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Problem with mirrored prints

Posted by RepMike 
Problem with mirrored prints
September 07, 2017 12:35PM
Hi, I have a self-made Prisa i3 rework (Ramps 1.4/Arduino 2560), built after the tutorial from the reprap-wiki and I have a problem: Everything seems fine except for the X direction of the prints, they seem flipped/mirrored.

If I sit in front of the printer, the X axis looks like this:
X:   193              0


X=0 is where S is, the left side where the motor is has its MAX at X=193. Homing brings E to S, i.e. X=0. The Max position is being respected by Marlin, I cannot go over X MAX. So far so good. Things print out fine, but the first thing with which X orientation did matter, printed mirrored. I've tried the advices from other forum posts, i.e. to flip INVERT_X_DIR and X_HOME_DIR, but that didn't work.

My current configuration is the following, I try to reduce the lines to the necessary:
#define INVERT_X_DIR true
#define X_HOME_DIR -1
(-1 with X_HOME_DIR means: MIN, the other value would be 1 for MAX)
#define X_MIN_POS 0
#define X_MAX_POS 193

I've tried changing INVERT_X_DIR to false and X_HOME_DIR to 1 (and combinations of those 2), but then I had to also define USE_XMAX_PLUG and nothing worked anymore (computer said "no" trying to compile). After that modification, a movement X+ in pronterface won't move X to X MAX saying "Endstop X hit", X- works though and moves away from the Endstop (i.e. to the left). Homing won't work, it lifts the axis a little, goes left a little and that's it.

I'm lost a little, what else can I try?
Would I have to rather change settings in Slic3r, would that be easier?
Any help would be appreciated.
Thanks in advance
Re: Problem with mirrored prints
September 07, 2017 12:55PM
The origin (0,0,0) must be located at the left-front or right-rear corner of the machine to conform to right-hand-rule coordinate space used by CAD and slicers. There are no explicit statements in the config file but the location of the limit switches and assignment of ordinate values implies the location of the origin. The motor rotation direction is set so that when a home command is executed, the motors move the extruder/bed toward the switches.

If you locate the printer's origin in either the right-front or left-rear corner of the machine, prints will come out mirrored.

Full explanation here: [drmrehorst.blogspot.com]

Edited 1 time(s). Last edit at 09/07/2017 08:27PM by the_digital_dentist.

Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
[SOLVED] Re: Problem with mirrored prints
September 07, 2017 07:54PM
I got the solution! Thank you! The mirroring is history now ...

And thank you for the link - very insightful explanation. So, on that website, in the summarizing table, I find myself in line #2 (and #4), i.e. best for my case would be to have the origin front-left, because my Y limit switch is located in the back and I am at Y=0 when I have homed the Y axis.

Line #2 of the table:
Bed Motion Axis: Y
Printer's Origin: Left-Front
Homing Switching Axis: X
Switch Location on Axis: Right
Home To: max
Ordinate Value: 193 (in my case)
Controller Limit Switch Input: Xmax

So, I've plugged in the limit switch in Xmax (2nd connector for X limit switches) and set the following variables:
(endstop inverting needs to be true, otherwise I get constant triggers by the endstops)
#define X_ENABLE_ON 0
#define Y_ENABLE_ON 0
#define INVERT_X_DIR false
#define INVERT_Y_DIR true
#define X_HOME_DIR 1
#define Y_HOME_DIR -1
#define X_MIN_POS 0
#define Y_MIN_POS 0
#define X_MAX_POS 193
#define Y_MAX_POS 172

What I needed to understand first: The homing position is not necessarily the origin and with that in mind, it was much easier to configure.


Greetings & thanks again
Re: Problem with mirrored prints
September 07, 2017 08:44PM
That's a good point- I never explicitly stated that the home position is not always the same thing as the printer's origin. I updated the blog post with specific statement of that fact.

I'm glad the info was useful!

Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
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