RE: Bogdanovich´s method for flamenco guitars

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ernandez R

Posts: 667
Joined: Mar. 25 2019
From: Alaska USA

RE: Bogdanovich´s method for flamen... (in reply to mango)

Mango,
Guess I should have added I've built 8 so far and none have a back strip. I'm thinking it's time to take my game up a notch, and you know, put my money where my mouth is ;)

I did make up a matching inlay for my tie block, headstock veneer, and rosette for my next series, I just didn't think about the back strip for mine until I thought how cool yours would look. I'm doing three piece backs, I think, so it could be interesting.

I'm just doing somthing simple using strips of dyed paper. Not sure my old hands and eyes could make the kind you have in your top.

HR

REPORT THIS POST AS INAPPROPRIATE | Date Jan. 25 2020 8:51:12

mango

Posts: 158
Joined: Apr. 2 2019

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

I just made this template for laying out the braces... any thoughts? As this part of the process doesn't seem to be an exact sience I just did it by guessing and imitating what I see...

One question: How will the doming be achieved that goes cross grain? Most braces in the doming area are going along the grain... Is it only done by the two cross grain braces at the lower bout?

Another question: Should I put a bridge patch or not? Normally I would think better keep it light by leaving this out... what are your thoughts about that?

thank you!

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REPORT THIS POST AS INAPPROPRIATE | Date Feb. 10 2020 12:21:02

Tom Blackshear

Posts: 2304
Joined: Apr. 15 2008

RE: Bogdanovich´s method for flamen... (in reply to mango)

quote:

One question: How will the doming be achieved that goes cross grain? Most braces in the doming area are going along the grain... Is it only done by the two cross grain braces at the lower bout?

There are a few ways to make a dome but the reality is, do you need it? Some builders just make a flat top and let the string torque pull the top behind the bridge. All this requires is to put a slight dome in the bridge.

_____________________________

Tom Blackshear Guitar maker

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 10 2020 15:25:34

JasonM

Posts: 1991
Joined: Dec. 8 2005
From: Baltimore

RE: Bogdanovich´s method for flamen... (in reply to mango)

You get a dome in the cross grain direction by making the center strut arch the most. The struts on either side arch slightly less and so on. This happens naturally by using a dish to glue the sticks.

I would love to know if a dome stiffens a top enough to affect vibration. Seems like it would, however many have said they can’t hear a difference. And from searching through this and delcamp forum, there does not seem to be much evidence that a top without a dome is more susceptible to cracks from humidity changes than a domed top.

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 10 2020 23:28:34

mango

Posts: 158
Joined: Apr. 2 2019

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

Ok... probably this is something I just have to try out... ;-)
I bought a set of 3mm carbon fibre sticks from local Ebay. They work great for clamping the struts.

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REPORT THIS POST AS INAPPROPRIATE | Date Feb. 11 2020 20:27:39

constructordeguitarras

Posts: 1626
Joined: Jan. 29 2012
From: Seattle, Washington, USA

RE: Bogdanovich´s method for flamen... (in reply to mango)

quote:

One question: How will the doming be achieved that goes cross grain? Most braces in the doming area are going along the grain... Is it only done by the two cross grain braces at the lower bout?

I don't know Bogdanovich's method, but normally the lower harmonic bar (the big bar right below the soundhole and side-to-side) is curved, which contributes to the doming, along with the fan braces being glued on with the soundboard on a domed solera (or a solera with a recess in the area to be domed).

_____________________________

Ethan Deutsch
www.edluthier.com
www.facebook.com/ethandeutschguitars
www.youtube.com/marioamayaflamenco
I always have flamenco guitars available for sale.

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 12 2020 0:44:58

mango

Posts: 158
Joined: Apr. 2 2019

RE: Bogdanovich´s method for flamen... (in reply to constructordeguitarras)

quote:

I don't know Bogdanovich's method, but normally the lower harmonic bar (the big bar right below the soundhole and side-to-side) is curved, which contributes to the doming, along with the fan braces being glued on with the soundboard on a domed solera (or a solera with a recess in the area to be domed).

I see. Bogdanovich's solara is only domed below the lower harmonic bar, so that's the way I did it. But somehow it seems to work... it looks like the wood wants to curve in both directions...

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 14 2020 0:36:08

mango

Posts: 158
Joined: Apr. 2 2019

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

I installed all the bracings and shaped them how I thought it would be right. Now I listen to the "Tap Tone" of the soundboard. I can clearly locate several different notes. The most obvious is about a G at more or less 200Hz, but I also hear a C much lower (about 60Hz). That means that C must be the "root note" of the natural overtone series. But which one is the "Tap tone" that some Luthiers like to have between F# and G?

I know that many of you guys don't give too much attention to "Tap Tuning" in a scientific way. But I thought this technique might help me as a beginner to find the sweet spot, because I work as an audio engineer and so I am familiar with frequencies, measurements and so on...

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 15 2020 11:45:49

Echi

Posts: 1080
Joined: Jan. 11 2013

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

You refer to the pitch of the air of the closed box.
You will get it when your guitar is fully assembled.
Bridge and back play a role too.

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 15 2020 11:52:19

mango

Posts: 158
Joined: Apr. 2 2019

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

I see...
So can you give me any kind of orientation for a fully braced soundboard before the box is assenbled? Which pitch am I looking for now?

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 15 2020 13:59:07

Echi

Posts: 1080
Joined: Jan. 11 2013

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

Hi, I wouldn’t like to mislead you.
I think you already thicknessed your top and glued the bracing according to your pattern.
At this stage you are just about to shape the braces.
If I was in you I would take care in shaving correctly the surplus of wood with an eye to the structural aspect of your soundboard more than the mere frequency. Keep in mind the tension of the strings and the pull off force of the bridge. Once you have done it, you may post some pictures for advices.

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 15 2020 17:58:52

Andy Culpepper

Posts: 3018
Joined: Mar. 30 2009
From: NY, USA

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

Hi mango,
I dug out a couple of old sheets of chladni pattern sketches from back when I used to keep records of such things. This was for my 5th guitar, a negra with Spruce top.
As you can see the resonances on the free plate in the first picture (top braced but not attached) are very different and more complex than the ones once the guitar is assembled (second picture). In the free plate you don't really see a proper monopole or main top resonance.
Once the edges of the top are attached to the box and you have the bridge glued and the air resonance active, you get the typical guitar modes like monopole, cross dipole etc.
As far as what to shoot for, it depends on if you have a guitar you really like that you're trying to copy or what design you're using. The resonances will vary depending on the design being used. In this case I was shooting to get close to the John Park guitar that I drew up the plans for after measuring everything meticulously. It's an amazing guitar.
Beautiful rosette by the way!

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REPORT THIS POST AS INAPPROPRIATE | Date Feb. 15 2020 19:17:19

mango

Posts: 158
Joined: Apr. 2 2019

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

Thank you guys!
Very interesting your Chladni patterns Andy! I get your point that it is very hard to tell anything about the final guitar from that, as everything changes when the box is assembled.

but... ;-)

... when I just knock on my free plate I hear several notes from a certain natural overtone series. Souldn´t the pitch of that give me information about the ratio between stiffness and weight? And shouldn't this ratio (with all structural aspects in mind) be within a certain range to achieve a good result?

Regarding the tap-tone of the final guitar body I remember two very different guitars that I owned several years ago. One was a classical one by Paulino Bernabe with a tap-tone at "A". It sounded nice with a great focus and good overtones, but it was impossible to amplify it with a mic. As soon as I put a mic in front I got huge feedback at that resonance. As "A" is an important note for guitars it also sounded weak to notch that feedback out. The other guitar was a Cordoba F10 Blanca. The tap tone was very low between "E" and "F". No problems with feedback at all, but the sound tended to be a bit floppy. And indeed, my favourite guitars all have that tap tone in between the two around "G". Of course I would like to achieve that with my own build...

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 16 2020 9:19:41

Echi

Posts: 1080
Joined: Jan. 11 2013

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

Your example makes me think that you refer to the main frequency of the box, not the top’s.
You cannot get the top frequency from an assembled guitar. Btw I’m aware of the Gore-Gilet method and the most common test with Audacity but I don’t think you refer to that.
Bernabe and Friederich guitars tend to have a very high pitch of the box frequency as they have quite rigid boxes with double sides.
Making some generalisations, the average of what you call modern concert guitar is close to G# while old school guitars are around F#.
Old Torres are down to F or even E. The rule here is to avoid the box frequency in the exact note to avoid unwanted resonances.
I don’t think it’s possible to give a general rule to couple the elements of the guitar.
Usually people try to tune the back a semitone higher than the top. I read some interesting topics of Alan Carruth about it.

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 16 2020 11:47:14

Andy Culpepper

Posts: 3018
Joined: Mar. 30 2009
From: NY, USA

RE: Bogdanovich´s method for flamen... (in reply to mango)

quote:

... when I just knock on my free plate I hear several notes from a certain natural overtone series. Souldn´t the pitch of that give me information about the ratio between stiffness and weight? And shouldn't this ratio (with all structural aspects in mind) be within a certain range to achieve a good result?

That is an interesting observation if you can really hear all those separate pitches in the tap tone. I think you would need to use an oscillator to accurately assess those resonances though. If you look at the patterns on my #5 top it looks like I had resonances at D, G, A, E, G again, then Bb, then somewhere between C# and D, then between D and Eb, then F#. Nothing about that points to the fact that my monopole resonance was later around G#. At this point in my building philosophy, I agree with Echi that at the point when you just have the top braced, your main assessment of it should be simply using the thumbs to flex and determine the actual structural properties of the braced top.
If you plan on making more guitars though, the more data about this one that you can gather the better. So make a note about what frequencies you feel like you're hearing out of that top, so later you can try to replicate it if you like the results. But no, I would not be trying to "tune" the top at this point because you're basically working in the dark if you have no previous guitars to compare it to. You can do that much more effectively later on when the guitar is assembled.

quote:

Usually people try to tune the back a semitone higher than the top. I read some interesting topics of Alan Carruth about it.

That's interesting because I would say that most of the guitars I have seen (and made) have the back tuned somewhere around a minor third to a major third above the top! I guess "at least a semitone higher" would be more accurate.

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 16 2020 23:52:28

Echi

Posts: 1080
Joined: Jan. 11 2013

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

You are right Andy.
I think Alan Carruth suggested “at least” a semitone higher but he also said the closest the better with the caveat that if the 2 plates fall in the same frequency you are likely to have wolf notes.
Also, do you mean with glued bridge or just the free plate?

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 17 2020 0:11:31

Andy Culpepper

Posts: 3018
Joined: Mar. 30 2009
From: NY, USA

RE: Bogdanovich´s method for flamen... (in reply to Echi)

quote:

You are right Andy.
I think Alan Carruth suggested “at least” a semitone higher but he also said the closest the better with the caveat that if the 2 plates fall in the same frequency you are likely to have wolf notes.
Also, do you mean with glued bridge or just the free plate?

I mean once the guitar is assembled with bridge glued. It's funny, I once accidentally made a guitar with the top and back at exactly the same resonance. It was my third one and my first classical. I did try to move it off but it actually sounded fine because they weren't directly on a scale note. The biggest thing to avoid IMO is getting your air resonance right on a scale note. Then you can really get a short/dead note at that frequency.

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 17 2020 0:24:53

mango

Posts: 158
Joined: Apr. 2 2019

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

I totally trust in your experience. When I think about all the variables that lead to the final pitch of the body it seems clear that its hard to tell anything for sure at this stage of the process. But just to show you the different pitches within my free plate tap tone now, I recorded it and caught it on camera for you... perhaps you can tell me if it sounds like yours or not ;-) haha.
I'm afraid to remove more material now, but on the other hand I don't want to end up with a rigid box unable to vibrate... the thing is that I have nothing to compare it to.

https://youtu.be/O-YzWPfnXkY

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 17 2020 20:55:36

mango

Posts: 158
Joined: Apr. 2 2019

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

here some pictures

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REPORT THIS POST AS INAPPROPRIATE | Date Feb. 17 2020 21:01:19

Andy Culpepper

Posts: 3018
Joined: Mar. 30 2009
From: NY, USA

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

Looks like it came together pretty well! It actually looks similar to the bracing I use except I shape my braces kind of "opposite" of yours. You have taller braces for the 3rd and 5th while I make the 2nd, 4th and 6th taller. Or rather, they all start the same and I plane down the others. Doing that helped to really dial in the pulsación where it was a little too stiff before, but your mileage may vary.

For shaping the braces in the future I would recommend a small palm plane. I have one of the green Kunz ones, but I ground away the edges of the sole so that it can shave the corners of braces down pretty close to the top.

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 17 2020 23:15:16

mango

Posts: 158
Joined: Apr. 2 2019

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

Thanks Andy.
I saw that taller 3rd and 5th bracing on a Conde and wanted to try it out... we'll see. And yes, one of these small planes would help, but this time I did the job with a chisel. Did you listen to the tap tone on the video? Does it sound like a stiff top to you? Or already too floppy?

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 18 2020 4:49:18

Andy Culpepper

Posts: 3018
Joined: Mar. 30 2009
From: NY, USA

RE: Bogdanovich´s method for flamen... (in reply to mango)

quote:

Did you listen to the tap tone on the video? Does it sound like a stiff top to you? Or already too floppy?

I did! It will be interesting to note the relationship between those frequencies and the and the resonant modes of the finished guitar. I'd say your top is perfectly reasonable to go ahead with.

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 18 2020 12:57:20

RobF

Posts: 1516
Joined: Aug. 24 2017

RE: Bogdanovich´s method for flamen... (in reply to mango)

I just noticed your video, good work. It doesn’t hurt to run the plate analysis and keep records for each guitar.

I thought I’d post a couple of pictures of the types of small planes Andy was talking about. The green one in the centre is the Kunz plane. They hold a good edge and are economical enough that you won’t mind rounding off the sides (as Andy mentioned, and as shown).

The other two planes are from Lee Valley. The smallest is one of the collectable miniatures they sell, but it’s a very usable tool. The other is like a Cadillac version of the Kunz, with high quality PMV-11 blade and full adjustability. It’s one of my favourite planes and I use it all the time, but I’d be happy owning one just to look at it, they’re that nice.

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REPORT THIS POST AS INAPPROPRIATE | Date Feb. 18 2020 14:27:43

JasonM

Posts: 1991
Joined: Dec. 8 2005
From: Baltimore

RE: Bogdanovich´s method for flamen... (in reply to mango)

On my top I had 58.5 hz (A1#) and a sub dominant peak further up at G2. Not that you should follow my example but your lowest peak is in the same neighborhood.

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 19 2020 2:10:16

mango

Posts: 158
Joined: Apr. 2 2019

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

I asked myself how to make this 15 foot radius without buying one of these expensive radius dishes... finally I printed a 15 foot curve out of my vector software, traced it to a piece of plywood and made this jig... seems to work fine.

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REPORT THIS POST AS INAPPROPRIATE | Date Feb. 22 2020 23:11:20

constructordeguitarras

Posts: 1626
Joined: Jan. 29 2012
From: Seattle, Washington, USA

RE: Bogdanovich´s method for flamen... (in reply to RobF)

I find it most convenient to carve fan braces using an itty bitty violin making finger plane https://www.diefenbacher.com/luthier.htm

_____________________________

Ethan Deutsch
www.edluthier.com
www.facebook.com/ethandeutschguitars
www.youtube.com/marioamayaflamenco
I always have flamenco guitars available for sale.

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 23 2020 2:42:07

RobF

Posts: 1516
Joined: Aug. 24 2017

RE: Bogdanovich´s method for flamen... (in reply to constructordeguitarras)

I have some of those, too. I also use the Lee Valley miniature shoulder plane. I like the Lee Valley miniatures because the blades are easy to adjust.

I have way too many planes (chisels, too). I have to stay away from flea markets...and the internets.

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 23 2020 4:20:02

mango

Posts: 158
Joined: Apr. 2 2019

RE: Bogdanovich´s method for flamen... (in reply to ernandez R)

Hey guys!
I just asked myself... why is nobody applying shellac to the downside of the soundboard? Wouldn't that protect the top from moisture changes and add some additional stiffness to to wood? Would the sound suffer from that in any way or what?

REPORT THIS POST AS INAPPROPRIATE | Date Feb. 25 2020 21:31:11

ernandez R

Posts: 667
Joined: Mar. 25 2019
From: Alaska USA

RE: Bogdanovich´s method for flamen... (in reply to RobF)

I made up a finger plane the other day.

I used an ignition point file as the blade. Do they even make those anymore? An old timer once brought me a bucket of rusty files saying they would make better chisels then anything you can buy today. He was mostly right, we were poor kids making bowls out of spalted oak log cutoffs and they worked great.

I didn't measure a thing.

I made four strips the same thickness on the bandsaw as the width of the file blade, cut the middle one the same angle of my small hand plane by eyeball using the miter chop saw. Glued the pieces together accordingly with CA. Drilled the pin hole about where it needed to be then took the drill bit out of the press slid it into the hole and cut off.

I made the wedge out of the forth strip in the band saw. Trimmed the pointy end of the wedge accordingly.

Took the most time to sharpen the file: smooth the tooth off of the top about five mm and the angle about 35 deg. Then polish with 600 WD paper.mtook three tries before I had see through shavings but I like about .005-7 inch shavings to get it done.

Thirtyfive minutes and some of the most satisfying shop work there is for me. Then about forty five more using it to shave tone bars...

I'll try to post some photos. Ah yes, can load *.jpg but can't load *.jpeg which I believe is the standard now?

HR

_____________________________

I prefer my flamenco guitar spicy,
doesn't have to be fast,
should have some meat on the bones,
can be raw or well done,
as long as it doesn't sound like it's turning green on an elevator floor.

www.instagram.com/threeriversguitars

REPORT THIS POST AS INAPPROPRIATE | Date Mar. 4 2020 21:46:45

ernandez R

Posts: 667
Joined: Mar. 25 2019
From: Alaska USA

RE: Bogdanovich´s method for flamen... (in reply to mango)

I've seen this shellac the inside conversation get contensious ;)

I pad on three layers of 8lb cut on the inside of the top and about six on the inside of the back and sides. I'm only eight guitars in so take my opinion with a shot or two of non dinatured grain alcohol.

HR

_____________________________

I prefer my flamenco guitar spicy,
doesn't have to be fast,
should have some meat on the bones,
can be raw or well done,
as long as it doesn't sound like it's turning green on an elevator floor.

www.instagram.com/threeriversguitars

REPORT THIS POST AS INAPPROPRIATE | Date Mar. 4 2020 21:51:13