[markus314]

Hey!

I'm using a turning machine with a fanuc O-T system .. Can anyone tell me whats wrong with this kind of code?

....
G70 P1 Q2
N1 G00 X 10.
....
...
....
G01 Z-30. F0.1
X30.
N2
G70 P1 Q2
G28 U0 W0
...

I expected the machine run to the cycle between N1 and N2 two times and return to home. I've done this many times with a G71 command first, which then had the cycle and the G70 commands like this later in the program:

G70 P1 Q2
G70 P1 Q2

But this time the machine after reaching X30. in the second run of the cycle started on another run of the cycle directly, trying to move to X10. from the end point of the cycle (X30. Z-30.). This caused a crash, can someone please explain why?

[dcoupar]

AFAIK, you must do the G71 first.

[markus314]

It's just so weird to make G70 work as a function if G71 is used first, but if not it works just like a GOTO.. It's just so unlogical!! And so unlike fanuc from my experience.

And what about if you start a program and then jump over the G71 command and goes straight to G70, will it still act like this? Or will it check for G71 in the program in some way? It sound crazy to me..

[Mike Stevenson]

G70 is the finish command for the G71 and G72 codes. It is not for jumping around in the program. Use a subprogram for that.

[markus314]

Ok, so you have to have a G71 command to have a G70 command? It's so strange that G70 don't have the same function if you don't use G71 first, you allready have a GOTO command! Why make an exeption in the behavior of G70 that has no possitive effect at all?

It looks like a flaw to me! G70 should read from P to Q no mather whats been done previously in the program. Since you have to write a G00 command at the same line as P this is a flaw that could cause a lot of problems in the case of typing errors or cases like mine where you expect it to work as it normally does because most likely the G00 would crash the tool..

[Mike Stevenson]

markus314,

I'm sorry newbee but It does not work that way.

[adamant]

AFAIK, you must do the G71 first.

Seems to me I have run a G70 without a G71,G72,G73 before.......................

I'd try it like this.

N1 G00 X 10Z.1
G01 Z-30. F0.1
X30.
N2G0 Z.1
G70 P1 Q2
G28 U0 W0

That should Run between the N1 and N2 and then repeat.

I could be wrong................It is fun to just plug the numbers in and see what works if you got the time.

[Mike Stevenson]

Seems to me I have run a G70 without a G71,G72,G73 before.......................

I'd try it like this.

N1 G00 X 10Z.1
G01 Z-30. F0.1
X30.
N2G0 Z.1
G70 P1 Q2
G28 U0 W0

That should Run between the N1 and N2 and then repeat.

I could be wrong................It is fun to just plug the numbers in and see what works if you got the time.

And are willing to risk a crash on a lathe.

[Geof]

Seems to me I have run a G70 without a G71,G72,G73 before...

I could be wrong................It is fun to just plug the numbers in and see what works if you got the time.

I played with a program on my Haas simulator and found it would do G70 without any G71 or G72.

[Mike Stevenson]

Maybe that's true in the HAAS world but I doubt it. Take it from an old Fanuc lathe guy, you know not what you do. Especially if you are jumping around with modal codes in place in your program. I hope I'm wrong. Can you please tell me why you want to do this lazy thing?

[Geof]

Maybe that's true in the HAAS world but I doubt it.......

.... I hope I'm wrong. Can you please tell me why you want to do this lazy thing?

"lazy" thing?

I am puzzled by your post.

I have a program with a G71 sequence that roughs out a profile which is then finished by a G70.

I deleted the G71 line and ran the program; it ran and the tool followed the profile path...that is the finished profile path.

Which is what I said in my post.

[adamant]

I played with a program on my Haas simulator and found it would do G70 without any G71 or G72.

Dang I was getting ready to make some money......

[Mike Stevenson]

Be puzzled not.

What if you have a previous G71, G72, G73 sequence in your program and you stop the machine and jump around the your later G70 code? What you ran in your simulator was one instance with one tool only.

[Mike Stevenson]

If G70 isn't to G71, G72, G73 what G80 is to G81,G83, G84 then I'm a monkeys uncle.

[Geof]

Be puzzled not.

What if you have a previous G71, G72, G73 sequence in your program and you stop the machine and jump around the your later G70 code? What you ran was one instance of this idea. Look at the larger picture please. The lazy thing is TO MACRO 4 LINES OF CODE!

"Be puzzled not" you say.

Okay, I will not use the word puzzled.

I am completely bewildered.

I thought the crux of this thread was whether a machine would run a G70 P, Q, sequence without having first done the G71 or G72; which is the conventional way.

Let me back-up a bit: My understanding of the G71/G72 and G70, maybe I should say the way it was described to me, is that the G71/G72 roughs out a profile which can then be finished using a second tool by G70.

Whether this is right or wrong that is how I use G71/G72-G70.

The question seemed to be could you take the P, Q, block and use it with a G70 without first having done the G72/G71.

My results say yes, you can have a P, Q, block and can run it via G70 without having first run it via G72 or G71.

[Geof]

If G70 isn't to G71, G72, G73 what G80 is to G81,G83, G84 then I'm a monkeys uncle.

G80 cancels canned cycles.

I do not see any connection or similarity between G80 and G70.

I am glad you are not my Uncle.

[Mike Stevenson]

Geof,

Why wouldn't you just run a program with the finshed profile and be done with it? Or do you mean can you skip to the tool with the G70 sequence?

[Mike Stevenson]

One more thing is I doubt very much your "simulator" allows you to run tools and modals out of sequence like you can do on the machine and get into trouble.

[Geof]

Mike;

To answer your last post first: The Haas Simulator completely replicates the machine minus the possibility of actually crashing metal into metal. Go to the Haas website for a description; it is a machine controller with software that replicates the spindle turning, the axes moving, etc. It will run any program in exactly the same manner the program runs on an actual machine.

To answer your penultimate post: For goodness sake go back and read in detail what I posted!!!!!!!!!!!!! I wanted to see if the machine would run a G70 p, Q, block in the absence of any preceding G71 or G72. I found that it would; no ore, no less than that.

In real life, on a machine with hard stuff in the spindle and tools in the turret this could be disastrous. The G72/G71 sequence roughs out a profile from original stock taking multiple passes at a cut depth defined by the D value in the G71/G72 line. The G70 simply follows the final profile taking off whatever was left behind by the U and W values in the G72/G71 line. If the G71/G72 line is absent the G70 is going to follow the final profile and the tool is going to find a hell of a lot of material in the way.

[adamant]

If the G71/G72 line is absent the G70 is going to follow the final profile and the tool is going to find a hell of a lot of material in the way.

Yeh, the time I ran it that way I was working with polly and wanted to run the exact same profile I had cut all with G1.

It did it.

Suprised me too.

BTW the haas I ran used a fanuc control.