cnc/cad/cam help

I am new to the whole CNC thing, having no experience with them other than I know how they work and kinda what they can do. I have mainly a computer back ground, some programming experience, as well as AUTOCAD and other CAD/CAM programs. My uncle runs a motorcycle shop, and has decided that its stupid to spend about $100k a year to oursource his CNC work so hes getting a CNC machine, dont know what model or when. But he wants me to figure out how to program the thing. I know you can use a CAD/CAM program to draw the part, and then translate that to G-code. This is the way we want to set this up. What programs can i draw the part in and export that to g-code? Do I have to set up the cnc machine to the computer to transfer the information? or can I output the drawing to G-code and then manually input it into the cnc control panel? is there an good reasources on the net to learn g-code? I have found a few g-code command lists, but nothing that gives any kind of details. Is the programs you use depend on the model of CNC machine? Whats most common? I know theres a lot of questions there, but I really have no idea, and web seaches usually only come back with schools offering training which I dont have the time or cash for. I appreciate any help I can get

I know that FeatureCAM can export through a serial cable to a CNC machine, and I’m pretty sure you can get from Inventor to FeatureCAM (and probably a lot of others), I just don’t know how. Usually, if you can’t export/import the right formats, you can get a plugin

I’m apprentice tool maker, I don;t have a lot of exprience with CNC, just the basic G, M, and F codes. From what I know each manufacturer and each machine slightly change with codes. I guess most of the basic codes you can find online and in books. I bet it would be cheaper if he hired somebody with CNC exprience to come in and work for him or hire somebody as Temp. to just to teach you or whoever is going to run the machine what to do. I bet if he looked around he could find somebody at a machine shop to work on the side on weekends or after hours up at the motorcycle shop. I might be way off on that assumption. I’m assumeing your uncle isn’t going to want much down time on the machine after he gets it, so it’ll probably pay off to hire somebody who knows what he’s doing to atleast teach whoever will be programming the machine how to run it. My school just bought about a million dollars of CNC equiptment and our teachers have been in the trade 30-35 years and I guess CNC has changed so much with newer machines than the machines 5-10 years ago so they decided to go ahead and hire somebody in the trade to work on this side to show them how to use the new machines and aspree (CAM).

From what I understand he wants me to do it, (hes going to pay me $50k a year to move to northern Cali) I dont expect to jump right in and do, once they get the mcahine, im gonna spend a weekend or two and go mess with it to see if I can do it. I jsut need to figure out what CAM program I need to learn to take their blueprints and put them in cad/cam to get the g codes out.

CAM software has g-code converters for specific machines. Among the CAM software available is MasterCAM, EdgeCAM, and SurfCAM. All CAM software should also be able to take any part drawing and import it provided the correct file converters are installed.

In addition, I recently read that AutoCAD is supposed to have the ability to export g-codes. Unfortunately, I don’t recall where I read this and don’t know if this applies to other programs, such as SolidWorks, Inventor, or ProDesktop.

Your best bet for getting answers to these questions would be the CNC Tech Talk Forum. The direct link is: http://www.websitetoolbox.com/tool/mb?username=mlynch
Registration is not required to use this forum. The people that use this forum are both advanced and novices with regard to CNC.

Also, see if the local university library has any books by Mike Lynch on CNCs. He normally does manual programming, but I’m sure the more recent books will have information about CAM systems in there.

As far as the actual learning, check with the company that your uncle chooses to buy from. I know that Fadal gives free training in Northern and Southern California, and I can’t imagine that the other companies wouldn’t do something similar wherever they happened to be located.

Hope that helps,
indieFan

Picking the right CAM program might be a little like trying to find the right religion. CAM people can be pretty opinionated about which is “best”, almost as bad as M$ v Mac. If your uncle’s new machine is a major brand then most CAM programs will support it. So in general you can pick the CAM system you want to use and then let it do the work on making G-code. Notice the disclaimer “in general”. No CAM program is perfect and all should be watched closely, everytime.

You have to be pretty meticulous about machine programming. It takes a special personality as well as special skills. I once had a part that was being NC’d. The program worked perfectly, so when it finished the operator walked up and pushed the “home” button to get the head out of the way so he could unload the part. It proceeded to take a straight line right through the part. I was standing right there and pretty near had a heart attack. Fortunately it was a foam practice piece and not the $100K chunk of Unobtainium we really wanted to machine. In this case, the programmer forgot include the return to home in the program (standard practice here). It could have been a very costly mistake.

If I were you I would definitely be checking out the local community college and see what they offer in the way of machining classes. Both basic machining and NC. You can’t program very well if you don’t understand the machine and you won’t understand until you’ve run one.

Good Luck

ChrisH

[quote=ChrisH
]

If you haven’t done much machining, I’d like to second Chris’ suggestion about taking a basic machining class. You need to understand cutting speeds and feed rates, cutting direction (climb vs. conventional), chip removal and a number of other things which are important to getting the part to come out right (and to not wear out your machine & cutters prematurely).

CNC is kindof like CAD: it makes the job easier and faster, but it can also let you make mistakes faster. You still have to know the basics for the job to come out right.

Where I used to work, they really encouraged designers and engineers to take a machining class at the local community college, even if they would never run the machines themselves - the experience made them appreciate how their designs would be made and the effort it takes to set a job up. Basically, it made them better designers.

(for the record, I don’t use CNC myself, but have spent a little time in shops where it is used and talk to the machinists)[/quote]

I’ll tell you straight out that MasterCam is the most popular program for CNC Machines holding over 40% of the market. The thing with MasterCam is its just good with just about everything. Yes the software costs about 13,000 dollars for the “full” version, but once you have it you’ll see why its most popular. You can do multiple things with MasterCam, when you make a program, you can look at the actual program in G-codes and just print that out or something and then manually putting it onto the CNC Machine, but the much easier way is to buy a cored that runs from your computer to the actual CNC Machine’s Controller, then it can essentially run the program straight from the computer. All you truely have to do is click 3 buttons on your computer and it transfers it to the CNC Machine within 30 seconds depending on the size of the program. If you actuallly like this idea or would like to continue our discussion Instant messange me or i will check up on the thred in about 5 days. I hope something works for you and ttyl.

Also, heres the site, www.MasterCam.com. But if you were to buy MasterCam off another site, it probably wouldn’t work seeing you need a special SIM that allows you to opperate the software.

If you are looking to buy a machine I would recommend a HAAS. They are packed with features, and pretty quick to learn and easy to use. They may not be the cheapest but they certainly are among the nicest. Try to pick up a used one and save a few thousand.

Here’s the HAAS basic G-Code programming manual. It’s a good place to start http://www.haascnc.com/Training/MillProgram_PDF/xmwb.pdf

I have to agree, Haas CNC Machines are reliable, and known for the quality of their preformance.

Our sponsor uses mostly Fadal and is pretty happy with them. They also sponsor at least one FIRST team (22), if that makes any difference. (and maybe it should in this case)

ChrisH

Oh, that sounds great. I actually havn’t heard of “Fadal” but i’m sure they get the job done. You really don’t need to get any kind of fancy CNC Machine just one that can accept MasterCam. Which is any of them ( as long as you know how to program it for that cnc machine… ). So what ever you guys get should work fine.

Hey, I’m exactly in your boat!

A company in Richmond, Jewett Machine, hired me to learn how to get their CAM software to work with their CNC lathes in the shop that are still running pure G-code. I’m working with a program called ESPRIT (not aspree, which was referred to earlier) 2003, which is kind of nice for lathe work. I haven’t tried the milling functions, but I hear they’re extremely easy to work with once you get the hang of them.

ESPRIT 2003 can import solid models and 2D drawings, all that good stuff. The basic distinction between ESPRIT and a true solid modeler is that ESPRIT goes a step further and defines “chains”, or lines across your existing model. These chains indicate where a tool needs to move across a part. You then define your tools and everything associated with them (for lathes, things such as nose radius, relief angles; for mills it’s more like 4 flute, 1/2" high-speed steel roughing end mill, and both need feeds and speeds), and then create tool paths based on the chains you defined earlier. Once you’ve defined all of your chains and tool paths, you can simulate the cut and watch the machine run across your part. You can also go through the trouble of defining your clamps, spindle maximums, and tailstocks in the case of lathes.

Anyway, you’ll find that you’ll have a great little computer-generated movie of your part being made, but now you need to get it to a CNC. I don’t know if MasterCAM does this, but ESPRIT requires you to edit what’s called a post-processor in order to translate your model’s instructions into G-code. As someone said earlier, all CNC controllers (and even down to machine models, if you’d believe it) have different sets of machine codes. For instance, M03 on the Ecoca lathe I’m working on (with a Fanuc O-TC controller) means main spindle on, clockwise. However, on the OMega vertical lathe I’m also working on (again, with a Fanuc O-TC controller), M03 means main spindle on, counterclockwise. You can see how that might mess things up a little bit…

You’ll find that you can learn whatever CAM software you have pretty quickly (assuming you have a working knowledge of a machine shop, another really good suggestion), but the post-processor will give you the most headaches. It’s easy to tweak variables like switching the M03 definition on the OMega and Ecoca lathes, but it gets really hard when you start getting into canned cycles. For instance, to switch tools, the Ecoca simply has to move to a position that doesn’t touch the part and turn it’s tool turret (G00 rapid movement, M63 toolchange). The OMega, however, has to retract to it’s home position, open the machine guard doors, move the turret to tool-change position, release, change the magazine, acquire the next tool, return to the home position, and close the machine doors (G28 U0 W0 home, M66 doors open, G30 U0 W0 change position, T# tool call, G28 U0 W0 home, M67 doors close). When you say “switch tools” in your CAM software for the first time, you may have no idea as to what your machine might do.

The good news is, once you get the post-processor right and tweaked to your machine, you’ll probably never have to mess with it again. Do it right, though; don’t translate code through it and then find one little nagging detail that you change at the machine just because you don’t want to find it in the post (This should really be a G72 instead of G71, I’ll just remember to change it). This will lead to extreme confusion if you ever have to switch CNC machinists.

If you were given the machine, the CAM program, and the appropriate starting post-processor on the same day, with all of their documentation, I’d say you could tweak it to near perfection and be turning out within-tolerance parts within 2 or 3 weeks. If you have a machinist who knows the codes, canned cycles, and trivia like machine home positions and codes that may not “work” (G28 can’t be used on the Ecoca, for instance; usually it means machine home, but if you are already home it will move to a random location. This would happen if you paused the machining cycle at G28, and then resumed.), I’d say you could really get going in 1 to 2 weeks solid. Whatever you do, though, don’t expect to hook up your computer to the CNC, make a nice little square on the screen and expect it to be waiting for you by the time you walk over to the CNC. It takes time, energy, and a lot of patience.

In case you’re curious, I spent my first week at my job training on the manual lathes, then moving up and watching some manual/CNC hybrids work, then finally spending two days solid watching/learning how to use the Ecoca. Working with a very well-trained machinist who was responsible for the Ecoca, I got a part program exported and working without “at-machine tweaks” in one and a half weeks. I started working on the OMega last Friday and have yet to make real progress on it because the canned cycles are giving me lots and lots of grief (stuff like refusing to acknowledge rapid moves before a canned facing cycle, etc).

Any questions, don’t be afraid to ask!