Z - Endstop - Where to mount?

Where does the Z-min endstop usually go?

At table height? or can I use the end stop at the end of travel and define the table height?

thats exactly how it is used.

You can mount it anywhere you want as long as you have a way to trigger it when the axis reaches the end of travel. I have mine mounted to the smooth bars of my prusa and I have an adjustable finger mounted on the x end to trigger it.

It's recommended to mount it on the X motor side since that's where it's the heaviest and most likely to reach it's downward travel first. I have mine mounted to the Z smooth rod so the x-end triggers it when the nozzle just touches the print bed. I find that (with my machine at least), bed leveling is the most important thing and the biggest PITA. Almost all other calibration values are more or less "set it and forget it", but bed height has to be recalibrated all the time and Z endstop position plays a critical role in that. If it isn't adjusted properly, prints will not stick to the bed or they'll be too squished and possibly cause a jam (or even cause a hot end failure). You'll also find that as the nozzle and the print bed heat up and expand, the point where they "just barely" touch will be different. Remember that when printing, your first layer will be deposited at your "first layer height" in your slicing software. It will home to the Z end stop, and then raise to that first layer height before extruding, so it's not going to block the nozzle if it's just touching the print bed when the endstop is triggered. If you have springs on your print bed, you want to make sure they aren't being compressed when the Z axis is homed to it's endstop. If you notice the nozzle is pushing down and compressing the spring before a print, cancel the print and make the necessary adjustments since the print will fail anyway.

None of these really answered my question.

My machine isn't a standard RepRap. It's a custom.

This video might better show the setup

http://www.youtube.com/watch?feature=player_embedded&v=E_mMcdNbK4M

Right now, the Opto End Stop is at the TOP of the Z-Travel.

So what I'm asking is,

Do I leave it there, and can I define somewhere in slic3r the starting Z-Point (aka 150mm from the endstop)
Or put it differently. Can my Z=0 be +150mm from the heat bed.

If yes, where in the configuration for Spinter or Splicer do I define this?

Or do I HAVE to move it to trigger at the point where ever my table will end up.
Meaning does Z=0 have to be just above the heat bed.

Thanks guys,

either way works. But try reading [hydraraptor.blogspot.de]

I dont think it's in slic3r that you do this. I think it's a firmware setting. Of course you'll also have to indicate the exact height above the bed, because the firmware must be able to move the head down to bed level when printing starts.

I think most people have their endstop at the bottom of the axis, but there are some out there that have it at the top.

lazzymonk Wrote:
-------------------------------------------------------
> either way works. But try reading
> [hydraraptor.blogspot.de]
> -up.html

Thanks for the info!

Looks like the Marlin Firmware has what I need.

I found in Configuration.h

Quote

// 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

#define min_software_endstops true //If true, axis won't move to coordinates less than HOME_POS.
#define max_software_endstops true //If true, axis won't move to coordinates greater than the defined lengths below. // Travel limits after homing

#define X_MIN_POS -100 #define X_MAX_POS 100
#define Y_MIN_POS -100 #define Y_MAX_POS 100
#define Z_MIN_POS 0
#define Z_MAX_POS (Z_HOME_POS - 0.1)

// The position of the homing switches. Use MAX_LENGTH * -0.5 if the center should be 0, 0, 0
#define X_HOME_POS (X_MIN_POS - 1)
#define Y_HOME_POS (Y_MIN_POS - 1)
#define Z_HOME_POS (203.0)

#define X_MAX_LENGTH (X_MAX_POS - X_MIN_POS)
#define Y_MAX_LENGTH (Y_MAX_POS - Y_MIN_POS)
#define Z_MAX_LENGTH (Z_MAX_POS - Z_MIN_POS)

It looks like I can set my Z-Home Position, maybe at th #define Z_HOME_POS (203.0)

I'll have to mess around with this, (with the heat-bed not installed) and see how it goes.

Is it possible for Slic3r/Pronterface to spit out the 3-axis movement of a test print without an extruder/etc all hooked up?

If I just want the printer to go through the motions for testing?

(I have to disable a wait for temperature command or something don't I?)

Edited 1 time(s). Last edit at 05/01/2013 01:59PM by ShadowRam.