Proper Drafting Technique

[Ryan Dognaux]

Originally Posted by scottydoh

Everyone who's used any kind of CAD software should know what im talking about here...when your drawing on the computer, especially 3d modeling, crazy stuff can just happen out of know where...

I'd disagree with this. Maybe at first the crazy stuff happens, especially when you're getting to know the in's and out's of a software package. However, the great thing about CAD packages these days is being able to derive your drawings from your parametric model and have those drawings update whenever a model is changed. If you were hand drawing this and the design changed , there would be a significant amount of time editing or creating a new drawing.

I agree that drafting by hand absolutely helps to understand proper drafting techniques and standards. That being said, it's almost 2010 - time to go digital people.

[EricH]

I once did 2 or 3 sketches inside an hour, by hand (pencil, paper, ruler). I was able to turn 2D sketches into 3D interior/exterior view just by changing the line. 2 years later, one of the sketches is still floating around the team I did it for. Still no CAD for that one, that I know about...

Until CAD software can take a pen/pencil drawing and turn it into a 3D model instantly, both are very good topics to know.

Now, if I had to do those sketches using a T-square and other drafting tools, it would take considerably longer. It's also harder to modify them well.

CAD's strength is that you can change anything you need to and see how the parts fit together. Freehand sketches are fast, but usually not to scale. Drafting is to scale, but not fast.

These days, I'd start with perspective and freehand, then move to drafting or CAD.

[scottydoh]

Originally Posted by Ryan Dognaux

I'd disagree with this. Maybe at first the crazy stuff happens, especially when you're getting to know the in's and out's of a software package. However, the great thing about CAD packages these days is being able to derive your drawings from your parametric model and have those drawings update whenever a model is changed. If you were hand drawing this and the design changed , there would be a significant amount of time editing or creating a new drawing.

I agree that drafting by hand absolutely helps to understand proper drafting techniques and standards. That being said, it's almost 2010 - time to go digital people.

Experience doesn't really have much to do with "crazy" stuff happening we have a mentor who has 7-8 yeard of experience with inventor and 10 or more years with autoCAD, and he still has unexplainable stuff happen. Its just a given when you have a computer program attempting to replicate your input.

But I do agree about the editing bit. I know what its like to be awake for 48 hours straight, up all night working on drawings, only to go to class and have the professor whip out his sharpie marker and completely change your drawing...Its a real downer. But as far as editing...I don't know how much hand drafting you've done, but its usually not that difficult or time consuming to fix with an eraser and eraser shield. I also think that the consequence of having to change the drawing forces you to pay more attention to your design decisions while your drafting, I know it has for me. Thus making you an all around better draftsman. Hey, we got by for literally thousands or yeard with simple hand drafting just fine. It can't be that bad.

[Molten]

I'm far better at AutoCAD because I know the methods used by manual drafting. I know different techniques and can draw most any geometry without using advanced commands. If you can draft by hand with just circles and lines, then you can do the same on AutoCAD. The problem is that it is a lost art. I'm not saying every draftsmen should need to sit down and manually draft everything. However, I will say that they should have the ability and understanding to.

Also, a note on "crazy" stuff: Inventor sometimes does weird things when you don't use parametric(I often don't, so I can relate). However, I have never had this problem with AutoCAD. It does exactly what its told every time. You just have to be careful how your telling it what to do. If you don't tell it right, it might interpret a different command. In this case, the blame goes to the ambiguous input and not the computer's fault.

[Big Ideas]

For me. CAD can be great for drafting. But there are times when you want to get a spacer made and a hand drawing only takes a minute if you know how to do it.

More important for me is that CAD tends to NARROW and FOCUS my thinking. This is good for detail design and drafting but death to brainstorming and broad concept exploration. Being able to sketch, render, and draft in multiple views by hand, is IMPERATIVE to getting concepts recorded, and shared with out the burden of knowing the little details of a concept. Even better is being comfortable combining BOTH skills. CAD drawings of known items (C-rio, wheels, motors, . . .) give you scale and hand sketching fills in the blanks. This is the "Paper Dolls" part of design, also know as "System Drafting".

In any case, a drawing is important. You should never machine anything without having a drawing of some type to work from.

[Akash Rastogi]

Oh I love working in CAD, I'm really interested in fundamentals of drafting though and I really appreciate the art of it.

[Denman]

[offtopic]

I thought this was going to be a thread about cycling (i am a triathlete in spare time)
[/offtopic]

I would have thought its a bit of a balance between using a computer and hand drawing. On the computer you can easily modify it , can correct mistakes easily however you miss out on the good practise of doing it by hand so its a bit swings and roundabouts :|

[Dick Linn]

I just did a search for "mechanical drawing" at Abe Books. There are several older books (1930's through 1960's) for $3.64 each with free shipping. Perhaps some of those could be useful. A school library may have several older books available.

[terryo]

Originally Posted by squirrel

I have enough of a challenge getting students to make sketches....hmmmm....

Squirrel, I have the same challenge. This year we're trying a new approach:
Plan before you build (go figure?)
We, the mentors, have mandated that no one picks up a tool until the concept is approved and the sketches are done.
We'll see.....