Official Luthiers Forum!

Wow, thanks, Don. Really good link.

Ron

_________________
OLD MAN formerly (and formally) known as:

Ron Wisdom

Somewhere in the middle of Arkansas......

[QUOTE=dubell]
P.S. - How do I convince my wife of this one? I have run out of excuses.

[/QUOTE]

Doug,

Try my standard excuse. It's a lot less expensive than my old hobbies and you can't get arrested building a guitar.

Joe Volin

[QUOTE=dubell] One thing I read in the Cumpiano book is that sanding this joint is inferior to planning because sanding leaves grooves. He says that the joint is too critical and should be planned by hand.

Doug
[/QUOTE]

Since the weekend is upon us, I say we should have an in-depth discussion of whether or not Cumpiano's theory of planing vs sanding has merit!

Yes, I am just trying to stir the pot. Glue pot, that is!

Steve

[QUOTE=sfbrown] [QUOTE=dubell] One thing I read in the Cumpiano book is that sanding this joint is inferior to planning because sanding leaves grooves. He says that the joint is too critical and should be planned by hand.

Doug
[/QUOTE]

Since the weekend is upon us, I say we should have an in-depth discussion of whether or not Cumpiano's theory of planing vs sanding has merit!

Yes, I am just trying to stir the pot. Glue pot, that is!

Steve[/QUOTE]

Time to trot out the US Forest Labs study from circa WW II that compared failure rates in laminated prop blades between sanded (higher failure) and planed (lower failure) joints. Al Carruth has the details, although he must be tiring of pointing that factoid out by now ;-)

[QUOTE=Mattia Valente] [QUOTE=sfbrown] [QUOTE=dubell] One thing I read in the Cumpiano book is that sanding this joint is inferior to planning because sanding leaves grooves. He says that the joint is too critical and should be planned by hand.

Doug
[/QUOTE]

Since the weekend is upon us, I say we should have an in-depth discussion of whether or not Cumpiano's theory of planing vs sanding has merit!

Yes, I am just trying to stir the pot. Glue pot, that is!

Steve[/QUOTE]

Time to trot out the US Forest Labs study from circa WW II that compared failure rates in laminated prop blades between sanded (higher failure) and planed (lower failure) joints. Al Carruth has the details, although he must be tiring of pointing that factoid out by now ;-)[/QUOTE]

Yes but how many revolutions per minute do your guitars do and at what altitude? Persuade your customers not to do "loop the loops" and I think the sanded joints will be just fine

_________________
Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

[QUOTE=Dave White] [QUOTE=Mattia Valente] [QUOTE=sfbrown] [QUOTE=dubell] One thing I read in the Cumpiano book is that sanding this joint is inferior to planning because sanding leaves grooves. He says that the joint is too critical and should be planned by hand.

Doug
[/QUOTE]

Since the weekend is upon us, I say we should have an in-depth discussion of whether or not Cumpiano's theory of planing vs sanding has merit!

Yes, I am just trying to stir the pot. Glue pot, that is!

Steve[/QUOTE]

Time to trot out the US Forest Labs study from circa WW II that compared failure rates in laminated prop blades between sanded (higher failure) and planed (lower failure) joints. Al Carruth has the details, although he must be tiring of pointing that factoid out by now ;-)[/QUOTE]

Yes but how many revolutions per minute do your guitars do and at what altitude? Persuade your customers not to do "loop the loops" and I think the sanded joints will be just fine [/QUOTE]


I always specify on mine they are not to be banked beyonds 75 Degrees.

OK, I plane mine, and yes a #4 seems to work just fine with a sacrificial longer board. But, I'm going to say that a sanded joint, well done, will be just fine. On the back it's going to have a reinforcement strip on the inside and maybe an inlay on the outside so there is going to be lots of HHG (or TB) holding it together plus cross braces. On the top there's cross braces, X braces, tone bars, bridge patch, bridge, oh and the rosette and FB all crossing the joint. On a classical there's even a fan brace running down the join. If it candles OK glue it up and worry about something else, taxes, global warming the Yellowstone supervolcano.........

Colin

_________________
I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

I'm still a newb so i wouldn't know what caliber to use to shoot! sowwy, was too easy!

[QUOTE=Mattia Valente] [QUOTE=sfbrown] [QUOTE=dubell] One thing I read in the Cumpiano book is that sanding this joint is inferior to planning because sanding leaves grooves. He says that the joint is too critical and should be planned by hand.

Doug
[/QUOTE]

Since the weekend is upon us, I say we should have an in-depth discussion of whether or not Cumpiano's theory of planing vs sanding has merit!

Yes, I am just trying to stir the pot. Glue pot, that is!

Steve[/QUOTE]

Time to trot out the US Forest Labs study from circa WW II that compared failure rates in laminated prop blades between sanded (higher failure) and planed (lower failure) joints. Al Carruth has the details, although he must be tiring of pointing that factoid out by now ;-)[/QUOTE]

Semi-serious question: Has the glue technology improved at all since WWII? I would like to see the report. Not that I dispute its results because I do think a planed joint is stronger but how good does it have to be to withstand the stresses of guitar building? Couple that with advances in technology and I would like to know if there is a more current study.

Oh, and I promise not to rotate my guitars any faster than 100 RPM.

Steve

[QUOTE=sfbrown]
Semi-serious question: Has the glue technology improved at all since WWII? I would like to see the report. Not that I dispute its results because I do think a planed joint is stronger but how good does it have to be to withstand the stresses of guitar building? Couple that with advances in technology and I would like to know if there is a more current study.

Oh, and I promise not to rotate my guitars any faster than 100 RPM.

Steve[/QUOTE]

Hehe...not a clue. And for honesty's sake, I really don't mind gluing sanded joints, and I do where I have to. But if I can plane, I do. It's fast, perfect surface, no dust, and just downright more *fun* than sanding.

As for glue tech...hide glue's what it's been for ever and ever, and I don't know how old Titebond Original is; for glues, I think tried-and-tested, been around for more than a decade is a good thing; you know the long-term viability of the things. Epoxy and Polyurethanes are, I'd guess, much newer in terms of chemistries, but the applications in lutherie are fairly limited...

[QUOTE=Mattia Valente] [QUOTE=sfbrown]
Semi-serious question: Has the glue technology improved at all since WWII? I would like to see the report. Not that I dispute its results because I do think a planed joint is stronger but how good does it have to be to withstand the stresses of guitar building? Couple that with advances in technology and I would like to know if there is a more current study.

Oh, and I promise not to rotate my guitars any faster than 100 RPM.

Steve[/QUOTE]

Hehe...not a clue. And for honesty's sake, I really don't mind gluing sanded joints, and I do where I have to. But if I can plane, I do. It's fast, perfect surface, no dust, and just downright more *fun* than sanding.

As for glue tech...hide glue's what it's been for ever and ever, and I don't know how old Titebond Original is; for glues, I think tried-and-tested, been around for more than a decade is a good thing; you know the long-term viability of the things. Epoxy and Polyurethanes are, I'd guess, much newer in terms of chemistries, but the applications in lutherie are fairly limited...[/QUOTE]

Exactly my thoughts. If all they had to compare was hide glue and white glue for instance, the results today, while interesting don't speak to the ultimate strength of state-of-the-art adhesives and their effect on glue joint prep. The other thing I have to ask is with current glues such as Tite-bond, that are stronger than the wood, isn't the additional surface area created by a sanding process actually advantageous? In other words, more surface area, more strength?

These are just thoughts. I'm not saying that I subscribe to anything I just said but it is a way to look at it.

Steve

[QUOTE=sfbrown]
Exactly my thoughts. If all they had to compare was hide glue and white glue for instance, the results today, while interesting don't speak to the ultimate strength of state-of-the-art adhesives and their effect on glue joint prep. The other thing I have to ask is with current glues such as Tite-bond, that are stronger than the wood, isn't the additional surface area created by a sanding process actually advantageous? In other words, more surface area, more strength?

These are just thoughts. I'm not saying that I subscribe to anything I just said but it is a way to look at it.

Steve[/QUOTE]

Well, re: 'greater surface area', my limited understanding of PVAs is that they're not gap filling. The glue has practically no inherent strength (Epoxy's the one exception to this, it seems), so while the surface area might be greater, the surfaces are also further apart, which is less than ideal. Probably.

Anyway, planing good. Sanding good. Planing less messy and makes nice 'snick' noise and fluffy shavings. Therefore planing better. Plus, more planing = more need for nice planes = good excuse to spend money at Lee Valley or Lie Nielsen.

...no, wait...

Just a quick note here from me, but it has been my experience you can join those 500 - 600 mm long guitar plates easily with a #4 plane if you have a shooting board and a nicely set up plane. I think the #7 is too bulky for this, in fact my favorite is the #5 1/2 size -- just the right heft and length. This is also my main plate thicknessing plane.

Hide glue for the center joint.

_________________
Rian Gitar og Mandolin

Good article on shooting boards at Woodcentral.

The Shooting Board

Joe Volin

[QUOTE=Mattia Valente] Anyway, planing good. Sanding good. Planing less messy and makes nice 'snick' noise and fluffy shavings. Therefore planing better. Plus, more planing = more need for nice planes = good excuse to spend money at Lee Valley or Lie Nielsen.

...no, wait...[/QUOTE]

I GIVE UP!!! YOU WIN!!! Your logic, as usual is unassailable!

Steve