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Thread: Help learning G&M Code???

  1. #11
    Join Date
    Mar 2001
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    Nottingham, England
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    15,232

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    Gotta agree with Macona on this one.

    A few years ago I would have said the same but what brought it home to me was that just up the road from me is an Aerospace company full of all singing, all dancing very, very expensive CNC machines. We play well together, their customers are not mine and we have no need to poach and so we can borrow off each other.

    Couple of years ago their lathe guy, one guy runs 3 lathes including programming on his own, came down to borrow a cut knurling tool.
    At the time i was screwcutting and he stood at the end of the machine watching until I'd finished.

    He said, "I'd love to screwcut" a bit amazed I asked him why he couldn't, his reply was he'd never run a manual lathe in his life, in fact out of the 10 operators they had only one guy had rum a manual milling machine.

    So I asked him how they went on and he said when they get a new machine 2 or 3 guys usually have 1 - 3 days hands on training on the machine and that's it, they learn on the job.

    Just as we mere manual guys had to, they also have to learn but it's a different learning curve.

    For a start they have access to tooling we can only drool over unless we are mega rich.

    Classic example, we choose speeds to suit material, and available tooling.
    Because they have access to this exotic tooling their only variable is feed.

    I watched a big 2 metre long travel bed mill doing wing spar brackets, as the code was ripping thru all the moves were G00, no G01 feed moves in sight. Revs were pegged on max at 15,000 and the only variable was depth of cut, bigger tools, deeper cut.

    I asked Alan what he runs his lathes at and again the answer was flat out, he screwcuts everything at 3,000 revs, depending on material determines the depth per pass.

    So when he said I've love to be able to screwcut, I replied I'd love to screwcut at 3,000 revs.
    .

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




  2. #12
    Join Date
    Jul 2002
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    3,870

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    Quote Originally Posted by macona
    I dont agree with that at all. What happens in a manual machine often had little relevance in the CNC world. Especially with modern cam software. Give it parameters for the material and tooling and it will handle feeds and speeds. And simulation will show you what you will get.


    true, but experience with manual machines will give a student an idea what speeds and feeds are effective for which materials. Which inserts work and why.What different amounts of coolant are effective. What a dull cutting tool looks like.
    Much better for them to make mistakes on a manual lathe and learn from their mistakes, than on an expensive piece of CNC machinery. my.02

  3. #13
    Join Date
    May 2009
    Location
    San Clemente, CA
    Posts
    148

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    Quote Originally Posted by macona
    I dont agree with that at all. What happens in a manual machine often had little relevance in the CNC world. Especially with modern cam software. Give it parameters for the material and tooling and it will handle feeds and speeds. And simulation will show you what you will get.
    That's true, but if you have no manual machining experience, how do you know which parameters to select. The feed and speed parameters given in a modern CAM system are only a place to start.

  4. #14
    Join Date
    Apr 2010
    Location
    Canada
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    Although fairly standard, G codes are also specific to a particular type of machine, Mills, Lathes, Plasma, Punch all have there own versions.
    In the case of M codes, these are written at the discretion of the MTB and can vary between the same machine types, so the MTB manuals are needed for the M code assignments.
    +1 on the Peter Smid book.
    Max.

  5. #15
    Join Date
    Jan 2012
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    In my class we are using the CNC Programming Handbook, Third Edition by peter smid, and think it is a pretty good book. Something to consider.

  6. #16
    Join Date
    Aug 2006
    Location
    Beaverton, OR
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    Quote Originally Posted by Steve Seebold
    That's true, but if you have no manual machining experience, how do you know which parameters to select. The feed and speed parameters given in a modern CAM system are only a place to start.
    You can also use the manufacturers data for the tooling to fine tune it. CNC is more science and less guess work than people are lead to believe.

  7. #17

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    the Tormach sight has a m/g code section . it has about all the info you need and examples . probabaly the best /simple direction ive seen

  8. #18
    Join Date
    May 2009
    Location
    San Clemente, CA
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    You can also Google G and M codes.

  9. #19
    Join Date
    Jan 2010
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    128

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    Thanks JEZX!

  10. #20
    Join Date
    Jan 2010
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    Well, Monday we started learning G&M code in class; yesterday I finished up my first three programs, and today I made two of the three parts. . .machining the third part tomorrow. The code is actually pretty easy and straight forward; there are a few intricacies as far as the order of the code or when a specific code needs to go before or after something else. I had to play with my tool offsets a little. . .especially after I figured out that the little Emco lathes we're learning on can't handle the .030 depth of cut (on the radius) and 0.010 feed rate that I thought that they could and my turret moved on me. After I figured out the offsets and the correct DOC and feed for the equipment I was getting my parts under .001"!

    Pretty cool actually and I can see now why if I had the money I would want a CNC in my shop. . .frees me up to do other things while the CNC is doing it's job.

    I'm starting my mill programs on Monday. . .should be just as fun, I hope!

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