chance to see and hear him jam with Kristina Olsen at a local concert using this same instrument. Definitely got a bit of a "buzz" from that experience!<g>

[Graham McDonald]

I think the neatest solution is to put a lengthwise curve in the top with longitudinal braces, around 15' radius as well as a transverse brace somewhere around the bridge which pulls the whole soundboard into a spherical shape. This also allows the neck to be kicked back a couple of degrees and keeps the fingerboard in line with the soundboard without the wedge. The small amount of neck angle allows a bridge a little less than 1/2" high which gives it enough break angle to drive the soundboard and the longitudinal braces help avoid the all too common sinking that happens just with a couple of transverse braces. The sinking is often a combination of the neck rotating a little as well as some subsidence of the top curve itself.

cheers

graham

[thistle3585]

Graham, can you provide a photo or drawing of the longitudinal brace?

[Graham McDonald]

Here is a pic of the 'H' brace set up. The start off at 1/4" x 1/2" and I put an extra 1/4" x 1/4" cross brace in below the soundhole. The lower ends lock into the tail block and the upper ends into re-enforcement blocks glued to the sides. The soundhole means they can't locate into the neck block unless I made it a lot bigger which I didn't really want to do because of weight

[brunello97]

Very interesting bracing idea, Graham. Do you have a view of the top 'sphere'? How do you feel it works with the overall sound quality?

I have been considering a version of this question/problem with a couple Italian bowlbacks that I have where the upward rotation of the neck has been compounded by the top seemingly giving way between the sound hole and the neck block (such as they are in Italian bowls) with the resultant top sinkage and subsequent neck alignment issues. I have shimmed a few fretboards to get a reasonable playing angle but am not ultimately satisfied with it as a solution.

On a pair of Martin bowlbacks I have looked at, an added layer of spruce was added to the top between the sound hole and the neck block apparently to stiffen this area. I have seen short segments of longitudinal bracing to either side of the sound hole, my guess of which is to stiffen this general area. I'm wondering whether your longitudinal brace configuration might be adaptable to a canted top mandolin to help with the above described issue. Obviously the braces 'top side' profile would follow the break of the cant.

Does this sound too radical? Feasible? Would a slightly thicker top be a simpler solution? I have seen any number of Italian bowls with this problem so it has me searching for a possible set of remedies. I guess the trade-offs abound.

Mick

[Graham McDonald]

I built one with that bracing and a bent/canted top one at the same time for the book, and both sounded remarkably similar. Definitely not an F5 but not an unpleasant sound #

As I am sure you have found, the major problem with bowlbacks is the neck rotating. Part of the problem is that the join of all the back staves to the neck block is often just not strong enough coupled with that there is not much soundboard above the soundhole to add much strength. Curved longitudinal braces might well help to stablise the neck body join, but I wouldn't bother extending them below the cant. Just putting the cant in with some degree of transverse arching makes a very strong structure. On the canted top/flat back I made I did spherise (to coin a word)the top half of the soundboard, which did kick the neck back a little, but that seemed the only way to get the bottom of the fingerboard to sit parallel to the soundboard as the transverse arching raised the centre of the soundboard above the plane of the sides. (Hope that makes sense). The hard bit in resurrecting a bowlback top might be locking in the longitudinal braces into the neck block, which I suspect would help in the longer term.

I have been following with interest the thread about building a new top for a bowlback in the classical section, and the tricky bit about joining the lower half of the soundboard. Lots of almost dead bowlbacks out there to practise on though !

cheers

graham