LinuxCnc default program is being engraved upside down!

Hi guys,

Before doing test cuts I wanted to try the default linuxcnc program, the one that engraves linuxcnc.
I removed the spindle command and I put a marker in the spindle.
The texs is written upside down and in the wrong direction.
Any idea why this happens?
If i jog from the pendant, the axis movement directions are correct.

It looks like you have a moving table arrangement. You need to remember that movements are supposed to be of the spindle relative to the workpiece. So if your machine moves the work piece and not the spindle the movemint will be opposite of the arrow on the keyboard. So a positive X move (right keyboard arrow) will move the spindle to the right of the work piece, or if it is the work piece moving, it will move to the left.

Sorry...I don’t understand what you say..
If I jog from keyboard, the table is moving in the dirrections of the arrow keys.
Also if I use the arrow keys, the cone that represents the spindle moves in the correct direction on the drawing.
But when I run the program, its upside down and writes to the left not to the right.

Having the table move in the direction of the arrows on the keyboard is opposite the normal convention. (You need to imagine the movement as if you were moving the spindle not the table.)

My x and y axis are inversed.
Right now when I press right arrow on the keyboard, the table goes right, when I press left arrow, it goes left.
I understand it should be the other way around.
I changed the sign of STEP_SCALE to minus.
Now when I jog with the keyboard, it goes the opposite as described above.
But now I have a problem with the dirrection of homing and soft limits.
I have read the documentation, tried to generate from pncconf, tried to change the values in code, I just can’t make it do what I want.

What I want: (talking only about x now)
- I want X axis to home by moving to the left, then to come back to the right up to the middle of the table.
- If my travel is between 0-400mm, and home position is at the middle of the table, I expect to see +200 on the DRO for X
My problems:
If I can make it home in the right direction, after homing instead of going back, it goes forward, passing the switch and crashing the machine.
My DRO shows some coordinates with minus sign, no idea where they came from.

Might be a simple task for many, but a month ago I have crashed the machine on X while trying to tune the homing, and when you have 1kw servo per axis..its not funny at all..

Please see the settings I have now, with X moving in the wrong direction, not relative to the spindle. If i change the sign of Step_scale, how do I need to change the other values so that the homming will back off to the middle of the table and the dro to show +200mm

Here are my current values, with the axis reversed. With trial and error, I have managed to tweak the homing and soft limits. However, after its homed, the dro still does not show values between 0-390, it shows smth with minus.

HOME = 200.0
STEP_SCALE = 400.0 (this one needs to be with minus in order to refer to spindle movement relative to the table)
MIN_LIMIT = 2.0
MAX_LIMIT = 392.0
HOME_OFFSET = 0.0
HOME_SEARCH_VEL = -30.0
HOME_LATCH_VEL = -0.5
HOME_FINAL_VEL = 0.0
HOME_USE_INDEX = NO
HOME_IGNORE_LIMITS = YES

I have a single switch per X axis and two trigger pins. See the mill picture.

Is the home switch also the left limit switch? If you want your home switch to be with the table moved all the way to the left that would be at the positive limit of travel. and your table has 400mm of travel. If you set your "HOME_OFFSET = 400" and "HOME = 200", I think you may get the results you desire. (You may also need to change the signs of your scale, search vel, and latch vel.)

"HOME_OFFSET =" sets the position value of the point where the home switch is triggered and "HOME =" sets position where the axis moves to and parks at the end of the home sequence.

Thanks Todd, using your explanations I was able to set the machine correctly and the soft limits.
I think the documentation is wrong, it says that HOME_OFFSET should be between MIN_LIMIT and MAX_LIMIT. I set the MIN_LIMIT=0, MAX_LIMIT=387, HOME_OFFSET = 390 and like this it works correctly, so that after its homed, does not bump into the switches.

3.6. HOME_OFFSET
Contains the location of the home switch or index pulse, in joint coordinates. It can also be treated as the distance between the point where the switch or index pulse is latched and the zero point of the joint. After detecting the index pulse, LinuxCNC sets the joint coordinate of the current point to HOME_OFFSET. The default value is zero.

Note
The home switch location, as indicated by the HOME_OFFSET variable, must be strictly within the soft limits. That is, MIN_LIMIT < HOME_OFFSET < MAX_LIMIT.

Yes, that doesn't seem right. I think the note needs to say that the HOME position has to be between the soft limits. However where the HOME position is, is partially determined by the HOME_OFFSET. (If HOME=0 then the note statement is true, but not for the reasons it seems to imply.) HOME_OFFSET also contributes to where the soft limits are as well, so really the HOME_OFFSET has nothing do do with needing to be between anything, it truly can be any arbitrary number and is up to your personal preference, but what it is will effect what your soft-limits and home positions can be.