3D Modeling Series 9: Using LOFT Command

[AutoCAD 2007 and higher versions]
[User must have advanced 3D knowledge]



LOFT is probably the most complicated part of solid modeling series of articles. It is not certain what this command is used for, however it has a great potential to create marvelous solids in hands of creative users. I’d better explain its use and you take back your notes and imagine what can be done by using it. May be the command is improved in future or some of you can find interesting ways of using it.


In the most fundamental way, this command is somehow a kind of RULESURF command that is used for solids. Thus, it combines two or more curves to create a solid. If the curves are open, it creates a surface; if the entities are closed it creates a solid.


Fig.1




While explaining the command, I will create the three examples that exist in loft.dwg drawing that you can download and you can see in Fig. 2.


Fig.2

The most basic form of LOFT command is to create a solid by selecting two number of closed curves.

Start the command and select the two circles one of which is on top of other. First select the one on top and then the other one.

Command: _loft
Select cross sections in lofting order: 1 found
Select cross sections in lofting order: 1 found, 2 total
Select cross sections in lofting order:
Enter an option [Guides/Path/Cross sections only] <Cross sections only>: C


Pass the last option by pressing ENTER.


Fig.3

You will obtain ‘Loft settings’ window that is shown in Fig. 3. The options that can be seen in this window have preview option and your entity will be updated as you change the settings here. In Fig. 4, I tried to give examples for some options.


Fig.4

In this first example, we combined two closed curves (here what we call them the cro<ss section curves) by using various options. When we come to the ‘Guides’ and ‘Path’ options of LOFT command:


Fig.5

This example that is shown in AutoCAD help files shows how the example starting and end cross-section are LOFTed by using aiding curves (Guides). Make sure that, while drawing these aiding curves, they must definitely intersect the curved that you are going to LOFT and the starting and end points should be exactly on the curve.


Fig.6

In Fig. 6, I made LOFT by using PATH option.


Fig.7

In Fig. 7, you can see that 4 number of curves were combined by using ‘Smooth Fit’ and ‘closed’ options.


Fig.8 ‘Normal to all cross sections’

As you can see, there are various options for LOFT command, however their usage is quite hard. It is a must to make practice in order to master its usage.

» Previous articles in this series:

• Introduction to 3D Modeling
• Creating Primitives
• UNION & SUBTRACT Command
• Positioning Entities
• Using POLYSOLID Command
• Using REVOLVE Command
• Using EXTRUDE Command
• Using SWEEP Command