[Fighter]

Hello,

I am trying to learn 3D shaded drawing using AutoCad 2004 mechanical.

Trying to draw a sphere.

If in "Front View" I draw a vertical line as an axis, then draw an arc on one side of it and enter the REVSURF command, it asks to select an object. I select the arc and press enter. Then it asks to define the axis, and then the degrees of rotation. I get through all that and it draws a funky looking shape that does not follow the arc line. I then switch to "Top" view, and from the top view it is a hexagon shape.

Why is it not round, and how do I make it round so that it produces a sphere?

Thank You!

[ger21]

SURFTAB1 controls the number of faces along the revolve
SURFTAB2 controls the number of faces along your profile shape.

The Default for both is 6, which gives you a hexagon shape.

[Fighter]

I reset it to 50 on both SURFTAB1 and 2 and it looks pretty good!

Apparently, the number represents the number of segments along the line?

Is there a max limit, or a common value used for a relatively smooth drawing?

Sorry for all of the questions, but this 3D stuff is all new territory for me!

Thank You!!

[ger21]

Not sure want the max is, but you want to keep it as small as possible, as large meshes will really slow down AutoCAD.

You might also want to look into using solids, as they are a lot easier to work with for beginners.

[Fighter]

Is solids something I can do with ACad?

The whole terminology thing with 3D is like learning a foreign language...

I have been searching for tutorials in YouTube for 3D drawing using AutoCad 2004, but most are in a foreign language that I don't understand.

Thank You!

[Fighter]

Perhaps I should start by addressing the "AutoCad Mechanical Help", which I have never found to be of any help whatsoever.

If I do a search for "REVSURF" I get "No topics found". I try "SURFTAB1" and get "No topics found". Neither of which are even listed in the "Commands" list. Even searches for common terms such as "TANGENT" return nothing.

Am I not using the "Help" correctly?

Thank You!

[ger21]

Never used Mechanical, but the regular AutoCAD help file is excellent, imo.
Rather than search, try using the Index?

[Fighter]

Earlier today I tried the standard AutoCad Help rather than the AutoCad Mechanical Help and that solved the mystery, and answered quite a few questions!

Thank you for the reply!

[Fighter]

Started playing with solids tonight. Created a few cylinders and a cube and used UNION to join them, then filleted the joints and a few edges.

Problem is, I have no idea how to position the objects in relation to each other. I wanted to create a cylinder and then join another cylinder perpendicular to it. They all want to align on the same axis, so I just stacked them on top of each other. Is there a command to orient the axes?

I don't know the terminology to use, so the Index isn't working out on this one...

Thank You!

[ger21]

Some people like to change the UCS. Newer versions of AutoCAD have Dynamic UCS which makes it easier to do that.

Personally, I don't use either. I prefer to use the 3D Rotate command to position objects. I also draw reference lines using 3D polylines to aid in alignment.
I also occasionally use the Align command to align complex objects.

Do you know how to move objects relative distances? Use Osnaps with the "from" command?

[Fighter]

All of the above would be new to me.

The purpose of all of this is to utilize my 3 axis milling machine, which I have only ever done 2.5 milling on due to the lack of 3D drawing ability.

Still trying to determine if Solid or Wire Frame would be the best way to go, as I know nothing about either.
.

Thanks!

[ger21]

Your choice of CAM program may dictate the methods you need to use.

[Fighter]

I drew two concentric circles and tried to extrude them as a tube. I tried BOUNDARY and REGION and even tried to hatch the area, and all I get is a solid bar when extruded.

Is there another command other than REGION or BOUNDARY to determineselect an area to extrude?

Thanks!

[ger21]

Convert them both to regions, and boolean subtract the inner region from the outer before extruding.

Or, extrude them separately and subtract the inner cylinder.

[Fighter]

I extrude two cylinders, one inside of the other.

Trying to SUBTRACT the inner cyl from the outer cyl.

Type in SUBTRACT and it asks to select objects. I select both cyls and it states "2 objects selected". I press the Enter key. Select object to subtract and I select the inner object. Press Enter

"No solids or regions selected"

Am I missing a step?

Thanks!

[Fighter]

In the previous post I had incorrectly listed the steps I took.

The post has been corrected.

Thanks!

[ger21]

Select the first object. Hit "Enter" Select the object to be subtracted. Hit "Enter". Note that you can select multiple objects to be subtracted before hitting enter.
You might find that it's much faster to configure the right mouse button to act as Enter during a command.
Then it's select, right click, select, right click. You can find the right click settings in the Options.

[Fighter]

That sorted it out!

Thank You! Your help is greatly appreciated!

[Fighter]

I was just creating some shapes and viewing in SW Isometric view. When I started the Z axis was vertical. The view has not changed, nor has the relation of the shapes to each other, but now I see that the Z axis is horizontal...

How did that happen?

Incredibly confusing, to say the least...

How can you create a part when the part stays in the same orientation and the axes keep changing?

Thanks!

[ger21]

When you change to the front, back, or side views, the UCS changes to align the X and Y axis to the view.
Going back to the top view will reset it, so, before using an isometric view, always make sure you go to the top view first.

This is actually a very handy feature.

I use AutoLisp routines to asign my number keypad to the different views, so that I can quickly switch back and forth.