[Kosh]

Time to start making the body.

Here are my bending forms, which were derived from the outline of the the guitar in the CAD model. They are actually reduced in size (offset from the outline) by the
thickness of my bending stack (sides, heating blankets, etc). The idea is to get them bent as accurately as possible to the desired model. These are used on the LMI bending machine, which is a derivative of the Fox Bender.

Attachment 353654

They bolt together in the exactly the same fashion as the ones you can buy from LMI.

Attachment 353656
Attachment 353658

Some pictures of the LMI bender in action

Attachment 353668
Attachment 353670
Attachment 353672

And then I have a body mold and cauls, all derived from the same CAD model. The difference between the mold and the caul is precise to account for the typical side thickness that I bend at (0.110")

Attachment 353660

The mold also mounts onto an "assembly platform" which has UHMV plastic inserts under the head and tail block areas. This way, I don't need to worry about glue squeeze
out sticking to it while assembling the ribs. This assembly platform is also indexable on the CNC machine (has a "zero" locator hole in it) for latter machining.... that will be another
post.

Attachment 353662

The molds are in single layers, and can be stacked with spacer to obtain any desired thickness for side support. More on why that's important later.

Attachment 353664

[warrenb]

Great work. I've been designing (ukes guitars cnc systems), setting up, building (jigs fixtures ukes guitars etc) selling, and installing CNC luthiery systems for about 10 years now. Your rig is very professional and well done. Thanks for sharing. I like the inlay trick. Some of my customers are completely phasing out lasers for inlay. One product I have had luck for holding inlay with is mitee-grip sheet wax. A simple hot plate and flat sheet of AL is all your need. A bit expensive but I like avoiding CA glue whenever possible. Some day I'll get my systems online posted...

[Kosh]

Great work. I've been designing (ukes guitars cnc systems), setting up, building (jigs fixtures ukes guitars etc) selling, and installing CNC luthiery systems for about 10 years now. Your rig is very professional and well done. Thanks for sharing. I like the inlay trick. Some of my customers are completely phasing out lasers for inlay. One product I have had luck for holding inlay with is mitee-grip sheet wax. A simple hot plate and flat sheet of AL is all your need. A bit expensive but I like avoiding CA glue whenever possible. Some day I'll get my systems online posted...

thanks warren. Why are they phasing out lasers? I had been looking at lasers as a way to get smaller details than you could with CNC bits.

[Kosh]

I also CNC the head a tail block. Since I'm using an articulated tripod mounted neck, it doesn't need to be a thick head block like for dovetail or M&T joints.

So I use high quality birch plywood, the stuff with like 15 layers to a 19mm thickness. I machine it out of a large piece, which is much safer than trying to run dados, etc
on such a small piece.

Attachment 354004

Attachment 354006

Attachment 354008

Chamfering off the fuzzies...

Attachment 354010

I also have it bore me tapered and pre-threaded holes for the threaded inserts that hold the set screws.

Attachment 354012

Attachment 354014

I have these in a linear pattern so if I ever wanted to get serious about production, I could just do an entire batch of them at once.

Attachment 354016

Attachment 354018

Attachment 354020

Attachment 354022

Attachment 354024

Here is one of the contact points that goes in the heel for the set screws to bear against.They have a concave radius surface to help capture the set
screw and keep the neck from rotating about the axis of the bolt that holds it on. I had these custom made by smallpartscnc.com and bought them in a batch of 30 to keep the cost per unit down. That's enough for the next 10 guitars.

Attachment 354028

Attachment 354026

And of course, I also CNC the heel block at the same time.

Attachment 354030

[InMesh]

It is a great Idea the neck block fitting I think some guitars get over engineered .That birch ply I believe has a greater strength than most woods ,we used to have a high end ply manufacturer and seller here in Aus gone now they had two sided micro ply nice bendable stuff for the sides sad to see them go .

[Kosh]

Ok, just trying wrap up all the CNC work before I start bending sides and putting the body together (tomorrow!).

First, I made the headblock "slider", which is a part that goes onto the headblock. It is really there for easy installation of the carbon fiber "axial" brace that I put between the
headblock and the tail block. So I CNC'd this and decided to get all fancy and make it all rounded, since I can now that I'm not making it by hand.

I'm cutting this with my new compression bit from toolstoday.com

Attachment 354518

Attachment 354520

Attachment 354522

Attachment 354524

So here is it removed from the matrix and final sanded.

Attachment 354526

As you can see, it "slides" in the dado on the headblock. the tailblock also has a dado for ther carbon fiber brace, and this just allows me to insert the CF tube into the slider, then side it down into position. Then it gets glued into place.

Attachment 354528

here's the CF tube fit into the socket on the slider.

Attachment 354530

[Kosh]

And now it's time to make the internal blocking for the beveled armrest. I'm using Kent Everetts approach here, (his DVD is well worth the money to learn how to do it).

But i automated it, of course. I'll have the CNC machine cut the profile on the guitar sides as well, but for now, here is the blocking being cut so that it is a perfect match to the sides:

I'm using nice birch ply for this for the first time. I think it will be better than solid wood for short grain situations and nobody willl ever see it. It's easier to get a piece big enough for the whole curve that.

Attachment 354532

Attachment 354534

Attachment 354536

And here it is removed from the matrix and cleaned up. The tabs don't even need to be removed, the outside ones will be gone after I bevel it, and inside can be cleaned up but aren't really significant.

Attachment 354538

Attachment 354540

[bostosh]

Nice work, good post, Have you done the soundboard top yet? I am interested in doing an integral bracing and board design..

[Kosh]

Nice work, good post, Have you done the soundboard top yet? I am interested in doing an integral bracing and board design..

Jointing plates today! Trying to decide if I have time to work through my ideas for cnc'ing the braces

[InMesh]

Kent Everett has some pretty good Ideas that's for sure .We have a Company here just up the road Cole Clark Guitars that use a fully machined braced top on their Aus wood guitars .I have always liked the Idea of arm rest guitar short arms jumbo bodies .

[bostosh]

How About it then ? Could I do one for you to test?, Ill duplicat the wood into a billet machinable If you could you get me a 2d cad profile of a board and location of sound hole and bridge. And test feasibility? of design? I'll do it in solids for the usual engineering stuff, things like weight deflection testing etc. I have never done a soundboard but have never built a guitar until recently.
I have to hollow out the backside of this. (pict of master) These guys are sinking 300-400- in wood so they can see what they get. archtop. Also I have a guy carving out cellos to a scan of a 200yr old cello. instruments and CNC ! That wood is astronomical. BrianO.

[Kosh]

How About it then ? Could I do one for you to test?, Ill duplicat the wood into a billet machinable If you could you get me a 2d cad profile of a board and location of sound hole and bridge. And test feasibility? of design? I'll do it in solids for the usual engineering stuff, things like weight deflection testing etc. I have never done a soundboard but have never built a guitar until recently.
I have to hollow out the backside of this. (pict of master) These guys are sinking 300-400- in wood so they can see what they get. archtop. Also I have a guy carving out cellos to a scan of a 200yr old cello. instruments and CNC ! That wood is astronomical. BrianO.

I'm not sure exactly what you're asking for, but I'm already pretty overbooked on commitments and projects.

[bostosh]

Hello,
I just need the outer profile of thr top soundboard, (do you have trimming excess?) Location of bridge and hole, thickness, in DXF or any format. My experience with lightweight flight structures and interest in instruments is begging to improve the guitar. I held a 100yr old $$$ Museum Martin once, and new Taylors and I am amazed at the bridge / deck concavities, I believe that I can do a soundboard which will be superior to existing. and after I laminate a 1/64 veneer no one will know there is featherweight rigid aluminum structure underneath. Installation on a actual guitar will be your choice.
I've been perusing the patents on this subject too.
https://www.google.com/patents/US9165539
OZZtosh LUMA Guitars

[InMesh]

Patents = money for patent attorney I think this is the way to go falcate bracing .

[Kosh]

Patents = money for patent attorney I think this is the way to go falcate bracing .

AL too heavy. Prob better off with a carbon fiber sandwich. I hear rain song doesn't even brace their CF tops.

Think this has all been tried. Ecclesiastes....

[bostosh]

Aluminum when done correctly is equal to maple,in the neck I have, lighter than plastic on the pickguards, and equal to wood on the guitar body. and rigid unlike wood. I can design comparable weight to wood and hit the button and calc the weight of a design. Machine to .025 thickness. deck and structure. ribbing.

I just want to do this and if it is not light enough switch to magnesium.

Carbon fiber sandwich is for expensive flight surfaces, honeycomb stuff.
I have seen alum balsa aluminum flooring, (dc-10)
Carbon needs molds, done too many of those. ovens, vacuum bags real complex.

I guess I'll just get a guitar kit and do it.

Thanks Guys,

[A_Camera]

This is a great thread. While I am not interested in building guitars I love watching your progress and all the special tools and fixtures you are using, as well as the methods you have in your work flow. Nice to see all the detailed images in excellent quality. Thanks for sharing this.

[Kosh]

ok, good progress this week. I've been making sure i get out to the shop each night after work, even if only for an hour or two.

Time to start building a body. I've got an INCREDIBLE set of claro walnut that (IIRC) I got from Oregon Wild Woods (toneswoods.com)

Attachment 355558

I CNC'd some new spacers for the ends of the guitar mold so that I have a totally solid surface to press against when I glue up the
sides to the head and tail blocks and had the molds spaced out for maximum height.

Attachment 355560

The sides being glued up.

Attachment 355562

After I joined the back plates together, I put it on the CNC and ran program to cut the dado down the centerline for the inlay strip/reinforcement. I use the "creep up"
method here. I have a program with the measured dimension of the inlay strip, and then several programs incrementing at 2 thousandths additional each run. So I just
keep running the wider programs until the strip fits snug. This one ended at a total of 4 thou over and a perfect press fit.

Attachment 355564

Then I run the outline contour and leave tabs in it to give it strength until I get the inlay actually glued in (there was only .030" of joint left after the dado! In the future
I plan to have a vacuum based jig for holding the plate while it's cut.

Attachment 355566

Here it is with the inlay strip pressed into place.

Attachment 355568

[Kosh]

And now that sides are together, time to use the CNC for some profiling magic. I actually figured out how to have the CNC profile
the sides for me for the beveled armrest and also the back profiling at 15 foot radius (including the taper from 4" down to 3 1/8" at the headblock.

First I need to center the assembly jig using a long bit so that the Z axis doesn't collide with my sides. In reality, I've saved the work offset of this jig, but I like to double
check it.

Attachment 355570

The first operation just roughs the beveled armrest profile and leaves 3mm in case of tearout.

Attachment 355572

Then the second operation spirals in from the sides with a climb cut to make sure there is no tearout.

Attachment 355574

Here's the armrest blocking I made earlier. It is a perfect fit to the side profile now.

Attachment 355576


In the following pictures I've flipped the mold over so the sides can be profiled for the back. Same approach, a roughing op that tapers the sides from the
tailblock down to the headlock (3/4" drop), it leaves 3 mm, then climb cuts from the side to get a clean cut. After that, I can just glue on the kerfing a little
high and a quick sanding on the radius dish for a perfect no stress fit of the back.

Attachment 355578

Attachment 355580

Attachment 355582

Attachment 355584

It also bevels the head and tailblock surfaces so they match the curvature of the back.

Attachment 355586

Attachment 355588

Attachment 355590

Here's the body mock up!

Attachment 355594

[Kosh]

OK, running of things to do with the CNC but there are a few more!

Today I made the bridge. This is a custom design of my own, it was actually the first thing I designed on the Fusion360 learning curve.

First I made a new vacuum jig for the bridge, since ver 1. didn't have enough room for the z axis touch plate. I made this from more VHMW, but I've decided not
to use this anymore. Unlike the first pieces I used, these came slightly warped. The piece for the new neck vacuum jig was warped in two directions and is not usable.
I contacted TapPlastics and they told me this is typical. So after some research, I'll be making all future vacuum jigs from surplus Corian stock. It is flat and very non-pourus. Plus, it will look like granite! :-)


Attachment 355598

Attachment 355600

First I surface the blank to thickness

Attachment 355602

Then I drill the bridge pin holes and slot for the saddle. The holes don't go all they way through to preserve the vacuum, and also it's easier to
use a vacuum clamp for bridge installation.

Attachment 355604

chamfering the holes and the slot

Attachment 355606

Contouring the bridge outline just to get rid of the excess. I remove it before continuing on

Attachment 355608

Z-axis touch plate for zeroing

Attachment 355610

Roughing the bridge to shop, I lave about 2mm of material

Attachment 355612

Attachment 355614

Then a parallel operation with .005" (.125 mm) stepover for an almost perfect finish. Very little sanding needed.

Attachment 355616

Attachment 355618