Specs for 1st Mandolin Project

[elExtranjero]

All,

I'm planning to build my first mandolin and have done extensive research here and elsewhere. I have the Siminoff "Ultimate" book on order, have a decent shop at home and access to a NICE wood working shop near work at a friends house, and have been an engineer for 20+ years. I think, with you guys help, I should be able to do a reasonable job and have a good time doing it! I anticipate this taking 6 to 12 months due to time required to build jigs, acquire tools, etc. So I'm in no hurry to 'do it wrong'!

I have an 'allowance' of $250 per month so, while I can't spend $3,000 all at once, over a year I can afford most anything I need in tooling and materials. 8 or 10 hours a week shouldn't be a problem for a time committment.

I would appreciate your comments on my plans as well as recommendations for a source for the first piece I want to start on; the top. And I'll apologize upfront for being an Engineer whose motto is: "If it ain't broke, tear it apart and figure out why!" We DO like to 'improve' on things!

Specs under consideration for comments:

Style: F5
Top: bookmatched Spruce (Sitka, other?)
Back: bookmatched Mahogany or Rosewood (warmer than topwood)
Neck: bookmatched hard rock Maple with Ebony 'center stripe'
Fingerboard: one piece with neck ala Telecaster maple neck
Peghead veneer: bookmatched to match back
Truss rod: yes, either 'skunk striped', gun bored, or pre-routed prior to assembling sections for neck
Hardware: yes
Binding/inlay: yes
Modifications to F5 style:
- one piece side/back
- compound radius fingerboard, probably 7 1/4 to 12
- oversize frets
- internal lightweight 'bridge' under actual bridge connecting top to back to transfer energy to back
- top and back tuned 'mounted' using a 'rim' on each piece glued to a tuning jig then cut away after tuning
- artificially aged during tuning process (see Acoustic Aging)
- strings mounted through-body ala Telecaster to minimize energy loss (yeah, this will require custom sets)

Thanks for your comments and all the information you've already posted here!

[John Bertotti]

Personally I am going with cf insert instead of a actual truss rod. The benifits and problems should still be in one of the threads here if searched.
Have you considered redwood for a top? John

[sunburst]

I'll probably be the first of several to remind you that mandolins work OK the way they are, and major changes in the way they are made are unpredictable at best.

However, I say have fun! I think I understand your curiosity and desire to experiment.

There are many good wood supliers.
Bruce Harvie of Orcas Island Tonewoods is a friend of lots of us here on the cafe. That's a good place to start.

[elExtranjero]

Personally I am going with cf insert instead of a actual truss rod. The benifits and problems should still be in one of the threads here if searched.
Have you considered redwood for a top? John

John,
I have heard of using a cf (carbon fiber) insert. As a guitar player for many years, I admit to being biased towards a truss rod. It scares me to think of NEVER being able to adjust the neck! But that's why I'm posting here, to get feedback.
I considered redwood, but the consensus here based on my search seems to be that spruce is a good choice for a beginner. That said, once I've built the first one (no one can build just one right ) and I've got the techniques down and tooling in place, for my 2nd project I would like to build one either brighter (spruce on maple?) or mellower (rosewood on mahogany?).

Thanks for the reply!

[elExtranjero]

I'm curious about mounting the strings through the body on an acoustic F5 mandolin.
I don't think I've seen that done before.

Jacob,
I think that it would be VERY difficult to ascertain a difference between the two. However,

a) being an engineer string through body is a more mechanically sound method, and,

b) the way I would do it there would be a tailpiece in place that functions as both a cover and a damper. I would be able to replace that with a standard tailpiece and the through body holes would be covered from the front. I would also be able to measure the difference that way.

Thanks for your reply!

[Hans]

I wouldn't connect the top to back with anything but air.

[elExtranjero]

I'll probably be the first of several to remind you that mandolins work OK the way they are, and major changes in the way they are made are unpredictable at best.

However, I say have fun! I think I understand your curiosity and desire to experiment.

There are many good wood supliers.
Bruce Harvie of Orcas Island Tonewoods is a friend of lots of here on the cafe. That's a good place to start.

Yep, "if it ain't broke don't fix it" is MUCH more common, and is generally good advice. But curiousity killed the cat (although satisfaction brought it back ).

I guess if I wanted a standard F5, that $3,000 would go a LONG way towards a Baird, Collings, or Weber!!! I'm looking at this more as brain food though. I actually considered two projects, the other being a custom chopper (old school style like Paul Sr. would build), but enjoy playing more than riding so it's a mandolin for me! But the 'custom' engineering is part of the enjoyment for me.

I would say that I will draw the line at building custom tooling that won't work on a standard. So if the first one doesn't work out, it's a 'test mule' and the 2nd will be more standard. So if you guys have some 'off the wall' ideas to try out, throw them out!!!

I had gotten the same impression on a source for wood from my research here, and had started this as a message to Bruce. I thought I'd post the total specs for general comments though.

Thanks!

[elExtranjero]

I wouldn't connect the top to back with anything but air.

Johann,

On the issue of connecting the top to the back: the theory is that, since the bridge transfers energy to the top, which vibrates and creates sound waves, a similarly constructed bridge connecting the top to the back would transfer energy to the back more efficiently.

Do you know if this has been tried?

Thanks for the reply. I really appreciate you guys that are professionals taking the time to comment and give information to us amateurs!!!

[John Bertotti]

A sound post has been tried and the findings I read were that it just muffled everything. I think the theory would be a mandolin is a plucked instrument sudden attack and decay. A sound post likely works in a bowed instrument because it is continually driven by the bow. From what I remember. I think it was Dr. Dave Cohen who answered my similar question a while ago. John

[elExtranjero]

A sound post has been tried and the findings I read were that it just muffled everything. I think the theory would be a mandolin is a plucked instrument sudden attack and decay. A sound post likely works in a bowed instrument because it is continually driven by the bow. From what I remember. I think it was Dr. Dave Cohen who answered my similar question a while ago. John

That makes sense to me. Tieing the two together also makes it a stiffer structure that would vibrate less. Thanks John.

[John Bertotti]

Yes, but how about those double top bowl back instruments. I'm dying to build up a level of proficiency and try to build one of them. Alec Marr sent me an mp3 of his Gellas and it sound excellent to me. Of course this is far from a bluegrass line of building. Sorry I digress. John
I'm the Scarecrow! If I only had a brain....

[Michael Lewis]

You stated that you have Siminoff's new book on order, so my advice is to wait until you have read the book before you re design the instrument. Also, you can gain a good perspective of the general structure and many of the operations from the "Making Archtop Guitars" by Bob Benedetto.

[Martin Jonas]

Yes, but how about those double top bowl back instruments.

They're a bit different in that the second top is suspended underneath the first (at least in the Ceccherini incarnation -- Gelas are different and seriously weird). It does not provide any stiffness between top and back and is also not fixed to the sides of the instrument. The second top has its own oval soundhole which connects the small air chamber between the two tops with the much larger air chamber in the main part of the bowl. How this works in terms of energy transfer, I'm not too sure, nor on how exactly the second top is driven, but it manages to produce a good complex tone at decent volume. I believe it's in effect a variation on a Virzi, although Virzis seem to be placed at a greater distance from the soundboard.

Martin

[Hans]

What reesaber said is correct. Connecting the top and back is for bowed instruments.
BW, it's a good idea to at least hang on to the box your stepping out of. Experimenting is good, but you've got to have something to relate to. Too many variables will keep you in the dark as to what did what.
Good luck on your adventure!

[Rob Grant]

"I have an 'allowance' of $250 per month so, while I can't spend $3,000 all at once, over a year I can afford most anything I need in tooling and materials. 8 or 10 hours a week shouldn't be a problem for a time committment."

..................

Michael's advice is good, get the book first, read it from cover to cover. "Making an ARCHTOP GUITAR" by Robert Benedetto is an excellent reference (think of the mandolin as a small archtop guitar with eight strings!<g&gt. Check out a couple of websites which actually show a mandolin being constructed step by step (there's one with the "Dude" which is fantastic when it comes to good ideas and tooling...URL???) Search through the archives of this forum and the Musical Instrument Maker's Forum (MIMF). Check out Frank Ford's FRETS site. Using the availiable search engines will probably answer most of your questions.

As far as tools go, I built my first mandolin (and a bloody good one at that) with a modified Siminoff mould (there are better mould designs), a 100mm angle grinder, a 100mm hand- held belt sander (thicknessing sides), a old hand drill, a simple homemade thickness caliper, razor blade scrapers and a lot of patience. You can design and build a lot of your own tools as you progress.

Most important: don't waste your time "reinventing the wheel." Anything can be improved, but it is best to make your first attempt a conventional design so you have a point of reference.

[elExtranjero]

Thanks for all the comments guys! Good advice in all cases.

I am very impatiently waiting for delivery of the Siminoff book!

[Chris Baird]

Hey BW, sounds like you've got a project! Drop me a line if you need advice.

[elExtranjero]

Hey BW, sounds like you've got a project! Drop me a line if you need advice.

Thanks Chris, I probably should just BUY one from you like we discussed (and I may still...), but I can't let you have ALL the fun I thought I'd at least give it a go.

[Flowerpot]

As for the strings going through the body, I would be concerned about two structural issues. First, I take it that the "break angle" of the strings passing across the bridge would increase (from a conventional design). This will increase the downward pressure on the top, increasing risk of caving. Secondly, I would be concerned about the area of the top between the tail block and the bridge -- particularly near the tail block at the recurve -- this area has to take the compression of the 175 lbs or so of string tension, and is normally graduated a bit thicker than other areas in the recurve to withstand the compression. (Ask me how I know this, and I'll show you a top which looks like an accordion.) Now you're going to take that vulnerable area and drill 8 holes in it? Or am I visualizing this wrong? That's my concern. The Tele is a good design, but it's not an archtop.

Edited to add: Good luck on your project! It sounds like you will be well prepared.

[elExtranjero]

As for the strings going through the body, I would be concerned about two structural issues. First, I take it that the "break angle" of the strings passing across the bridge would increase (from a conventional design). This will increase the downward pressure on the top, increasing risk of caving. Secondly, I would be concerned about the area of the top between the tail block and the bridge -- particularly near the tail block at the recurve -- this area has to take the compression of the 175 lbs or so of string tension, and is normally graduated a bit thicker than other areas in the recurve to withstand the compression. (Ask me how I know this, and I'll show you a top which looks like an accordion.) Now you're going to take that vulnerable area and drill 8 holes in it? Or am I visualizing this wrong? That's my concern. The Tele is a good design, but it's not an archtop.

Edited to add: Good luck on your project! It sounds like you will be well prepared.

Flowerpot,

Thanks for the comments! Some comments:

Through Body String Mounting

On an electric guitar, it is generally accepted that a trapeze tailpiece gives a warmer and 'jazzier' tone relative to a solid tailpiece like on a Les Paul. Basically the string is still a whole unit, which is of course why you have string dampers; the tag end of the string is going to do SOMETHING based on what happens on the lead end, it's diameter, and tension. Allowing the tag end to oscillate sympathetically means the lead end waves are larger. Stopping the tag end like on a Les Paul makes the waves sharper.

The plan would be to have the through body holes located in the tailblock. The tailblock may not be the correct terminology; I haven't gotten my Siminoff book yet! I'm referring to the block in the tail that the tailpiece screws into now! This means the stress on the mandolin would be in essentially the same place it is now. Yes, there would be slightly different bending moments to be considered.

The tailblock would have to be made slightly larger, although it could be scalloped to reduce weight. The holes would be drilled through the top, tailblock, and bottom and ferrules used on both top and bottom like a Tele does on the bottom. This would put the string angle only a few degrees more than the current setup. I'd then put a wooden 'faux' tailpiece on to cover the through holes. I could also put a leather damper pad on the bottom of the tailpiece.

Using a damper, I'm not sure there is anything to be gained as the strings aren't ringing anyway. If you did not use a damper then you would be both reducing the loss of wave peaks in the primary string and transferring energy more efficiently to the top AND bottom plates. This should generally result in a warmer and more complex tone.

Again, theoretically, hypothetically, and supposedly There is a more efficient energy transfer to the body. Of course, this isn't necessarily a good thing! You could generate MORE unwanted noise! This brings up the next design point regarding tailpieces:

Tuned Tailpieces

Existing tailpieces have the tag ends of the strings 'out of tune'. The lengths are different so each set of strings when perfectly in tune on the primary side are about a half step out of tune on the secondary side! If you were to put these 'in tune' would the 'unwanted' harmonics that string dampers are used to eliminate contribute to tonal richness? This is of course a separate issue from through body, you could do this on a standard tailpiece.

Going further with this (WAY off in ya ya land now!) let's say you modified the length of the secondary string similar to the way many archtop tailpieces have where the treble string secondaries are shorter or longer than the bass strings. The theory on these is that the shorter secondary brightens the treble and the longer secondary warms the bass.

So to 'warm up' the mandolin you would reduce the secondary on the bass strings relative to the treble strings. This would tend to reduce 'boominess' and increase 'brilliance'.

One more step into the engineers asylum brings you to the conclusion that, maybe you should tune the secondaries along with the body? As an example, my Kentucky resonates pretty consistently at F. What if I 'tuned' the secondaries to the 1, 3, 5, and 7 of F Major? Would the whole mandolin be 'sweeter' or just noiser?

If you've ever seen the video of the Tacoma Narrows bridge destroying itself in a high wind back in the early part of the century you've seen the impact of sympathetic frequencies. If you can tune the secondaries to the mandolin wouldn't the whole unit resonate more and have a larger, clearer voice? Is this what is actually happening over the years as an acoustic instrument 'opens up'? Are the wood molecules just aligning themselves to the frequencies in the instrument?

Practically speaking it may not be worth chasing down and building custom string sets... But I enjoy 'white boarding' and appreciate you guys actually giving thoughtful feedback on my LOONY TUNES ideas And, for the record, I'm an engineer, NOT a wave physicist, I don't even think I spelled it right! So I base most of my ideas on observations rather than calculations. Sometimes that's a good thing and sometimes it ain't!

[Flowerpot]

"The tailblock would have to be made slightly larger, although it could be scalloped to reduce weight. The holes would be drilled through the top, tailblock, and bottom ..."

I fear you may have missed my point about string tension. An electric guitar has six light guage strings and the body is made of solid hardwood (except for the area routed out for the pickups). A typical mandolin string set will have 175 pounds of combined tension, borne primarily by the top, the thickness of which is on the order of 3mm (or even less) close to the tailpiece. Imagine clamping the peghead in a vice so that the peghead faces down and the butt end points to the ceiling. Now stand on the the tail block and balance on one foot. If you weighed 175 lbs, that's what the mandolin withstands all the time. Now drill 8 holes in the top between the tail block and the bridge. Care to stand on it again? How much did you just weaken a critical area?

I'm not saying it's impossible, I'm just suggesting to do your homework carefully, perhaps some experimentation to see if you still have a structurally sound design, before investing a lot of time in it.

[Dfyngravity]

I think he was saying he would drill the hole in the tail block not in between the bridge and tailpeice. But I may be wrong.

[elExtranjero]

I think he was saying he would drill the hole in the tail block not in between the bridge and tailpeice. But I may be wrong.

Yes, that's what I was saying. I believe you'd actually be transfering more of the force to the back and relieving pressure from the top by doing this. I'll have to draw it up and do the moments to better analyze the impact. When I get further along on the project I'll do some sketches and post the jpg's so you can see what I'm talking about (as scary as that might be! )

In either case, Flowerpot is absolutely right about there being grave consequences! And others are just as correct in stating that changes can have unintentional effects.

Regardless, I still enjoy analyzing problems and trying new things

[Bill Snyder]

The Weber Sweet Pea is a small/travel mandolin with a 14 inch scale length that has an integral tailpiece system.
I am just posting this to show that it can be done on a hollow (albiet flat top instead of carved) mandolin with a scale length pretty close to the standard length of 13.875 inches.
Mentioned is the fact that one of the reasons it was done on this small instrument was to get a greater break angle in order to get more volume out of the instrument.
Like previously mentioned you would need to take that into consideration when carving/bracing the instrument.

[Flowerpot]

OK, so maybe I was visualizing the whole thing wrong. Sorry! I need pictures! I want the drawings ready first thing Monday for an online design review, followed by sign-off by all senior members of the cafe. Can you tell I'm an engineer too?