Cannot subtract objects?

[SFG13]

Hi,

 

 

I have a drawing of an object containing four circles(circles are within an object), two small ones are D=.875, and the two larger ones are D=1.5, 2.25. I ext the two small circles and large circles. I tried to subtract the two small circles but the command kept saying "no solids or regions selected." What am I doing wrong?

[lpseifert]

Turn the circles into regions prior to the subtract command. Set Delobj=1 if you don't want to retain the original entities.

 

What do you mean by "I ext the two..."?

[SFG13]

I extrude the two circles. I typed in Delobj but what happens next?

[lpseifert]

Maybe if you were to post a portion of the dwg or a screenshot it would be easier to understand what you're asking.

[ReMark]

Most likely you have multiple copies of circles sitting one atop the other. When you make your pick AutoCAD is "seeing" a plain 2D circle which it knows is not a solid nor is it a region.

 

Go back to the beginning when all you had were four circles all in 2D. Start the Region command and select all four circles. AutoCAD should tell you that 4 loops were extracted and 4 regions created. Now subtract the smaller circles from the larger circle(s) using the same Subtract command you use for working with solids. Since we have no idea of the configuration it is difficult to give precise instructions regarding exactly what large circle(s) we're talking about. Once the subtraction has been done then extrude the resultant geometry.

[SFG13]

Okay I will try that and see what happens, thanks!

[ReMark]

After a night's sleep I got to thinking...

 

You said "circles are within an object". Are all four circles being subtracted from this object? Are any of the circles being subtracted from each other? Get we get an image to see what you are working with?

[SFG13]

Yeah you can see in the attachments what the drawing should look like:

 

You can't see the first smaller middle circle but it's D=1, then 1.5, 2.25. I just canit figure out how to subtract the 3 circles.

[JD Mather]

Yeah you can see in the attachments what the drawing should look like:

 

I'm not sure I understand - is the screen capture your work or someone else's work?

 

Can't you simply attach your dwg file here?

 

Looks like excellent use of presspull to me.

 

Also - your dimensions don't look correct. If the large circle D=2.25 how are the small circles moved a R that looks to be about 2.25 and the R and D for mounting holes don't look proportional to the large circle?

[MikeScott]

JD's right of course (as per usual and I'm tempted to type that in my sig lol)

 

However, since you wanted to know about subtraction, let's address that.

 

You might want to change your SHADEMODE to 3d wireframe so you can see your shapes hidden within the main shape.

 

They should have been regioned along with everything else, and extruded.. If not, that's your problem.. region it all together first..

 

Next, you can extrude it or don't.. it'll work either way, but it will give you an error message if you select a 2d object that has not be regioned first... This is because a region is the same thing as a 3d face.

 

However, just to stay on the same page as your drawing instructions, go ahead and extrude it first.

 

So, start the "SUBTRACT" command.

First select the main shape, then hit enter

Then select the two cylinders you want to subtract from the main shape, and the holes should appear immediately.

[ReMark]

The image you posted clearly outlines the steps, in order, to be taken. I'm having a difficult time understanding why you are unable to follow along.

 

The two smaller holes you mentioned are the bolt holes for the flange right? And the two larger holes you mention must be the O.D. and I.D. of the center collar right?

 

Look at JDM's excellent "demo" and keep in mind that before you use Extrude or Press/Pull that you can utilize Regions to accomplish part of the task.

 

Note: We have talked in the past about the use of Regions. It seems you are still having a problem grasping the concept. I would consider asking your instructor for clarification on any concept you do not fully understand.

[SFG13]

Yes I know about Region and have tried it first every time. Sorry for responding late, I attached my drawing. i'll try and follow from what you all recommended and I hope it'll turn out right. Thanks!

Extra credit 1.dwg

[ReMark]

SFG13:

 

I see the reason now why you cannot do the subtraction. The profile of the main portion of the flange is NOT a solid it is a surface. Thus, the command will not work.

[ReMark]

Upon further examination I notice that the body of the flange (in blue in your drawing) has some geometry that does not meet correctly (at least one line and arc don't meet up the way they should) and there is at least one arc segment (right hand end) that has been duplicated. In other words, you have the same line reproduced right on top of itself.

 

This last error is troubling since I have mentioned your tendency to duplicate lines atop one another in the past. It's like you copy or mirror geometry atop itself. WHY?

 

And yet another anomoly. In your drawing the collar or cylinder in the center does not have a hole all the way through it as the image you posted depicts. Is there a reason for this?

[ReMark]

Note: Whenever you see geometry that you have extruded appear similar to a flat grid suspect that you have a surface and not a solid.

 

I'm going to need a longer piece of paper.

 

Another thing we have discussed on more than one occassion. That is your habit to draw everything on layer 0 then override the layer color. Please don't do that. Use layers creatively and to your advantage. And assign each layer a name that makes sense and a different color.

[ReMark]

To prove the object can be produced from your drawing.

 

[ReMark]

SFG13:

 

Have you made any progress in solving your problem yet?