need help with a drawing

[scary2003]

I'm totally new to cad, I have finished drawing an object in 2 D.  I'm a student in the HVAC-R field and working on duct fab.  I have a project I'm trying to confirm I have drawn it out and want to make sure that the 2 pieces fit together correctly, but need to fold them 90 degrees first. Can anyone help??

[JDMather]

This won't be of much help to you, but after using the sheet metal tools in Autodesk Inventor, I consider AutoCAD 2D to be pretty much fantasy - not a good digital representation of the real world.

A couple of things to consider - Autocad dimensioning defaults to 4 decimal places, but even in precision machining most work is done to 3 decimal places.  I would not expect to see a sheet metal part like this dimensioned to 4 decimal places.

This dimension in particular does not make any sense to me (I added the yellow line).

And zoom way in in the area of the red circle.

In Autodesk Inventor the flat pattern would be an after-thought.  I would model in the finished form - what I really really want, and then Inventor would generate the flat pattern for me.  I considered for a moment folding up your part in Inventor, but decided that would be something akin to torture.  I guess you could print it out and fold the paper model to get something of an idea of if you are headed in the right direction.  That is what we used to do when I was in school back in the last century.  Such a "solution" would not be very satisfying to me in this century of digital prototyping where I expect my CAD model to faithfully represent the real world.

[scary2003]

that dimension is suppose to be 1" the width of that tab.  It will be a pittsburg used to join 2 pieces in duct work.

[scary2003]

Here is a scan of what I'm trying to get drawn out to scale so that I can actually verify my hand drawn prints.  I have to actually build this in class, and I was told my drawing I did isn't right so I want to try and figure out what I did wrong.  Hopefully someone can help me figure this out.

[JDMather]

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@scary2003 wrote:

.... I'm trying to get drawn out to scale....  I have to actually build this in class, .....

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If you are actually building this - I think first thing I would do is make a digitial prototype of the 3D model.

I assume you will be asked to use "last century" techniques to create the flat pattern.

From the 3D prototype (ignoring that real parts have to have radii bends - not sharp corners, and real parts have to have thickness (which wasn't provided in your image)) measurements can be taken directly.

So fast! So easy!

The 3D model as the single source of truth.

(I will post another hint tomorrow if you haven't figured it out.)

[steven-g]

I totally agree with JD on this, 3D is the easiest way to go, but here is something very basic to try, print your design on a sheet of paper and cut it out, then fold it up by hand to see what you get. Don't worry about scale at the moment, just print it as big as you can on a sheet of A4 you will see then what the problem areas are.

[scary2003]

This project is the reason I downloaded autocad, I drew everything out by hand, but the measurements I had on my drawings aren't correct.  I figured I would try to figure out how to draw it on here and maybe that would help me get all the measurements I need.

[scary2003]

I was trying to figure out how to import the drawing I have so that maybe I could get it close to the size I need. But, I couldn't figure out how to get it to import.  How should I do that?

[JDMather]

You do not need the image - you have all the dimensions.

I will try to remember to post step-by-step solution later today.

[JDMather · Accepted solution]

These are the dimensions.

[scary2003]

Thank you for your help.  that is what i needed. Now to make that into 2 pieces.  The whole project is suppose to be able to be made out of one sheet of metal that is 12"x36" and made in 2 pieces. One long and One short joined as one piece.  I was close with what I figured by hand I think.  I was trying to figure out if I could draw each piece in inventor as seperate parts and then join them as an assembly.