techniques to 3d drawing besides drawing out all three faces in 2d mode

[ninjuninju]

Is it easier to draw out all faces of the 3d object and then merge them together later on or is there a method that allows me to be able to dimension and extrude my object as I work from the 3d space?

 

Say, I created a square and extruded it into a block. Then I want to look at one of the sides and poke 3 holes in it. My problem is I cannot use annotate to change the geometrical constraints on them, like if my circle is out of place or if it is too large or small.( or at least they don't show up for me.)

 

I'm learning about the UCS system but I thought if I moved the UCS system to the face I want to draw on and change from 3d modeling back to 2d annotation I can go ahead and annotate from that face of interest. Please give me advice

[Dadgad]

In Autocad 2012 you can create or use an existing 3D Model, from which the VIEWBASE set of commands will enable you to extract all of your 8 standard orthogonal and isometric views in somewhat less than a minute, once you get the hang of it. You really don't even need to understand UCS to use these features, although you should certainly learn about it. While you are modeling, try opening your VIEW toolbar or VIEW palette on the ribbon, and selecting your views there. If you do, you will then be able to work on them, without changing your UCS independently, as both the VIEW toolbar and the VIEW PALETTE will reset your UCS every time you select an orthogonal perspective. If you select an isometric perspective the coordinate system will reset to WCS. If you turn on your VIEWPORT CONTROLS in the lower left corner of your 3DModeling tab in options (right click in your commandline) then you can change your VIEWS & UCS by accessing the controls in the upper left corner of your MODELSPACE.

Edited February 25, 2012 by Dadgad

[ReMark]

You can't apply constraints to a 3D solid.

 

If you have an extruded square with three holes in it and you need to modify the size or location of any or all of the holes it can be done using some of the solid editing commands.

 

Learn how to manipulate the UCS manually or use the Dynamic UCS.

 

2D annotation? Are you talking about dimensioning a 3D model?

[ReMark]

Dadgad mentioned VIEWBASE. To see an example of what can be accomplished using this command click on the link below then take a look at post #6. Post #5 has is an image of the 3D solid model.

 

http://www.cadtutor.net/forum/showthread.php?67102-orthographic-projections&highlight=viewbase

[rkent]

Is it easier to draw out all faces of the 3d object and then merge them together later on or is there a method that allows me to be able to dimension and extrude my object as I work from the 3d space?

 

Creating solids is generally easier than drawing various faces.

 

Say, I created a square and extruded it into a block. Then I want to look at one of the sides and poke 3 holes in it. My problem is I cannot use annotate to change the geometrical constraints on them, like if my circle is out of place or if it is too large or small.( or at least they don't show up for me.)

 

This is a serious limitation of 3D in AutoCAD, once there it is difficult to move or modify. With Inventor you can change the dim of the circle of the dim controlling its location and the solid model is changed for you.

 

I'm learning about the UCS system but I thought if I moved the UCS system to the face I want to draw on and change from 3d modeling back to 2d annotation I can go ahead and annotate from that face of interest. Please give me advice

 

You can annotate anytime with the UCS in any orientation. You will have to pay attention to the direction the X, Y and Z point so the text reads correctly. See the attached from Cadalyst.com November 2011 for more on dimensioning in 3D.

3D dimensioning 9-28-11.pdf

[ninjuninju]

Thank you for everyone's inputs, I found this:

http://www.wisc-online.com/Objects/ViewObject.aspx?ID=ENG19204 from remark's post very helpful in explaining the basics of drawing.

 

And excuse my jargon with autocad, I did not know I cannot dimension (not annotate) an object once it goes into the 3d view (or that I would need inventor to do so)

 

My current problem is that I am trying to construct a block with something similar to a cross-wrench hidden away on the inside. I thought I can draw a circle on one face and onset a dimension within the block and drag it down to the other face (the block is suppose to be hollow on the inside) But apparently that seems completely restricted. Do you guys have any suggestions to how to approach this type of modeling?

 

Thank you for the initial input

[Jack_O'neill]

Creating solids is generally easier than drawing various faces.

 

 

 

This is a serious limitation of 3D in AutoCAD, once there it is difficult to move or modify. With Inventor you can change the dim of the circle of the dim controlling its location and the solid model is changed for you.

 

 

 

You can annotate anytime with the UCS in any orientation. You will have to pay attention to the direction the X, Y and Z point so the text reads correctly. See the attached from Cadalyst.com November 2011 for more on dimensioning in 3D.

 

The thing to remember about Autocad solids is to create the features where you want them and how you want them to look. Inventor and programs like it let you create a circle, then decide how big it should be, and where it should be by adding dimensions and constraints. In autocad, if you want a 2x2x1 block, you would draw a 2x2 square then extrude it 1 unit (or a 1x2 rectangle extruded two units). If you want to put holes in it in a specific place, put a ucs on one surface, draw a circle the size you want it at one corner, then move that circle in x and y to where you want the hole using direct distance entry. you can then extrude and subtract or press-pull as needed. Its not hard to do, just sometimes cumbersome. If you put the hole in the wrong place, draw another circle on top of it (or use presspull) and extrude it, then use the union command to make it one piece. Like i said, not hard, but cumbersome.

 

You can take full advantage of array and copy and all that too. If you have several holes to put in, like a circular bolt hole pattern in a flange for instance, you can array a circle, then extrude and subtract them all at once, doesn't have to be be one at a time.

[ReMark]

On the contrary, you can dimension a 3D object you just have to use the proper technique.

 

Post an image of what you are trying to do and we'll try to talk you through the process of creating the object.

 

It almost sounds like you are trying to create a mold. Is that it?

 

I think part of the problem is your use of terminology which may be due to the differences in the language you speak and the way you are translating it into English. What is your native language?

[Jack_O'neill]

 

And excuse my jargon with autocad, I did not know I cannot dimension (not annotate) an object once it goes into the 3d view (or that I would need inventor to do so)

 

 

As Remark said, you can dimension in autocad in 3d, but you do it after the fact as I tried to explain.

[Jack_O'neill]

A picture is worth a thousand words as they say, so here is a pictoral representation of what I was trying to describe in post #7

There are many other ways to do what this shows, some faster and fancier, but this is about as simple as I could come up with for a beginner. This method will put the center of a 1/4" diameter hole 1/4" off the corners of the block, regardless of its size. If you want them to be a specific distance apart, then you'd have to copy the holes to that distance instead of mirroring them.

 

After you get the part made, you can then go to paper space and create your viewports and put the dimensions on. In Inventor you can put dims on as you go that will drive the model, but not the case in autocad. Dimensions merely document what size the object is. If you want it 2 inches long, you have to draw it 2 inches long.

[Jack_O'neill]

And as if it weren't confusing enough, you can use parametric constraints, both dimensional and geometric in AutoCAD (well, 2010 and up) but only in the 2d sketch. Once you extrude the object, you can't change it with those constraints without undoing back to the sketch. In this example, I've added 3 perpendicular constraints to the corners of a rectangle, a dimensional constraint to the horizontal portion and another to the vertical portion. The vertical constraint is in the form of an equation, which in this case simply says that d2 is to be 2 times d1. If I double click d1 and change the 0.7500 to 1.500, then d2 automatically increases from 1.500 to 3.00 and it updates the dims in red. The perpendicular constraints are there to make sure that the corners stay square.

[ReMark]

Starting upper left to lower right.

 

A baseplate with four bolt holes drawn in 2D.

 

Using the REGION command, five regions are created. Using the SUBTRACT command the holes are subtracted from the plate.

 

Using the PRESSPULL command the baseplate is given a height. (cyan color)

 

Using the MOVEFACES command one of the holes is relocated. (magenta color)

[ReMark]

In this example I used the MOVEFACES command to remove (right off the face of the baseplate) one of the holes.

 

Notice that one hole diameter is now larger? I did that by extruding a larger diameter circle through the baseplate then using the SUBTRACT command to get the desired results.

[Jack_O'neill]

See? Other ways to do it already. If you know ahead of time where you want the holes, Remark's method will save time and steps.

[ReMark]

How can you make a hole smaller (or larger)?

Another method would be to use the OFFSETFACES command.

The hole that is circled in red was made smaller in such a fashion.

 

So as you have seen the Solids Editing tools available to you in AutoCAD will allow you to make a number of changes/edits to the original geometry thereby saving you from having to redraw it all again.

 

One last suggestion...set the system variable DELOBJ to a value of 1. This will save the underlying 2D geometry used to create your 3D objects.

[ninjuninju]

Here are some pictures of what I am trying to do, only I have to model it for a bunch of different sections.

 

Hopefully it's understandable.

 

I came from a Solidworks background, so I was pretty spoiled about dimensioning my objects and positions.

[ReMark]

Doesn't look that difficult. The EXTRUDE or PRESSPULL commands would work on profiles of everything you have shown.

[ninjuninju]

The 2nd picture is not the close end, I was just squeezing stuff onto one paper,

 

It is the cutend, as referred to from the first picture