Prusa I3 Rework Y-Min Endstop

First of all, hats off to BLUE ICE for all the help and advice!

This is my first 3d printer build and it's been (and still is) quite a ride. There's lots of information to wade through and a lot of the threads tend to stray off of the main topic, but that's the way it goes.

I am one of the few people who built their I3 Rework printer with the Y-Min limit switch in the front of the printer. My endstops are as follows:

Y-Min - Front of printer
X-Max - Right side of frame
Z-Min - Bottom left of frame

Here's a picture of my setup:



My HOME position ended up putting the 0,0 position in the right rear corner of the print bed. It seems that the standard HOME position is at the front left corner of the print bed.
I wanted to maintain my HOME start position at the limit switches without having any mirrored printing problems, so I made two changes as follows:


1. Changed the X_Home_Dir to -1 which made my X-axis endstop an X-Min, and
2. Changed the X-Endstop on the Ramps board to the X-Min position.


I recommend the following additional TEMPORARY changes so you don't have to worry about the axis' crashing into the endstops without stopping the machine in time. I highly recommend these changes for first-timers setting up their axis' and endstops, since it gives you more time to shut down the machine without incurring damage.

Marlin changes:

Line 475: HOMING_FEEDRATE - changed to (50,50,10,0)
Line 481: DEFAULT_MAX_ACCELERATION - changed to (100, 100, 5, 1000)
Line 483: DEFAULT_ACCELERATION - changed to 10
Line 484: DEFAULT_RETRACT_ACCELERATION - changed to 10

The last two changes are just precautionary - I slowed down the speeds of anything that may have affected the motor speeds. Again, this is TEMPORARY - restore to the original numbers once you're sure the end-stops are set correctly.

I also temporarily raised the hot end an inch or so above the bed and took a pen and attached it to my extruder fan duct with rubber bands so I could test the movement and directions on a sheet of paper. I played around with the G-code commands to make sure what I was trying to draw wasn't inverted. I tried to draw a 'block" capital letter E to make sure the X and Y axis were moving in the right directions when I manually gave it the g-code commands.



The way my limit switches are set should print a proper object (without mirroring) - only it will be upside down as shown in this drawing:



The normal movement for a HOME position in the front left corner should look like this:




The home position is at the right rear corner of the bed, as before. When I select Y+ the bed moves to the rear/print head moves toward me. When I select X+ the print head moves left. I believe this is how it should operate given that the origin 0,0 is in the right rear corner of the bed. It will still be a little awkward, since everything will print upside-down, but it shouldn't be inverted (hopefully).

Now, I have to work on my initial setup and try to do a test print. If there's anything I got wrong, please let me know. I'm just a newbie too!

Edited 1 time(s). Last edit at 06/06/2015 09:39PM by psneddon.

Letter E or letter H,X, O etc. are not the best way to test orientation, because they all are "mirrored" in a way. Better try to draw a "F" or something.

But, you got your orientation right, so far.
-Olaf

OLAF,

You're right. I realized that last night and was going to chop off the bottom leg of the 'E' it off to make an 'F', but my computer started acting up a bit and I wanted to get some COD time in before it got any later. LOL Thank you for letting me know my orientation is right.

Here are some diagrams for the letter 'F'. The first is when you're printing with your HOME position (0,0) at the front-left corner of the print bed:



The second diagram is when you're printing with your HOME postion (0,0) at the right-rear corner of the print bed:



Either of these mirrored "F"'s is what you'd get if your settings aren't right:



Edited 2 time(s). Last edit at 06/07/2015 09:37AM by psneddon.