Experimental top introduction

Tops only
jread
Posts: 253
Joined: Wed Feb 13, 2019 9:52 am

Re: Experimental top introduction

Post by jread »

Skarsaune wrote:Have to be an epoxy, I’d say.

I’m not volunteering. No time for this, can’t even get my builds done.

Nope.

Never mind that spare set of Mahogany over there.

Nope. Not volunteering.

:-)

I've got a pile of plates 6" tall. I apparently love to design guitars and collect the parts. I wish I could buy some extra days in the week.

^^^ Let's see what Diane comes up with for sure!
AluminumTop
Posts: 9
Joined: Mon Nov 30, 2020 1:42 pm

Re: Experimental top introduction

Post by AluminumTop »

Diane Kauffmds wrote:I might be interested in experimenting with this top.
Couple of answers, I made the outer edge thickness (.080) 2mm as original and the inner between brace panels on this version .030 with the "isogrid" panel stiffeners .080 (weigh saving stuff) The braces are .050 thick x .375 high. The board is flexible and weights 400-435 grams. Which will get lighter next version. The board machining starts flat, curls concave when material is removed from the underside, Then I straighten it by hand to get to flat again. The soundboard is installed without a "dome" and when the strings are tensioned, it creates a .100-.080 doming from the string pull.
This versions' thicknesses are a raw guess, and the brace positions are derived from the Geo.Luthier supply drawing. (1914 Martin soundboard) Next version will be lighter
The "Tap Tuning" is a deep gong with long decay duration (i don't know the frequency).
Before the first one was made, the luthier said "it won't work" he was astounded when he first heard it plugged it in. So have other master Luthiers.
The 6061 t6 material Vs wood differential expand/contract question is moot. It provides a stable base for everything else to attach to.

Keep up the questions, I think they keep me motivated.
Thanks,
BrianO
MaineGeezer
Posts: 1352
Joined: Wed Aug 13, 2014 12:14 pm

Re: Experimental top introduction

Post by MaineGeezer »

Have you thought about trying a different alloy? (2024,maybe?)
Don't believe everything you know.
Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion
AluminumTop
Posts: 9
Joined: Mon Nov 30, 2020 1:42 pm

Re: Experimental top introduction

Post by AluminumTop »

MaineGeezer wrote:Have you thought about trying a different alloy? (2024,maybe?)
Yes i have, 6061 t6 is an easy plentiful, cheap choice About $32 per, with a certificate of quality.
So i used this first.

2024 is very soft and is what the Apache Chopper is made from, soft for vibration (stress crack) tolerance. I forgot the heat treat condition Very "gummy" to machine.

The harder 7075 and lite lithium aluminum's would be the best choice. $$ more $$
I would really like to do one in magnesium like the bridge.
The weight can be controlled by machining thinner or thicker where the metal is needed.
I have machined reliably to .035" And have the machining down to 1.25 hour.

I am stocked with tops because i do not build the guitars.
And need a luthier to complete the assembly.
MaineGeezer
Posts: 1352
Joined: Wed Aug 13, 2014 12:14 pm

Re: Experimental top introduction

Post by MaineGeezer »

Are you sure you have the characteristics of 2024 right? I've always found 2024 harder and less gummy to machine than 6061. It does cost more though. 7075 of course, is big bucks compared to 6061. I have no experience with magnesium , but it's an interesting idea.

One thing isn't clear to me: are the braces machined as part of the top, or are they glued on?
Don't believe everything you know.
Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion
AluminumTop
Posts: 9
Joined: Mon Nov 30, 2020 1:42 pm

Re: Experimental top introduction

Post by AluminumTop »

MaineGeezer wrote: I have no experience with magnesium , but it's an interesting idea. Mag will cut like walnut, so nicely
One thing isn't clear to me: are the braces machined as part of the top, or are they glued on?

2024 "O" condition Wing Spars AAH

Integral, monolithic, one piece.
This is why our rockets are flying,
this is from the 1960's rocket parts machine shop stuff

Hey i just adapted this to a soundboard, that's all..................
I was on a tour of Taylor and the idea struck me when i saw the inside structure of their soundboards Great tour.!!
ruby@magpage.com
Posts: 1477
Joined: Thu May 24, 2012 8:03 am
Location: Chestertown Maryland

Re: Experimental top introduction

Post by ruby@magpage.com »

Here is the story of a replica of a 1935 Bugatti, one-of-a-kind, that went missing. The replica, like the original, had a magnesium body. They said they had to be extremely careful cutting the material because it can start on fire from the friction

https://www.motorauthority.com/news/112 ... esium-body

Be careful out there
Ed M
MaineGeezer
Posts: 1352
Joined: Wed Aug 13, 2014 12:14 pm

Re: Experimental top introduction

Post by MaineGeezer »

Ah! That's the difference. My only experience has been with 2024 T351, if my memory is correct. Anyway, it wasn't O temper.
Don't believe everything you know.
Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion
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