The Acoustic Guitar Forum

Go Back   The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Build and Repair

Reply
 
Thread Tools
  #1  
Old 11-12-2019, 10:11 AM
packocrayons packocrayons is offline
Registered User
 
Join Date: Jan 2017
Posts: 100
Default Building all-lam/weatherproof

Does anyone have experience with custom weatherproof guitars? I know the way-to-go is rainsong or similar carbon fiber guitars, but that's not in my budget and I prefer to build my own instruments.

I'm looking for something I can transport/leave in my car in the winters of Canada without concerns of cracking the second I walk out into the cold. I could go buy a cheap all-laminate guitar, but that also feels like cheating.

Laminate sides (and backs) I see have been done, and a 5+piece neck gives stability. The only remaining thing is also the most finicky, a laminate top. I have carbon/fiberglass experience, but I don't imagine I have enough to make a guitar top unless I buy 1/2mm carbon sheet.
Reply With Quote
  #2  
Old 11-12-2019, 11:12 AM
Earl49 Earl49 is offline
Registered User
 
Join Date: Jan 2014
Location: Idaho
Posts: 7,816
Default

I applaud your ambition to build, but it seems like reinventing the wheel. There are several options, some of which you've noted. Martin uses HPL (high pressure laminate, often referred to colloquially as Formica). Cheap imports use all laminated tops along with the laminated bodies. The ultimate is a composite material like carbon fiber or eKoa, but it doesn't come cheaply. I suspect that most fiberglass lay-ups would have too much resin content that would heavily dampen any vibrations. CF is usually vacuum bagged during curing and uses "pre-preg" (pre-impregnated cloth) to achieve an absolute minimum of resin.

Your guitar won't necessarily crack just from getting cold. A nitrocellulose finish will crack (cold-checking) if thoroughly cold-soaked and then warmed quickly. Some of my guitars have traveled all day in the unheated back of a truck at -40°F between Anchorage and Fairbanks. As long as there was a dampened sponge in the case to provide some moisture as it was allowed to warm slowly, I did not have any problems with cracking.
Reply With Quote
  #3  
Old 11-13-2019, 11:06 PM
saltytri saltytri is offline
Registered User
 
Join Date: Jun 2017
Posts: 6
Default

About six years ago, I built tenor ukulele that was to live full-time on a small sailboat mostly in the tropics. This is a difficult environment because of humidity swings and the certainty that everything on a small boat gets wet from time to time. It has done just fine. The body was built conventionally out of mahogany and coated inside and out with this penetrating epoxy before finishing with a polymerizing oil:

http://www.smithandcompany.org/CPES/index.html

Someone might howl that this treatment changes the tonal properties of the wood but that effect, if present at all, was not detectable by me. In truth, the epoxy doesn't penetrate sound wood much at all, except perhaps into end grain, but it does saturate and seal the surface of the wood. In any event, this method certainly meets an aesthetic goal that HPL never will.
Reply With Quote
  #4  
Old 11-14-2019, 05:17 AM
Quickstep192 Quickstep192 is offline
Charter Member
 
Join Date: Aug 2002
Posts: 1,043
Default

You could make a double top with a Nomex core. It wouldn’t be completely bullet proof, but it would be more stable than just spruce.
Reply With Quote
  #5  
Old 11-14-2019, 07:54 AM
redir redir is offline
Registered User
 
Join Date: Aug 2011
Location: Mountains of Virginia
Posts: 5,020
Default

I was going to suggest nomex too but for everything, back, sides and top. Some interesting ideas here too. I could see epoxy being a good coating, I mean after all they use it on boats. But that is different from a cold dry Canadian environment too. You would most certainly want to build it very dry.
Reply With Quote
  #6  
Old 11-14-2019, 09:12 PM
printer2 printer2 is offline
Registered User
 
Join Date: Dec 2012
Posts: 3,787
Default

But a double top has a thin skin and is not all that robust. If you have access to a drum sander you can make your own spruce laminate. A laminate back and sides with a non-live back makes sense. But all these construction methods take a learning curve to get right. For doing a single guitar you might need to do two to get right.

One thing I just thought of, I don't know how light a fabric carbon fiber comes in but I have some 0.6 oz/ft glass cloth that was used to cover RC aircraft. Maybe just do a single layer pasted on the inside of a solid top. All you really are trying to do is stop cracks from forming. Or use a nylon fabric instead on the inside of the top. I may have to try this out now to see if it will work.
__________________
Fred
Reply With Quote
  #7  
Old 11-15-2019, 08:24 AM
redir redir is offline
Registered User
 
Join Date: Aug 2011
Location: Mountains of Virginia
Posts: 5,020
Default

Nomex laminated to even a thin top makes it incredibly strong. In fact when you make up the top sandwich it feels like a braced top. It creates a honey comb matrix, really strong in all directions.
Reply With Quote
  #8  
Old 11-15-2019, 08:59 AM
Skarsaune Skarsaune is offline
Registered User
 
Join Date: Jan 2013
Posts: 536
Default

Quote:
Originally Posted by redir View Post
Nomex laminated to even a thin top makes it incredibly strong. In fact when you make up the top sandwich it feels like a braced top. It creates a honey comb matrix, really strong in all directions.
Very interesting.
How did you brace this sandwich top - or did you ?
And how did it sound once assembled?
Reply With Quote
  #9  
Old 11-15-2019, 10:31 AM
packocrayons packocrayons is offline
Registered User
 
Join Date: Jan 2017
Posts: 100
Default

Interesting ideas all around here. I've worked with carbon/fiberglass and that may be an option, a very thin top, lightly braced, and then vacuum bag that whole thing in carbon fiber comes to mind.

I'll definitely have to do this build in the peak of winter.

Lam sides and back and a many piece neck.

Has anyone ever done a multi-piece fingerboard? Could get some cool taper effects with 3 pieces.
Reply With Quote
  #10  
Old 11-15-2019, 03:13 PM
redir redir is offline
Registered User
 
Join Date: Aug 2011
Location: Mountains of Virginia
Posts: 5,020
Default

Quote:
Originally Posted by Skarsaune View Post
Very interesting.
How did you brace this sandwich top - or did you ?
And how did it sound once assembled?
I was told to brace it as normal so I did. This was a Torres style classical so 7 fan braces. Once I got it all together I was not very pleased with the tone but I left it for many months like that. This was my first double top so it was never going to be for sale. Then I decided to shave the braces and the tone came right out of it. It's still doesn't sound any better then my traditional classical guitars, it is loud though, I will give it that.
Reply With Quote
  #11  
Old 11-16-2019, 03:54 PM
printer2 printer2 is offline
Registered User
 
Join Date: Dec 2012
Posts: 3,787
Default

Quote:
Originally Posted by redir View Post
Nomex laminated to even a thin top makes it incredibly strong. In fact when you make up the top sandwich it feels like a braced top. It creates a honey comb matrix, really strong in all directions.
Oh I know. When I was working for an aerospace manufacturer I helped destruct some nomex carbon fiber production samples. I was thinking of a wood, honeycomb wood sandwich. Most people go pretty thin on the two wood layers.
__________________
Fred
Reply With Quote
  #12  
Old 11-16-2019, 07:48 PM
redir redir is offline
Registered User
 
Join Date: Aug 2011
Location: Mountains of Virginia
Posts: 5,020
Default

Quote:
Originally Posted by printer2 View Post
Oh I know. When I was working for an aerospace manufacturer I helped destruct some nomex carbon fiber production samples. I was thinking of a wood, honeycomb wood sandwich. Most people go pretty thin on the two wood layers.
Very thin indeed! I'd have to look up my specs but iirc it was scary thin. I used epoxy to join every thing together being very careful not to fill the honeycomb. So each chamber is full of air.

I have read of luthiers who claim that they still use good tonewood and in fact some that even go as far as using spruce for the top and cedar for the bottom and make claims that they can control the tone this way. I have my doubts. It seems to me that the Nomex is the dominant variable in that system as is the thickness of the outer layers. But in the end what you are making is a composite material that is very light weight and strong.

As far as I am concerned a double top guitar is a laminate top and it approaches something more like a carbon fiber guitar where the goal in producing tone for a guitar is to have a super light weight top that is still strong enough to not destroy itself under string tension.

Carbon fiber guitars sound great! Different but great. So do double tops.
Reply With Quote
Reply

  The Acoustic Guitar Forum > General Acoustic Guitar and Amplification Discussion > Build and Repair

Thread Tools



All times are GMT -6. The time now is 09:11 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright ©2000 - 2018, The Acoustic Guitar Forum
vB Ad Management by =RedTyger=