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  1. #21
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    Default Re: How I use CNC in acoustic guitar building

    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.

    How I use CNC in acoustic guitar building-img_0468-jpg

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

    How I use CNC in acoustic guitar building-img_0470-jpg
    How I use CNC in acoustic guitar building-img_0471-jpg

    Some pictures of the LMI bender in action

    How I use CNC in acoustic guitar building-img_1103-jpg
    How I use CNC in acoustic guitar building-img_1104-jpg
    How I use CNC in acoustic guitar building-img_1105-jpg

    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")

    How I use CNC in acoustic guitar building-img_0516-jpg

    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.

    How I use CNC in acoustic guitar building-img_0518-jpg

    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.

    How I use CNC in acoustic guitar building-img_0519-jpg



  2. #22
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    Default Re: How I use CNC in acoustic guitar building

    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...



  3. #23
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    Default Re: How I use CNC in acoustic guitar building

    Quote Originally Posted by warrenb View Post
    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.



  4. #24
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    Default Re: How I use CNC in acoustic guitar building

    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.

    How I use CNC in acoustic guitar building-img_2181-jpg

    How I use CNC in acoustic guitar building-img_2182-jpg

    How I use CNC in acoustic guitar building-img_2185-jpg

    Chamfering off the fuzzies...

    How I use CNC in acoustic guitar building-img_2187-jpg

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

    How I use CNC in acoustic guitar building-img_2191-jpg

    How I use CNC in acoustic guitar building-img_2209-jpg

    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.

    How I use CNC in acoustic guitar building-img_2213-jpg

    How I use CNC in acoustic guitar building-img_2215-jpg

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    How I use CNC in acoustic guitar building-img_2218-jpg

    How I use CNC in acoustic guitar building-img_2219-jpg

    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.

    How I use CNC in acoustic guitar building-img_2171-jpg

    How I use CNC in acoustic guitar building-img_2220-jpg

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

    How I use CNC in acoustic guitar building-img_2183-jpg



  5. #25
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    Default Re: How I use CNC in acoustic guitar building

    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 .



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    Default Re: How I use CNC in acoustic guitar building

    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

    How I use CNC in acoustic guitar building-img_2232-jpg

    How I use CNC in acoustic guitar building-img_2233-jpg

    How I use CNC in acoustic guitar building-img_2234-jpg

    How I use CNC in acoustic guitar building-img_2249-jpg

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

    How I use CNC in acoustic guitar building-img_2250-jpg

    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.

    How I use CNC in acoustic guitar building-img_2251-jpg

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

    How I use CNC in acoustic guitar building-img_2252-jpg



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    Default Re: How I use CNC in acoustic guitar building

    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.

    How I use CNC in acoustic guitar building-img_2255-jpg

    How I use CNC in acoustic guitar building-img_2256-jpg

    How I use CNC in acoustic guitar building-img_2257-jpg

    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.

    How I use CNC in acoustic guitar building-img_2258-jpg

    How I use CNC in acoustic guitar building-img_2259-jpg



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    Default Re: How I use CNC in acoustic guitar building

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

    Been doing this too long


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    Default Re: How I use CNC in acoustic guitar building

    Quote Originally Posted by bostosh View Post
    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



  10. #30
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    Default Re: How I use CNC in acoustic guitar building

    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 .



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    Default Re: How I use CNC in acoustic guitar building

    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.

    Attached Thumbnails Attached Thumbnails How I use CNC in acoustic guitar building-imag0331-jpg  
    Been doing this too long


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    Default Re: How I use CNC in acoustic guitar building

    Quote Originally Posted by bostosh View Post
    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.



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    Default Re: How I use CNC in acoustic guitar building

    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

    Attached Thumbnails Attached Thumbnails How I use CNC in acoustic guitar building-us6664452-composite-soundboard-pdf   How I use CNC in acoustic guitar building-skateboard04-jpg   How I use CNC in acoustic guitar building-soundboard-steel-strings-jpg   How I use CNC in acoustic guitar building-soundboard-nylon-strings-jpg  

    Been doing this too long


  14. #34
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    Default Re: How I use CNC in acoustic guitar building

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



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    Default Re: How I use CNC in acoustic guitar building

    Quote Originally Posted by InMesh View Post
    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....How I use CNC in acoustic guitar building



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    Default Re: How I use CNC in acoustic guitar building

    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,

    Been doing this too long


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    Default Re: How I use CNC in acoustic guitar building

    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.

    https://www.youtube.com/c/AdaptingCamera/videos
    https://adapting-camera.blogspot.com


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    Default Re: How I use CNC in acoustic guitar building

    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)

    How I use CNC in acoustic guitar building-img_2261-jpg

    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.

    How I use CNC in acoustic guitar building-img_2285-jpg

    The sides being glued up.

    How I use CNC in acoustic guitar building-img_2286-jpg

    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.

    How I use CNC in acoustic guitar building-img_2291-jpg

    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.

    How I use CNC in acoustic guitar building-img_2293-jpg

    Here it is with the inlay strip pressed into place.

    How I use CNC in acoustic guitar building-img_2296-jpg



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    Default Re: How I use CNC in acoustic guitar building

    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.

    How I use CNC in acoustic guitar building-img_2298-jpg

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

    How I use CNC in acoustic guitar building-img_2301-jpg

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

    How I use CNC in acoustic guitar building-img_2304-jpg

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

    How I use CNC in acoustic guitar building-img_2306-jpg


    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.

    How I use CNC in acoustic guitar building-img_2307-jpg

    How I use CNC in acoustic guitar building-img_2309-jpg

    How I use CNC in acoustic guitar building-img_2311-jpg

    How I use CNC in acoustic guitar building-img_2312-jpg

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

    How I use CNC in acoustic guitar building-img_2313-jpg

    How I use CNC in acoustic guitar building-img_2314-jpg

    How I use CNC in acoustic guitar building-img_2319-jpg

    Here's the body mock up!

    How I use CNC in acoustic guitar building-img_2327-jpg



  20. #40
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    Default Re: How I use CNC in acoustic guitar building

    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! :-)


    How I use CNC in acoustic guitar building-img_2336-jpg

    How I use CNC in acoustic guitar building-img_2337-jpg

    First I surface the blank to thickness

    How I use CNC in acoustic guitar building-img_2340-jpg

    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.

    How I use CNC in acoustic guitar building-img_2342-jpg

    chamfering the holes and the slot

    How I use CNC in acoustic guitar building-img_2344-jpg

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

    How I use CNC in acoustic guitar building-img_2347-jpg

    Z-axis touch plate for zeroing

    How I use CNC in acoustic guitar building-img_2348-jpg

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

    How I use CNC in acoustic guitar building-img_2349-jpg

    How I use CNC in acoustic guitar building-img_2350-jpg

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

    How I use CNC in acoustic guitar building-img_2352-jpg

    How I use CNC in acoustic guitar building-img_2356-jpg



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How I use CNC in acoustic guitar building

How I use CNC in acoustic guitar building