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Transferring 3D objects to paper

Discussion in 'Luthier's Corner' started by Ozzel, Apr 1, 2004.

  1. I recently bought a very nice swamp ash bass body off eBay, for which I am going to craft a neck. Unfortunately, the seller didn't make the body and doesn't have the plans which were used to cut the shape and rout the neck pocket and control cavity. So, before I can begin designing the neck, plus the control cover plate, I need to somehow transfer those shapes to paper, or some other media, which I can then scan into my computer.

    I cannot just scan the neck pocket, since my scanner has a "lip" around the glass, and the body will not lay flat. And I don't want to take a digital picture, as the lens will surely distort, if only a little bit, which could present problems. I did try a rubbing on paper with artist's chalk, but the edges of the wood transferred kinda messy, as you can well imagine.

    I suppose I could just try transferring the measurements into my illustration software. Maybe that's the best way. Any ideas? Thanks.
  2. Measure your neck pocket widths, leave the heel square in your illustration program. Take a carpenter's contour guage:


    (it's a tool, found at any hardware store: consists of a rule with hundreds of metal pins in a straight line that you push into a detail to create an exact dupe of a contour in perfect 1:1...they use them to re-create the profiles of moldings and such for mating parts) they're like 10 bucks for a med. size one.

    then, get your neck profile cut, and take the profile you created, and transfer it to your neck blank for shaping the exact fit. You don't wanna guesswork this stuff...take the slow route. Works great.
  3. Thanks for your reply, Mon Rominee. I understand the first paragraph, but the 2nd isn't so clear to me. After I use the contour scriber, can I then copy the shape to paper, then scan that into the computer? Once I've done that, I should be able to print a line drawing of the neck which will fit the pocket perfectly, then transfer that to a cheap hardwood in order to cut a full-size templete. Am I on the right track?
  4. Yup, on the right track. Make a template off of a trace of the contour made from the guage.
    You can scan the tracing, sure...just didn't know where you were going with it in your illustration program. (was unsure if you were going to CNC your neck blank vs. a scrap wood template)

    Good luck with that! It works very well.

  5. Mon Rominee,

    Yes, I am planning on a neck template made from wood, or some other material which is smooth and easy to cut. Do you suggest something else, or will wood work just fine? I'm thinking maple, which isn't too expensive.

    But your mentioning CNC raises another question. I've heard the term CNC but don't know what it is or what kind of machinery is required for it. Is this a better way to make a neck template? Please explain, and thanks again for taking the time.
  6. Using wood is perfectly fine, but I would almost opt for a lexan, or some composite sheet, as there is less chance of shrinkage...but regular wood, heck, even cardboard is more than sufficient. When I said "take it slow" is that you can rough the initial shape of course, but fine, baby-steps always gets the better fit... sand a little, check, sand more....

    As for CNC, and my comments re: it, CNC is a "Computer Numeric Control" machine. It is used in conjunction with raw-text, or drafting/illustration programs to produce a myriad of things, from guitar parts to engine blocks, to p.o.p. makeup displays...endless uses. I use (in my spare time)multi-tool, multi axis CNC's (I program them here at EAW) to cut personal body styles, and neck blanks, to get perfect mating parts. Some call it "cheating" but it's a real timesaver.

    Just another means to the same end.
  7. Thanks again for your generous time and patience, Mon Rominee. It's all pretty clear to me now on what I need to do. May I refer you to another post of mine, regarding hardwoods? I'd love to have your opinion. Thanks in advance.

    Here's the link:
  8. Ozzel, IMO the shape duplicator can't produce a clean line with precision. Here's how I do it:

    Just take your neck and place it on your scanner without the lid on and scan it like you would anything. Then you can use a print of your neck heel OR trace it into a drawing program for addional tweaking for your layouts.

    A word of warning though - make sure you establish a precise centerline for placing your artwork. You might even measure and draw a pencil centerline on your neck heel before scanning. This will be very important when you begin placing your pattern on the body. A small bit out of line with the center will mean a larger error at the bridge.
  9. Suburban


    Jan 15, 2001
    lower mid Sweden
    Ham is on it again!
    Ozzel, you will make the pocket to fit the neck.
    If you do it backwards, make the neck fit the pocket, you may get into the same trouble as most folks I've heard about: having to make several necks until you finally found out how not to make it too narrow for the pocket!

    A method that works very well, is to fisrt make the neck, then use that for pocket template!
    Have a look: http://www.buildyourguitar.com/resources/pocket/index.htm
  10. Now THAT'S what I'm talking about - great link Suburban!

    The pics also show a good example of using straight edges for aligning the neck. That's the easiest way of all. Well, besides my own template system that I use.

    The only thing that I disagree with - and it's minor, I admit - is that the bit used in the link isn't called a "flush trim" bit. It's actually called a "pattern" bit because the bearing is on the top of the cutters. A "flush trim" bit is used widely in laminate work and has the bearing mounted below the cutters. With the bearing on top it can follow a face mounted pattern. With the bearing on the bottom it can trim laminate flush with the facing edge of the countertop. You can't use the flush in this style of cut (neck pocket). I do have flush trim bits in my shop and they are useful in other types of cut.
  11. Well, I've never had a problem doing it the way I described, nor have I had to ever make multiple necks...always follow the golden rule: measure twice, then twice more, before you cut. besides, the template is used for the fit considerations...why make more work for yourself making the neck and then re-refitting the pocket?

    but there you have it, some other very good possibilities for success.

    Good luck with the project.
  12. Suburban, yea, it woulda been swell if the neck pocket hadn't been cut yet. Otherwise I would've bought a neck from Warmoth, cut the pocket to fit, and this thread wouldn't exist. But as it happened, I loved the shape of the body, and the fact that the all the contours had already been cut, as well as the control cavity, so I just had to have it. I knew making a neck to fit the pocket would add even more difficulty to the task of making a neck for the first time, but I've got to deal with it.

    To conclude this thread, I did find a scanner in the office with almost no "lip" around the glass. So I was able to get a pretty sharp image of the pocket. I will outline it and apply it to my existing tracing of the body and I'll be on my way.

    Thanks again for all your great replies!

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