CNC Tips & Techniques, Page: 1 2 3 4 5 6 7 |
CNC Tips & Techniques (p. 4)
A custom macro B math question
While custom macro B has some pretty helpful arithmetic functions, it doesn't have them all. For any arithmetic function you don't currently have, you can write your own as long as you know the logic behind the function. As you said, to square a number, you simply multiply the number by itself. The square of 4 is simply 4 * 4. Represented in custom macro as...(Article)
How does direct numerical control work?
Frankly speaking, there's not all that much to it as long as the CNC control truly allows direct numerical control. For Fanuc models 6MB and more recent, for example, as long as your communications protocol is properly set up (baud rate, stop bits, handshaking, etc.), the actual task of running a the CNC machine from an off line computer is pretty easy. This is pretty much the same protocol used for distributive numerical control (transferring a program in its entirety), but with an emphasis on handshaking - usually with xon/xoff . Usually a setting parameter controls whether the cycle start button will activate a program in the control's memory or a program from the serial communications port (computer). With Fanuc controls, it's usually on the setting page and labeled Input Device. For most control models, it must be set to RMT (For remote) when you want to run directly from a computer. (Article)
Can you explain the use of G61 for machining centers and turning centers?
For Fanuc and Fanuc-compatible controls, G61 is the modal exact stop check command. Note that G61 is cancelled by G64, which places the machine back in the normal cutting mode. There is also a non-modal exact stop check command (G09). The exact stop check function is used whenever you want the machine to come to a complete stop between motion commands. Exact stop check is most commonly used when a programmer wants the tool to machine "sharp outside corners" when milling a workpiece. In the normal cutting mode, the cutting tool will flow through its series of motions smoothly (without stopping). This is usually very desirable since witness marks will be left on the workpiece in many cases if the tool comes to a stop between motions. (Article)
What is the difference between the Absolute, Relative, and Machine display screen pages on Fanuc controls?
These coordinate systems provide three different ways to track the machine's movements. Each has a different point of reference - or origin. (Article)
Are You Breaking Taps?
If your machine does not have a spindle encoder, you should be using a "floating" tapping holder. The holder will extend or compress to make up for mismatches in speed and feed. The spindle takes longer to reverse directions than the feed. A machine with a spindle encoder will recognize this, and adjust the feed to match (rigid tapping). If you don't have an encoder on your spindle, a floating tap holder is the way to go. I have heard of and seen people get away without one by running very low spindle speeds. But if you tap many holes at all, the holder is worth the money. If you go with the floater, you can kick your spindle speeds back up to normal. Just remember a couple things...(Article)
Calculating the lead of a twist drill
I see a lot of people use trig to calculate a drill tip or to calculate how much deeper to go with the countersink. A quicker way to calculate a 118 degree drill tip is to multiply the dia. by 0.3 ie: 0.250 X .3=0.075 The .3 is a standard established by the fact that your answer would be .3 if it were trig'd out for a 1" dia. Try it! You can do the same for different countersinks, too. Use the value 0..575 (instead of 0.3) for an 82 degree countersink. (Article)
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