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cnc or standard machine?

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  • cnc or standard machine?

    I have a chance to buy a CNC bridgeport series 1 with protrack or a regular 2 hp bridgeport.My question is this is it hard to learn the cnc language? can you use it in a manual mode or should I just stick with a manual machine? Thanks for any input.

  • #2
    The prototrak control is easy to learn and use. It is not programmed using standard G-codes. It is a conversational control and asks you to respond to questions and writes the program for you. It can be used as standard machine also and this makes it very versitle. I would opt for the CNC control.


    • #3
      I am not a machinist yet, nor a craftsman, yet. But I am learning CNC on a Bridgeport series I Boss 5. I would urge you toward the CNC machine because it is really a lot of work to do a manual facing. These machines will also do more reproducable and extrememely accurate work. You should check to make sure it has a PC interface. This will enable you to make an unlimited variety of computer generated objects. One thing I saw yesterday at the engineering department at the University of Utah recently was a model of an aircraft made for wind-tunnel testing. That sure looked cool and I'd like to make something like an X-15 on my machine. Imagine doing that by turning the handles!



      • #4
        Spence, not to take anything away from your enthusiasm but "turning the handles" produced the wind tunnel models for most of the aircraft that are flying now.


        • #5
          I was watching an episode of Reading Rainbow with my kids and they were taking us through the prototyping of a new (last generation Camaro) Matchbox car...once the scale was drawn I was delighted and surprised to see the 3D model generated by a machinist with a manual vertical mill milling to scribed lines...

          Snip> Imagine doing that by turning the handles!

          Spence[/B][/QUOTE]<End Snip

          Edit #1: The episode is called "Hotel Animal" and there is a clip from it here:

          Unfortunately the clip ends just as the part is transferred to another machinist (Female, by the way) who uses a tracing attachment to copy the model (and possibly reduce the scale further but my memory fades a bit). I've seen tracing attachments go relatively cheap on was nice to see one in operation.

          [This message has been edited by abn (edited 09-14-2003).]


          • #6
            Aircraft are curved in all three axis and so I would like to know how you could, or even how the operators of the past, could manage to turn all three handles at the same time? Could they do large internal threads in a decending helix? I expect the answer is yes but this is not something that a novice will be able to do anytime soon. Moving in all three axis simultaneously is a problem manually I would think for even the best professional, but not a problem at all with CNC. I don't have any reason to want to turn the handles manually although I like the feel of turning the handles on my lathe. A lot of time it is rote work and difficult to get consistent results.



            • #7

              Obviously all of the tasks you mentioned/questioned were accomplished successfully .

              Spend some time in the engineering section of your library, examine the older texts especially.

              You could actually go back to the Wright brothers. No CNC there, just bicycle technology ...


              • #8
                C. Tate:
                I concur.

                You do what you have to with the tools you have - the most important of which is your brain. CNC will not make you good machinist - it can make you a better utilized machinist by using your skills to supervise and operate several CNC ot once - producing mass quantities of goodies.

                I am constantly amazed at what past master machinists did with inferior equipment - it makes me wonder what they would think of our bitching and complaining about the superior equipment we have.

                Randy never pointed out that before CAD/CAM companies like Boeing drew paper plans for jets like the 747 - hundreds of thousands of line drawings for one plane - a logistics nightmare. Making wind tunnel models was easy in comparison.


                • #9
                  You will not find me critisizing any of the engineers from ANY era. I am amazed by all the work they have done. I have only one objective and that is to create an object that I have designed. I only hope it is better than any of the past because of my access to the information that my forbearers didn't have. Time tells all.



                  • #10
                    Thrud: Boeing (and others) made some plans by putting a "lofting stick" on the floor, put weights on the stick until it conformed to the curve they wanted, then they picked up a weight and the stick should stay in place. If it did not then there were stresses being confined. And thats how some of those old planes got such nice curves and great strength with so little weight. THen they traced the stick to a paper for documentation. Never saw it done myself so I can't say for sure that they did it that way.

                    Old engineering/construction? How did they design those cathedrals with out calculus? Shucks- how did the greek design those building doing their calculations with Roman numerals? The travel in most of the world was as slow in 1800's as in the times of Alexander the great. And here is the real puzzler- how did they lubricate machinery before petroleum was refined?

                    Seems funny (God at work?) that when whale oil was running out, and internal combustion engines came along that petroleum stopped be a nuisance and became valuable in just a few years. And as (supposedly) natural fuels become in danger of running out, that we "discovered" nuclear energy.


                    • #11
                      Buy the CNC...if it is in good working order and the dollar amount is right for you. You can jog through the CNC controls to manually mill if you need to.

                      Thrud... Bravo! one's brain is a tool. Computers are just another simple machine that supplies mechanical advantage to your brain. They won't do your thinking for you, at least not yet. Most of the time i tell kids they need their pencil, paper and their brain for my classes. I can deal with suppling the rest.



                      • #12
                        Matt, Spence

                        Don't get me wrong - I thenik CNC is the best thing since sliced bread. The best part is that as a sophisticated tool it can accomplish what I want in considerably less time.

                        I like to fantasize that it is actually me moving the table through the force of thought - ah crap, its true! So much for fantasies...