Pick Off/Pull/Cutoff

[ahaslam]

Can any one help me get started on the Pick Off/Pull/Cutoff function for lathe? I have worked with a number of mill posts and a little lathe work too but I have never tried to get the Pickoff together. Can any one help me enable it and list the parameters involved? I can't seem to find it in the MP Documentation.

 

Thanks.

[ahaslam]

Scratch that, I just found the Application Guide. Just the same, any advise would be appreciated.

[#Rekd™]

I think it will be easier to create a sub program to achieve this.

[The Cathedral]

On our non-millturn machines, I ended up accomplishing POCO by using a macro/subprogram on the machine. Then I would use "stock transfer" in the misc. operations, and had my post pull parameters from that op to populate the macro. I had cutoff speeds/feeds set to a default, but could override it using a misc value when needed. Part length, cutoff length, and grip point were pulled from the op, the rest was handled by the macro. 

 

I wish I could still do this on our MIll/Turn machines. 

[Colin Gilchrist]

Since you've found the applications guide, that should give you the information about how to enable POCO in your Lathe post. You need to modify the header line, and include a special "command variable" to turn on the POCO processing.

 

POCO works by creating different "Chuck" events (NCI 900, 901, 902, 903).

 

Each of the different NCI "gcode" values is listed inside the "Generic Fanuc 4X MT_Lathe" post processor. For NCI 900, the post block called is 'pstck_trans$'.

 

Each of these post blocks has a list (as comments in the text) of the variables that are available for each event. (MP automagically sets the values of these variables, based on the values in the NCI file).

 

When you run the "Pickoff/Barpull/Cutoff" utility inside Mastercam, the software gives you some options on what type of operation you want to create. This basically allows you to program a "sequence of events" that occur.

 

So in this one utility, you can program many different sequences of events. For example, you might want to do:

 

• Barpull Op (Allows you to pull more bar, using the Right chuck)
• Pickoff Op (Allows the Right chuck to grab a "single stock piece" and transfer to the Right Chuck for further machining)
• Pickoff/Cutoff (Allows the pre-position of the cutoff tool, approach and secure the stock with Right Spindle, cutoff stock, and transfer to Right Spindle)
• Pickoff/Barpull/Cutoff (pre-position cutoff tool, approach and clamp stock, open main chuck, pull bar length, clamp main spindle, cutoff sequence (synchronize chucks), retract Right Spindle)

 

When you select your "main" operation type, this changes the options available on the next Tab. The 2nd tab shows you a list of the various Chuck and Tool operations, and allows you to customize the parameters for each operation. The dialog box also "remembers" the values you type in, so they "persist" to the next session.

 

Take a look at the 'pchuck$' post block. This shows some examples of the type of logic you need to write. "if <condition>, is true, <then>, do something"

 

These "Chuck Events" even have a separate set of "misc values". They give you 8 Misc Ops Integers, and 8 Misc Ops Real Numbers. This allows you to customize the output fully to support any machine options you need to output.

 

The first task you need to figure out is "what sequence of G-codes and M-codes do I need to support this machine?". Once you answer that question, it is much easier to advise you on how to proceed.

 

For example, I had setup several of the "miscops misc. values" as follows:

 

• Misc Int. #1 - Chuck Air Blast. 0=off, 1=Left Chuck Only, 2=Right Chuck Only, 3=both chucks
• Misc Int. #2 - Torque Skip during POCO, 0=off. 1-99 = % of Torque Skip value OVERRIDE
• Misc Int. #3 - Synchronize Chucks? 0=off, 1=on
• Misc Int. #4 - M00/M01 after clamp? 0=no, 1=M01, 2=M00
• Misc Real #1 - Main Chuck Clamp Dwell Time
• Misc Real #2 - Sub Chuck Clamp Dwell Time

Then, it is just a matter of adding logic to test these "miscops" integer and real number values in the 'pchuck$' post block, and outputting code when the values are output.

[ahaslam]

I think I am going to work the post out to run the whole thing without macros in the machines. I have a pretty good idea on how I want to do this. I am going to use a sub program merge and post two programs with the one post. No big deal but I am struggling on one thing. I want to add some logic to my post that says if I am working with the right spindle then post that section out to the sub program. I don't know any variables off the top of my head I can use to achieve this. Is there one for the axis combination?

[ahaslam]

If there isn't one I could just use the work offset as the trigger, but I would rather have something more solid. Worst case I could always have the MISC INT and use that.

[Colin Gilchrist]

Oof. Why would you want to go that route? The reason I ask is that the Generic Fanuc 4X MT_Lathe post has a bunch of code built into it that determines the active spindle, and active turret, and allows you to make changes to the output, based on the spindle/turret, and the type of operation being executed.

 

For testing which spindle is active, there is a pre-defined variable, 'spindle_no$' that tells you which spindle is active. (0 for main, 1 for sub). The variable 'lturret$' is used to check upper/lower turret.

 

The thing is, there is a bunch of logic that already exists in this post to setup and control the output for different cut types. I would not recommend going down the road you are going.

 

It is much easier to just modify the 'pchuck$' post block to support the Pickoff/Barpull/Cutoff actions.

 

First, start by getting the actual "hard distance" between your chuck faces. From there, you can enter that data into the "Stock setup", where you enter the information about both the Main and Sub spindle setup.

 

The distances inside the stock setup can be captured, and used as reference data for outputting "G53" position data (machine position).

[ahaslam]

But the control requires two separate programs, one for the main spindle and one for the sub spindle. How else would I be able to get two programs in one shot?

 

 

EDIT: Fixed Typo

[ahaslam]

Colin, I got the sub to work with the spindle_no$. I suck in a few sub triggers and a submerge and it looks good. You have me a little nervous that I missed something. Why were you thinking this was such a poor way to do it?

[Colin Gilchrist]

I was worried you might step on the existing logic for Subprograms, but it appears that the Generic Fanuc 4X MT_Lathe post doesn't make use of the 'SUB' file or 'EXT' file. It might use the AUX file, and LCC files. (I know it uses the LCC file...)

 

So, you should be good to go. Just set 'subout$' to '1' to write to the Subroutine file, and set it back to '0' to write to the main file.

 

Are you going to use the POCO utility to program the sequence of events to move the right spindle, clamp/unclamp, and re-position the right spindle? That is what is is designed to do inside the post. You can program the Z Axis (W?) for the second spindle, and enter the "pickoff" positions. You can also enable/disable dwells, air blasts, and so forth, during the pickoff sequence of events.