Thread cutting. Teams G-33 and G-76.

[LEOOZERAN]

I want to create my own postprocessor for Siemens NX. And FeatureCam. For a lathe! As far as I understand, GRBL HAL does not have a ready-made one. I would like to know what codes GRBL HAL supports. I know that it supports both G-33 and G-76. G-33 and G-76 have different thread processing methods. And different postprocessors have different processing cycles. Can I get code fragments from someone? These G-codes use different fragments in different postprocessors. But many postprocessors use standard ones! With which postprocessor, for a lathe, did GRBL HAL start? For a lathe. What to take as a basis (can you give several examples)? I would like to use both G-33 and G-76. And create several postprocessors for ease of use. The machine is assembled for professional processing, taking into account 4 axes. It is possible to work in Linux CNC with Rasperdi PI 5. But it is still in the assembly stage. Now I have a Devtronic CNC controller board. A simple 2000-pulse encoder. Testing. I would like to fully understand Grbl Hal, especially for a lathe. Since I plan to assemble two machines on different boards and with different software. Please correct me, this Grbl Hal project is very successful and is no worse than Linux CNC. There are many postprocessors! In different programs. But for the full operation of the lathe, you need to at least know. Which of them is best suited for Grbl Hal. Or several. Please help. I will share the results later.

[terjeio]

grblHAL mainly follows the LinuxCNC specification for the G- and M-codes supported. The main list of supported codes is found here.

Plugins may add M-codes, most of these are according to Marlin specifications.

There are some links to post-processors here, if you create a new one it would be nice if you could add to that.

[LEOOZERAN]

Autodesk/Fusion 360. Solidworks.
These are postprocessors based on 3-4-axis CNCs. But they're not lathes. I'm interested in thread cutting cycles. Turning. Different postprocessors have different configurations. For example, GrblGru is a lathe. When loading different CNC programs from different postprocessors, it doesn't generate errors in its emulator. In fact, its program contains various cycles, thread cutting, and so on. The cycles are in the library itself, in the program itself. Most likely. Here's an example of your cycle. G 33
m3s200
g0x2
g0z2
g1x0f50
g33z-15k1.5
g0x2
g0z2
m30

Standard example
G00 X8.0 Z5.0 ; Quick return to safe position
G01 Z-10.0 F0.5 ; Go to the beginning of the thread with feed
G33 X-20.0 F1.5; Cuts an M10 thread with a 1.5 mm pitch
G00 Z5.0; Return to the safe position.

It's difficult to find a postprocessor for your cycle. The letter K is rarely used.

Gi 76
X = Minor (major) thread diameter
Z = End point of flow
P = Thread depth
Q = First cut depth
F = Thread pitch
Example:
T1212 M06;
G97 S400 M03;
G76 P040060 Q100 R0.2
G76 X18.2 Z-18.0 P180 Q160 F1.5;
G00 X25.0 Z10.0;

Example of G-code for cutting left-hand threads (general principle)
Below is an example of the general principle of cutting left-hand threads using the G76 cycle on a Fanuc machine. Specific parameter values ​​and commands may vary depending on the machine model and its control system.
Preparatory commands:
N100 G50 S1000 — sets the maximum spindle speed (1000 rpm).
N110 G00 G90 G54 X100 Y0 — positions the tool in the work zone.
N120 T0101 — selects tool (cutter) #1 and adjusts its length/radius.
Left-hand thread cutting cycle:
N130 G97 M04 — starts the spindle at the set speed (in this case, M04 is counterclockwise).
N140 G76 P010060 Q50 R0.01 — thread cutting cycle parameters. Where:
P01 is the number of roughing passes (1).
00 is the thread profile angle (0 degrees).
60 is the initial thread diameter (60 mm).
Q50 is the cutting depth in one pass (0.05 mm).
R0.01 is the final thread depth (0.01 mm).
N150 G76 X95 Y0 Z-50 I0.0 J0.0 — thread cutting parameters. Where:
X95 is the final thread diameter.
Y0 is the part coordinate in the transverse plane (for external turning).
Z-50 is the final thread cutting depth.
I0.0 is the X offset from the thread start.
J0.0 is the Z offset from the thread start.
N160 G00 G90 G53 Z0 — returns the tool to the safe zone along the Z-axis.
N170 M05 — turns off the spindle.

And, essentially, your program won't generate errors.
Examples of popular postprocessors:
For Fanuc systems:
Postprocessors for Fanuc 0i-MF Plus, Fanuc 0i, 21i, 30i, 31i.

For Siemens systems:
Postprocessors for Siemens 840D and Siemens 828D.

For DMTG equipment:
Postprocessor for DMTG lathes.
Turning is becoming increasingly popular!
Try making changes or adding variations to various turning cycles, especially in GrblHal and Web Builder.
There are boards based on STM chips. They are quite good, even very good. Since only an STM chip can handle the high-speed operation of an encoder, it's possible.
Add some more. Different cycles in Grbl Hal. For a lathe. Then I'll be able to make a decent postprocessor for various programs.

[terjeio]

So you want a different (or optional) implementation of G76? You can do that?

[LEOOZERAN]

In principle, yes. And not only for G76, but also for G33.

There are even postprocessors, for example, Fanuc, that can cut threads according to G32.
I'm currently testing two programs: Siemens NX and FeatureCam. I'm creating several CNC programs using different postprocessors: for facing, roughing, finishing, and threading. I'm also testing them with GRBL HAL. I can send them or post them here. Several versions, machining, and different postprocessors.

By the way, the letter K is used more often in the G32 cycle than in the G33 cycle. I'm still figuring out G76 and looking for as many suitable variants as possible. In different postprocessors. To create a single program that can be used in different programs. Essentially, it all comes down to the beginning of the G-code, the end, and, most importantly, the machining cycles.

If you add cycle variations to the firmware, GRBL HAL will not throw an error. That is, it can be made a postprocessor for a lathe-mill machine. In lathe mode, it is in ioSender. For example, permission to use four axes is required. They do not necessarily have to be in the interface. For a lathe, it is in ioSender. But it should work the same as other axes. This is suitable for using the (O) word, that is, like in LinuxCNC. Then I can, for example, compile ... Axis A. For tool change.
Now I have my own version, a tool holder. Tool change (carousel type). So far, it has four inserts. Uses a stepper motor. Fully assembled, the latest version. I will post it here. And then you will be able to use the (M6) command. Like the (O) word.

I also noticed a drawback. At the beginning of the control program. For a lathe. There is a drawback. It lies in the coordinate system. Not all programs begin with a G-code responsible for working in the XZ plane - this is G18. A lathe should understand and allow the use of other coordinate systems.

If you're willing to work on these shortcomings, we can continue this topic. I'll post the results of my experiments, including any new modifications, here.

Edit: added whitespace for readability