Official Luthiers Forum!

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Billy Dean Thomas
Covina, CA

"Multi famam, conscientiam, pauci verentur."
(Many fear their reputation, few their conscience)

If you want consistent sound by using a consistent shape (or grooves), then you have to assume that the material is consistent as well.

Unfortunately wood is a variable, you can never get two pieces of the wood of the same shape to have the same density, therefore the same sonic properties. That's why it takes a human luthier to tap and tune the plates to the right sound, because each wood is different enough that if you used the same thickness for every soundboard, you would have a bell curve of bad sounding instruments, good sounding instruments, and everything in between (which will be most of them).

Things like this might work with engineered material that have consistent and predictable density, flexibility, etc. like carbon fiber or fiberglass, and even those will vary depending on how they're manufactured.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Todd Stock wrote:

The groove is there to loosen up the top at the edges - faster, cheaper, less effective method versus thinning the top as done by some hand builders...
On your bud's theory...not sure anyone has figured out a good way to make topwood behave like a diode,

I'm pretty sure he got it from the Taylor rep, He owns a guitar store... for whatever that's worth.

Todd Stock wrote:

See the thread below this one titled 'I Was Pokin Around' for more discussion.

I didn't read that thread before hand. About the same thing, a lot of discussion..no numbers. If I had better access to a Taylor I would do it myself. I only know one guy with a Taylor, let alone, in pieces and it's too old to have the groove.

Thanks anyway guys.

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Billy Dean Thomas
Covina, CA

"Multi famam, conscientiam, pauci verentur."
(Many fear their reputation, few their conscience)

Billy,

I have access to two Taylors, and looked pretty closely at both of them. What I saw jives with what people here are saying. That the 'groove' is a generic feature that is used on all of their guitars (at least above a certain model level).

One is a Rosewood/Sitka 2004 Grand Concert (It's actually a limited edition XXX-RS and has some differences from a GC), and a 2006 GS-5, which is a large'ish body Cedar top/Mahogany body affair.

In both, at least to my eye, the groove is exactly the same. it's a rounded, "U" shaped groove that starts right at the thinnest point of the waist, and follows the lining all the way around the lower bought (there are no interruptions, even at the tail block). The groove is approximately 1/4" wide... maybe slightly less. The depth is difficult to determine, but my guess is, that in both cases, the depth of the groove appears to be approximately half the depth of the top. As far as it's relationship to the lining, the groove is snugged right up against it. I didn't put the mirror back by the tail block to see what was done back there. Looking at the picture, it doesn't look like the tail block touches the top, and the groove passes by that area uninterrupted...


The pictures in the other thread give might help.
viewtopic.php?f=10101&t=33527

Here is a higher res version of the first picture
http://hansenonline.org/images/xxx-rs-big.jpg

I have the strings off of the GS-5 for the time being if you want anything specific that I can measure without bandsawing the guitar ;P

hope this helps...

Jim

Edit:
Also, I meant to ask. Where does the term "Blood Groove" come from?

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Jim Hansen

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"It's a Tone Faerie thing"
"Da goal is to sharpen ur wit as well as ye Sgian Dubh"
"Sippin Loch Dhu @Black lake" ,Kirby O...

I believe Taylor calls it a "relief rout". Taylor started re voicing their guitars in the late '90's for more bass. This is one of their methods, that I believe started in 2003 or 2004. To my ears they still sound like "Taylors".

Taylor guitars are second to none in marketing. Their workmanship is also second to none. I've never heard a Taylor that got my attention. Obviously tone is subjective.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

Thanks Jim! What I've heard done from frets.com is people take a ziplock sandwich bag and partially fill it with plaster and press it into the form to get a pretty close pattern of what's there. It's difficult to measure brace profiles, heights and other various properties while they are inside the guitar. You've given me a good starting point none the less. I mainly bring the up as a good way to share techniques rather than asking you to do it. I think I have what I need from your assessment. Thanks again! That helps.



Blood groove is a term I apply as a joke, It refers to bayonets having a groove on either side to relieve suction after it is driven in the body. Sometimes the bayonet doesn't want to come out quickly. The groove allows atmospheric air pressure into the wound to prevent this. Every luthier should know this!

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Billy Dean Thomas
Covina, CA

"Multi famam, conscientiam, pauci verentur."
(Many fear their reputation, few their conscience)

I hadn't seen the plaster article on Frets.com.

I do something similar with a firm modelling clay I bought at a local art supply store. This stuff is firm enough to holds its shape pretty well, and soft enough for light impressions. I'm not sure i'd want to press it into the soundboard, up against the linings hard enough to get an impression of that groove, as I'm afraid it might leave some residue in the kerfed slots.

I form it into a small block and lightly press it up against a brace to get an impression that I can use to measure height. It's not the most accurate way, but it's a good way to get reasonably accurate measurements to get you in the ballpark.

It took me a couple of tries, using test pieces of wood, to find clay that was the right consistency to not stick to the wood and leave residue. I don't remember the brand name, but it ended up being the firmest modeling clay they had.

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Jim Hansen

It's easy, wrap the clay in saran wrap or plastic bag and it won't stick to things...

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

It may be Chavant, but that stuff has to be heated first, in some grades. It's the stuff used for prototyping concept cars and sculpting. Heating usually makes all clays softer(oil based especially), this may help with pressing into a form. Stick into a thin fold top sandwich bag, form it and stick it into the freezer to firm, then it can be pretty durable for measurement. If you could give me the height and width I can figure the radius, though I'm pretty sure it's a standard rad (1/2,3/4...)

_________________
Billy Dean Thomas
Covina, CA

"Multi famam, conscientiam, pauci verentur."
(Many fear their reputation, few their conscience)