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using CONIC SECTIONS rather than ARCs for neck profiles

Discussion in 'Luthier's Corner' started by frederic b. hodshon, Dec 14, 2002.


  1. frederic b. hodshon

    frederic b. hodshon Supporting Member

    May 10, 2000
    Lake Forest, CA
    None.
    i get much better results with conic sections when modeling neck profiles.

    you can control the end point angle values while changing the shape of the curve with the RHO value of the conic.

    with proper blending into the heel and the headstock, i can get pretty darned close to a 3D scan.

    thoughts?

    f
     
  2. frederic b. hodshon

    frederic b. hodshon Supporting Member

    May 10, 2000
    Lake Forest, CA
    None.
    here's a screengrab of my Pro/Engineer session:

    [​IMG]

    you can see that i used 2 CONIC SECTIONS tangent along the center of the neck and 90deg at the fongerboard corner.

    did the trick!

    f
     
  3. ThunderPig

    ThunderPig Guest

    Dec 15, 2002
    Oakland California
    I'm impressed. I'm using AutoCad R13 and I can't wait to give this a try. My biggest problem is not creating or assembling entities, but accurately measuring the curves of an existing model. I'd be very interested in any info you may wish to share on that subject. I'm not familiar with Pro Engineer, but if it reads DFX and you'd like to trade some guitar and guitar hardware files, let me know.
     
  4. frederic b. hodshon

    frederic b. hodshon Supporting Member

    May 10, 2000
    Lake Forest, CA
    None.
    Pro/Engineer is a solids modeler, a 3D CAD system.

    it can read DXF files, but i only use DXF if i need to export the drawing of the 3D part to Illustrator or some other app.

    i have a couple of techniques that i've developed over time that work really well with capturing complex shapes.

    you definitely need digital calipers to start with.

    private message me about my methods. don't really want to publish them to the world just yet.

    at this point my bass data has been created for specific builders. the info is proprietary and i've signed non-disclosure agreements.

    so, legally i can't share them. sorry.

    it has been a serious learning experience. i've modeled 3 complete basses now in Pro/Engineer. feels like i've gone through an apprenticeship with these builders, while at the same time, i've helped them to fine tune their designs.

    fun time!

    here are a couple of screengrabs of the new Lightwave Systems Saber bass that just hit the streets - i've posted them before, thought this would be a good thread to post them again:

    [​IMG]

    [​IMG]

    and a couple of renderings:

    [​IMG]

    [​IMG]

    [​IMG]

    f
     
  5. frederic b. hodshon

    frederic b. hodshon Supporting Member

    May 10, 2000
    Lake Forest, CA
    None.
    weird, i can't get the images to show up in the post.

    just the links.

    any ideas?

    f
     
  6. ThunderPig

    ThunderPig Guest

    Dec 15, 2002
    Oakland California
    I can understand your point on trading files. I know it's a serious amount of work to just give away. I probably have 50 hours in my model of the Gibson tune-o-matic bridge and tailpiece. The reason I mentioned it is because me and a couple of friends from my CAD class have been have been working on guitars and guitar hardware to create the most highly detailed virtual guitar models as a side project and it's been a lot of fun. I certainly did not mean to dig into your business...I apologize for that.
     
  7. frederic b. hodshon

    frederic b. hodshon Supporting Member

    May 10, 2000
    Lake Forest, CA
    None.
    thunderpig:

    no need to apologize!!!

    i hope i didn't come off harshly. didn't mean to.

    i'll be coming up with a more "generic" design that i can share here and at the MIMF.

    i'm almost done modeling every little component myself.

    the lightwave, especially, has been fun.

    f
     
  8. ThunderPig

    ThunderPig Guest

    Dec 15, 2002
    Oakland California
    WOW F! Your Lightwave renderings are friggin stunning! I'm very impressed, so much so that I feel a new inspiration to do more with my models. You da man.
     
  9. frederic b. hodshon

    frederic b. hodshon Supporting Member

    May 10, 2000
    Lake Forest, CA
    None.
    hey TP!

    thanks for the comments!

    i've spent many a year with these programs, i finally feel like i know my way around them now.

    fun stuff!

    let me know if you want to chat off-line about some of my techniques.

    f
     
  10. frederic b. hodshon

    frederic b. hodshon Supporting Member

    May 10, 2000
    Lake Forest, CA
    None.
    thanks for fixing the image linking Paul!

    much bettah!

    fred
     
  11. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    US-NY-NYC
    hey fred,

    Any idea why the lower bolt on the bass side of the neck is so high up? Seems to me that it would be at least equally low as the lower one at the treble side, or even could be lower, taking advantage of that "point" at the end of the neck.
     
  12. frederic b. hodshon

    frederic b. hodshon Supporting Member

    May 10, 2000
    Lake Forest, CA
    None.
    good question.

    if that hole was moved lower, a different screw length would be required.

    if you notice, in that area on the fron of the neck, there is no fingerboard. just an aesthetic.

    to avoid manufacturing confusion, its better to use the same screws. otherwise, there would be a chance that a longer screw would get assembled, and damage the neck.

    f
     
  13. reachjkh

    reachjkh

    Nov 21, 2002
    Lee's Summit, MO
    since you do such awsome artwork, couldn't you get that drip off of the guys nose in your avatar?

    drives me nuts:p
     
  14. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    US-NY-NYC
    Indeed. Good DFA.
     
  15. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    US-NY-NYC
    What I'd like to see is the whole cartoon - I keep wondering what would be in the text ballons. Is that R. Crumb?
     
  16. frederic b. hodshon

    frederic b. hodshon Supporting Member

    May 10, 2000
    Lake Forest, CA
    None.
    it is indeed Crumb.

    its the cover of XYZ Comics.

    and no talk balloons!

    [​IMG]

    f
     
  17. Woof. Very cool. I use Autodesk Inventor at work. Lot of lofting and sweeping.

    Looks like you just used a loft between two sections? Good idea for a changing section. You could also use some assymetry to gain an even more sculpted profile. Possilbly multiple sections to even go further, and fit the neck better. You could make some truely innovative body shapes also. Do you use any other modelers? I've been playing w/ Rhino even more, allowing some true NURBS based modeling along w/ Inventor's mechanical design features. When I have some time, I'll play w/ some bass designs also. I've got a couple I've done a few of. Plus some shelling for advanced surfacing.

    We just bought a FARO arm at work (Portable Cordinate Measuring Machine) to reverse engineer things, which will make hand models into actual surfaces in the 3D modeling world.

    Manufacturing tools are coming a long way. Way to experiment man!

    BTW, what kind of file formats can you handle? I can make a .sat, .iges, or .step of some parts, and let you see what I've been up to.
     
  18. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    US-NY-NYC
    Man. I admire you designers who can work with surfaces like that. In my engineering I use mostly simple solids, but I know from a few attempts that the stuff you do is not too easy.
     
  19. frederic b. hodshon

    frederic b. hodshon Supporting Member

    May 10, 2000
    Lake Forest, CA
    None.

    from measuring the sample neck i was given, the profile was symmetrical.

    i even asked the builder if he wanted any asymmetry in the loft. he said,

    "whatever you measure from the neck i gave you."

    turned out to be elliptoid, which is what conic sections are anyway.

    so, what i did wound up fitting the neck really well.

    for other area of this bass and others, i've had to these surfacing techniques:

    1. variable section sweeps
    2. bounded surfaces with control point and tangent edge control
    3. swept blends
    4. relations and graphs to control the section shape along the trajectory parameter.

    among others...it can get pretty instense.

    loves it though.

    fred
     
  20. frederic b. hodshon

    frederic b. hodshon Supporting Member

    May 10, 2000
    Lake Forest, CA
    None.
    i can handle all the formats you mentioned and others.

    that would be cool to see what you have done.

    feel free to e-mail them to me...PM me for that e-mail.

    fred