Home positions and endstops

Hello!
How do I know what the right home per axis is?
How do I know are my endpoints min or max and do i need to invert?

It's Tevo Tarantula and it's my first printer.

Also, what is home? Should it be a corner or a middle of the bed? My printer seems to get to hit endpoints and then goes to the middle of the bed. Have not tried to print anything yet. Trying to learn basics first.

Home is front left of the bed on most machines (except deltas), some 'really weird' people also use back right, its valid, but very confusing.

min/max depends on machine configuration. For a I3 type machine its the following.

X is left/right. Min is left, Max is right, X- moves head left, X+ moves head right.
Y is front/back, Since the bed moves vs the head. Min is at back, Max is at front. Y- moves the bed back, Y+ moves the bed forward
Z is up/down. Min at the bed, Max is up top. Z- moves head down, Z+ moves head up

You can home which ether way you want, as long as you tell the machine in firmware.

Homing is just so the machine can work out where it is, when it turns on it can not tell where it is, so it moves home till it hits the endstop. from there firmware tells it that it is at a known location.

Edited 2 time(s). Last edit at 07/11/2017 05:38AM by Dust.

So when I click +Y in Pronterface, the bed should move towards me?
Because, now it moves away from me on +Y.
Should I invert Y stepper?

OK, I inverted the Y motor. This seemed right to me. Am I correct in thinking that the lower left corner of the bed (closer left) should be the origin?

I have another trouble. No matter what I do in configuration.h, the z_min end stop always returns TRIGGERED when not pressed and "open" when pressed on M119 command.
I have a mechanical endstop currently, as the sensor seems not to be working.

M119 on all axis middle:

SENDING:M119
echoD init fail
Reporting endstop status
x_min: open
y_min: open
z_min: TRIGGERED

M119 on manualy triggering only z_min endstop:

>>> m119
SENDING:M119
Reporting endstop status
x_min: open
y_min: open
z_min: open

I have following configuration.h part:

//===========================================================================
//============================= Mechanical Settings =========================
//===========================================================================

// @section machine

// Uncomment one of these options to enable CoreXY, CoreXZ, or CoreYZ kinematics
//#define COREXY
//#define COREXZ
//#define COREYZ

// Enable this option for Toshiba steppers
//#define CONFIG_STEPPERS_TOSHIBA

// @section homing

// Specify here all the endstop connectors that are connected to any endstop or probe.
// Almost all printers will be using one per axis. Probes will use one or more of the
// extra connectors. Leave undefined any used for non-endstop and non-probe purposes.
#define USE_XMIN_PLUG
#define USE_YMIN_PLUG
#define USE_ZMIN_PLUG
//#define USE_XMAX_PLUG
//#define USE_YMAX_PLUG
//#define USE_ZMAX_PLUG

// coarse Endstop Settings
#define ENDSTOPPULLUPS // Comment this out (using // at the start of the line) to disable the endstop pullup resistors

#if DISABLED(ENDSTOPPULLUPS)
  // fine endstop settings: Individual pullups. will be ignored if ENDSTOPPULLUPS is defined
  //#define ENDSTOPPULLUP_XMAX
  //#define ENDSTOPPULLUP_YMAX
  //#define ENDSTOPPULLUP_ZMAX
  #define ENDSTOPPULLUP_XMIN
  #define ENDSTOPPULLUP_YMIN
  #define ENDSTOPPULLUP_ZMIN
  //#define ENDSTOPPULLUP_ZMIN_PROBE
#endif

// Mechanical endstop with COM to ground and NC to Signal uses "false" here (most common setup).
const bool X_MIN_ENDSTOP_INVERTING = true; // set to true to invert the logic of the endstop.
const bool Y_MIN_ENDSTOP_INVERTING = true; // set to true to invert the logic of the endstop.
const bool Z_MIN_ENDSTOP_INVERTING = true; // set to true to invert the logic of the endstop.
const bool X_MAX_ENDSTOP_INVERTING = true; // set to true to invert the logic of the endstop.
const bool Y_MAX_ENDSTOP_INVERTING = true; // set to true to invert the logic of the endstop.
const bool Z_MAX_ENDSTOP_INVERTING = true; // set to true to invert the logic of the endstop.
const bool Z_MIN_PROBE_ENDSTOP_INVERTING = true; // set to true to invert the logic of the endstop.

//===========================================================================
//============================= Z Probe Options =============================
//===========================================================================

//
// Probe Type
// Probes are sensors/switches that are activated / deactivated before/after use.
//===========================================================================
//============================== Endstop Settings ===========================
//===========================================================================

--EDIT--
Found it literally minutes after posting: [github.com]
Comment
#define BLTOUCH

This interfeers. Now it works properly

Edited 1 time(s). Last edit at 07/11/2017 12:45PM by Mandor.

I am experiencing the same symptoms of Z axis not homing unless Z endstop is pressed (inverted logic). I tried switching the boolean states of -> #define Z_MIN_PROBE_ENDSTOP_INVERTING true <-, but that didn't change anything. I then tried to comment out BLTouch as you suggested, but that gives me errors with "Unified Bed Leveling".

I also just noticed that -> //#define Z_MIN_ENDSTOP_INVERTING false <- is commented out. Is Z_MIN_PROBE and Z_MIN_ENDSTOP the same thing? I'm curious why probe is used and not the regular variable?

Quote
Dust
Home is front left of the bed on most machines (except deltas), some 'really weird' people also use back right, its valid, but very confusing.

min/max depends on machine configuration. For a I3 type machine its the following.

X is left/right. Min is left, Max is right, X- moves head left, X+ moves head right.
Y is front/back, Since the bed moves vs the head. Min is at back, Max is at front. Y- moves the bed back, Y+ moves the bed forward
Z is up/down. Min at the bed, Max is up top. Z- moves head down, Z+ moves head up

You can home which ether way you want, as long as you tell the machine in firmware.

Homing is just so the machine can work out where it is, when it turns on it can not tell where it is, so it moves home till it hits the endstop. from there firmware tells it that it is at a known location.

That is very helpful. Exactly what I was looking for as I wait for delivery of my i3 clone from Flsun.
I read somewhere that one of their instruction manuals has the belt layout wrong on the Y-axis.
Confusion can arise when looking at the photos depending on whether it is a Top View or Bottom view.
To avoid any mistakes, before assembly, I plan to do a dry run connecting motors to the motherboard.
It would help a lot if I can confirm rotation direction by looking at the motors with shaft facing up.
As I figure it, the X-axis motor should be Clockwise to Home
Y-Axis Anticlockwise to Home
and Z- Axis with lead screw I guess is Anti-Clockwise.to Home
Is that correct?

Edited 1 time(s). Last edit at 08/05/2017 07:58AM by dolon.

Quote
As I figure it, the X-axis motor should be Clockwise Y-Axis Anticlockwise and Z- Axis with lead screw I guess is Anti-Clockwise. Is that correct?

correct.