Guitar neck/volute issues

[Michael_Anthony_Farl (Michael Anthony Farlow)]

Hi All,

I am new to Rhino3d (love it BTW) and I am coming to Rhino3d from Fusion360(have hated it a while now).

I am attaching the file I have been working from and hopefully it will tell the tale better than I. I do have a bunch of patches that kinda work to illustrate how I want things to flow but there is no way that I know of yet to make it clean and able to be made into a solid for the CNC side of things.

In short, I am trying to make the back of the neck a smoother transition into the volute area. Loft with rails worked in Fusion360 to a point but with that software I was able to select several rails, not just two.

I was not able to get sweep with two rails to work on this and loft does not work either… though it is entirely possible (likely expected) that I am not doing it right as I have a grand total of 5 or 6 days of using Rhino.

I am open to any instruction or ideas that will help the neck/headstock transition to be smooth and clean, while respecing the edges that are present…

Please forgive any drawing issues that might be making things worse… I think I have the artwork pretty clean but I am using Rhino on a laptop that has a few years on it and the graphics capabilities leave a lot left to be desired.

Thanks in advance.

Mick

PS. I have watched a few of the guitar neck and volute video’s out there for Rhino and they are good but this neck has some additional geometry and lines that I’ve never seen done anywhere else… Rhino or Fusion.

K2-Rhino.3dm (2.3 MB)

[phcreates (peter harris)]

Since nobody is chiming in yet, I’ll say start by building surfaces that you know how to build, then post here to see if someone can help with the tough bits.

[can.aysan (ACAN)]

Curves are a bit problematic to create a decent surface… Ideally they should be made of same number of CV’s.

I can try to help you but I didn’t understant the volute geometry that you try to create. It looks too big/deep ?

[martinsiegrist]

Your file contains a huge circle

[markintheozarks]

K2-Rhino guitar neck.3dm (2.8 MB)
Is this where you are heading?—Mark

[Michael_Anthony_Farl (Michael Anthony Farlow)]

true and I have no idea how I did that… clearly an operator error!

[Michael_Anthony_Farl (Michael Anthony Farlow)]

Thanks guys for taking a look… I am attaching some pictures of a neck that was handy and has a great example of what I am trying to recreate…

When my luthier friend does these, he just sculpts away everything that is not a volute and it turns out smooth and amazing. This is a lot easier said than done in the digital realm it seems.

There are so many intersecting lines and facets. So far I have not been able to get it modeled correctly.

Hopefully these pics will help. I also have some additional geometry in the file now so I am going to upload another version shortly… absent that HUGE circle!

Thanks again!

[theoutside (Kyle Houchens)]

have you seen this video? these guitar necks build quite nicely in subd.

Getting Started with Rhino7 for Windows guitar full build

[Michael_Anthony_Farl (Michael Anthony Farlow)]

Hi Kyle,

Yes I have seen that video actually… and I had planned to use SubD when I get around to doing a sculpted top for this body… I will watch more videos on SubD tonight and see what I can come up with.

This volute is a unique combination of sharp and organic curves so I wasn’t sure how that could be handled in the SubD environment.

We shall see because I’m gonna jump in.

Thanks!

[Tom_P]

just a fast idea - with some fine-tuning it might give a nice result.
I recommend to use deformable arcs (approximations) instead of arcs.

basic idea: build a planar curve with this double s-like hill
_/\_
_curve degree 3, with 8 to 12 points
finetune with _curvatureGraph and gumball
next two helping surfaces _extrudeCrv, green

my example shows a simple loft with start / end tangent between the surface edges.

you can still build a more complex surface (sweep2) between those surfaces.
or even fine-tune the green surfaces / its local direction first.
or edit the above loft with control point modelling…

main benefit: there is only one surface.
but of course the edges are the result of intersections.
but this is the way they where created in a more manual production process

looking forward to see your final solution …
kind regards -tom

[theoutside (Kyle Houchens)]

do the entire part in subd and use creases for all your hard edges.

Since I assume this will be machined then hand sanded, don’t even worry about the small radii on the edges, they will come for free at that time. Larger radii that need to be specified, place hold them with creases, then convert to Nurbs when you are happy with the main forms and then do the final blending and radii in Nurbs.

A lot of folks are getting stuck in either nurbs or subd, however they really work very well when used together, and you will get a better results if you use the tools for what they are best at instead of forcing the whole model into one process or the other.

[sgreenawalt (Sky G)]

Here’s another way to skin the cat:

All your base surfaces - take for instance the main loft of the neck - have way too many points. I’ve rebuild the neck main body so that it’s a simple degree 5 x 1 surface for each half - the deviation between yours and this was around few thou. Having a cleaner and simpler neck loft will allow you other ways of solving this problem. Similarly, I rebuilt the curved surface that comes off the head:

This portion of the neck to head blend:

Is simply a blendsrf between my neck main volume and a simple guide surface I made at the corner of your head.

I put an ortho line at the end of my centerline curve, and then made a blendcrv like this:

Now we have a four sided hole, and we can fill it with EdgeSrf:

From here, it’s a matter of using MatchSrf to align that blend with main loft of the neck (eta - and setting the centerline tangent), and then just moving the control points around manually to get the shape you want. Having simple and clean surfaces to start with are what allow this workflow:

Your can then trim those two surfaces relative to each other:

You can see it’s all very well ordered, matches the design intent in the photos, and the crease fades very nicely:

Opposite side would be done the exact same way, the proportions would be different but the approach identical.

There is one tradeoff with this workflow - you can’t control EXACTLY what your intersection between the two major surfaces of the blend looks like - you’re indirectly creating that intersection by the shape of those two primary surfaces, so there will be some trial and error involved if you’re say trying to reverse engineer from laser scanned data, rather than capturing artistic intent. The flip side is that once setup, you can very easily edit the shapes with simply moving your control points, so iterating is a breeze.

-Sky

GuitarNeck_SG.3dm (4.3 MB)

[pascal (Pascal Golay)]

@sgreenawalt

so there will be some trial and error involved if you’re say trying to reverse engineer from laser scanned data, rather than capturing artistic intent.

One way to ease the pain somewhat here is to Intersect the two primaries weith History on, and noodle the surfaces until that intersection curve closely matches the target/desired shape.

-Pascal

[theoutside (Kyle Houchens)]

first off… It’s almost annoying how good Sky is at this stuff…

secondly, you can run intersect with history on before you start editing the blend surface, that way as you edit the surface, the historically activated intersect curve will update and you can compare the intersect curve with your design intent curve. This is a super powerful way to find complicated intersection shapes, and is how I find headlight shapes on super organic cars like a jag xke. Very useful, yet highly under used technique.

[theoutside (Kyle Houchens)]

the above technique is shown in detail in this video-
I used it to make a door handle pocket, but the principals remain the same here.

[sgreenawalt (Sky G)]

@theoutside

first off… It’s almost annoying how good Sky is at this stuff…

Ha! I once had to convert a whole bunch of hand carved necks to surfaces for a well known boutique mfg, so really I just had a head start is all - guitar necks tend to be VERY tricky little problems, the sort that my brain tends to churn on.

[markintheozarks]

I wasn’t sure if I was seeing things correctly but, the headstock and the neck are not parallel. Maybe it is intended that way.—Mark

[Michael_Anthony_Farl (Michael Anthony Farlow)]

Mark, if I understand correctly, you are correct, the neck and headstock are not parallel. The headstock is tilted back about 7 degrees.

[Michael_Anthony_Farl (Michael Anthony Farlow)]

Fortunately we are not worried about it being exact… just an excellent representation that is 90-95% of the way there.

I really like this approach and am eager to learn it.

[theoutside (Kyle Houchens)]

make sure to watch sky’s EXCELLENT tutorial series… I can’t recommend it enough if you have not seen this info before it will change your game completely.

whole series here-