Official Luthiers Forum!

I am going to be starting my first guitar build. I have all the tool except for a drum sander for thickening. I found that LMII will do this for you when you buy the wood from them and also joint them. they only charge $50 which seems pretty reasonable. Their standard that they thickness to is backs-.095", sides-.090", and tops .110". they will do custom thicknesses also for no extra charge. Im building a grand auditorium and im using sitka spruce for the top and indian rosewood for the back and sides. will those thicknesses work or should i have them do different thicknesses?

I think unless you have particular reasons for deviating from those numbers, which you probably don't since it's your first guitar, that those are very reasonable specs.

"Sides" should be about .078" (same as the Martin Factory) --- I believe trying bend material that is too thick can be one of the biggest frustrations for the new builder (and not so new builders as well).

_________________
Ken Cierp

http://www.kennethmichaelguitars.com/

+1 When I started taking my sides to .075 - .080 my life got way better, the trees leafed out, I won the lottery, I grew back hair, got taller, and smarter too.

Seriously though .078 is a great number IMO.

Growing hair on you back was a plus??

You're a weird dude, Hesh.

I had LMI do the same on my first few guitars and it worked fine, with those specs.

Steve what' wrong with back hair?

I have thinned the sides down even more than that (Bubinga and Jotoba), but you have to pray for no wrinkles, as you will thin them down even more when you flatten them out.
Glue in braces to the sides as well.


Sent from my iPhone using Tapatalk

_________________
"It is easier to fool a man, than it is to convince him that he has been fooled"
Mark Twain

they said the lowest they can go is .085

For your first guitar I still think .090 is just fine, especially since rosewood is so cooperative. That gives you a lot to work with for flattening the sides and such. After a few, you might decide you want to go thinner, but .090 will get the job done for you.

I'll second what Ed just said. I've only built 10 guitars but my standard has been back and sides at 0.09 and tops at 0.11 to 0.10 (I've done two western red cedar tops and left them at about 0.12). Back and sides have been of different wood species on all 10 guitars, and I've had no problems thus far (knock on wood).

Then at least have them do that -- thinner wood bends easier and has less spring back. I have no doubt that very thick sides have been bent -- but that's not my point of offering this advice. Besides there is always the chance that you can grow "back hair" like Hesh!

Here's some wood bending science:

http://www.fpl.fs.fed.us/documnts/usda/ah125.pdf

_________________
Ken Cierp

http://www.kennethmichaelguitars.com/

The back hair can be removed but cracked sides can ruin your day... +1 to what Ken and others are saying here.

Just as in interesting data point our 1870 Martin that just got way more valuable because Tarantino let the one from the Martin museum get smashed has sides in the neighborhood of .063"... Of course they are cracked in lots of places but that's what glue is for.

You guys wanna talk about glue? Just kidding....

.085 is fine. You can always take it down a little with a ROS and 220 paper. You will want to smooth it some anyway

_________________
Joe Beaver
Maker of Sawdust

0.110 seems a little thin for the starting point of the top to me. 0.115-0.125 would give you more wiggle room for stuff like rosette leveling and voicing the closed box.

_________________
It's not what you don't know that hurts you, it's what you do know that's wrong.

So true. That's why it is so nice to thin the top after the rosette goes in. It can also be true of the back if you are using a back strip. But with careful work you can do both after the top and back are joined and thicknesses.

It is a good reason to have LMI do those on the thick side. Then after the rosette and back strip are leveled you can flip them over and finish with a little ROS and scraper.

The sides are different of course.

_________________
Joe Beaver
Maker of Sawdust

I haven't had LMI thickness anything for me for a while... mostly because I'd like to do the work myself (there's a bit of fine tuning needed here) and also I join the plates before any thicknessing to avoid trouble. Get a hand plane and learn how to thickness tops.

Back and side is a fair game though, probably pays to have them thickness it for you, especially to a thickness that is easy to bend.

_________________
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

IMHO, appropriate side thickness is totally dependent on the wood. I run it through the sander multiple times, checking it for flexibility after each pass. I just bent some quartered wormy chestnut at 0.100" and it bent just fine. I have gone down to 0.070" on the really dense, stiff woods. Slab cut sides are more likely to ripple, so I generally leave them a bit thicker.
The standard LMII thickness for backs and sides should be fine, but IMHO 0.110" for the top thickness may be too thin on a grand auditorium if the top is not relatively stiff. I would start at 0.120" and do the rest myself, based on the flexibility of the individual top.

_________________
John

For a big guitar .125 is a good beginning it/s easier to sand off 5 to10 thou and a lot harder to add to it later

Martin Guitar factory tour gave out discs from the sound hole cutouts as souvenirs. Mine is 0.125".