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  • #31
    Originally posted by ttok
    After seeing the drawings, the builder asked for full dimensions in feet and inches for everything depicted! A couple of weeks later, the builder emailed a series of excellent CAD drawings to us - done by a 23 year old girl in China!! I knew right then that we were in trouble as a country - where could we find a girl that age to program such things here??

    As for time required, I can produce drawings of equivalent quality to CAD drawings of the same subject in about 75% of the time as a friend (former NASA computer guy) can. I had one 3-hour mandatory drafting class in college 48 years ago...

    A.T.
    Finding a 23 year old female CAD expert is fairly easy. Any decent student out of a community college that teaches autocad classes should be able to do what you asked.

    As for drawing by hand versus CAD, your friend must be real slow. Thats not intended as a dig or put down, just simple logistics of drawing with CAD.

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    • #32
      Originally posted by Mcruff
      Finding a 23 year old female CAD expert is fairly easy. Any decent student out of a community college that teaches autocad classes should be able to do what you asked.

      As for drawing by hand versus CAD, your friend must be real slow. Thats not intended as a dig or put down, just simple logistics of drawing with CAD.
      Fully agree, it's not the quality of the drawing that matters but accuracy and electrons beat paper every day.

      Recently I had to modify a machine spindle for one of the Chinese machines. I was able to draw this up in about 40 minutes including all the notations on surface finish, concentric to, parallel to etc and Email it to China, later that day [ remember time differences ] they confirmed they were working on this and 2 days later Fed-Ex delivered a new spindle.

      I never had to move out of the office or use anything other than the computer.
      .

      Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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      • #33
        It's not just the accuracy that you get with CAD. I can draw a bunch of parts, assemble them, then produce absolutely accurate working drawings. Now the really important step, I can modify parts of the assembly, hit update, and all my assemblys and drawings are updated, and no parts are overlooked. I know you can't be that efficient working by hand.

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        • #34
          Originally posted by John
          Then you draw a vertical line and a horizontal line then offset lines from that, just like we did with construction lines.
          That is exactly what I do in SketchUp. It's a snap and circles are as easy as pi. SketchUp has very good facilities for placing and using construction lines in 3D, both Cartesian and polar. It automatically remembers dimensions you enter for precise placement of subsequent lines and with a plugin or two a large range of options exist. SU has a huge number of tricks up it's sleeve that aren't obvious when you first begin to use it.
          Free software for calculating bolt circles and similar: Click Here

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          • #35
            I have done it every way you all have described except the 3D CAD. I learned drafting in high school and the main lesson I came away with was whatever method you used, it MUST be correctable. They required a perfect ink drawing to complete the course.

            My shop also has stacks of pencil and ink sketches. Stacks and stacks. Main problem here is some parts just do not come out right if the drawing is not to scale. Too little space between holes or sides, too thin, too thick, etc, etc, etc. I once made a somewhat complicated custom control panel that way and one section wound up being supported by a 1/16" by 1/4" arm of PC board. I had to add an extra, makeshift support to prevent breakage and I still worried about it's long term viability.

            Many simple parts are just made "on the fly". I do the drawing on the part: it is called "layout". For many things there is simply no time for anything else.

            I use a 2D CAD program for as much as I can find the time to do so. I have used AutoCAD in the past at various employers and was NOT impressed. It may be the "industry standard" but it is expensive and very hard to learn. In short, the only thing going for it is it was one of the first CAD programs on personal computers and has improved little since then. I use a far less expensive program called FastCAD. I bought the simpler version called EasyCAD over 18 years ago and have upgraded many times since. I chuckle when I read about people who have taken two or more classes in AutoCAD: I taught myself how to use EasyCAD/FastCAD and was making a real drawing within an hours of starting with it. There are no classes for it as none are needed. A few minutes and you just start drawing. It has done every 2D drawing I ever wanted in that time frame. And in my opinion, the support is excellent. They have a web board like this one and the head programmer monitors it daily. He discusses problems and actively asks for the opinions of the users. I once posted a problem and he posted a fixed version on their web site the very next day. All registered users could download that fix for free. PROBLEM FIXED THE VERY NEXT DAY! You can't even talk to AutoCAD programmers, much less get a fix from them in less than months or years. And I am not any kind of beta tester or other special relationship with the company, just an ordinary user.

            I do want to get and learn a 3D CAD program as I do feel the need for it on many occasions. I do have a fairly good 3D imagination, but often details can escape me until I start building.

            Which method is best? None and all. It just depends on what you are doing and how complicated or simple it is.
            Paul A.
            SE Texas

            And if you look REAL close at an analog signal,
            You will find that it has discrete steps.

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            • #36
              I also started out on Easy Cad, it was a great simple to learn program (DOS) in it's day and it did everything I needed.

              If you are doing something simple sketch it out on the back of an envelope and go cut metal.

              If you are doing something more complex and are used to drawing at a board then download Solid Edge 2d cad program. It is free and relatively simple to learn and you use it the same way you would an old fashion pencil and paper drafting board drawing, construction lines, views etc. 2d programs are literally a replacement for the pen and paper approach but it is simpler to get a better level of accuracy and you can print out as many copies as you need. 2D is also a good way to generate path ways for CNC equipment.

              If you need to design a object or many fitted objects (assemblies) then 3D is the way to go. You can achieve a level of accuracy and speed that blows the old paper and pencil away. 3D programs are more of a design program then a straight drawing program so they don't operate in the same manner. The learning curve jumps up a lot but the basics can be acquired relatively fast. If you design a part and it "fits" onto another part without any interference, the better programs have ways of checking this, then machine the parts according to the drawings you printed, the parts will fit together first time. Modern car and aircraft design is all done on 3D cad without mockups or models being built any more, they cut metal right off of the cad program. Boeing's 777 aircraft was one of the first planes produced this way and they fly OK.
              The shortest distance between two points is a circle of infinite diameter.

              Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

              Southwestern Ontario. Canada

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              • #37
                I started on a drafting board in High School, then learned AutoCAD (v2.9!) in college. When I started out professionally we used an entirely different 2.5D cad system, then migrated into SolidWorks.

                I can say, with some certainty, that if you don't learn pen and paper, or at least 2d, first, you tend to make utter garbage in 3d.

                That said, I find I can design a part and make a usable print in SW in less time than it would take me to think it out and jot it down on paper - AND I would typically discover problems in the model long before I start making chips.

                For the hobbiest, I would recomend learnign how to make a usable print on paper, then switching immediately to a solids modeling program. Yes, you'll spend a few hours learning how to use it, but it's fun and very rewarding and before you know it, you'll be looking at a part from the perspective of 'how do i model this' the same as you see it from the 'how do I machine this'

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                • #38
                  Originally posted by loose nut
                  Modern car and aircraft design is all done on 3D cad without mockups or models being built any more, they cut metal right off of the cad program. Boeing's 777 aircraft was one of the first planes produced this way and they fly OK.
                  Are you sure Boeing built straight from the model without mockups? Mockups are still used even in 3D design from the CAD model.

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                  • #39
                    I am one of the oldies that started out on the board. However, unlike some of the comments I moved easily to the 3D CAD world and also the 2D world. At work, 2D is now reserved to schematics and other simple layouts.

                    I use 3D MBD (Model Based Design) and have even started using it in my home shop. What is 3D MBD? Simply drawing a 3D model and using it to drive everything down to the manufacturing and inspection or even technical manuals.

                    With a 3D model, you can check assemblies, installations kinematics and one thing I have not seen mentioned is the model can also be used to determine stress loads and actually proof the design before anything is cut. I use it all the time to do simple checks of my designs to make sure they can actually perform as expected. Not good to do a lot of work on a part only to find out a certain area was not thick enough and was over stressed.

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                    • #40
                      What I like about 3D modeling is it is just like machining. Your mind set is the same. You are starting with a block of material and adding features. As I model something in 3D cad build the model the same as I would machine the part. Saves lots of real life materials!

                      Here is an example of a 75mm x 75mm x 10mm piece with 8 holes in a bolt circle.



                      Now the bolt circle layed out.

                      finished part. Less than a minute and if any changes are needed no problem.
                      Location: The Black Forest in Germany

                      How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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                      • #41
                        Originally posted by Magnum164
                        Are you sure Boeing built straight from the model without mockups? Mockups are still used even in 3D design from the CAD model.
                        Yup! Saw it on, what was that thing we used to watch before the interweb, oh,ya, TV.

                        There was a show about how it was designed on a custom made 3D cad system and specifically how they didn't do any mockups, couldn't afford them. The cost of designing and prototyping something like a 777 is so expensive that they couldn't do it. That's why they switched to 3D cad design.
                        The shortest distance between two points is a circle of infinite diameter.

                        Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

                        Southwestern Ontario. Canada

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                        • #42
                          They do make some mockups, especially of the passenger compartment, just not full mockups.

                          Just google for '21st century jet' and you should find the entire program available on google videos and/or youtube. Worth watching all parts of it. It is in five parts. Each just short of an hour.

                          http://video.google.com/videoplay?do...31641323350192

                          The first mockup is at about 15 minutes in.

                          IMO this is the best kind of thing that TV and the intertubes has to offer. The project manager, Alan Mulally (now Ford CEO) is a very impressive character.

                          Enjoy.

                          -DU-
                          Last edited by Void; 09-22-2011, 11:17 PM.

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                          • #43
                            I believe that was the show I was watching and yes they did do some mockups but they where for PR work, sales etc. not engineering mockups.
                            The shortest distance between two points is a circle of infinite diameter.

                            Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

                            Southwestern Ontario. Canada

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                            • #44
                              Originally posted by JoeLee
                              I have auto CAD here or mechanicle desk top, what evere it is but I really need someone to sit down and get me started on the basics of it. I've played around with it off and on over the last few years but haven't been able to get anywhere with it to where it would be of benifit to me.

                              JL................
                              The way I learned to draw in AutoCAD was by taking an image of a drawing and setting that image as the background. I then used AutoCAD to trace the image. At the time I was converting old photocopies of building floor plans to AutoCAD files. It makes it alot easier to learn the program if you are not having to be creative with an original part at the same time.

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                              • #45
                                Originally posted by JoeLee
                                There are times when I wish I had kept better notes and diagrams on some of my projects.
                                I have a spiral notebook with "workbook" written on the cover. I try to put all the notes in that. At minimum it helps to reduce the "what is this scrap of paper?" questions. Unfortunately, it has not completely eliminated those questions!

                                I like to do CAD drawings because I have crummy handwriting/printing, and being able to reliably read dimensions is handy. Sometimes my manual math is not so good, and a dimensioned drawing with one hole halfway off the surface can point out that I need to doublecheck that dimension.

                                Alibre will automagically generate a 2D drawing from a 3D model, and you can even request it to put in an isometric view with hidden lines and all that.

                                As someone mentioned being able to print off a full size paper template can be pretty handy, especially if you want a second template that is slightly different (or one that has a few edges moved out X").

                                Paper works well for sketches, but for drafting/drawings I prefer electrons.

                                cheers,
                                Michael

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