BL Touch and Makerfarm.

[Roxy]

Also make sure your Configuration.h file looks like mine in this section. If you don't have things like mine, you won't be able to home in the center of the bed:

// @section homing


// The center of the bed is at (X=0, Y=0)
//#define BED_CENTER_AT_0_0


// Manually set the home position. Leave these undefined for automatic settings.
// For DELTA this is the top-center of the Cartesian print volume.
//#define MANUAL_X_HOME_POS 100
//#define MANUAL_Y_HOME_POS 100
//#define MANUAL_Z_HOME_POS 20


// Use "Z Safe Homing" to avoid homing with a Z probe outside the bed area.
//
// With this feature enabled:
//
// - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
// - If stepper drivers time out, it will need X and Y homing again before Z homing.
// - Move the Z probe (or nozzle) to a defined XY point before Z Homing when homing all axes (G28).
// - Prevent Z homing when the Z probe is outside bed area.
#define Z_SAFE_HOMING


#if ENABLED(Z_SAFE_HOMING)
  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
#endif

[BLKKROW]

Also make sure your Configuration.h file looks like mine in this section. If you don't have things like mine, you won't be able to home in the center of the bed:

// @section homing


// The center of the bed is at (X=0, Y=0)
//#define BED_CENTER_AT_0_0


// Manually set the home position. Leave these undefined for automatic settings.
// For DELTA this is the top-center of the Cartesian print volume.
//#define MANUAL_X_HOME_POS 100
//#define MANUAL_Y_HOME_POS 100
//#define MANUAL_Z_HOME_POS 20


// Use "Z Safe Homing" to avoid homing with a Z probe outside the bed area.
//
// With this feature enabled:
//
// - Allow Z homing only after X and Y homing AND stepper drivers still enabled.
// - If stepper drivers time out, it will need X and Y homing again before Z homing.
// - Move the Z probe (or nozzle) to a defined XY point before Z Homing when homing all axes (G28).
// - Prevent Z homing when the Z probe is outside bed area.
#define Z_SAFE_HOMING


#if ENABLED(Z_SAFE_HOMING)
  #define Z_SAFE_HOMING_X_POINT ((X_MIN_POS + X_MAX_POS) / 2)    // X point for Z homing when homing all axis (G28).
  #define Z_SAFE_HOMING_Y_POINT ((Y_MIN_POS + Y_MAX_POS) / 2)    // Y point for Z homing when homing all axis (G28).
#endif

Mine looks similar. I found a work around from the G92 command.

I changed the following while trying to find my Z-Offset:

#define Z_MIN_POS -10
#define MANUAL_Z_HOME_POS 0

This allows me to home using G28 and lower the Z axis by up to 10mm. After I found my offset, I changed these back to defaults. Now I am trying to figure out what the Bl Touch is doing as it is behaving erratically.

[Roxy]

Now I am trying to figure out what the Bl Touch is doing as it is behaving erratically.

Where did you get your BL-Touch? How much did you pay? There are a lot of counterfeit BL-Touches starting to show up and they don't behave like a BL-Touch. Some of them even need an inverted setting on the Z_MIN_ENDSTOP option. Search at GitHub.com/MarlinFirmware/Marlin for threads about BL-Touch and counterfeits. There is a huge amount of work that has been done to identify which 'clone' you have and how it should be set up.

But we do have the real BL-Touch probes working perfect!!!! It is the 'clones' that are having problems.

[BLKKROW]

Where did you get your BL-Touch? How much did you pay? There are a lot of counterfeit BL-Touches starting to show up and they don't behave like a BL-Touch. Some of them even need an inverted setting on the Z_MIN_ENDSTOP option. Search at GitHub.com/MarlinFirmware/Marlin for threads about BL-Touch and counterfeits. There is a huge amount of work that has been done to identify which 'clone' you have and how it should be set up.

But we do have the real BL-Touch probes working perfect!!!! It is the 'clones' that are having problems.

I bought my BL Touch from Colin at Makerfarm.

I got it working, and was having issues with the probe speed.

[Roxy]

> I got it working, and was having issues with the probe speed.

If you got it from MakerFarm, it is my belief it is legitimate and not a 'clone'. But the thing is... This is kind of backwards... BL-Touch probes work better at higher probe speeds. The problem is they put out a 5 ms pulse saying they are triggered. And because of how Marlin handles the stepper motors, if the probe is moving very slowly, the stepper motors are not fed new information as often. The end stops are only checked when the stepper motors are being serviced and a 5ms pulse isn't much time. I'm not saying to make the probe speed super high.... But for sure you don't want the probe speed to be super slow!

With all that said... If you have a RAMPS board... You can enable Marlin's interrupt endstop capability now. And it doesn't have to be a RAMPS board. If your electronics has all of the endstops on pins that can provide interrupts... You just turn that on and you can run the probe at a ridiculously slow speed. It will be fine!

[dasaint80]

I'm having a heck of a time adjusting the offset with the BL touch.

once I run G28, my Z is 5 mm off. if I adjust my offset to -5 them G29 causes errors on my BL touch!

Configuration.h

I attached my Config file. I'm running marlin on a megatronics v3.

[Roxy]

Did you do a M502 and M500 after changing the values in your Configuration.h ? The latest RCBugFix has an option where you can use Z-BabyStepping and it will automatically adjust your Z-Offset.