G200 "index on the fly" ???

[colton_m]

Hey hey,

I was poking around in the manual and discovered the G200 code in the list. After reading the super short description I have a few concerns...

How would you determine suitable values for "U" and "W"? I am assuming "U" would have to be enough so your longest O.D. turning tool clears the part and "W" would have to be long enough so your longest boring bar or drill clears the part...

Next, could the X and Z values be your next safe position in air prior to cutting?

Forgive me if my question is confusing, I am simply trying to understand the correct SAFE way to implement this code. It is something I could really benefit from on "zippy" small parts that use lost of tools!

Below is an example of a program format I would typically use when MANUALLY programming a part. If someone could edit it to effectively use the G200 code so I could understand it better it would be greatly appreciated.

Or if anyone has some example programs using G200 that would help too.

I have tried a quick thing in MDI to see how it preforms with the G200 code and it seems to just be coupling the unlock and lock phases of the tool change with the rapid motion away from the part. It's neat!

So here goes:




%
O1234 ( - TEST PROGRAM - )

(TOOLS)
(T01 - O.D. ROUGH - CNMG 432)
(T02 - O.D. FINISH - VNMG 331)

(MATERIAL)
(2.125" DIA. 1018 M/S - 5.0" LNG.)

(PROGRAM ZERO)
(G54 - 0.03" IN FROM ROUGH STOCK)

G20 G40 G80 G99
G50 S3000
G28 U0.
G28 W0.
G54

N1 (FACING / ROUGH O.D.)
(T01 - O.D. ROUGH - CNMG 432)
G28 U0.
G28 W0.
T101
G96 S700 M03
G54
G00 X2.1 Z0.003 /M08
G01 X-0.063 F0.008
Z0.1
G00 X2.01
G01 Z-1.5
X2.1
G28 U0.
G28 W0.
M09
M01

N2 (FINISH O.D.)
(T02 - O.D. FINISH - VNMG 331)
G28 U0.
G28 W0.
T202
G96 S1000 M03
G54
G00 X2.1 Z0.0 /M08
G01 X-0.063 F0.008
Z0.1
G00 X2.0
G01 Z-1.5
X2.1
G28 U0.
G28 W0.
M09
M05
M30
%




Any ideas are appreciated!

Thanks,
Colton.

[double a-ron]

I haven't found a practical use for g200. If Uxx.xxxx Wxx.xxxx is a safe place to change tools then why not make that your tool change position. I use G53 for my tool change position. All you have to do is jog the machine to as close to your part as you can get with your longest od and id tools like you said then look at the position page and use the machine coordinates as the tool change position. Example: the safe position is X-3.1 Z-5.3. It would code like this:

G00 G53 X-3.1
G53 Z-5.3

If any one else can give me a reason why if Uxx.xxxx Wxx.xxxx is a safe place to change tools, we are letting the machine continue on it's way home (G28), let me know. For you people with the bigger lathes this seems like a real waste of time.

[colton_m]

Thanks for the G53 tip!

I've had some more time to play around with this,

As I understand it the benefit of the G200 code is the fact that the un-clamp and clamp portion of the tool change is coupled with the motion to and from your desired tool change position:

1. move while unclamping
2. index
3. move while clamping

Whereas using the G53 method takes the regular ammount of time to index tools:

1. move
2. unclamp
3. index
4. clamp
5. move

However, it would seem that the quicker tool change is not the only practical use for this code.

It could also be used to streamline programs that are run on a variety of different sized lathes with minimal editing from machine to machine like would be required in your G53 method.

Since Uxx.xxxx and Wxx.xxx are relative distances it would figure that any program you create would operate exactly the same on small or large machines without having to change the values on your G53 lines depending on weather you're using a tiny SL-10 or a longer SL-30 (as an example).

What I am trying to figure out now is if using the G200 code could cause a crash when the turret pops out if the tool is not already far enough away from the part when the G200 code is read.

Would it be a problem if the tool was 0.100" away from the workpiece?
Or should it be 1.000" away to make up for how far the tool pops out?

- Colton.

[Geof]

Are you now using G200?

Does it save much time?