Could use some advise on learning CNC?

[Beezer]

I have worked as a machinist for 15 years now with the same company, ever since I graduated highschool. I never did an apprenticeship so I don't have any papers but I have always been interested in learning how to operate and program CNC machines. The company I work for has expressed a general interest in getting a 3- axis CNC mill in the future and seeing how I am the senior machinist in the company would like me to learn how to program, plus operate it.

My question is what is the best way to teach myself the programming and operation of a CNC machine before being able to get my hands on one? I have always been very good at teaching myself how to operate machines when I had access to them to experiment but in this case I don't know how long it will be till we get the mill and I would like to be ready when that time comes.

I have taught myself how to use AutoCAD over the years but only in 2D and have only just started to play around with it in 3D. I plan on giving Soldiworks another try also.

Are there any books on CNC that I could pick-up that may help me?


Even if we never get a CNC mill at work I would still like to learn it since it never hurts to have others skills behind you, not to mention I am very interested in building a CNC Router.

Any advise would be appreciated.

Thanks,
Carl

[wjbzone]

Carl,
Learning to program cnc can be done without a machine to some extent. I learned a lot before I knew what a mill was by programming plotters. Operation will depend on the machine you actually get.

Using G codes for XYZ movement (G0 G1 G2 G3) are probably where to start. The technical articles in cnczone has a list of G and M codes.
http://cnczone.com/articles.php?action=viewcat&catid=8

Learning Tool radius compensation is probably the next step. G40, G41, G42.

Check for classes at a technical school in your area.

Since you mentioned using Autocad, you might want to tryout a couple of programs I posted on my website. Gcodeout will generate gcode from a polyline, and Gcodein will read a gcode file back into Autocad. You can test your own code. These programs do not use the tool compensation

Bill

[NeoMoses]

I would recommend starting off by learning how to manually program GCode as well. Take a look at the technical article wjbzone noted and you'll be off to a good start. If you're a machinist already, GCode is very simple to pick up. Another pretty good resource is TurboCNC's help file. (That's where I first started learning GCode.)

Once you've started writing some sample GCode, you'll quickly want to get a backplotter to see exactly what your toolpaths look like, and to catch any mistakes. I'm sure there's plenty of people around here who can recommend good backplotters.

Finally, start taking a look at CAM programs. They're quite nice, but I recommend learning what GCode means first; it'll help you debug later.

Good luck and enjoy!

[duluthboat]

Hi Carl,

Having been is your shoes at one time I know how you feel. You have 2 big pluses; you have a good background in basic machining and you want to learn something new. These days CAM software has taken most of the pain (the tedious math) out of CNC programming. But if you don’t understand what the software is doing it will control you instead of the other way around. My advice is to learn the G and M code basics, get past that point where it’s just some characters on paper to where you can read it and visualize what the cutter is doing. Make simple 2D drawings on paper with dimensions. Then write the code for the path that the lines represent. This skill is basic to CNC programming the same as squaring a block is basic to machining.

Gary

[CrazyRonny]

Hi Carl,

I think the faster way to learn is like Gary said, "jump both feet in" it's not as complicate as it look... find a simple Cam software and do some simple part at first. Look at the code that was generate by the soft. With a "G" and "M" code chart you will be able to visualise what your program will do after some practice... For a faster start on G code you can buy a book for helping you to learn the basic.

Good luck.

Ron

[Al_The_Man]

Carl, As someone who is not a machinist, the two exellent books that I find a help for reference and instruction is 'Computer Numerical Control Programming' by Machael Sava & Joseph Puszai (Prentice Hall) I believe it is now out of print but there are still some sources where it can be picked up, the second is 'Computer Numerical Control' by Warren Seames and is a SME publication.
Both cover most aspects of CNC programming with plenty of practical examples.
Al

[cadcam]

Carl, I would also look in to the schools around you.
I teach at the Local NTMA training centers here in California.

We teach from Beiung a machinst to CNC programming to Learning Mastercam(cad-cam software).

The CNC classes cover understanding Gcode and writing samle programs and some math to actully hand coding and cutting on the CNC a part.

So what I am saying there might be some thing like this at a local college.

I forgot I teach for the local College to and the offer a vary simlar options.

Link of my site to the NTMA www.lantma.org

[HuFlungDung]

Carl do this, Carl do that, so I might as well get my 2 cents in

If there were any way that you could get your hands on one of the inexpensive routers that some of these guys have built (assuming you don't want to build one yourself), it would give you a toy to at least move around and practice what you are learning from the books. This would be assuming that the machine runs on standard gcode.

Unfortunately, a lot of the learning is specialized according to the quirks and features of a particular controller. I know gcode, but I wouldn't be ready to step up and operate someone's Integrex machining center/lathe, without making sure I had already gone to the bathroom

[Beezer]

Well this is just fantastic. I sure am glad someone posted this forum's url on the r/c helicopter forum I belong to. The vast amount information and help from people such as yourselves is great.

I agree with the concept of "just jumping in with both feet", because that's what I tend to do with alot of things and it most cases it works out just fine but not always. I have never been a fan or comfortable with the classroom enviroment hence the reason I never went for my apprenticeship. I have had a couple chances to go back to night school to further my knowledge, so to speak, but just didn't have an interest in doing so or want to spend my free time sitting in a classroom. I have learned far more doing things on the job that I think I could ever learn in a class. Also alot of the college courses I was looking at had prerequisites which meant I could be taking alot of courses before I got to the one I wanted.

I agree I should learn how to write G-code manually to get a better understanding on how it works.

Last night I download one of those free
CNCsimulator programs and was running through some of the sample projects that came with it. I like that it had an option to run through the project step by step and you could view on the screen what the simulated cutter was doing for each line of code. That is going to be a very helpful program for me to learn with. I have a few CAD drawings that I would like to try converting to G-code just to see how they would run. Just need to find a freeware version of a conversion program.

I have a feeling I will be able to pick-up the G-code programming pretty quick once I unsdertand how it works and the terminologies used. My work does send out some machining jobs to other shops when we are too busy or are just not equiped to handle the job. I know one of them has a few CNC machines so I could always pick their brains for help also.

I would like to build a CNC Router in the future so until then maybe I will keep my eyes out for some reasonably priced servo motors, motor drives, contorller and anything else electronic that I may need. I could use these things as a bench test platform to test any code that I work out. I will need to search other areas of the forum on recommended equipment to get.

The company I work for builds custom NDT equipment and some of the equipment is multi-axis, immersion, scanning systems which basically look like large CNC routers but have a ultrasonic probe on the end instead of a router and the work areas is a tank of water instead of wood or metal. I don't think they operate off of G-code but some other system but I never really thought of it till now. I will have to talk with the guy that rights the software on Monday and ask him. I know the systems have alot in common with a CNC machine with them using stepper or servo motors, motor drivers, and a main controller card in a PC or a seperate PLC.

Well it looks I have got my work cut out for me but it is very interesting.

Thanks for all your advise and I'm sure I will be asking for more of it.

Carl