Elliptical cross-section body for T-formed "Quilted" acrylic

[StratsRdivine]

So this is my first "real" build after my foray into the land of make believe (as many of you likely think) when I modded a squire with my thermoformed acrylic face called the "Dichrocaster".  

I am teaming up with a very well respected local luthier to make my necks and bodies for the next few guitars, and want to make his job a bit easier considering my non-traditional approach.  

My big questions are about using a type of elliptical cross section to the body design for two reasons:  Lessen the weight of the guitar to counter for the 1/4" acrylic face, and to add another dimension of light refraction off the quilted face.  I really have not seen guitars with this type of slimmed down cross section, so there must be an obvious reason (I am only two months old in my guitar building obsession, so don't know a lot yet).    

The central part of the body will be 1-3/4" thick in wood section, 2" thick with the acrylic face, therefore the top and bottom edges and the horns will be significantly thinner.  Horns may actually be delicately thin, like about 5/8" average, getting thicker closer to body center -need input for that reason.  

Wondering also if they make shallow switches to accomodate for a depth of only 1" or maybe less, unless I move the switch closer into the central thicker part of the body.  

See initial diagram, which is directed to my luthier, but you get the picture.  Pic of Dichrocaster attached as well, so you understand the "acrylic face" concept. 

The other question is whether to mount the humbuckers to the wood body, and cut the acrylic out around them, or (easier way) to mount them to the acrylic face with swimming pool rout (which is essentially a giant pickguard, the way pups are mounted to strat PG's).  

Remember, I am real new to this, and don't always see the obvious.  

 

[charisjapan]

Okay, so an "Ovation" strat! 

SRD, I think the concept is valid, but maybe the ergonomics won't work very well.  I'm not an expert by any measure, but my own take on the strat (and I love most everything about them but the scale) is that the tummy cut and the arm contour combine to give a "wraparound" feel, a "snugness" that would be lost with your design.  To me a strat needs that flat back to make the contours work.  If weigh is one of your major concerns, then the easiest way is to do some weight relief under your "cap."  Or ... thin the whole body 1/4~3/8".  One of the nicest strats I ever held was an early MIJ, total body thickness was 1-5/8" and the tummy cut and arm contour were more aggressive than any I have experienced.  It was factory original ... kind of like a Japan market Custom Shop.  Lightweight and drop-dead gorgeous. 

... just my thoughts.

[curtisa]

Have a look at the Ibanez S series. Your elliptical body cross section idea is very similar to theirs.

[StratsRdivine]

Great Response - thanks!! 

I did chamber out the Dichrocaster with a 1" spade bit with with ground down point.  Removed a whole 5 oz after an hour.  I do love the bevel coupled with the tummy cut - great wrap feel and contour, but I am limited due to the fact that acrylic only bends easily in single dimensions.  I really thought about the convex thermoform AND a bevel, but that would require high oven heat, and lots of post form leveling / wet sanding / buffing, but will try it anyway sometime.  The thinning out at top is "functioning" as my bevel, and it will have some tummy contouring.  

Thanks, Curtisa, for the Ibanez S series tip.  I looked them up, and they are carved alot, for thin edges.   This thread about their thin profile - http://www.harmonycentral.com/forum/forum/guitar/acapella-41/1110211-  debates the thickness / tone issue a bit, as well as shallow switch routs.  My design is along these lines in that the thicker, solid area is in the central middle section, giving you the tone / sustain needed (whatev that comment is worth).  Right now its 1.75" thick in the wood only, 2" with acrylic. I am happy with 2" of wood in the center, 2-1/4" with acrylic face, then tapering edges to reduce weight, plus some chambering. 

 

So yeah, CJ, I think its an Ovation in reverse!!! 

 

 

[Andyjr1515]

Clearly great minds think alike.  I have on my drawing board my next project.  Very similar top profile, but similar curve on the back too!  My customer is looking for  "a contact lens cross section profile".  I'll drop some shots when I'm back on my desktop.  

I've done similar shaping on various projects and concluded that there really are no restrictions other than assuring enough depth for the hardware, pickups, etc..

I'll be looking at your progress with great interest - it looks a nice design

[Andyjr1515]

This is my cross section:

See what I mean about contact lens? 

When I get round to it, I'll pop a thread on the Design area about some of the plus's and minus's and practical issues I've come across - particularly when concaving the back.  For all that, I think the look can be great and they are amongst the most comfortable to play.

I think the same will go for yours: you get arm relief - at both sides - for free   I look forward to seeing it develop.

[curtisa]

On 3/7/2017 at 9:45 AM, StratsRdivine said:

Remember, I am real new to this, and don't always see the obvious.  

Only just realised the CAD drawing had comments all over it (duh), and maybe you were after pointers.

MHO of course. Take it as you like:

• Bring the volume and tone pots closer to where the picking hand normally rests. Positioned behind the bridge makes them awkward to reach, particularly if you install a tremolo and have the player reach over the arm to get to them. Keep the selctor switch nearby too.
• Consider the practicalities of the eliptical cross section through the length of the body. If you make the cross section constant, the edges will be thicker where the width of the body is narrow. If your goal is constant edge thickness, the radius of your eliptical cross section will need to reduce around the narrow part of the body to maintain the edge.
• Pending your decision on the above, the acrylic sheet will be easier to thermoform to the body if you're only dealing with one curve (constant eliptical cross section). Trying to get the sheet to constantly changing curves may be challenging (constant edge thickness).
• Blade switches tend to be made with only one target audience (Strats or Teles) and the dimensions will not vary by much. If the carve is too deep to make fitting a blade switch practical your only choices are a different switching method, moving the switch to a thicker area of the body or reducing the aggressiveness of the curve to leave more depth for the switch to fit. Same goes for the jack socket.

[Andyjr1515]

For anyone interested, and to avoid hi-jacking @StratsRdivine's thread, I've kicked off a thread in the Design Bar here Concave Bottoms and Related Obsessions 

[kmensik]

My last build looks just like your drwing. It came from the Ibanez S principle, but went half way only with the carving. I made two S bodies before handling the tasks you are asking about. Those very thin japanese sabres use a lower profile OTAX VLX91 switch.

 

[StratsRdivine]

Super nice responses - Thanks everyone!  

10 hours ago, Andyjr1515 said:

 

I've done similar shaping on various projects and concluded that there really are no restrictions other than assuring enough depth for the hardware, pickups, etc..

I came to the same conclusion - one must know their limitations, therefore knowing this rather open design envelope allows tremendous freedom.  I saw a video on pickguard guitars (solid body, exactly the size of a Strat pickguard) and th guy compared tone against a real strat - he couldnt tell the difference.  However, I love the visual sexy lines of a thinned down strat body. 

I will follow your lens design as well.  Carving the inside radii appears to be a PITA.  Lots of gooseneck scraper work, or I will have to let you borrow my huge 8" DIA pneumatic drum sander.  

9 hours ago, curtisa said:

• Bring the volume and tone pots closer to where the picking hand normally rests. Positioned behind the bridge makes them awkward to reach, particularly if you install a tremolo and have the player reach over the arm to get to them. Keep the selctor switch nearby too.  My guitar tech likes them behind the dials, and I didn't agree for your same reasons.  
• Consider the practicalities of the eliptical cross section through the length of the body. If you make the cross section constant, the edges will be thicker where the width of the body is narrow. If your goal is constant edge thickness, the radius of your eliptical cross section will need to reduce around the narrow part of the body to maintain the edge.
• Pending your decision on the above, the acrylic sheet will be easier to thermoform to the body if you're only dealing with one curve (constant eliptical cross section). Trying to get the sheet to constantly changing curves may be challenging (constant edge thickness).  Totally foresaw all that, which is why I am still going to have a slight tummy cut on top.  I plan to make a form that is perfectly cylindrical (20" radius), and thermoform the whole panel (24 x 30") prior to laser cutting.  Compound radii won't work at all on 1/4" (6mm) acrylic.  
• Blade switches tend to be made with only one target audience (Strats or Teles) and the dimensions will not vary by much. If the carve is too deep to make fitting a blade switch practical your only choices are a different switching method, moving the switch to a thicker area of the body or reducing the aggressiveness of the curve to leave more depth for the switch to fit. Same goes for the jack socket.  Confirmed - thanks. 

 

5 hours ago, kmensik said:

My last build looks just like your drwing. It came from the Ibanez S principle, but went half way only with the carving. I made two S bodies before handling the tasks you are asking about. Those very thin japanese sabres use a lower profile OTAX VLX91 switch.

 

Gotta look up that switch.  My radius is 20", BTW.  I plan to use my jointer for most, then hand plane, then the back of my belt sander (unbacked part will conform to the curve - hitting high spots only - most of you know what I mean)

Here is a preview of the "Faux" quilted pattern in the acrylic.  My updated design actually has facial imagery within the quilt pattern, that will appear like the guitar has eyes looking at you.   I patterned the quilt based on photos of actual AAAAA quilted maple, but then it struck me that I actually have design priority to change it up a little, so the quilt is mostly hand drawn to emphasize vectoring, facial imagery, and some other tricks that will be seen when done.  Going with bookmatched figured maple in the fretboard as "homage" to the real, next to the "faux".  

[StratsRdivine]

So here is the first casting of the "quilted" acrylic.  I strafe-coated the topography - gold from bottom, silver boro from top.  The two tone effect is not lighting - its actually gold on one side of the "quilt billows" and silver on the other side.  

 

[Andyjr1515]

That's remarkable....

[StratsRdivine]

Just cast another panel with the quilt mold.  This time I sprayed the same colors as the Dichrocaster in the opposing strafe spray effect.  Blue2Red boro from bottom up, and Red2Gold mica from top down.  I left the clear poly masking on the acrylic in the large pic, but smaller pics are without the masking.  As an idea of scale, a full guitar body could fit in the whole frame of first pic (which, BTW, is the whole point of even making these panels).

 

 

[Norris]

<Drool>

[StratsRdivine]

Enough of the sample panels.  Now just cast the 1/4" thick ones for the actual guitars.  Did a fade burst after spraying the silver and gold boro.  Thermoforming Friday, then laser cutting the faces with pups and electronics openings prior to scribing / fitting / flush trimming / polishing them to the basswood bodies.  

[Prostheta]

How the hell did I miss this?

[StratsRdivine]

 

57 minutes ago, Prostheta said:

How the hell did I miss this?

Maybe I should change the title of the thread to "Completely new and original category of guitar design that you will either love or hate"  

[StratsRdivine]

So my thermoforming test just ruined the quilted acrylic.  unreacted monomers from a coloring agent in the "backfill" hit vapor point and bubbled the perfect metallic.  The test panel formed great, but it had been sitting in my rack for about a month.  Need lots of patience dealing with polymers.  

Todays test panel of my tropical fish inspired mold worked out good.  I was going to wait til my new pigments arrived in the mail to cast it (Lamborghini Orange Metallic) but the candy is on backorder.  Tested anyway using pearls and rattle can yellows and reds.  Glad I did the test casting cuz I need to rework the mold, and change my masking procedure.  

I think I'm more excited about this one rather than the gold quilted one.  

 

[StratsRdivine]

So I got pissed off at the bubbling that occurred during thermoforming yesterday.  Turns out it was a good thing, because when I get mad, I reach deep, pray, and turn it up to 11 in my resourcefulness, and kick the problem's ***.  

I hurried up and cast a new panel, mixed my "paints" and sprayed a waaayyyyy better panel.  The burst is better, (two blended shades), and sprayed gold until the gun emptied to really enrich the effect.  

I lasered the bad thermoformed panel anyway and rounded and polished the edges as a sample panel to give to my luthier for test fitting.  

Compare the panels - the new one with masking removed on the right has much better depth due to the better burst and the heavier gold.   Then I discovered a wonderful new effect from polishing the teardrop roundover - the refraction line.   

 

[Prostheta]

That's the way to be, John. Some cope with adversity, you seem to take it around the back of the chemical sheds to get the beating of its life! Truly exceptional stuff.