Building a mandocello...

[Bernie Daniel]

I've decided to bite the bullet and build at least one mandocello. I would clearly like to start with a kit but as we all know there are no mandocello kits for sale.

But I wonder if anyone in this community knows of a workshop that leads the participant through the construction of an arch top guitar? I guess I am thinking of something akin to Roger Siminoff's workshops in California where you can built one of his kits (i.e., F-4, F-5 & H-4 H-5) under his eye in the shop.

If such a work shop exists one could merely make some strategic changes to the neck and fretboard and end up with your own mandocello?

Alternatively, finding no workshop could a person could start with an arch top guitar kit? I've seen a few for sale -- like Blues Creek Guitars. Seem reasonable?

[pfox14]

Are you looking to build something like a Gibson K-5 mandocello? The K-5 was basically an L-5 archtop guitar body with a mandocello neck. I built one using a 16" wide archtop guitar body and it came out pretty good. I don't believe Blues Creek sells an archtop guitar kit, nor have I ever seen one to be honest. Good luck with the project.

[Rvl]

Bow River in BC has archtop kits, wood only $240
Mandolin kits are $70

[Bernie Daniel]

Thanks for the tips - I will check them out

As luck would have it did find a luthier who gives a course on building arch top guitar in his shop! This would be Frank Finacchio of Nazareth, PA.

Frank supplies the wood (you chose the types) and the guidance. He then takes you though the process and you build an 16" lower bout arch top guitar in about a week.

He thought it would probably be easy enough to make the necessary changes to the neck, fret board and head stock to end up with a mandocello

He has three sessions a year in his shop and is a great guy to talk to as well.

[Bernie Daniel]

Bow River in BC has archtop kits, wood only $240
Mandolin kits are $70

Thanks! I looked at the Bow River site. I see what you mean by "wood only". The kits are the basic woods cut out for the guitar but the actually building would require bending the sides and carving the top and back etc. I would need to find a workshop or course where I could get the instructions required -- looks like some very nice tone woods though.

[Bernie Daniel]

Are you looking to build something like a Gibson K-5 mandocello? The K-5 was basically an L-5 archtop guitar body with a mandocello neck. I built one using a 16" wide archtop guitar body and it came out pretty good. I don't believe Blues Creek sells an archtop guitar kit, nor have I ever seen one to be honest. Good luck with the project.

Yes that is what I had in mind -- an arch top based mandocello. I did not find the pic of your build -- perhaps it was a while ago and its gone now?

You are right about Blues Creek -- they do not sell the kits but rather they sell the forms and the other accessories you need to build a guitar -- my error.

[Dave Cohen]

Frank Finnocchio is a great guy. I took one of his flattop guitar courses a long time ago, back when he taught them at the Peters Valley Craft Center. He was still working for Martin back then. I saw him at the ASIA convention in 2009, and he had what was probably a prototype for the kind of archtop guitar you would be building in his class. His classes are usually short duration, ca one or two weeks. Most of what you would be learning is assembly. Valuable in its own right, but a long way from making the parts. My guess is that you would be using pre-supplied arched plates pressed on a form from ca 3/16" - 1/4" thick solid wood flat plates. Not sure if that is what you had in mind. They are really hollowbody electric archtops.

You are gonna hafta consider some physical and engineering factors in going from an archtop guitar to a mandocello. Maybe my warning you about even one of them will save you some money and time. Not the least of what you will have to think about is total string tension and how it affects the instrument structurally. That in turn affects not only the tendency of the instrument to fold in on itself, but also scale length, which in turn has some affect on how you carve and graduate and brace the top plate. Almost forgot; it also affects where you put the soundholes. Even with the short Gibson 24.63" or 24.75" scale lengths, the total tension from the eight strings in a D'Addario J78 (mandocello) set is about 35-40% greater (iirc) than the tension from a medium gauge guitar set on a large guitar with a 25.4" scale length. Another point of reference; the total tension on a mandolin with a J74 set and 13.88" scale length is in the same ballpark as that on a large guitar w/ medium gauge strings. So, mandocellos are way up there, tension-wise, and you have to build 'em with that in mind.

http://www.Cohenmando.com

[PT66]

There is a guitar builder in Cincinnati named David Schneider (not me, just the same name) that builds some nice looking arch top guitars. It might be woth a shot to see if he is willing to tutor you.

[Bernie Daniel]

There is a guitar builder in Cincinnati named David Schneider (not me, just the same name) that builds some nice looking arch top guitars. It might be woth a shot to see if he is willing to tutor you.

Thanks! Yes I am aware of him and have often wonder when you posted in the past if you were related to him!

He is apparently a well-respected builder of guitars and his instruments seem to sell (from what little I know of it) for some serious money.

My only contact with him was maybe 10 years ago I asked him about re-fretting an F-4 mandolin and I felt his charges were pretty high so I went elsewhere. Of course, if his instruments sell for big money his time would be correspondingly expensive I guess.

Never thought about approaching him for assistance in building a guitar though.

[Bernie Daniel]

Frank Finnocchio is a great guy. I took one of his flattop guitar courses a long time ago, back when he taught them at the Peters Valley Craft Center. He was still working for Martin back then. I saw him at the ASIA convention in 2009, and he had what was probably a prototype for the kind of archtop guitar you would be building in his class. His classes are usually short duration, ca one or two weeks. Most of what you would be learning is assembly. Valuable in its own right, but a long way from making the parts. My guess is that you would be using pre-supplied arched plates pressed on a form from ca 3/16" - 1/4" thick solid wood flat plates. Not sure if that is what you had in mind. They are really hollowbody electric archtops.

You are gonna hafta consider some physical and engineering factors in going from an archtop guitar to a mandocello. Maybe my warning you about even one of them will save you some money and time. Not the least of what you will have to think about is total string tension and how it affects the instrument structurally. That in turn affects not only the tendency of the instrument to fold in on itself, but also scale length, which in turn has some affect on how you carve and graduate and brace the top plate. Almost forgot; it also affects where you put the soundholes. Even with the short Gibson 24.63" or 24.75" scale lengths, the total tension from the eight strings in a D'Addario J78 (mandocello) set is about 35-40% greater (iirc) than the tension from a medium gauge guitar set on a large guitar with a 25.4" scale length. Another point of reference; the total tension on a mandolin with a J74 set and 13.88" scale length is in the same ballpark as that on a large guitar w/ medium gauge strings. So, mandocellos are way up there, tension-wise, and you have to build 'em with that in mind. http://www.Cohenmando.com

Thanks for the good thoughts Dave. Yes, I think you are generally right about the course Frank gives - it is over one week. I think you bend the sides, make the neck and assemble the instrument. In most cases, do to time constraints, I think he prepares the top and back plates from the wood you choose in advance.

I was intrigued by the fact that he can press solid woods because it obviously save a lot of tone wood. I did not consider that the strength of a pressed versus a carved top might be different so I did not bring the topic up. I did mention that I would make a mandocello neck and he was OK with that --he also makes mandolins. But being mostly a guitar builder I expect that he may not be aware that the tension on a mandocello (25" scale) maybe 180 - 185 lbs. I should have raised that issue. I also forgot to ask about how he handles the truss rod too.

I guess you are one of a comparatively small club of builders who have made both arch top guitars and mandocellos. I take it from your comments that you do approach the top plate differently for the two instruments differently?

I have often wondered how the top plates of the Loar-era K-5 and L-5 might compare. I raised this question in several previous strings. The fact that so few K-5's were made probably excludes the possibility that direct comparative measurements have ever been done. However, several experienced builders familiar with Gibson instrument of the period have ventured the opinion that the tops of the K-5 and L-5 were probably similar in terms of the gradations?

[Dave Cohen]

I want the apex of my longitudinal arch to be at the bridge location. Change the scale length, and you change the bridge location. It also means that you change the neckshaft length. I suppose you can just default to whatever guitar scale length Frank supplies. However, if you do that, you are not taking into account your playability requirements and total string tension. You are also gonna hafta reinforce the neck a lot. Also, the upper bout of the body will distort under all that string tension. I'm not just postulating this; I know it from experience. Remember what I said earlier; 40% more total string tension! I know from experience that Frank won't be able to accomodate you on some of those factors.

Regarding arching, I wrote an article on curtate cycloid arching in American Lutherie #96. The article explains how to locate the apex of the longitudinal arch in a guitar body. That is useful information even if you are not using a curtate cycloid arch. I don't claim any magical attributes to the curtate cycloid arch; it's value lies only in the fact that it is a mathematical function, and you can lay out the arch in 3D with precision and change it easily and at will to adapt to new demands.

Regarding neck and upper bout body stiffness, Gibson got around those problems in the K1-4 models by making a deeply V'd tree of a neck, and the mandolin-shaped body, being much narrower near the heel, is stiffer than a guitar body in the upper bout. I don't know what they did in the K5. I have been putting a lot of CF reinforcement in the necks even in my K-type mandocellos.

http://www.Cohenmando.com

[Pipeous]

I am waiting for Don Kawalek to finish a kit for mandocello right now. it might be worth dropping him an email to see how that's coming along. I am just being patient and waiting for an email from him to say it's ready

just picked up 3 sets of strings for my om yesterday. covered for a while since nobody stocks those string sets around here

[Bernie Daniel]

I am waiting for Don Kawalek to finish a kit for mandocello right now. it might be worth dropping him an email to see how that's coming along. I am just being patient and waiting for an email from him to say it's ready

just picked up 3 sets of strings for my om yesterday. covered for a while since nobody stocks those string sets around here

Is he a luthier at Bow River?

[Bernie Daniel]

I want the apex of my longitudinal arch to be at the bridge location. Change the scale length, and you change the bridge location. It also means that you change the neckshaft length. I suppose you can just default to whatever guitar scale length Frank supplies. However, if you do that, you are not taking into account your playability requirements and total string tension. You are also gonna hafta reinforce the neck a lot. Also, the upper bout of the body will distort under all that string tension. I'm not just postulating this; I know it from experience. Remember what I said earlier; 40% more total string tension! I know from experience that Frank won't be able to accomodate you on some of those factors.

Regarding arching, I wrote an article on curtate cycloid arching in American Lutherie #96. The article explains how to locate the apex of the longitudinal arch in a guitar body. That is useful information even if you are not using a curtate cycloid arch. I don't claim any magical attributes to the curtate cycloid arch; it's value lies only in the fact that it is a mathematical function, and you can lay out the arch in 3D with precision and change it easily and at will to adapt to new demands.

Regarding neck and upper bout body stiffness, Gibson got around those problems in the K1-4 models by making a deeply V'd tree of a neck, and the mandolin-shaped body, being much narrower near the heel, is stiffer than a guitar body in the upper bout. I don't know what they did in the K5. I have been putting a lot of CF reinforcement in the necks even in my K-type mandocellos.

http://www.Cohenmando.com

The discussions of mandocello string tension do make me apprehensive. Not only for the possibility of using the pressed top on the discussed project -- but also the 1940 Vega arch top guitar that I converted did has a relatively thin top board on it and it is 17" across on the lower bout but so far (3 months) it looks very good and stable. You probably saw it before but this is the one I'm talking about. (since I've taken that pic I've move the fret board dot on 9 down to 10 where it belongs and add "The Vega" and a star in MOP to the headstock)


Regarding the Gibson K-series -- yes for sure those early K-1 to K-4 models had ponderous necks. However, following 1920 when the truss rods were added they were much slimmer and more rounded. I expect as the K-5 was introduced in 1922 or '23 it also benefited from that.

[Dave Cohen]

A truss rod alone is just not gonna do it. All of my mandocello necks have had truss rods. What you have to remember about a truss rod is that (a) it does not actually 'stiffen' a neck, and (b) it does not permanently fix curvature in the neck. Once the neck has adjusted to the configuration imposed by tightening the truss rod, string tension continues acting on it, whereupon it bends again, whereupon you tighten the rod again,....., and so on. Iow, truss rods are excellent at adjusting the 'relief' of a neck, but you can't expect them to permanently maintain the neck in a given configuration.

I don't really have any problem with the strength of Frank's pressed top plates. From what I have seen, Frank does not graduate them. So my problems with them have to do with mass and responsiveness. As I said, he designed them primarily for use w/ a pickup. So, they aren't going to have the responsiveness of a top designed specifically for a primarily acoustic mandocello.

http://www.Cohenmando.com

[Bernie Daniel]

A truss rod alone is just not gonna do it. All of my mandocello necks have had truss rods. What you have to remember about a truss rod is that (a) it does not actually 'stiffen' a neck, and (b) it does not permanently fix curvature in the neck. Once the neck has adjusted to the configuration imposed by tightening the truss rod, string tension continues acting on it, whereupon it bends again, whereupon you tighten the rod again,....., and so on. Iow, truss rods are excellent at adjusting the 'relief' of a neck, but you can't expect them to permanently maintain the neck in a given configuration.

I don't really have any problem with the strength of Frank's pressed top plates. From what I have seen, Frank does not graduate them. So my problems with them have to do with mass and responsiveness. As I said, he designed them primarily for use w/ a pickup. So, they aren't going to have the responsiveness of a top designed specifically for a primarily acoustic mandocello. http://www.Cohenmando.com

Thanks, now I see the picture. Indeed I had not really been thinking of having an amplified mandocello.

However your answer also begs a question. If indeed you can further graduate the pressed tops I am wondering if that would not be an ideal way to make the larger arched top instruments? That is press out the general shape and then fine tune it with the appropriate graduations like would be done on a plate coming off a carver. This would seemingly save both wood and time?

[Jim Rowland]

Bernie,if you are considering building from scratch,you cannot help but benefit from the archtop guitar building tapes or DVDs developed by and featuring Robert Benedetto. You will learn a lot and enjoy the experience. A good deal of the information will carry over to mandocellos but will not address the concerns that Dave has broached.
Jim

[Dave Cohen]

Pressed tops cetainly do save material compared to fully carved archtop plates, but they don't necessarily save time. Several reasons for that. First, you have to press the top in two halves. That means carving a mold for the inside of the arched plate shape. Change the scale length, and you are changing the bridge location, which in turn means just enough of a change in the plate arching that you will have to carve another plate mold. Then after you have the two halves of the arched plate in hand, you have to joint them, then glue them together. That is because the molding/pressing process will leave the center seam edge far from straight. Then when you have one whole pressed arched plate, you will have to begin carving recurve and graduations. The carving of a pressed plate will be breaking new ground compared to carving a conventional completely carved plate. The conventional plate has differing amounts of runout in different locations as a result of the carving process. That will be completely different in a pressed plate. I would not consider the carving of the recurve to be trivial in either case. I've carved a lot of 'em (fully carved plates, that is), and I still find the recurve to be something that I have to approach with great care. Which direction to point your fingerplane to deal with the vagaries of grain direction, runout, etc., is something that you will learn slowly by experience. Finally, most of the time that goes into carving a plate is in the recurve, graduations, etc. Iow, the labor that comes after the pressed plate is joined is nearly as much as what goes into a fully carved plate. When I do top plates on the pantograph, the outside is roughed out in about 30 minutes. The inside might take another 20 minutes. Then, the carving that goes into recurve, graduations, etc., is another coupla days or more, depending on the plate. Larger plates take more time than smaller plates. If you don't have a pantograph or CNC, and are using the old drillpress method, drilling all of the holes takes a comparable amount of time, maybe 45 minutes for the outside, 10 minutes for the inside. Wasting all of the stuff between the drill holes is maybe half a day, maybe less. So certainly less than a day to rough out a plate on the drill press. Then you still have anywhere from a couple days to several days of carving and scraping recurve, graduations, etc.

That was a long way of describing what goes into carving a plate. I oughta charge for this stuff.

http://www.Cohenmando.com

[Bernie Daniel]

Pressed tops cetainly do save material compared to fully carved archtop plates, but they don't necessarily save time. Several reasons for that. First, you have to press the top in two halves. That means carving a mold for the inside of the arched plate shape. Change the scale length, and you are changing the bridge location, which in turn means just enough of a change in the plate arching that you will have to carve another plate mold. Then after you have the two halves of the arched plate in hand, you have to joint them, then glue them together. That is because the molding/pressing process will leave the center seam edge far from straight. Then when you have one whole pressed arched plate, you will have to begin carving recurve and graduations. The carving of a pressed plate will be breaking new ground compared to carving a conventional completely carved plate. The conventional plate has differing amounts of runout in different locations as a result of the carving process. That will be completely different in a pressed plate. I would not consider the carving of the recurve to be trivial in either case. I've carved a lot of 'em (fully carved plates, that is), and I still find the recurve to be something that I have to approach with great care. Which direction to point your fingerplane to deal with the vagaries of grain direction, runout, etc., is something that you will learn slowly by experience. Finally, most of the time that goes into carving a plate is in the recurve, graduations, etc. Iow, the labor that comes after the pressed plate is joined is nearly as much as what goes into a fully carved plate. When I do top plates on the pantograph, the outside is roughed out in about 30 minutes. The inside might take another 20 minutes. Then, the carving that goes into recurve, graduations, etc., is another coupla days or more, depending on the plate. Larger plates take more time than smaller plates. If you don't have a pantograph or CNC, and are using the old drillpress method, drilling all of the holes takes a comparable amount of time, maybe 45 minutes for the outside, 10 minutes for the inside. Wasting all of the stuff between the drill holes is maybe half a day, maybe less. So certainly less than a day to rough out a plate on the drill press. Then you still have anywhere from a couple days to several days of carving and scraping recurve, graduations, etc.

That was a long way of describing what goes into carving a plate. I oughta charge for this stuff.

http://www.Cohenmando.com

Thanks much! I certainly see the point you are making. I suppose it all boils down in the end to the same as most problems the value of the labor (in time) versus the savings on materials. If the time is more or less a wash as you suggest you'd still have material savings but perhaps there are additional technical difficulties that would eat significantly in to the "savings", I suppose the pressing approach to the construction of solid wood arch tops will have to stand the test of time and in the end if it really is a step forward others will start using it.

"I oughta charge for this stuff."

Yes, you really should charge for the information. Likewise, there are many others on this forum that are willing to expound (sometimes repeatedly) what they have spent a lifetime learning. I've often wondered why technical people are like that!
Not so many years ago as research scientist in charge of significant chunk of a federal research program on drinking water safety I found myself doing the same thing. I often wondered why the detailed technical professional expertise I acquired in the years of doing research in the trenches was considered free information and it was part of my job to endlessly expound on it -- but when ever a lawyer opened his mouth money changed hands.

The irony is a relative handful of people in the world knew what I did (on this particular subject) -- and for everyone of us technical authorities there were a million lawyers who could have been used to answer the legal questions. Picking on the legal profession just to make the point.

But we'll probably never have an answer for that...

[Bernie Daniel]

Bernie,if you are considering building from scratch,you cannot help but benefit from the archtop guitar building tapes or DVDs developed by and featuring Robert Benedetto. You will learn a lot and enjoy the experience. A good deal of the information will carry over to mandocellos but will not address the concerns that Dave has broached.
Jim

Thanks Jim,
Yes without a doubt you are correct on that. Learning to build an arch top guitar would be a huge step forward. Certainly the additional graduations that Dave mentions would need to be dealt with on the top plate.

But in terms of the neck issues I still can't get past the point that Gibson was able to make go of the K-5 mandocello. And that was -- I suggest -- essentially the approach that I am thinking about taking, i.e put a mandocello neck on an L-5 arch top guitar body and call it a K-5 mandocello.

As far as I know there these Loar K-5's have stood the test of time and yet if you look at the neck on them -- or on any of the Gibson K series after 1922 when they started putting truss rods in -- you find a slim guitar-like neck. I have a 1936 K-1 and the neck is actually slimmer in width at least than a guitar (the fret board is narrower on a mandocello).

What fails on the K-1's and K-2's regardless of the build period is the top plate -- it sags under the bridge - but the neck is usually not a problem?

[Dobe]

[QUOTE=Bernie Daniel;1056812].... you build an 16" lower bout arch top guitar in about a week.

[Bernie Daniel]

[QUOTE=Dobe;1057295]

.... you build an 16" lower bout arch top guitar in about a week.

Hey! I'm just the messenger. Contact Frank Finocchio at his shop for details!

[Audio Artillery]

Bernie, glad you're thinking of biting the bullet! The neck on my #1 w/ C.F. rods has held perfectly straight so far btw. My next one will have a thinner neck since I went kind of nuts on neck thickness the first time around. I'm also glad I did a bolt-on design, I must have removed and re-installed the neck 5 times after the first stringup to tweak something.

[Bernie Daniel]

Bernie, glad you're thinking of biting the bullet! The neck on my #1 w/ C.F. rods has held perfectly straight so far btw. My next one will have a thinner neck since I went kind of nuts on neck thickness the first time around. I'm also glad I did a bolt-on design, I must have removed and re-installed the neck 5 times after the first stringup to tweak something.

I'm thinking hard about it. Since you have CF in the neck what parameters can you adjust by removing the neck? Just curious. Also do you happen to know how much relief you have dialed in to your mcello neck? Also how did you measure the relief? I am going to change strings in a few days on one of mine and I am thinking of increasing the relief -- I have 0.009" now measured at the 7th fret.

[Audio Artillery]

I don't have feeler gauges handy but I think about .006" relief at 7th fret. All I did was make the neck, plane it dead flat, glue on the fretboard, and bolt it to the instrument.

You can adjust the neck angle by removing it and tweaking the joint. Since the body adjusts a bit under tension I had to account for this after stringing it up. Also my fingerboard extension turned out to be contacting the top so I shaved the underside a bit to prevent this. And then I did the finish work with the two pieces separate.