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  • Learning CNC maching

    I am looking for advise on trying to learn CNC (home shop level) starting from zero. And possibly attempting to build a simple unit. Basic book(s) web-sights etc

    Tools available:

    SB 16x6 heavy
    Clausing 12x36
    Bench mill
    Big old B&S No2 horizontal with a Bridgeport addition ( rebuilding currently)
    SB shaper
    TIG etc
    Plasma cutter

    Electronic experience: (long time ago) building various HeathKits

    Computer experience: (operating only, no programing) starting with Radio Shack Model 3

    Drafting: ok

    Thanks
    Jim

  • #2
    How about converting a rotary table or dividing head to CNC.?
    Won't be wasted as it can be used on a future CNC machine as a 4th axis or on a manual machine as a stand alone
    .

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



    Comment


    • #3
      Jim,
      Let me be a little self-serving here and suggest some back issues of my articles in Digital Machinist magazine. (click on it at the top of this page) Starting in the Winter 2010 issue, I did a series of articles chronicling my own plunge into CNC machining, starting from zero.

      I started with a small manual X-Y table that I converted to stepper motors and initially used bolted to the table of my Bridgeport. Later I built a frame with a z-axis and spindle and used the x-y table with that.

      More recent articles involve conversion of a mini-mill to CNC, and a 4th-axis attachment is coming next.

      I can go into specifics if you wish.
      Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
      ~Practitioner of the Electromechanical Arts~

      Comment


      • #4
        Speaking from someone who also would love to learn cnc .. my observations are ...

        I think the mechanics and cnc commands them self are not too bad. But the whole
        CAD/CAM thing is a rough hoe.
        John Titor, when are you.

        Comment


        • #5
          oldjim
          Personally i would look into learning the G-Code and code by hand at first then move to CAD/CAM.

          Ive done alot of hand g-coding for lathes for some time now, never use a CAD/CAM system in production (play a little at lunch time). One thing i noticed with a couple people at work who can pop out CAM programs is if there is a problem with the program or if it needs to be fine tuned or tweeked, they have a real hard time because none of them could hand code. Not that i know this from first hand, but it kind of seams like flying an air plane in "auto mode" and then having to fly the plane in "manual mode".
          Just some food for thought.

          Originally posted by Weston Bye View Post
          I started with a small manual X-Y table that I converted to stepper motors and initially used bolted to the table of my Bridgeport. Later I built a frame with a z-axis and spindle and used the x-y table with that.
          That sounds interesting. Am i understanding this correctly that if/when you wanted to use the Mill as a manual machine, you just took off the modded x/y table ? I like that. Been wanting to motorize the lead Z screw, might give thought into a servo now for furture use with a table like you described.
          - Thanks.


          _
          ~ What was once an Opinion, became a Fact, to be later proven Wrong ~
          http://site.thisisjusthowidoit.com
          https://www.youtube.com/user/thisisjusthowidoit

          Comment


          • #6
            You dont need to learn g-code. That is like learning postscript. We taught people to use the cnc mills and router at techshop without learning g-code and it works fine.

            Just pick up a decent cad and cam and go for it. TurboCAD with the CNC add on can be found cheap on ebay and will do most everything you need.

            Comment


            • #7
              Originally posted by macona View Post
              You dont need to learn g-code. That is like learning postscript. We taught people to use the cnc mills and router at techshop without learning g-code and it works fine.

              Just pick up a decent cad and cam and go for it. TurboCAD with the CNC add on can be found cheap on ebay and will do most everything you need.
              I agree. You should be able to read gcode and understand it, but programing anything other than simple shapes probably isn't worth it. Here's a handwheel/damper for a Nema23 stepper motor that was done in Cambam. I used Visual Cadd to draw the original and then Cambam to generate the toolpaths:


              If you haven't used a cad program, then starting with one that's 3D would be better. ViaCad is an inexpensive 2d/3d cad program that's been recommended by others (I haven't had a chance to use it yet). I've tried to use Sketchup, but its user interface gives me migraines

              Comment


              • #8
                Have you been here:

                http://www.cnczone.com/forums/benchtop_machines/

                Phil

                Comment


                • #9
                  I also was in a similar position about 8 years ago. I had a Atlas knee
                  mill and was either going to sell it or do something with it. I decided to
                  convert it to CNC. To make a long story short, I would have never been
                  able to do anything useful with it if it was not Vectric VcarvePro.
                  I did not understand stepper, bob, mach3, or any of the other things
                  that must come together to make things work. But by far the
                  design of items was the most questionable for me.
                  VcarvePro was very easy to understand and tons of help from http://www.vectric.com/
                  VcarvePro generates the Gcode for you.
                  Just my .02
                  olf20 / Bob
                  Last edited by olf20; 12-31-2013, 07:39 AM.

                  Comment


                  • #10
                    Originally posted by iMisspell View Post
                    oldjim

                    .....That sounds interesting. Am i understanding this correctly that if/when you wanted to use the Mill as a manual machine, you just took off the modded x/y table ? I like that. Been wanting to motorize the lead Z screw, might give thought into a servo now for furture use with a table like you described.
                    - Thanks.
                    _
                    Yep, just so. The original control I presented had an LCD display that paused and prompted the operator to set the z-axis and then push a button to continue. The system had some shortcomings that motivated me to move on to Mach 3. If you use Mach 3, you will have to edit the G-code to pause before every z move so you can manually set the tool height and then resume. The editing seems tedious, and could be considered a great motivation to automate the z-axis, but can be done fairly easily with the MS Word find-and-replace function.

                    As olf20 says, Vectric V-Carve Pro is great, and indeed, its less expensive brother, Cut 2D, is what got me started in CNC. It came to me as a door prize at the Digital Machinist CNC Workshop. I then had to build a system to use it.
                    Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                    ~Practitioner of the Electromechanical Arts~

                    Comment


                    • #11
                      start learning gcode and by the time you can use it you will be really good at it . i started learning gcode and got a machine 6 months later , still had lots of confusion , the cadcam stuff seemed easy for some programs , but a ton of un needed cutting .
                      building a machine vs buying one would be my question . lots out there to chose from .

                      Comment


                      • #12
                        As part of my association with Sieg and Arceurotrade I have to do a lot of training by email, phone and in person.

                        This needing to learn G Code ALWAYS crops up. Usually by some clueless person who has no experience repeating by rote what he has heard from some other clueless wonder.

                        Hard fact is in a morning I can get any one who wants to learn and isn't a complete moron from a drawing to a finished part.
                        I even have a Mach screen that has no G Code display on it just to show them it isn't needed.

                        Now having said not needed and some knowledge of it isn't the same thing. What happens in real life when approaching CNC is that you have a learning curve that's almost vertical and looks daunting. However if you split it up into blocks like CAD, CAM, the controller and the machine it's easier to handle.

                        Take CAD out of the equation because you have been given the drawing and that's one block less.

                        Take CAM out by using a simple program like Cut2D and believe me I have come across nothing simpler and you are now left with the controller and machine to learn so now your learning curve is only 45 degrees.

                        Later when this is down to 10 or 15 degrees [ never gets to zero you are always learning ] you can go back and address CAD and CAM better.

                        If you are interested enough go to Vetric's web site at http://www.vectic.com and find the tutorials for CUT 2D and watch the video of the con rod.

                        The demo version on the site will allow you to do the 4 tutorials and get code off them but not process your own job.

                        Must say usual no association with Vectric other than being a user.

                        Now what happens is as you get more proficient with doing jobs and the machine it suddenly dawns on you one day that you can read the code, it happens by osmosis.

                        So in practice learning and understanding comes AFTER learning to use the machine.
                        .

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



                        Comment


                        • #13
                          Thanks guys for the good suggestions. Much appreciated. I will follow up on the web sites suggested. I am OK with 2d cad so it sounds like this should help somewhat.

                          Sir John, the suggestion to start with something simple like adapting my rotary table sounds like a very good place to begin.

                          Weston, I want to order the back issues of Digital Machinist, addition to Winter 2010, that cover your early work. Could you identify which additional issues would apply.

                          Being a bit thick headed, some of the ideas seem still a wee bit over my current pay grade. (Be helpful to have a brain like Evans!)

                          Comment


                          • #14
                            Weston, I want to order the back issues of Digital Machinist, addition to Winter 2010, that cover your early work. Could you identify which additional issues would apply.
                            There are a number of articles involved, in two different series, that recount my adventures with CNC machinery.

                            The first series, Winter 2010 through Fall 2011, is somewhat unconventional, modifying a manual x-y table and scratch building a controller using a dedicated microcontroller. Later in the series I describe an alternative Mach 3 control system using the Geckodrive G540.

                            The second series, Summer and Fall 2013, describes a nearly turn-key solution using the PMDX-340 CNC controller with a Little Machine Shops mini mill. Although not really part of this series, in the next two issues of Digital Machinist I will be presenting a fourth axis suitable for use with the mini mill as well as other machines.

                            In the two CNC series I discuss G-code basics, and the use of Vectric and Mach 3 software to get things running.
                            Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                            ~Practitioner of the Electromechanical Arts~

                            Comment


                            • #15
                              My advice for G-code: start conversational. Rather than turning a dial to move X axis to 2.456 inches you learn G20, F, G0, and G1 and off you go. Your eyes and brain are really handy at moving to something.000 or whatever but the computer doesn't care if its 1.2345 or 1.0000 and its really fast and never gets tired and never screws up. Its sort like manual machining but you don't read dials anymore you just type in numbers.

                              I wouldn't start gcode by trying to write some crazy 10000 line program or rigid tapping or cutting arcs. Not to start.

                              Next thing you know you're typing in the same commands over and over... and then you put a list of them in a text editor and cut and paste them into the conversational interface. Then you save that text file and load it in the CNC controller. And then you're a noob gcode programmer. Lots more to learn of course, assuming you want to go down the gcode road.

                              You're learning about the right speed if you start wishing gcode had features you don't know yet. Hmm imagine if there was some kind of offset or incremental system... time to learn about G90 G91... Imagine if the computer could convert between metric and inch for you... next up, G20 G21 ... Writing peck drilling instructions sure is boring, I wish the computer could drill holes for me ... G81 G83 and a bunch others ... Imagine if the computer could cut arcs for me instead of me typing in 50 little steps and using a file.. G2 G3... Why can't my computer do my arithmetic for me... G1 X [2.0 / 3 * 1.5 - 5.5 / 11.0] ... this here computer is smart, bet it can calculate bolt hole circles using polar coordinates ... (too long to fit here, but yeah it'll do that)

                              There's a time and place for each technique.

                              I occasionally have to locate and drill precision located holes for TO-3 outline transistor packages in aluminum heatsinks. There's no way I'm going to spend 3 hours trying to draw that bad boy in CAD and then run it thru the CAM processor and copy files all over creation on flash drives blah blah blah when its literally just four lines of conversational gcode to move to the correct X/Y coords and let me manually jog the Z to spot and/or drill the four holes. The CNC controller doesn't care if the X coordinate is 2.43279 or whatever it just does it incredibly quickly and accurately. Microwave waveguide butchering is easy, mounting all manner of little metric electronic device packages in chassis is fast and fun and the holes always match up, its a breeze. Oh so you want an E-field probe in that waveguide 5.423151 inches from the end? No problemo and it roars over there faster than any human could turn the dials and never makes a mistake. Awesome! Doing that kind of stuff by hand, to that level of accuracy and precision, is super tedious compared to typing one line and hitting enter.

                              On the other hand it would be very hard to write the gcode by hand to mill an outboard motor propeller. So there's a time and place for the heavy CAD/CAM software too. Although maybe not at the very start.

                              One advice I have is if you go conversational unless you invest in amazing protection systems your keyboard and mouse aren't going to live very long, so I'd stick to piles of $5 cheapie specials rather than trying to keep a $150 super keyboard alive.

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