Official Luthiers Forum!

Hey Bob, I'm normally inclined to agree with you when it comes to this stuff but in this case I might not. Specifically, I'm thinking about my experience with the VisualMill plug in for SolidWorks and this may not entirely apply to RhinoCAM because of the differences between Rhino and SW. (Oh, and I checked, the VM plugin/RhinoCAM/VM stand alone are all $1250 now)

Some may not know that the biggest difference between Rhino and SW is that SW is a parametric modeler with a design tree - features are built on top of each other, have a historical hierarchy and can have various relationships between each other. This can make initial modeling a bit more difficult than in a more free form modeler like Rhino but it adds tremendous power if you're tweaking designs a lot. When modeled correctly, it allows you to change parameters early in the design tree and have all the features update and re-build correctly taking into account the new dimensions etc. (to be truthful, it takes some planning for all of this to work out correctly! Sometimes things don't update how you'd like them to).

So the obvious advantage is that if you do tweak a model (e.g. a fretboard with a new scale length), with integrated CAM, it's just a mater of pressing the regenerate button to update all of your tool paths to the new dimensions. For my fretboard service, I have a design table driven parametric model. When I get an order in for a new custom fretboard, I simply enter the parameters into the design table spreadsheet (things like width at the nut, scale length, nut compensation, radius etc.), rebuild the model with once click and finally, click regenerate in VisualMill and boom - I have my updated tool paths and G-code (okay, there's one more click to post the file).

With a stand alone, you're re-importing from scratch and have to re-select, re-define regions etc, which can be very tedious. But there's yet another advantage.

Anyone who's been doing this a while knows that if you get a model from an outside source, there's often tweaking that needs to be done to machine it with your setup. It might mean drawing certain 2D sketches to contain a toolpath, or eliminating 3D features (specifically cuts) for better surfacing or whatever. VM Standalone is actually the VM plug-in that's running in Mechsoft's CAD server, something called VisualCAD or something like that and as one may guess, its drawing and modeling features don't hold a candle to those of a dedicated modeler like Rhino or SW and - both SolidWorks and Rhino have really good import tools.

For me, it's kind of a non-issue though as I'm running VM4SW pro which comes with the stand alone license too. That said, I've not run the stand alone version even once other than to see if it works. With my workflow, I always import into SolidWorks first since I know it best and do any tweaking in there.

I will add the asterisk that all of my experience is with SolidWorks, a little bit of Rhino (which is still free for the Mac), and VisualMill. The only other software I use is Vcarve Pro (Which is wonderful for certain things by the way). Things may be different with different work flows and different software.

_________________
http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Well,

while Rhino itself is not parametric modeler,
a free plugin called Grasshopper makes it one.
Yes, it takes some tweaking, but makes it very possible
to make parametric models of guitar parts and such.

I have not tried that for guitars since I do not own cnc (yet),
but I have used it for making thousands of unique cnc manufactured wooden
parts for buildings, and I am just a stupid designer,
not an engineer and even less a computer geek.

I agree completely with what you've said with respect to parametric modelers, Andy. Though Solidworks is something many of the question-answerers on this board have access to, it's not something any of the question askers will end up buying, so it doesn't even enter my mind when answering. If VM has a shared codebase so they're always putting full features in both products and keeping synced releases, then there's no reason not to use the plugin unless the standalone version has better import capabilities than your CAD system (but Rhino has the best import/export).

Grasshopper is parametric, but it's not the same sort of streamlined tool Solidworks or another parametric solid modeler is. Grasshopper is more of a visual scripting language. The plugins wouldn't be able to 'automatically re-toolpath' the generated models the same way they can in Solidworks, because as far as they're concerned it's a completely new set of surfaces every time you change something in Grasshopper. You might be able to get around that by using regions instead of surfaces for your toolpath, or if there's some way for the plugins to pick up surfaces based on name or color or something?

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Bob,

you are correct about Grasshopper,
and it was not my intention to say that it would turn Rhino into SW.

And I have no hands on experience of the CAM part of the deal,
my duties have stopped before that.

However, while I am not expert in Grasshopper,
I have managed to use it when I have had to have a
"parametric" Rhino model in CNC production situations.
It always amazes me what can be done with it and
how relatively easy it is.

Here is one interesting video, to provoke some thoughts:

http://www.grasshopper3d.com/video/gcod ... or-surface

-J-

I've used Rhinoscript (which is the commands Grasshopper calls) to do some pretty fancy toolpathing. It's one of the proprietary ones, so I can't really talk about the specifics, but I can say it's totally possible to use Grasshopper/Rhinoscript to generate complex toolpaths that your CAM software might not be able to. I had it go point by point, interpolated them into smooth curves, and had my CAM software 'cut along a 3D curve' to generate the G-code.

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

That sounds cool, Bob,
I have some golleagues who do
something like that with rhinoscript,
and while I envy them from time to time,
I am happy to be able to do something
similar with Grasshopper while knowing nada about
"real" coding.

But I believe Mr. Rutten´s intention was to get dumb
architects to code without really knowing it...


-J-

I don't think there's a huge gap in understanding if you can already do something in Grasshopper: it's the same commands and inputs, you just need to type them out. If I scripted Rhino more often, I'd use Grasshopper instead of scripting. Since I already coded, it was longer to learn the Grasshopper interface than to type in what I needed. Even if a program starts getting complex (mine were only a couple pages), it'd be much safer to use Grasshopper to remove human error from the code.

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I'm bringing this one back to the top as I don't believe I've ever seen anybody mention SolidThinking evolve? I've been playing with this for the last couple of weeks and truly believe it to be the best solution for the guitar maker. It has incredibly powerful surfacing, a full parametric history tree plus direct modelling including subd, assemblies, a superb renderer and is native on both Mac and PC. Here in Europe it's priced around 50% more than Rhino and way less than Solidworks.

http://www.solidthinking.com/ProductOve ... y=Products

These are some older videos but worth a look

http://www.youtube.com/watch?v=DpuEPaKhgkE

http://www.youtube.com/watch?v=C4h9DJ3q6oA

http://www.youtube.com/watch?v=x6GJjYj-U34

http://www.youtube.com/watch?v=rlqN_WNaH8I

_________________
www.morganguitarworks.com
www.morgancustomguitars.com