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Massive project - custom molded carbon fiber inserts.
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10123&t=54350		 Page 1 of 1
Author:  Stuart Gort [ Mon Aug 23, 2021 7:47 pm ]
Post subject:  Massive project - custom molded carbon fiber inserts.
There is far too much to try to make clear....but the carbon travels from the butt of the neck THROUGH the headstock transition and into the headstock. I used to manufacture composite aircraft propellers so molding this is basically nothing. I can mold whatever shape I want. this neck looks like wood, and it is, but you are only looking at a fairly thin veneer.

The neck is RIGID. No truss rod here....except for the intensely stiff carbon.

The frets were LEVELED on the cnc machine at the same time the scallops were cut. This became the finest, most accurate playing surface I'd ever touched.

Any questions on these pics I'll answer.

The process of building this will be nothing like you've ever seen before. Before the final cuts I have a glued block with EVERTHING in the neck...in the block. The position markers, the fretboard, the carbon part (of course), the logo....it's all glued into the block.

Once the two last cuts are complete (top and bottom) the whole thing is done and ready to finish and fret.
Author:  Durero [ Tue Aug 24, 2021 4:56 pm ]
Post subject:  Re: Massive project - custom molded carbon fiber inserts.
Wow this is spectacular instrument design and use of CAD/CAM/CNC workflow!

Super inspiring! Thanks for the descriptions and photos.

Your fixtures always make me drool with envy!
Author:  Chris Pile [ Tue Aug 24, 2021 6:15 pm ]
Post subject:  Re: Massive project - custom molded carbon fiber inserts.
So all you have to do is polish out the frets once you've machined the neck?
Author:  Jim Watts [ Tue Aug 24, 2021 6:37 pm ]
Post subject:  Re: Massive project - custom molded carbon fiber inserts.
Having molded a lot of carbon fiber myself, that's a super job! Very nice work.
Author:  rbuddy [ Wed Aug 25, 2021 9:21 am ]
Post subject:  Re: Massive project - custom molded carbon fiber inserts.
Now that is interesting! And it looks great.

Like everything else in stringed instruments, maintaining the balance of materials and how they play together makes for the happy life of an instrument.

I see a beautiful neck that should be super stable, then the gazillion questions creep in.

I guess the biggest one is is how do the solid wood "veneers" and the CF play together on that scale? CF reacts (I assume) to temperature and wood to RH. So the first question I'd have is, have you subjected a completed neck to the range of temps and humidity's a guitar can be expected to experience, and did they play well together?

Thanks for posting, very interesting and nice work.
Author:  Stuart Gort [ Wed Aug 25, 2021 5:06 pm ]
Post subject:  Re: Massive project - custom molded carbon fiber inserts.
Jim Watts wrote:
Having molded a lot of carbon fiber myself, that's a super job! Very nice work.


Thanks. I was considered an expert in my little field of composite aircraft propellers. Did a lot of aerospace projects. I like to think I took everything about that with me into guitars. I certainly mold the hell out of carbon. Of course, I don't have to design guitars to be aerodynamically superior to a Flying V....but they probably are....subconsciously.

One of the Lockheed projects...I made the props on that. there's the mold. That one was bladder molded.
Author:  Stuart Gort [ Wed Aug 25, 2021 5:21 pm ]
Post subject:  Re: Massive project - custom molded carbon fiber inserts.
Chris Pile wrote:
So all you have to do is polish out the frets once you've machined the neck?


That's it! ...and sand and finish. but yes...that's the objective. Let the machine make the action. It's just more accurate. Especially when a complex contour is desired.

In practice one would always still level the frets but it would take mere moments...and it would be more as a check against the machine.

The one I did first took about a minute per fret of sanding with 800 and then 1500 grit....I can program it to probably only need the 1500. Just takes longer on the machine. You have to go over the top a few times at different angles to get it particularly smooth.
Author:  Jim Watts [ Wed Aug 25, 2021 10:07 pm ]
Post subject:  Re: Massive project - custom molded carbon fiber inserts.
Stuart, that's super nice. I've done things from honeycomb cores for leading/trailing edges and helicopter blades to medical/recreational products out of carbon. Even made a pair climbing boots out of vectran and a highly toughened resin that went up K-2. This was many years ago and miss it dearly. I like seeing your stuff, it takes me back to good times.
Author:  Durero [ Thu Aug 26, 2021 2:26 am ]
Post subject:  Re: Massive project - custom molded carbon fiber inserts.
Your work is utterly fascinating Stuart.

I have no experience at all with carbon fibre moulding but your posts make me dream of exploring it.

Love to hear more about your new frets production methods.
Author:  Stuart Gort [ Sun Aug 29, 2021 10:35 am ]
Post subject:  Re: Massive project - custom molded carbon fiber inserts.
Durero wrote:
Your work is utterly fascinating Stuart.


It's a "what if" thing. I have the time and equipment to explore ideas in my retirement. I thought I would retire at 50 and build guitars...but it's really just been more R&D over the last 15 years. I've built 21 playable guitars (four distinctly different models) and have enough very good bodies and necks to assemble another 40 or so.

The real interesting stuff for me are experiments.

In my life I've made 1000 test pieces or tiny molds to research various ideas. I had a business and paid machinists to create these things for me until the day I got royally screwed for about $16K by a machinist. The next day I put down cash ($85,000 on a new Haas VF4 - and $20,000K for Solidworks and Mastercam, and $100K down on a house to put it in) and I didn't know ANYTHING about how to use any of it.

That was the biggest risk I ever took and the best payoff after I won the bet. Changed everything. In a few short years I was making the best propeller molds and automation tools in the business. My business flourished after getting full creative control under my roof. I bought four large cnc machines shortly after that.

I mean....check the heated, pneumatic press built for fretboard gluing (for one model). Can't do that without the machines and cad/cam. You can sort of hokey it out but you can't make a seriously precision device of this nature without the machines. It applies pressure down EVENLY all over the glue area. Use the correct caul in the press and you can't get more even pressure. Once this proves out (it did) I make it out of aluminum....If I want repeat production. I'm never going to make one because I'm not into production...but I built every guitar and its tooling with production in mind.

My biggest kick is telling you....and having you say that you became interested in a subject based on my posts. That's a real satisfying compliment. Thanks.
Author:  Chris Pile [ Sun Aug 29, 2021 8:03 pm ]
Post subject:  Re: Massive project - custom molded carbon fiber inserts.
What's the wall thickness on your CF neck forms?
Author:  Stuart Gort [ Mon Aug 30, 2021 7:33 pm ]
Post subject:  Re: Massive project - custom molded carbon fiber inserts.
Chris Pile wrote:
What's the wall thickness on your CF neck forms?


It can be whatever I like. I'm wrapping multiple layers of thin uni-directional pre-preg carbon tape around a silicone tube and inflating it inside a sealed, heated aluminum mold.

If I wanted I could add strips or little rolled up sticks into any area that needs more material. The pressure is 150 psi and as soon as is gets warm it all melds into one homogenous cross section.

To go further with this I can build custom shaped silicone bladders and then control to a much greater extent cross sectional placement of the fiber and the shape of the cavity. That WOULD change the thing acoustically. Not that I know now what the cavity should be shaped like...but changing the shape of the cavity will alter the tone.
Author:  Chris Pile [ Mon Aug 30, 2021 11:33 pm ]
Post subject:  Re: Massive project - custom molded carbon fiber inserts.
It doesn't take much carbon fiber to reinforce a neck. You don't think they are over-engineered a wee bit? (not that I'm complaining.....)
Author:  Stuart Gort [ Tue Aug 31, 2021 11:15 am ]
Post subject:  Re: Massive project - custom molded carbon fiber inserts.
Chris Pile wrote:
It doesn't take much carbon fiber to reinforce a neck. You don't think they are over-engineered a wee bit? (not that I'm complaining.....)



Think about propellers. Better over engineered than under.....then....in testing...take out material uniformly to find the stress risers.

Now....there's a thing called ANSYS...which is a software engineering package where I can take a computer model, input all materials, and then simulate all kinds of loads...static or dynamic. So...when you get good testing data you stick it in there...and when you do that enough and get more testing data (real empirical data) into the software it just gets better and better at producing real world results. I almost pulled trigger on that...as a critical tool necessary for my business to reach the level of true "aerospace" capability. The blimp project is as close as my stuff got to "space"...but a propeller operating at a constant -120F (that's at 60,000 feet) is not slouch stuff.

So the issue (for me) on a neck is NOT engineered lightness but rather engineered rigidity...of which I cannot imagine "overkill". Simply put...the more rigid...the better...unless you WANT to bend the neck as a stylist. Then you'll want to engineer a bending capability, which can be done easily through iterations using various materials. In that case I'd probably use S-glass instead of carbon and then vary that fiber load. The design architecture and molding process allows for any type of fiber to be used in any amount required for whatever load...without altering the mold.

If I want relief in a neck...I put in the design and then design for RIGID. I've not needed any though. I built everything rigid and flat (no relief) and they've all played spectacularly. I have four guitars playing at my house with no adjustable truss rod. They have given me the confidence that an adjustable rod added to this concept is foolishness.

Of course, this leaves out the entire rest of the guitar building world since anyone that touches the instrument after production will probably not understand it. Standard methods of observation and repair are likely to mess up the things I put into it...but I have only 19 guitars out there in the hands of strangers and most of those are normal guitars with truss rods.

This is just a quest for playing action and molding experience....not sales. :) I quest. I gain XP. I level up. :)
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