Help with Orthographic Projection

[Behemothrex]

Hello Gents,

 

Well I have a problem. I am taking college classes online to learn CAD and I have hit a bit of a snag. Not to go into immense amounts of detail but I am taking classes online. My class advisor and the course catalog both stated I could take this class without any knowledge of CAD or Drafting, in fact is is recommended to take first.

 

Apparently the instructor thinks you should have had basic drafting, cad, blueprint reading, etc, etc before you take the class I am in. His instructions so far have basically been you should know this, this is just a refresher, okay here is the assignment go.

 

Well up until this point I have been fine, but now we are doing orthographic projections and he has given me squat for instruction. I have read my text book I have the basic concept, but it would have been nice to get at least one example that was not a box or a L shaped box to look at LOL.

 

So I am uploading a pic of my assignment to see if I have done it correctly. I used photoshop to enhance the lines so you can see them a bit better. I have placed two red circles over areas I am sure I have made mistakes in but am not sure how to do it properly.

 

I know this is a giant wall of text but I appreciate your help, advice, thoughts LOL. If you have any links to tutorials that actually show more complex drawings that would rock too.

 

Okay enough blather.

 

Here is the drawing.

 

[Dadgad]

For the most part, very well done.

Doing this in CAD you should have your ORTHO or POLAR turned on though, and your END snap running.

The only mistakes that I see are that you should have also shown HIDDEN lines,

which would be on their own layer, with a different color, I use 11 for them, and their linetype HIDDEN.

 

There is a small mistake in the lower right drawing, where the tapered face of the upright meets the slab (at the bottom, right?)

These are reasonably challenging, for purely geometric shapes, looks like you have got a pretty good handle on it, despite those omissions.

[Dadgad]

If you look at the VIEWBASE generated images here, you will see that the HIDDEN lines are represented by HIDDEN line type and in a different color.

These are quite random, I would never use all these views of one part, just wanted to show you a bunch of different perspectives.

 

These were all generated by the software in a few seconds, they represent a 3D model of the item which I created in modelspace. All I did then was to change the color of the HIDDEN lines in my layer properties manager. :wink:

[SEANT]

Alternate intepretation of the figure on the left.

[Dadgad]

Well done SEANT.

Revisiting the first post I am inclined to guess that your interpretation is most likely the one they are after.

I misread the right hand view, yours is correct, and the OP was correct about a mistake in the red circle.

This provides a good example of the ambiguities of a single view and the reason we always

have to use multiple perspectives to nail down the representation of 3D objects, especially complex ones

[SEANT]

I think that figure was drawn purposefully to be confusing. Given the Isometric projection,it is hard not to see that as a full “V” channel.

Edited August 25, 2012 by SEANT
corrected spacing

[Dadgad]

I agree, and they did a good job of it.

Coupled with the brain's never ending search for symmetry, and reading from left to right, it works.

[Dana W]

Plus One to Seant.

 

If the "V" is intended to be there, then there are two pieces to the example.

 

If the "V" is not supposed to be there, then the example seems to show the far "right" side structure one unit too high, and the long narrow horizontal surface on top of the far "right" side also appears to be one unit too far to the right side.

 

The long narrow horizonal surface only appears to line up with some of the vertical grid lines at the right front corner, which are actually in the foreground relative to that surface.

 

I don't think the left example shows enough info to include all the hidden lines. I don't know where the tunnel ends. I'd leave them for the next lesson.

[Behemothrex]

First of all thank you all for your great responses. Just to clarify a bit I have to do this freehand as this class is a drafting class not an autocad class. I just scanned in what I had hand sketched out, then traced over it roughly with Photoshop so you could see the lines better. I would be in heaven if I could use CAD to draw this out, I would still be a bit confused but it would be much easier to produce. And we are not required to use hidden lines yet, just to do a rough sketch of the projections.

 

I have to say that your perspectives on this have really changed how I look at the drawing on the left. I can see now that the V channel is probably not supposed to be a channel and it was just my brain trying to make it appear as one. At least that makes drawing the other side of object easier.

 

And Seant, I bow to your greatness LOL you didn't have to put so much work into a response but man am I glad you did! That is exactly what I was looking for just an example of how it should look. I mean you can read all you want about how to do orthographic projections but unless you see some examples its a bit difficult.

 

I know with time and practice my eye will adjust and it will get easier but I feel a little like a kid thrown in the deep end of the pool. And I really don't want to turn in an assignment that I know is wrong LOL.

 

I will check out the links you guys provided and do some more work and see if I can get a better handle on it.

 

I let you know how it turns out.

 

Thanks again!

 

Gah the more I look at it the more it starts to look like one of those magic eye 3D illusions LOL Think I will take a break from it for a moment and let my eyes readjust.

Edited August 25, 2012 by Behemothrex
additional comment