Ken McKay guitar build log for OFC

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by dotmkr, Mar 14, 2014.


  1. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    I thank you again for your attention and once again I would like to point out that this is for Cliff who is a powerhouse in the guitar boutique and amplifier business


    Sent from my iPhone using Tapatalk
    Ken
     
  2. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    I think Dan from Henriks Guitars will stop by the thread to share some insight soon. I highly recommend Dan if you need CAD services.


    Sent from my iPhone using Tapatalk
    Ken
     
  3. Madureira

    Madureira Member

    Messages:
    41
    Joined:
    Apr 7, 2011
    I guess that this is the time where I chime in.

    Dan here, from Henriks Guitars.

    As Ken mentionned, this was a very interesting project that started with the idea of reverse engineering the plaster molds that were used to create the laminated plates.

    These molds wear out after a few times of laminating the plates, so Ken wanted to find a way to reproduce these molds consistently and more importantly reducing the time needed to make them.

    I work in a manufacturing context, using CNC's and laser scan machines to achieve similar results, although for other applications in the automotive world.

    Technology has advanced quite a bit, and these days we can laser scan a piece within 0.001mm (yes, you read well...a thousandth of a millimetre) tolerance and with relative ease create what we call a "skin", or surface that will be almost a perfect match to the actual part we want to recreate in 3D CAD format.

    Now, here's the problem...this technology costs a lot of money. So, we had to find an alternative.

    We transformed Ken into a human laser scanning machine. Basically, we laid out a grid of 1/2 inch pitch onto the original mold that Ken had, and then measured the depth at each intersecting point.

    This is how the coordinates looked when Ken send them.

    [​IMG]

    Now, how in the world all those coordinates will eventually become a 3D model of a 335, you ask?

    Keep on reading.
     
  4. Madureira

    Madureira Member

    Messages:
    41
    Joined:
    Apr 7, 2011
    Now, here's the cool part.

    I work with a software called CATIA V5. There are a few functions that were created within this software, that are specific for working with digitized parts. That applies to millions of points created by a real laser scan machine, or just a couple hundred - like the ones Ken did manually.

    So, after figuring out how to import those coordinates into the software, here's how it looked.

    [​IMG]

    The actual 335 contour was imported as well to have a reference to position the points.

    Then, using a technique called "best-fit", I created a "skin" that remotely resembled a 335 shape. This "skin" is basically a mathematical approximation of the point cloud created by Ken.

    [​IMG]

    Then after a bit more tweaking, finished looking like this:

    [​IMG]

    Awesome, you say? Yes, pretty interesting and most important quite a few hours of work. This isn't an exact science, and getting a proper "skin" that looks smooth and close the the reality is FAR from being a straightforward process.

    So, I decided to go to the next level and really create a mathematically correct surface.

    At this point Ken introduced me to the incredible world of curtate cycloids, these wonderful beings that live inside the head of great luthiers like Amati, or Stradivarius families.

    How are these luthiers related to a 20th century guitar like a 335?

    Good question, hein?
     
  5. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    Thanks Dan for chiming in that is fascinating work.
    Having the model allowed me to change things quickly.
    Keeping the same geometry in regards to neck projection, string length and a few other factors was an important consideration in altering the design for specific a purpose. So from the bigger design of the original plaster cast I wanted a slightly smaller guitar and I wanted the neck to join the body similar to a Les Paul standard.

    This kind of thing is easy if the arching in the upper bouts is flat. However I wanted to retain the interesting arching that I saw in early designs of the 50s golden period.

    So together we used mathematical methods to create the arching. That brings us to curtate cycloids.
    This is a crosswise arch that infinitely changes from the base to the neck.

    It's not fuzzy math or modern computer math. It's an old method that can easily be drawn using very simple tools. I'll put a link up.
    But even as a child I remember using this method. Basically if you imagine a button being rolled along a straight edge with a pencil in one of the holes as it moves along it will draw cc curve.
    There is a lot of evidence that stradivari instruments are arched with this type of curve. In fact all of the Golden age of violin making arching looks similar.




    Sent from my iPhone using Tapatalk
    Ken
     
    Last edited: Apr 5, 2014
  6. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    [​IMG]
    So back to the guitar at hand.
    The above picture shows the contour brace.
    A contour brace fills the entire space between the underside of the plate and the center block. This is from a different guitar. just for illustration.


    Sent from my iPhone using Tapatalk
    Ken
     
  7. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    [​IMG]
    I now need to create a jig to cut the contour brace shape it and glue it in place.
    The actual geometry of the brace is taken from the plan and the jig is created.
    The little strips of wood represent the outline of the brace.


    Sent from my iPhone using Tapatalk
    Ken
     
  8. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    [​IMG]
    They are glued in place with the exact dimension of the actual brace between them.


    Sent from my iPhone using Tapatalk
    Ken
     
  9. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    [​IMG]


    Sent from my iPhone using Tapatalk
    Ken
     
  10. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    [​IMG]
    [​IMG]
    This is the actual contour brace material. It is Sitka Spruce of High quality I believe this element is a central in creating the slightly opened, punchy yet sustaining tone I'm after. It has to fit right and has to be high-quality. Then when it's glued tightly to the center block it creates a tone that no other guitar can replicate without using this exact method. So if there's a secret I just let it out-of-the-box.

    This one block will create two braces. One for the top and one for the back.

    You can see that there are kerfs or grooves running lengthwise down this brace on the top and the bottom I do this on the tablesaw. The purpose of the curves is to allow flexibility so the brace can conform to the side to side arching. The long wise arching has to be nearly perfect though. It is slightly flexible but a perfect fit is ideal.


    Looking at the jig, you can see that there are two sides. The top will need to be shaped slightly different than the back this is not a symmetrical design.

    I don't have a really good picture yet for the rest of this. I spent a lot of time making this jig and I just plain ran out of time so that's it for today.
    Next I will show you how I cut the contour brace glue it in place and make it level.


    Sent from my iPhone using Tapatalk
    Ken
     
    Last edited: Apr 5, 2014
  11. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    [​IMG]
    Thanks for looking and I'll update as soon as possible


    Sent from my iPhone using Tapatalk
    Ken
     
  12. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    [​IMG]
    [​IMG]

    This is how we did the grid.
    the original cast is shown. The grid are depths and the lines for horizontal and vertical X-y-z for each number.
    After helping me with the transcription my expert assistant and chief apprentice was so over come by joy (that he was finally finished) that he nearly forgot about the 13 dollars he was paid for the work.
     
  13. Barkster

    Barkster Member

    Messages:
    25
    Joined:
    Feb 14, 2014
    Lol, So you mean if I offer Thomas money I may get him off the video games for a while?
     
  14. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    Hah, only if he needs new video game $.
     
  15. Madureira

    Madureira Member

    Messages:
    41
    Joined:
    Apr 7, 2011
    I'm back with a little more insight of how the idea for this guitar eventually came to life.

    So, after many hours of modelling and head scratching Ken came up with the idea of using a kind of singlecutaway neck on the Sunrise 16. The idea was having a 335-ish guitar that played like the familiar single cutaway. .

    Or was it a single cutaway that played like a 335-ish...? I don't exactly remember. What I do remember is that we started trying out different ideas, and the final result looks like this:
    [​IMG]


    Notice the compairison between a 335 and the new Sunrise 16 - green contour. (16 being the fret number where the neck meets the body). Also notice the difference in size, the Sunrise 16 being a bit smaller than a vintage 335.

    Then, after a while, and many clicks...here's the final result:

    [​IMG]

    [​IMG]

    At this point i'd like to add that the CAD files where a very powerful tool in order to visualize the final result. As you can all see from the build along, Ken does his instruments the old fashioned way. Manually. With personality. With love. Ok you get the point.

    This was a real challenge for me, and a great endeavour. Ken and I eventually continue to develop new ideas, so stay tuned!
     
    Last edited: Apr 8, 2014
  16. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    Thanks Dan you do good work and I know this modeling is not easy. In fact it takes technical and artistic ability.

    I am trying to get up to speed in the digital world but it is a steep learning curve and I trust my eyes, fingertips and sharp tools which have been with me for so many trials and tribulations.
    When planing some plastic binding, the other day, I realized I even relied on my sense of smell for determining if I was going to fast.
     
  17. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    [​IMG]
    [​IMG]
    Load up the brace material into the sled.
    [​IMG]



    Sent from my iPhone using Tapatalk
    Ken
     
  18. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    [​IMG]
    And saw it off. The contour brace remains in the sled and the cut off gets moved to the other side where it can be sawn off also.


    Sent from my iPhone using Tapatalk
    Ken
     
  19. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    [​IMG]
    Sand to the pencil line.
    And observe.
    [​IMG]



    Sent from my iPhone using Tapatalk
    Ken
     
  20. dotmkr

    dotmkr Member

    Messages:
    487
    Joined:
    Oct 9, 2012
    Location:
    Northern Michigan
    [​IMG]
    I should be able to come up with something useful for the cut off. Any ideas?


    Sent from my iPhone using Tapatalk
    Ken
     

Share This Page