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help needed in orthographic projections

A

aerdna

New member
Hello all,


I am not an engineer, in fact,I'm studying for dentistry. For me to get into dental school, I must do well on DAT (Dental Admission Test), and part of that test includes a section on orthographic projections.


The questions will be set-up as follows: Of the three views (Top, Front, End), only two will be given. And then we must choose the correct third view. It is all muliple choice.


I am familiar with all of the rules, with dotted lines, and solid lines, etc, but for some reason, I am not very good at these kinds of problems.


Would you be able to provide me with some tips and tricks on how to do well.


I was wondering if I could have some kind of step by step procedure on how to tackle these problems.


I know that if there is any place that I can get help, it is an engineer forum, which brings me here as my last hope. A lot of my Pre-Dentistry friends are also having a tough time.


Thank You,


Andrea
 
The first thing you have to know is are you using first angle (most europeans but not Brits) or third angle projection (USA)? If it is first angle projection, just take the part and roll it 90 degrees in the direction of the new view. If it third angle roll the part 270 degrees in the direction of the new view or -90 degrees if that seems easier to picture mentally. It helps to hold an actual part in your hand until you get used to it.
 
thank you dr_gallup for your post,


i'm not very advanced in orthographic projections, but i would guess we are using third anlge projection. we are given four quadrants, on the top left is the 'top view', on the bottom left is the 'front view', and on the bottom right is the 'end view'.


solid lines is anything that is visible, dotted lines are not visible


the questions are on flat pieces of paper, and we must solve the 3-d object by looking at two of the three views (which are given), and then choose the third view, in the multiple choice. I hope you can help me,


Thank you again
 
i think it's harder than what you all think, (no respect to any engineer)


We are given ONLY two of the three views, and we must figure out the third view, without being given the 3-d object (the objects are actually various shapes and sizes of cylinders, cones, holes, curves - you name it! - features are combined to result in some complicated form!)


I've been only told that solid lines are visible and dashed lines are not visible from the view under consideration.


based on this, i was hoping someone else here could give me some tips that i would understand, THANKS!
 
u might be better off just making some 3d objects and getting pro-e to
generate the views for you, then u can see how they are done.
 
Can i be 'old school' and suggest you do this as a paper excercise. Before we had 3d CAD software people designed things on a drawing board, practise by drawing something very simple (step shaft) do the first view in plan or front, then (crucially) draw up (or across) feint leader lines from the OD of the shaft and then the smaller diameter. This then gives you the size of the features for you to then draw the next view, etc etc.


3rd angle: If you have a plan view at the top, you will have front elevation below and side elevation in line with one of these (usually in line with front).


1st angle: Front elevation and side at the top and plan below (common). The key to first anlge is that the views hinge, whereas 3rd angle slides out.


Sounds complex but if you try and look at some eng drawings what i am saying would be a little clearer.


Hope this helps - good luck in the exams.


Arlo
 
Take some simple objects and practice holding them and turning them so you see the different views, then sketch them. You will quickly get the hang of it. Just don't use a ball or a cube since they look the same in all projections. Try a book or a paper clip, anything simple. Since your test is multiple guess, that makes it really easy. All you have to do is eliminate the obviously wrong views & narrow it down to the correct one.
 
I'm going with what the dr. says here too. You can read up on some of it, hit the public library.. chances are it's going to confuse you more tho.


Tape a sheet a paper to a box and draw something all around, then untape it. you'll get the hang of it... and you said there are other students having the same problems.. get together with them and make some fun out of it.


It is multiple guess.. solve the easy ones first.. then go to the others ruling out the obvious one... one thing they may pull is have you choose from a right and left view to see if you get the correct one


They are not going to make ittoo darn hard .. they do want people to get in the program
 
markp - you are my LIFE SAVER ------- WOOOOOOOOO HOOOO


Thank you SO SO SO much, Those links are absolutely fantastic! Wsylvester - Thank you too for your e-mails.


I don't know how to thank you all enough, and also Dr Gallup.


But those links are SPOT ON, where the hammer hits the nail in terms of what I'm looking for.


Thanks Again Everyone, for helping someone you don't even know, I guess the world is NOT full of hate afterall,


Andrea (is not only a girls' name!)


I'm gonna try find other websites like those!
 
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