Quick 3d modeling tutorial, Rhino

rockappalla

Senior Member
Joined
Jul 15, 2008
Messages
488
Reaction score
186
rockapalla, first make a "mold" of the lp shape, so u have a block with inside an lp contour cut out. Then use that block to cut your symetrical model. Like baking heart shaped cookies :)
Thank you, that's a grat advice...i'll be at home in an hour, can't wait to try Magnus' method and yours :thumb:
 

Knarbens

Senior Member
Joined
Feb 18, 2008
Messages
2,299
Reaction score
705


That's what happens with my models too! Magnus, you said the curve has to be continuous, but I have no idea what's wrong with them!? Is there any command to make a wrong curve right?

One more. When I import a polygon model to Rhino, it's (of course) very subdivided. Would that be a problem when it comes to CNC carving or is it just the surface that does matter?
 

ihavenofish

Senior Member
Joined
Jan 17, 2010
Messages
2,444
Reaction score
895


That's what happens with my models too! Magnus, you said the curve has to be continuous, but I have no idea what's wrong with them!? Is there any command to make a wrong curve right?

One more. When I import a polygon model to Rhino, it's (of course) very subdivided. Would that be a problem when it comes to CNC carving or is it just the surface that does matter?
if its a polygon model and its low resolution, it will machine like that in most cases. i did that by accident making a guitar bofore. forgot to smooth the mesh and it machined all the little facets. pain to sand out.
 

Knarbens

Senior Member
Joined
Feb 18, 2008
Messages
2,299
Reaction score
705
Yeah of course - it has to be smoothed! But nurb modeling and Rhino is a better way to start a guitar and I'd really like to know all I need to model guitars with Rhino. I know
3ds Max and C4D, but Rhino would be the first nurb/cad program. Actually Rhino is pretty simple to use, but carved/arched tops are difficult.

Can somebory answer my first question in post #62 above?
 

GooCart

V.I.P. Member
Joined
Jun 23, 2008
Messages
1,699
Reaction score
1,224
Here I'll try to show you why you have problem with the radius tool.

First, a basic extrude.


Then a 5mm corner fillet. Lets pretend that this is the cutaway horn.



4mm fillet around the edge, no problem.



Here I used a bigger fillet then the corner fillet and it's just not possible to sweep the 5,5mm fillet around the 5mm corner radius and that's the problem.
If the extruded surface is build with a "bad" curve you might have spots that have a curvature that is smaller then the fillet radius you want to use.



So, look over the initial curve. It's very important that it is optimal, not just for the extruded surface. You'll also use it to create the top carve and if it is to complex you'll end up with a mess. Take a look at the pics I've posted here in the thread and you'll get an idea how you can use the points.

Here's a great tool you can use if you want to evaluate your curves, the curvature graph tool.
Here's two curves, one that is pretty optimal and one that I draw with a lot of points. They look pretty much the same, don't they?




But take look at the curvature graph!



Irregularity like this will most definitively be visible in the cnc cut piece. Maybe not until you've painted it but then it's a little to late....
 

Knarbens

Senior Member
Joined
Feb 18, 2008
Messages
2,299
Reaction score
705
Thank you Magnus for taking your time posting the pics! I know what you mean ... let's see how it turns out.

I know, the less points a curve has, the better you can work with it. I've drawed a spline curve in Cinema 4D - I used only a few points. I exported the file to DXF and when I open it with Rhino, the shape is there, but with quite a bit more controlpoints!? Why is that? Post pics later.
 

ihavenofish

Senior Member
Joined
Jan 17, 2010
Messages
2,444
Reaction score
895
Thank you Magnus for taking your time posting the pics! I know what you mean ... let's see how it turns out.

I know, the less points a curve has, the better you can work with it. I've drawed a spline curve in Cinema 4D - I used only a few points. I exported the file to DXF and when I open it with Rhino, the shape is there, but with quite a bit more controlpoints!? Why is that? Post pics later.
dxf only supports very limited types of lines. anything like a bezier curve or other types of splines it cant interpret it will turn into line segments.

your best bet is to redraw it in rhino using the old one as reference. i often do this in solidworks.
 

Knarbens

Senior Member
Joined
Feb 18, 2008
Messages
2,299
Reaction score
705
Okay Magnus. I got it! That was the problem with the radius on a cutaway. But what about this? Both shapes are created the same way. I'd like to model a sharp cutaway with no radius down the body, only the top.

 

GooCart

V.I.P. Member
Joined
Jun 23, 2008
Messages
1,699
Reaction score
1,224
I can't tell whats wrong based on the pic. If you want you can send me the file and I'll look in to it.
 

Knarbens

Senior Member
Joined
Feb 18, 2008
Messages
2,299
Reaction score
705
I've been experimenting around with Rhino and the knowledge for a flattop guitar is there, or at least I think that's where I am. Here are some screenshots of my test tries and I wonder whether this is already ready for CNC cutting. Most was done with the boolean functions ... is that a usual way? What do you say?

 

duff

Senior Member
Joined
Dec 8, 2008
Messages
890
Reaction score
373
looking good! i wouldn't bother with the radius around the body, it's probably something u will want to do without the cnc. Altough it's ofcourse possible on the cnc.(but quicker by hand)
 

ihavenofish

Senior Member
Joined
Jan 17, 2010
Messages
2,444
Reaction score
895
i would also leave all fillets off the model whether you plan on doing them on cnc or not.

reason is that in the big round overs on a flat top youll want to use a radius cutting bit, and for that you need the actual edge there to program it (usually).

otherwise youll be running a ball nose around and around and it could take an hour to make something that should take 1 minute.

for smaller radii, or where its blended into thte forearm, its easiest to sand in the radius afterward.

something like goocart had done with the sg - trying to get an exact one off replica based on a existing guitar - you might justify the time putting in all the details and waiting for it to cut with a ball nose.
 

Knarbens

Senior Member
Joined
Feb 18, 2008
Messages
2,299
Reaction score
705
Thank you guys!
I've seen it quite a few times that people set a radius around the body, so I was just copying that. How big is the expenditure before the CNC maschine can start cutting? Is it something you have to be trained in as well, or is it something every woodworker can do?
 

Knarbens

Senior Member
Joined
Feb 18, 2008
Messages
2,299
Reaction score
705
Here another post. Like you can see above, creating flat top guitars is quite simple. Arched tops in contrast, are hard for a noob. I created a surface out of points and simply tried to shape an arched top. Coming from polygon based 3D software I gotta say Rhino works some different.

Here's a comparison of a similar geometry in Rhino 3D and Cinema 4D. It's easier to work with the Cinema 4D controlpoints. How come the Rhino surface looks that grubby?

I'd really like to know how to do arched tops (I know there are e few ways). Some PRS style top would be my goal - two horns, with an even pickupplane.

 

Grey

Senior Member
Joined
Apr 20, 2010
Messages
1,443
Reaction score
849
How come the Rhino surface looks that grubby?
It has to do with how light is hitting the faces in Rhino, Cinema4D will let you get away with alot of ugly geometry errors.

I work with 3Ds and Maya though so I can't get much deeper than that, and the kind of work I do is for game resources so there are alot of different restrictions with ngons and the like.
 

ihavenofish

Senior Member
Joined
Jan 17, 2010
Messages
2,444
Reaction score
895
It has to do with how light is hitting the faces in Rhino, Cinema4D will let you get away with alot of ugly geometry errors.
the c4d one has been smoothed to a high poly count. the rhino one looks to be quite low resolution. somewhere in rhino there should be a way to up the display resoution (i havent used it in a long time).

I've seen it quite a few times that people set a radius around the body, so I was just copying that. How big is the expenditure before the CNC maschine can start cutting? Is it something you have to be trained in as well, or is it something every woodworker can do?
people tend to model things "finished" in 3d. they want to see the final result. this is fine for viewing, but often not ideal for cnc which mostly functions on outlines and pockets and only on 3d contoured surfaces when absolutely necessary.

the learning curve when you get a cnc is high. woodworking experience is useful, but wont really put you ahead. the biggest things youll need to figure out is what speed the machine can run while giving a good surface (no tearing), and finding ways of holding down and registering both sides of the part.
 

Knarbens

Senior Member
Joined
Feb 18, 2008
Messages
2,299
Reaction score
705
Thank you! I understand. What about these programs, that control the CNC machine? Do I need to tell them all the paths the cutter head has to follow to shape the contours and surfaces, or is that something this program does itself? Sorry ... bad English ... don't know how to say it better right know.
 

ihavenofish

Senior Member
Joined
Jan 17, 2010
Messages
2,444
Reaction score
895
Thank you! I understand. What about these programs, that control the CNC machine? Do I need to tell them all the paths the cutter head has to follow to shape the contours and surfaces, or is that something this program does itself? Sorry ... bad English ... don't know how to say it better right know.
theres 3 stages.

1: model your part in 3d.
2: send the part to a CAM software and devise cutting paths.
3: run the cnc program in the software that control the cnc machine directly.

step 2 is where you have to tell it what tools you are using and all the other useful info. most of this software is very expensive, but there are a cuple cheap/free ones out there. i use "visual mill" as it came with one of my machines (normally its $1000, which is "cheap" in the CAM world).
 

neno

Junior Member
Joined
Apr 15, 2010
Messages
6
Reaction score
0
Hi!

I want to say thanks for these tutorials and tips!! Especially to GooCart for his will to help out with his knowledge!

So I just want to share with you what I'm working on:

It's a 3D Model of the Esp Ma-Ctm (Custom Shop)



I'm doing this model for my pesonal portfolio and maybe I'll build this guitar in future (CNC).

Here's what I've got so far:







http://i800.photobucket.com/albums/yy286/mrneene/6.jpg[/IMG
[IMG]http://i800.photobucket.com/albums/yy286/mrneene/7.jpg






There are some areas where I don't know how to model the surface. Here is a pic of one area on another Model:



maybe someone can help me out :)

When I finish all the parts I will move to the body :) Thanks again for the help and tutorials!!

As Knarbens I'm used to other 3D Softwares (I'm working with 3Ds Max professional). So I'm a Poly-modeller and my goal is to model a guitar with Nurbs, because it's very precise. Sometimes I'm working for a carpenter who uses Rhino for his CNC. Anyway, to model a Les Paul in Rhino is harder than everything what I've done so far :). If someone is interested in my work: MobileMe Gallery

neno


P.S.: Echt tolles Les Paul-Modell Knarbens!!
 


Latest Threads



Top