Re: [CAD_CAM_EDM_DRO] Re: Rhino + Guitar curves

Hi, ddgman2001

Not to disagree too much with you, but having done a bit with Rhino,
Millwizard and my own home brew CNC router, once the system is set up I find
it amazingly fast to go from concept to router.

Two big caveats to anyone new working from Rhino to CNC. If you are using a
real, serious, deadline based project to get up and running, as I once
mistakenly did, forget it. I still, after many parts and successful runs,
have to listen to a wife who always seems to remember my "one month from
receipt of the 80/20 to finished parts" when I make rash promises about the
beauty and ease of CNC. So if you are not now using CNC to make parts, don't
expect this to be easy or quick. Second, the toughest part about Rhino is
creating a "water tight" solid. It is a NURBS based surface modeler, not a
solid modeler. So while it is quite easy to make a solid out of a series of
surfaces, you always have to be vigilant in the creation of the solid.
You will have to dig deep for a while to make sure your edges are not naked,
the seams are tight and you understand G0, G1 and G3 continuity. I had to
take an entire continuity class at Alias/Wavefront in Toronto, (maybe the
best big city on earth, at least during the summer, BTW) to be able to teach
it to the car design students. So, given Rhino's greatest ongoing weakness,
which is filleting, you may have a bit of trouble at least at first with the
nasty seams often created by Rhino's filleting.
On the other hand, they have developed many nice tool for helping you
create good models.

Mike Rainone
PCD, Inc.
Brushy Creek, Texas

----- Original Message -----
From: "ddgman2001" <sheldon@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, March 18, 2003 9:17 AM
Subject: [CAD_CAM_EDM_DRO] Re: Rhino + Guitar curves


> John,
>
> There are many more experienced with CNC and Rhino than me, but I've
> built and designed a lot of guitars.
>
> If you are already up and running with Rhino and have a system in
> place for turning your designs into parts that's one thing.
>
> If you are starting from scratch that's another. In the time it would
> have taken you to learn Rhino, convert your stl file to tool paths
> and code, then build your fixturing, cut your first part, realize a
> few mistakes, try again... you could have made your master by hand
> and probably had it cast.
>
> In other words, going the high-tech route will be lots of work, trial
> and error, materials and time. But you will learn a lot in the
> process.
>
> Going the manual route will save you time and aggravation and be a
> more organic experience.
>
> Sheldon
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, johnhe-uk@s... wrote:
> >
> > Hi,
> >
> > I just downloaded Rhino again to try and build a guitar body in
> it. I am
> > almost toally new to it in comparison to most of you guys. I
> started by
> > drawing a set of curves on the front veiw to create a contour, then
> joined
> > them and extruded out the shape to the correct length of the body.
> That's all
> > fine. Then cut out the pockets for the pickups, bridge, neck etc.
> Easy.
> >
> > From there I needed to profile the edges of my contoured block
> (Top and
> > bottom contoured only so far). I guess I kind of cheated here
> rather than
> > finding out how to do it properly and used the fillet tool with a
> massive
> > radius set to create the first simple curves at the back end of the
> body. I
> > now have a top and bottom contoured block with a rounded end (The
> end furthest
> > from the neck).
> >
> > And now I'm stuck! :P I was working through the
> tutorials, my duck was
> > going great till it came to trimming the extruded neck into the
> body. Dumb
> > duck! Click inside the body inside the extuded area? I think not!
> Being new to
> > it I kept pressing F10 with my guitar body to try and get control
> surfaces up
> > to profile the kind of figure of 8 shape most guitar bodies are,
> but alas 'Can
> > not use control points on polysurfaces'. I also kept trying things
> like using
> > trim to cut the body profile but the cutting tool, my curvy line,
> doesn't seem
> > to want to do much cutting (Would I create the curve in top down
> view then,
> > anywhere vertically above the body, then use it to cut through?).
> Could I use
> > the curved line as a cut plane? Another idea was to create a curve,
> extrude it
> > down, extude it back, then use the difference tool to cut the shape
> into the
> > bodie's side. But there must be an easier way than that judging by
> how much
> > easier other things are in this! So, any help with this would be
> majorly
> > appreciated.
> >
> > My second problem was... If the body is contoured on both sides
> how could it
> > be machined in the real world on a knee mill? It could contour one
> side, then
> > you'd need to flip the block over and have it contour the other.
> But as it
> > worked it'd be slowly cutting the sides through to the other (To
> make an
> > almost fully rounded edge along the sides of the guitar) and I am
> imagining
> > the work piece could drop out of the block as it came close to
> finishing the
> > edges due to the tool pushing down on it, or atleast it'd deflect
> somewhere.
> > My answer to this was to leave something like 1cm uncurved on the
> edges to
> > hold the work in place (In the block it's being cut from), then cut
> the work
> > out with a saw. I was thinking of making this from something cheap
> like MDF so
> > the tool pressure wouldn't be massive on the contouring. I wanted
> to create an
> > MDF version then have it cast from magnesium for one seriously mad
> guitar. A
> > billet of the right size is a mere 800 Pounds stirling!!! So
> machining it out
> > from a billet is _not_ an option. Cast it's more than halved in
> price. Does
> > Rhino have a scale option where percentages can be used rather than
> using the
> > mouse to scale it? This would be to allow for the 1.3% shrinkage
> from pattern
> > to cast. Can any of you guys think of a way that the work could be
> held once
> > it's cast and contoured? Having it cast bring up the concern of the
> neck
> > binding or something else being just slight too small to fit the
> neck so it'd
> > probably need machining after.
> >
> > Of coarse, just buying a guitar is not good enough, you're on this
> list, you
> > know how it is! :)
> >
> > Sorry it's so long! Can you tell I'm stuck?
> >
> > Thanks for any help,
> > John
>
>
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