Marlin - Y Axis pushes past endstop?
June 14, 2014 04:41PM
I've built a prusa i3 box frame, I'm using a RAMPS 1.4, and I'm having a bit of trouble wrapping my head around the configuration of the marlin firmware.

I can move each axis in each direction in pronterface, but the Y endstop seems to be behaving strangely.

Y-Axis: Endstop is on the +Y side. It does not stop when it hits that end stop. However, it does stop when I manually trigger the endstop while it's moving towards the -Y side.

X-Axis: Endstop is on the -X side. Stops when it hits the endstop.

Z-Axis: Endstop is on the -Z side. Stops when it hits it.

I posted this same question on the reprap community on reddit, and someone recommended that I change this part of the code:

// ENDSTOP SETTINGS: // Sets direction of endstops when homing; 1=MAX, -1=MIN
    define X_HOME_DIR -1
    define Y_HOME_DIR 1
    define Z_HOME_DIR -1

So that the Y home direction is -1 as well. But my Y endstop -is- actually on the +Y side of the axis. Either way I set that value for the Y, it still acts the same way. I suppose I could put the endstop on the -Y end, but I've seen every other Prusa i3 set up with it on the +Y end. Plus, I'm afraid if it's on the -Y that I'll bump it.

I also just read a tip that suggested I check to see if the endstop was plugged into the +Y spot on the board, which it was not. However, after plugging it into the +Y spot, The bed is unable to move in the -Y direction.

Also, whenever I hit the home buttons in pronterface, it kills all the endstops, none of them work and the axes crash past them. I have to disconnect and reconnect to get them working again.

I uploaded my configuration.h file here:

[pastebin.com]

If someone could look at that and tell me if anything jumps out at them as being incorrect, I'd really appreciate it. I literally have no idea what I'm doing when it comes to configuring this and I'm pretty much just blindly following guides online and hoping they work.

Thank you for your time.
Re: Marlin - Y Axis pushes past endstop?
June 16, 2014 08:29PM
A fundamental misunderstanding of how the Y axis worked is what lead to this problem.

In pronterface, when I clicked +Y, it moved towards me, and not away from me. I interpreted this as meaning that I needed to invert the axis, so -Y moved towards me, and +Y moved away from me.

Apparently, you need to imagine that the build plate is stationary, and that the hotend is what's moving back and forth. So when the plate moves away from you, the hotend is actually moving "down" the Y axis.

I wish that that had been written in big red letters somewhere, I stumbled across that fact watching a random youtube video featuring an i3.

Changed:
define INVERT_Y_DIR true

to
define INVERT_Y_DIR false

and switched:
define Y_HOME_DIR 1

back to
define Y_HOME_DIR -1

Anyway, just thought I'd update my post in case any other newbies like me run into the same problem in the future. Thanks for your patience, everyone.
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