Engineer, need help with rounded corners and extrusion

Hopefully with all of the professional talent here someone might be able to help me out. I’m working on a project which involves modeling the experiment and doing light reflection tests. Standard engineering tools would be nice but they are exceedingly expensive. For those reasons I’m using Blender to do everything. I am use to designing parts in engineering programs so I’m a little lost as to how to do a few things.

Curved edges: In the tools I’ve used in the past I could simply select an edge and add a smooth curved bevel after defining the radius of curvature. No matter what I try I can’t do it in Blender.

Extrusions: I have been able to do some basic extrusions but not the type I need. The method I’m use to is to select a surface, draw a 2D layout, and extrude into or out of the surface. In Blender I’ve created a thin rectangular object. On one of the surfaces I’ve created some mesh circles. When I try to go extrude them through the first object it won’t let me.

Blender seems to have a lot of potential for what I want to do if I can only figure out how to do some of these basic modeling methods. I’ve searched the internet for help to no avail. Any tips or howtos would be much appreciated.

Blender is not a CAD system so most of the dimensions are missing
everything is in Blender unit which can become wahtever you want

1 BU = 1 Foot or 1 Meter or anything else you want

but Blender in its dimensions BU is limited from 9999 down to 0.001

so you may have to use a scale factor X2 or X 4

1 - First why don’t you try the Bmae and caliper Script
Metric and English dimensions


2 - Curvature well pick a circle of the right dimension and remove the vertices that you don’t need and attach it to the object that you want.

That will give you the curvature you need.

Good Lick


the best advice i can give you is if you are serious about learning blender, then read the manual, there are lot of explanation there and hopefully most of your basic questions are already answered, sorry for pointing you to a 300 pages(increasing) link but there is no way to go without it, otherwise you will be knocking your head, and the link is google blender wiki manual, there you go.

I realize Blender is not specifically a CAD program. It does have a lot of similar basic capabilities though. Both Blender and CAD programs are designed to allow the user to model objects and visualize them.

The Blender Wiki page was the first I used to familiarize myself with Blender. I’m a long time user of Linux so I’m quite familiar with the term RTFM. I exhausted my search capabilities before posting here. By posting here I was hoping to get advice from experienced designers which would normally take some time to figure out and learn. Comparing Blender to some CAD programs I find it hard that 3D artists would have to take so many more steps to model the same simple object than a CAD user might. At least it seems that way to me.

Is there a “draw” mode where I might create a 2D cross section by creating points and connecting them? From there I would like to extrude the surface.

you can go into side view (numpad 3) and create a new object(doesn’t matter what it is). by pressing space, clicking mesh, and clicking any one of the choises. when it apears it’ll be in edit mode. press ‘a’ until all of the vertices are yellow. press ‘x’ and say yes. (yes, they are sopposted to diapear.) hold down control and click to make a vertex.(make sure your in side mode) keep adding vertices untill you have what you want. you can connect them into faces/edges by selecting the 2-4 vertices and pressing f.(blender does not support faces with 5+ vertex faces)

EDIT:: Added the help image.

gizma, can you post some pictures of what do you want to achieve?

With the software you’re used to, of course.

Normally what is a cross section ifor you ? - side view is in the Z-Y plane

Front view is for Z-X and top view is for the X-Y plane

But this is 3D modellers - you can make photo realistic !
So it also depends up to what quality of rendering you looking for!

But one thing i’v learn is that the 3D world is not that simple and yes the learning curve for Blender is not easy - But it is a small software which is very powerfull and at the price you paid for it it is worth a hec of a lot more then that.


gizma i dont see any troubles at all using blender to draw as you would on a cad program working in 3d is just one more axis so if you can work in 3d you necessarily can work in 2d too, but blender doesnt have all the measurement tools as you would expect on a engineering designing tool thats fair, i see a lot of people who works with architetural visualization working in 2d in a cad program like qcad which is also free but costs a little and importing the dxf into blender then extruding and making what else is needed, if you want to see some examples you can access this page he does this works all the time with blender and even has some tutorials if you can understand portuguese.

First, thanks for all the great replies.

me1, thanks for the instructions. For as hard as tried I could not find that on the web or the Blender uber tutorial.

RJ2005, a cross section is a two dimensional object which can be repeated along an axis (cartesian or otherwise) to create a 3D object.

As soon as I get a chance I’ll put together a step by step description of how I’d model a test object in Solidworks (it will be in SketchUp but the steps will describe Solidworks’ method). Fortunately all CAD programs seem to be able to export to dwg/dxf files which Blender can also do.

Mirrors: This is something that has been causing me a great deal or problems. I am able to get a surface that mirrors the scene but I can’t get it to reflect source light. Images will be posted tomorrow when I put together the CAD description. For that reason I’ve looked into alternate renderers. So far I’ve tried both Indigo and Yafray (I just recently realized Blender wasn’t rendering in Yafray by default).

Is there an option I can toggle/adjust to make the mirror reflect source light? Is there a way to adjust the percent of the light reflected?

End Blender stuff----------------------------------------

The Project: The project I’m working on is the design of an open top Mesocosm for biological research. The canopy (which is what I’m trying to model) is a vertical duct 15ft tall x 5ft x 5ft. Lining the inside surface of the canopy are highly reflective panels (97% reflective). I intend to model where the sunlight strikes the bottom of the canopy using a ray tracing renderer. I realize this is trivial for a duct but much more complex cases will evolve from the base case (the panels will be warped to see if hot spots form).

A Mesocosm is an apparatus used by environmental scientists which allows them to systematically test how certain environmental variables impact an environment. They come in many forms from fully enclosed and artificial (lighting, wind, temperature, gases, etc) to open (natural atmosphere, light, temp, etc).

Is there an option I can toggle/adjust to make the mirror reflect source light? Is there a way to adjust the percent of the light reflected?

I think what you’re looking for is the Mirror Transp panel in the materials button panels. The Ray Mirror button turns mirroring on for the material (assuming you’ve got Ray tracing enabled in your render settings) and the Ray Mir slider determines how much of the incident light is reflected. The depth setting sets the number of times the light ray can bounce off something before its ignored.

Source light is not rendered neither reflected, unless it is a mesh with emit value above 0. You can put a shiny mesh in the same place of your light point to looks like the souce light you imagine.

For rounded corners, if you just want them to shade rounded, that’s very easy to do: You just add a cut (Shift-K) on each side along the (otherwise sharp-looking) bend. And make the whole surface smooth-shaded (select all facets, W -> Set Smooth. Why a cut on each side? Because, if you just bevel the corner, say at 45 degrees, the edges of the bevel will have computed normals at 22.5 degrees. But the way OpenGL works is it interpolates normals across faces, so the big flat planes will look like they have a slight curvature.
So, it is imporant that the last piece of geometry near the edge be coplanar with the big surfaces, if you want the latter to look flat. The panels on my ship, here, each have 3 cuts: 1 at an angle, and 2 flat:

In fact, if you look at the edges of the panels, you’ll notice the sharp angles.

If your main surfaces are at 90 degrees, this would work in ogl rendering, but it won’t work in Blender’s rendered, because it limits angles to 80 degrees maximum. So you are forced to have a 45 degree bevel; but there again, if you want the main surfaces to look flat, you’ll need to flank the bevel with 2 more cuts. Four cuts total.
If you look at the whitish part at the top right on the pic, that part is done like that: 2 cuts for a 45 degree bevel, and two more flat cuts on the sides of the bevel.
Or maybe I have one more cut; can’t remember; but that’s only for the outlines to look rounded. In terms of shading, 4 cuts do a great job.

MADCello, is it possible to control the light direction from a mesh source? I need to model the sun so the rays of light must be coming in parallel to each other. I’m afraid a mesh source would emit light in all directions. I don’t care much about the diffuse light coming from the atmosphere.

chuck_starchaser, thanks for the method. I’ll give it a shot next chance I get.

Here is the method I would use if I were doing this in Solidworks. This Fiberglass Fitting is the piece I am trying to model. My model is based off of measurements off of a piece I have at hand. The model I’ve made also looks more like the actual piece. The annotations are for your reference.
Final SketchUp File: File
Final DXF File: File (right click and save as)

Basic Outline (image): Draw a 2D basic outline.

Reference Lines (image): Draw reference lines. Draw circles at the intersections of the reference lines.

Extrude (image): Extrude the surface to create the 3D object.

Bevel Edges (image): Select an edge and bevel it with a given radius of curvature. The bottom and far right curves have 1/4" radius of curvature. The inside curve has a radius of curvature of 3/8". The large curve has a radius of curvature of about 1 15/16".

Dublicate and Position (image): Duplicate the object and position it relative to the first.

Draw Plane (image): Draw a plane.

Extrude (image): Extrude the planes and it’s finished.

My attempt in Blender has been less than spectacular. I created two cubes and reshaped them to get the correct dimensions. Then I created circles on the surface. From here I cant’ seem to extrude the circles. I was going to extrude the circles into cylinders then do a boolean operation on the set of cylinders and boxes to cut out the holes. My attempt in Blender can be found here.

Is it possible to extrude non-mesh surfaces (nurbs and so on)?

Other than for dimensional lines, I use these techniques in Blender all the time.
To draw in 2D:

Place the cursor at a point where you want the 2D plane to pass through.
Choose a view normal to the plane you want.
Place a plane.
Delete - vertexes. (This is unintuitive, but it’s the way to do it. The vertices are gone, but the plane is still there.)
Put the selection mode as for vertices (as opposed to edges or faces).
Now press Ctrl and left-click to place each vertex. If you want them to snap to grid, place them close to grid points, and when you finish the outline, Ctrl-L to select all vertices, Shift-S for snap, and Selection to Grid.

To extrude, say that your outline is on an x-y plane, rotate your view, select the outline, E (for extrude), Edges Only, Z if you want to constrain the extrusion direction to the Z axis, then move the mouse, or enter the amount on the keyboard. Sometimes you may want to extrude and scale rather than move. No problemo: E, Escape, S, and pull the mouse. If you want to do these things on planes at odd angles, it’s easier to make the part orthogonal, then rotate it afterwards.

Blender internal does not support ilumination with meshes, unless you use radiosity (afaik), and you cannot control the direction at that precision (afaik also). To get paralel shadows, use a sun lamp with raytraced shadow (don’t forget to turn on “RAY” in render panel (F10)).

I talk about the mesh with emit value, because you said you want to see light source in the reflections. As you cannot render a light source, this is a way to fake a visible light (like the sun, or a lamp).

I’ve gotten the extrusions to work (my bad for doing them in the wrong mode). I put in a mesh circle, filled it (SHIFT-F), and extruded it. The problem I’m having now is that the boolean operation isn’t working. It either takes a while and does nothing or takes a while and then crashes Blender with no error messages.

The model I’m using is here. The series of commands I use it W and 3.

My approach to model this is:

1- Draw the 2D lines, draw the circles inside, and put vertices at the center point of the ars (that 90 degrees corners you have in the model).

2- Use the tool “Spin” to make all the arcs (this way you have control with number of edges in the arc).

3- Delete temporary center point vertices and remove doubles.

4- Use Fill (SHIFT+F) to create all the faces ( if fill does not work as expected, use the script “vertices to faces”).

5- Now duplicate (in editmode) and extrude the faces that remain selected. Remove doubles.

Now is just copy that side to the other and make the easy part.

if you’re just trying to make holes in the piece, and that is what the boolean operator is for,
try this tutorial I found under “Tutorial Links” on the main blender wiki.

As someone experienced with CAD and SketchUp, I highly recommend just spending a good day or two going through all of the tutorials you can find related to what you want to do on that tutorial list above. It has eased the headaches I had intially when I first began to learn. At the end of the tutorial list there are links to more tutorial lists!

Blender is totally different, but much faster and with cooler tools once you learn all the commands. Blender is like driving a Porsche built by your friend down the street, while CAD is like driving a tank from world war II that’s been renovated with high-tech equipment.

I’m skeptical about finding a solution to your specific uniform directional light problem, though. You might want to post that specific problem in the lighting support forum though, it’s a good one and I would like to know how to do that too.

You can do something like this using ProCAD (an italian script)…

command “SMU” (using ProCAD):
Creates a fillet, (rounded corner or a beveled edge) at the intersection of two lines on the XY plane.
You can choose the radius and the number of segment.

By the way, man, if you’re looking for ‘light reflection tests,’ like, ACTUAL light reflection tests, I wouldn’t use blender’s internal renderer, or even yafray. The internal renderer is a scanline renderer and, while efficient and a good artists tool, has no-where near the amount of accuracy you’d need.

Yafray supports reflection and refraction and GI and photons, but it’s intensely biased and suffers the same accuracy problems. For a completely unbiased renderer, for free, I’d go with indigo, it runs off of a physical light transport system so it’d be much better suited for light tests.