What a Mesh

Back to basics: Extrusion in AutoCAD part 5

So, now that we know how to use Path for the extrusion, let’s do some direct manipulation on the extruded object.

Let’s start by clicking it and see what we can do. We’ll see grips for the profile, grips for the path (in this case an arc), and another grip for position of the model. It is important to understand that there is no associativity between the arc and the object. The grips belong to the model, although they will be coincident with those from the arc before you make any changes.

In the following image you will see what I mean. As soon as we use that grip (center grip along the path), the curvature changes, and once we finish the operation, the arc is still in its place. After the operation, the arc is not relevant for the model itself.

The grips that belong to the profile can be moved very easily by using the Gizmo, into pretty much any shape that does not create self intersections. In this case, I just moved one vertex up, and the AutoCAD reacted in a very predictable way (for an extrusion). If you just wanted to move that vertex up, then there’s an extra step (use the command BREP). But that’s another post for another time.

If we were doing some very basic conceptual design, even after doing the extrusion, we have the chance to adjust the volume to another object. In this case, I’m moving the grip so as to be coincident with the height of the adjacent box, and that’s it. No need to worry at the beginning of the design. You can be as flexible as you want.

 

 

Now, I’ll just leave you with the final image. Just wanted you to know it was done with just two more clicks. Wonder how? Yes… you got it. That’s another post.

Back to basics: Extrusion in AutoCAD part 4

The last option to cover within Extrusion is Path. This will take four complete posts, but I think it’s worth examining the options very carefully.

Last time we talked about Direction, which would somehow do the same as Path, if the latter was a simple segment. If you have a polyline, 3dpolyline or spline, then Path is the right option.

Let’s see how it works.

First of all… where do we locate the path? Well, there are some rules for that.

Normally, the path will be located in a point that touches the profile. The path does not need to actually start in the profile, but it normally helps to better understand what you are doing. However, this may vary. You could have the path starting at a midpoint in one of the segments of the profile, or even have the path starting anywhere, and at some point intersecting the profile. Actually, the command will also work with a path which does not touch the profile! The result may not be too predictable, but there’s always a rule for that too (but not today).

Let’s assume that the path starts at the bottom vertex of this rectangle. Once we invoke the Extrude command, we need to add the path, since what we’ll see by default is the dynamic preview of the profile extruding along its normal. Once we access Extrude options (down arrow, right click if you use mouse sensitivity, or command prompt), we select Path, and then click on the entity which will act as path. And voila!

 

 

This is the before and after selecting the path (images above and below respectively)

Let’s see what happened in this process. If we go to a Top View, we’ll see that the angle between the profile and the path was kept. I have heard people asking why (in a similar case) the ending of the extrusion is not vertical. Well… that’s not the way the command works. If you need something like that, a loft between two profiles and a guide would be better.

Does this work in any case? Let’s try with this other arc, which starts almost tangent to the profile. Almost is the magic word here. Since it is not tangent, the command works perfectly, as you can see in the two images that follow.

 

In the following image, we can see a scenario where the command will fail. The path intersects the profile, and it will be impossible not to generate a self intersecting solid. That’s something that AutoCAD will not accept. Some applications can force the creation of a non valid solid, but that will lead to problems at some point.

 

One last case for today. The following path and profile don’t have any trouble in creating an extrusion. But if we move the path to the other end of the profile, it will fail, since the path’s curvature is smaller than the length of the profile, which will evidently cause a self intersection. Pretty obvious, but tends to happen, and sometimes in the middle of a very long day, we may oversee this kind of conditions that Extrude with Path needs for a successful operation.

In the two images that follow, the command succeeds, while it fails with what seems a small change in the starting conditions (last image).

 

 

Back to basics: Extrusion in AutoCAD part 3

Back to blogging, in this case continuing with solid modeling. As I said before, there may be little to say about the Extrusion command for advanced users, but some of you may find this interesting, and I would also recommend it to anyone that has not seen the enhancements after 2007.

The Extrusion command has an option called Direction. It can be accessed from the command prompt or by right clicking and getting to the in canvas menu (after having selected the profile and started the extrusion).

Why do we have that option? If you have a situation where instead of needing to do an extrusion along the normal of the profile, you need to do it along a certain direction, you would have two ways to do it. The long one is to draw a path and then select Path in the Extrude options. But if you have references that can be snapped, and the path is straight, then Direction is much easier, since you just need to select the first and last point of the direction of a non existent path.

Let's say you have two pillars, and need to create a reinforcement along the diagonal. These would be the steps:

In this case, I already have the pillars, and the profile to be extruded diagonally is already drawn next to the left pillar.

Once the Extrude command starts and we select the profile, if we right click or hit enter, the profile will try to extrude along the normal (in this case, vertically). That's when we right click and get to the in canvas menu, where we'll select Direction.

So, what points should I choose in order to get this result? Since the profile was a rectangle with half the width than the pillar, the first point to choose will be the profile's vertex coincident with the midpoint at the bottom of the left pillar. The second point will be the vertex at the top of the right pillar as shown in screen. It's quite obvious, since we need to select two points that will generate a path for the profile to move along.

That was easy! No more auxiliary lines for these situations. Just two clicks!

Now, we may need to edit the extrusion. Let's check its properties.

In the properties palette, under Solid Type, we see Extrusion, and we can change height and taper angle. In this case, height will be a vector along the path formed by the two points selected. Looks quite obvious, but in following postings, we'll see that an extrusion is not always such when we check the solid type. But I'm not going to steal my own thunder.

If we select the extruded object, we'll also see the grips that control the profile and the one for the height. As usual, this means that we can use direct manipulation in order to change the shape of the rectangle (as long as we keep four vertices, this works - meaning you can't add a new vertice), or we can also change its height by clicking on the control at the top of the extrusion and simply moving the mouse (or you can also type a specific distance).

And that's it.

You may wonder if there's a difference with making a path. We'll check that in the next post.

 
 
 
 

Back to basics: Extrusion in AutoCAD part 2

I just wanted to point out a couple of things about simple extrusions, before getting deeper into some more functionalities in following posts.

I received the question about how we could achieve the same results with numerical input and not press/pull.

There is really not much to say about numerical input. Once the command starts, you can obviously introduce a value for height through the command prompt. If you decide to use Taper Angle, just select the option from the command prompt (the shortcut is T), and once you enter a taper angle, the operation will prompt for the height.

One of the existing options is to repeat the last height, provided there has already been an extrusion done. This is actually the default, so if you just click enter, you will get the same height as the last object extruded.

If you already have the extrusion done and you click on the object, you can change both height and taper angle from the properties palette, if you really don't want to use in canvas editing.

Now, let me talk a little bit about in-canvas editing. Press/Pull is only a fraction of the options available for editing the object by having a direct interaction with it.

We have control over the height of the extrusion, the grips that belong to the profile, and we can also use direct manipulation over the faces, edges and vertices. Some of the old solid editing commands are probably not allowing that much flexibility as direct manipulation, and this is a trend that you will see getting more and more enhanced everywhere. Just take a look at Inventor Fusion and you'll see what I mean. We're not alone in this trend.

One last thing for today, and again, most of you will find it obvious. In the past, every command that requested for a distance would allow clicking in two points of the screen and retrieve that distance as input for the current command. This was also the case for extrude.

However, starting in 2007, if you just click on the height of any object in the screen, extrude will take the distance from the xy plane where the profile is placed to the Z of the selected object. So, if you just opened the file and you don't have the last extrude height, or maybe you are trying to retrieve any extrusion height which was not the last one you did, this option is tremendously productive.

In this image, I'm extruding a circle in order to get a cylinder, and I'm about to click any of the upper vertices of the box.

Both models have the same height now.

More on direct manipulation in the next post.
 
 
 

Back to basics: Extrusion in AutoCAD

After some weeks of adjustment and some sleep deprivation, I'm back with more tips and (hopefully) useful data about modeling in AutoCAD.

Talking about extrusion seems a little too basic, but I still need to cover some basics about it in order to get to more advanced topics.

The Extrude command has been around for some time already, and also allows other options than just the basic operation of generating a model that makes use of a profile and uses the normal to that profile as path.

AutoCAD 2007 introduced real time preview of the operation, and also introduced a couple of new controls in order to manipulate the extruded geometry. The real time preview can be seen in the image below. Once you select the profile, you will be able to define the height, or also access other options. It is important to clarify that the preview only happens if you select a single profile for extrusion. If there are multiple profiles selected, Extrude will prompt for the height without showing the preview of the operation.

The other options inside the Extrude command can be accessed by right clicking and using the shortcut menu, by using the cursor and then selecting the desired option, or by simply using the command prompt. These options include using the last height of a previous extrusion, taper angle, direction and path.

Let's focus on taper angle today. A positive taper angle will make the extruded faces converge. Once the taper angle is selected, you need to specify a height. The real time preview does not work after adding a taper angle to the operation.

 

So after finishing the command, the results would be the following:

 

If you now click on the extruded model, you will see grips along the vertices of the original profile, and a control at the top of the extrusion. Let's talk about the latter. If you click on this control, you will be able to change the height of the extrusion and have a real time preview. The curious thing is that we can see the preview even if we have used taper angle, even though the preview was not enabled during the creation of the extrusion.

 
 In older versions of AutoCAD, if the taper angle and the height produced a self intersection, the command would fail. After 2007, you can keep dragging the control for the height even up to the point of self intersection, and still get a predictable result. If you select the object again, you will see the extrusion control not on the edge that was defined at the convergence of the faces, but on the height where you dragged it. If you select it again and drag it down, you may recover the top face, if you go down the point of self intersection.

In the next post, we'll see what happens when we edit the vertices in the profile, and when we do some direct manipulation over the model's subobjects.

 
 

In canvas editing of solids in AutoCAD 2010

These days have been quite intense around here, with the baby coming any time between right now and next week. Anyway, while we wait to rush to the hospital, I found some time to make a new video about AutoCAD 2010.

I have been in many situations in which I'm told that AutoCAD is a complex tool for 3d, but this statement normally comes from people that have not been around AutoCAD 3d for the last years.

In AutoCAD 2007, we made solid editing much easier with some in canvas editing. This means that by directly manipulating the objects on screen, we can get to results that needed commands like Move Face, Offset Face, etc etc.

I don't think I've used those ever since AutoCAD 2007, and have not had the need for 3d move, 3d scale and 3d rotate after AutoCAD 2010 either.

In this video, I'll show you how to make the best out of in canvas editing of a solid. I'll try to post a couple more videos on this subject, probably between diaper changes.

As usual, the video is in HD if you click on the YouTube link.

Back to Basics - Press/Pull in AutoCAD.

Ok. This is not exactly a new functionality, but it does not mean that everyone knows about it. Press/Pull was implemented in AutoCAD 2007, and made certain operations so much easier.

Let me give some examples of its use, and remind you of the amount of steps that we had to do before. When for any reason, I need to check out something in an older version of AutoCAD, that’s when the value of some of the enhancements really shines.

In this first example, you can see many lines that don’t have any kind of connection on their vertices. But we need to extrude the shape contained within.

 

Any ideas? Let me throw a couple of the ways I would have done this before 2007.

·         Edit the grips and make them coincident. Then use PEDIT to convert one of those lines into a polyline, and join the rest (and wish we really made the vertices coincident). Finally, we could extrude the polyline.

·         But that takes a long time, so another option would be to use FILLET with radius 0 to get coincident vertices (or did someone say TRIM?). Then, back to converting one segment to polyline, join, and extrude.

·         And you will always find people that will generate a polyline tracing over the lines, and then extrude. This would not be too bad for objects with not many segments, but totally inefficient for bigger segments.

 I must admit I once had to create a single polyline from an insane amount of segments which were not exactly well drawn (coincident vertices seemed to be the exception to the rule). 25km of coast that had to be joined into one polyline. There were more than a thousand segments. Ouch.

By the way, none of the previous three methods would work if you have a spline as one of the segments. Now what?

·         I’m sure most of you know the command BOUNDARY. It has a similar behavior as HATCH, since it detects a closed boundary, but in this case, it generates a polyline. So back to our initial problem, the user would just click BOUNDARY, select an internal point, and you’ve got a polyline that you can extrude.

But wait! What if one of the limits is a spline? Then, BOUNDARY will derive the detected boundary into a Region. And we can now extrude a Region… yay!

So can we make it easier than two commands and four clicks? What about one single click? Sounds good?

How does Press/Pull work? Wherever you have a space enclosed by entities that are coplanar (lines, arcs, polylines, regions, splines, boxes, etc), Press/Pull will try to detect the boundary. Sounds familiar? Well, it’s using a very similar method to the boundary for detection. You will notice that once you invoke the command either from the Ribbon (Modeling panel in the 3d Modeling workspace Home tab), or by its new shortcut (because it changed in 2010), which is Ctrl+Shift+E, part of the linework  will seem to flicker for an instant. That’s basically happening when AutoCAD looks for the boundary. If you have a massive amount of linework, the command will take a while longer to detect the boundary. So the same strategy that you may already use for making hatches faster (have less objects on scree), is also valid for Press/Pull.

Once you see the boundary detected (with dashed lines), just click anywhere inside the shape, and the extrusion will start. It is actually slightly different to the EXTRUDE command, since you don’t have access to the different options within EXTRUDE. The command will finish as soon as you click again. You can snap to elements that already have the desired height, or you can type the height of the extrusion.

 

Let’s check some other interesting options in following postings.

Press-Pull in AutoCAD 2010

Some time ago I made a post about some changes in Press-Pull in AutoCAD 2010. I just created a video supporting the previous post.

Where is Press Pull in AutoCAD 2010?

Hi,

Today I'm going to talk about Press Pull. This will be the first posting about Press Pull, and about Solid Modeling.

I received a comment that there was no way to get to Press Pull from a keyboard shortcut in AutoCAD 2010, and the fact is that the shortcut was changed.

To make Press Pull with a keyboard shortcut in AutoCAD 2010, you need to press this combination: Shift + Ctrl + E.

Press Pull will enable you to extrude an element from any enclosed boundary between lines that are not necessarily a closed polyline. By clicking the combination of keys or going to the icon in the Ribbon, on the Modeling tab in the Home panel (in the 3D Modeling workspace), you'll see that AutoCAD will try to detect a boundary (just like in Hatch), and then you'll be able to just drag the volume to the desired height, and finish the command. The combination of keys is only needed until the first click that starts the extrusion.

 

This was introduced in AutoCAD 2007, and has many other possible uses that we will be covering in other postings.