Official Luthiers Forum!

Well I've been playing with Rhino now since last June and think I am progressing pretty well with it considering my training is trial and error and what I can learn on youtube. I've modeled a bunch of different necks, fretboards, bodies, etc. On my necks ,where the shaft meets the peghead and heel transitions, there is a pretty abrupt change in the bit movement which shows up in the cut. Is there an easy way to make that transition more gradual?

The other question is this. I take a guitar jpeg and put it in the background. I plot points on all the curves using " near" mostly. Is there an easy way to smooth out the curves that are bumpy? I tried adding more control points but I was wondering if there is a smoothing command I missed that might help in that regard.

Thanks in advance.
Marty

Marty, while I'm not a Rhino user, I am a long time CAD user. Many systems have a command called smooth, you might search your help files. Also, removing points in the bumpy areas will smooth your spline also and probably more effectively. You currently have points that don't lie directly on a smooth spline, so the system is driving the spline through the points your points resulting in a bumpy spline. Some systems have a command called "sparse" which allows you to define how far off of the point the spline can pass.

So in a nut shell, fewer points will produce a smoother spline than more points. Generally use the minimum number of well placed points to produce the smoothest spline.

_________________
Jim Watts
http://jameswattsguitars.com

Hi Marty,

You should be able to construct you body outlines with very few control points - you are using control point curves right?

Here's a quick (but accurate) outline of a 59 Les Paul showing the control points - I've seen it done with fewer but I'm not able to manage it.



If you'd like to post up your files or email them to me - see profile for website - I'm no expert but I'd be happy to take a look at them.

Neil

_________________
www.morganguitarworks.com
www.morgancustomguitars.com

The best curve is the one that stays within bounds of the target curve and uses the fewest control points; it's also the smoothest. Here's the process, with commands highlighted.

First rebuild the curve to get rid of the majority of the excess points. After that, turn control pointson and drag points around while deleting points manually to see if you can improve on the rebuild command. To get initial geometry, interpcrv is often the fastest way since you can just click around your reference. There are times when fitcrv can be useful, but you're unlikely to need it very often except in advanced cases.

So far as your 3D tangency problems, it would be a lot easier to diagnose if you post a screenshot of your problem areas. Commands like mergesrf, matchsrf, and edgesrf can be very helpful in those cases where you can't seem to directly construct the surface you want. Sometimes you can get where you're going with a process of successive approximation by making surfaces, then taking their intersection with a plane or a line that is projected onto the surfaces using projectsf to get curves which you'll use to build a new, better surface. Use the methods above to clean up the constructed curves before making a new surface.

The best surfaces tend to be made with loft between curves, sweep1 rail, sweep2 rails, and surface from curve network,networksrf, which gives a very high degree of control over the surface created and is both one of my favourite tools and one of the tools in Rhino that no other CAD software I know of can match. Surfaces created with multiple curves tend to work best if you rebuild the curves to have the same number of control points.

This stuff's quick to explain and takes forever to master, but that's the process. As you spend more time making surfaces and curves, you'll get an idea of what sort of curves to construct in the first place to leave yourself less work down the line as well as an intuition for what's likely to result in a wrinkly or otherwise poor surface. There will be much of this , followed by , and the finally figuring out how to do stuff in twenty minutes that used to take you eight hours

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Check out my neck surface tutorial which is on here somewhere....this shows a range of the usual commands that you can use in Rhino to help make nice blends, etc. If you build your framework correctly, it's much easier to make everything blend well.

Have fun
Trev

_________________
http://www.PeakeGuitars.com

That one's double plus true. Every surface problem is really a curve construction problem; 99% of the work on a good surface is done with tools under the Curve and Edit menus.

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

It'e even triple plus true! It's really imporant in surface work to get the curves right.

_________________
Jim Watts
http://jameswattsguitars.com

Thanks for the ideas. I'll give them a try. When modeling a Gibson neck and transitions, I found that many of my surfacing commands wouldn't work with the curves I drew. I then would split things up until they did work. I guess my control point logic is the reverse of what was mentioned. I thought the more the merrier . I guess I'll have to do more manual work than I had hoped which is OK.

Hi Marty,

As the others have said accurate simple drawing is the key. I have modelled many Gibson style necks (although I prefer a full width tenon) and although getting the transitional blends is a bit daunting at first once you have the technique down it doesn't take long to get a water tight model.


I used the following curves to get the headstock transition



A lot of people helped me when I started out with Rhino five years ago, for which I'm very grateful, so if I can help out in any way feel free to send me the files.

Neil

_________________
www.morganguitarworks.com
www.morgancustomguitars.com

So Neil,
On your LP body. Are we looking at one closed curve with all the points on or many open curves with the points on?

Guys, I went back and looked at a pickguard drawing. I exploded my one closed curve into 36 curves. I have a millon points. If I rebuild one 3 inch long curve with fewer points, then the curve becomes more like a bunch of straight lines intersecting at each point??? In this case I traced a pickguard and scanned it to a jpeg. I then loaded the jpeg into Rhino and plotted points on the perimeter of the guard. I then connected points to create curves. Should I have done something differently here?

The LP body outline would be one closed curve drawn using two straight lines for the heel and a single control point curve for the rest. I don't try and 'trace' an outline using interpolate points but draw an approximate outline using the minimum number of points possible with a control point curve. I then edit the outline by moving the points until I get it as close as possible only adding a point when absolutely necessary

_________________
www.morganguitarworks.com
www.morgancustomguitars.com

FitCrv can help you out if you've got an overly complex compound curve, and that's specifically what it's made for; it fits a curve with the minimum number of control points to your curves within whatever tolerance you specify.

I make a control point curve when I'm drawing new geometry, and InterpCrv when I'm using a reference (image, etc). I rebuild after that, which usually catches any excess points.

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

the fair command is also a good one...

_________________
http://www.PeakeGuitars.com

Something useful, which I just noticed when reading the help in Rhino, is that all the curve simplification commands mentioned show up on the same page in help if you look up rebuild and then scroll down. The Rhino help is really good for both learning the commands and what they do, as well as learning how they actually work.

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Well I've gone back and created simpler curves which look a lot better, so thanks for those tips. I found that the Fair command did more than rebuild in many cases to smooth out the bumps. Anybody try any contours on an SG like body? I'd be interested in which surfacing command works best. I played with Sweep2 and I think that may work.

Sweep2 is a good command. I use it a lot, and go to NetworkSrf if I need more control than it can provide.

I do most of my 'harder' work with loft, sweep2, and networksrf in that order. When I started, I made a mistake that I've seen a lot since then which is trying to overextend what loft can do (which makes nasty surfaces) and trying to get large sweeps to blend between curves that don't want to be blended between. Often it's easier to split a large sweep into two or three sections and then use mergesrf or matchsrf to maintain continuity at their borders. If you want to, you can then take curves from the 'compound' surface and reconstruct a smooth version of the whole.

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

This is really good advice.

I've been trying to draw a bridge tonight in Rhino. I've never used it before..... I've used TurboCAD very little. I got most of it drawn and the easier surfaces putt on, but some of the compound curve surfaces are eluding me. They get all funky/wrinkly. I'm sure I've drawn something strange, but since I'm a newb I don't have a clue. I drew it off a prototype bridge I made the other day.... what's sad is it's taken me like 4 hours to do this ! .. lol

If anyone wants to smack a newb upside the head and help me out let me know. I can send the files to look at/edit/give pointers. I suppose they are compatible. I'm running their free Mac beta version.

Screen shot in wireframe.....

_________________
John Mayes
http://www.mayesluthier.com

and one without the surfaces

_________________
John Mayes
http://www.mayesluthier.com

John,

Very nice looking bridge and 4 hours is pretty good for a first attempt at modelling in Rhino. I'm assuming you're having trouble with the indentations on the wings. Might I suggest trying "Boolean Difference" rather than trying to build it with a bunch of separate curves. In other words, model the bridge without the indentations then model the indentations as a separate piece. Place them into the bridge and then subtract. I use MOI3D which is basically Rhino Lite. There may be easier ways to do this in Rhino (commands that MOI does not have). I'm in no way an expert, but whenever possible I try to model in solids rather than surfaces. For example I would extrude the silhouette of the bridge then draw some curves and use Boolean difference to create the profiles. The end result will always give you a solid model. But there are always different ways of getting the same result.

I haven't even got to the scoops yet. Just trying to surface the top is giving me fits, and I'm sure the scoops will be even worse! Here is a shot of what it looks like when I try to surface the top.

_________________
John Mayes
http://www.mayesluthier.com

So I got the scoops sort of surfaced. I actually want the scoop to go "in" further rather than the sort of slope/chamfer that they are. Don't know how to do that, but the top surface still eludes me. I thought that maybe one I got the scoops surfaced the top would realize that the point of the scoop didn't go back, but still getting that wrinkle.

_________________
John Mayes
http://www.mayesluthier.com

Hi John,

While I am not as good as some of the Rhino users here, I would be glad to take a look at the bridge. Beautifully designed by the way.

I will send you an email directly to your site link.

Mike

Just some quickies, but these are on the list of important Rhino revelations and should help out:

Making a surface to a pre-determined outline is often much harder than making a larger surface and then trimming out the piece you want with the trim command. In this case, it would be much easier to make the whole top surface as if the scoops didn't exist, then cut out the chunk of the surface where the scoops go and then build them in. As an example, the 'wings' on my belly bridge models are actually rectangular surfaces which have been trimmed. If need be, then you can change the profile (trimming) curve, then untrim and retrim the surface to get a new profile.

One technique for refining a surface is to use an intersection with a plane or a curve projected onto the surface to get an interior curve, then edit that curve to your liking (control points) and re-generate the surface using the new curve. This sort of 'intersect and refine' modelling can be really useful in some places in Rhino when you need a visual guide to get the curve just right. In other software with more limited surfacing tools, this can be the only way to generate certain surfaces at all (though it's much more tedious in those cases!)

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Well big thanks to turmite he got the rest of it surfaced. I know he used a patch command, but other than that I'm not sure.

I get the basics of what your saying Bob. I'll have to try it to really understand what your saying I suppose, but great advice.

Here is a shot of the bridge...

_________________
John Mayes
http://www.mayesluthier.com