weird behavior when starting a print

Hi guys, was wondering if anyone could help. I'm using marlin firmware and the newest slic3r and the newest pronterface. After loading up g-code and pressing print, the axes go to home, the heater gets ready to correct temperature, the the z axis goes the wrong way and doesn't stop. I assume it's looking for a min end stop or something but I only have a max for z. Where would I begin to look for the problem? Thanks.

Have you ever printed with this machine before?

Have you changed the pin definition in pins.h to reflect you are using Z-max?

Have you changed the config to reflect you are using Z-max?

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

Hi, I have printed with this machine before with sprinter. In pin.h, I changed the pins on the Max to the same as min. In config, I got homing working by making adjustments to the z direction and homing. The only thing I'm not 100% sure about is if I changed the pins correctly. Thank you for all the great ideas so far.

You need to either set the homing direction or set the Z-Min pin to -1 so it won't home Z at all in the firmware.
Or in a pinch in the start GCode tab in Slic3r you can just remove the M28 which is the Home command, but you'll have to manually set the 0's before starting the print with G92.

I have made z min -1 in the firmware and got rid of the homing sequence for the print. It still heats up then goes the opposite direction. If I slice the file in slic3r .71 , I don't have the problem. Is there a setting I could try or should I just stick with the old version of slic3r? By the way, I just tried .84 and I still have the same problem. Thanks for the input.

If your firmware is setup correctly then the only thing it's doing is following the GCODE that slic3rproduced, can you post the first dozen lines of code or so, working and not working, since the error is at the start that shood be enough.

You aren't trying to use the 0.7.1 config with 0.8.x are you?
There are known incompatabilities.

Ok, here is the beginning of a file. Anything that might explain this weird behavior?

; generated by Slic3r 0.8.4 on 2012-06-24 at 23:11:56

; layer_height = 0.25
; perimeters = 3
; solid_layers = 3
; fill_density = 0.4
; nozzle_diameter = 0.4
; filament_diameter = 1.75
; extrusion_multiplier = 1
; perimeter_speed = 30
; infill_speed = 60
; travel_speed = 130
; scale = 1
; single wall width = 0.42mm

M104 S185 ; set temperature

M109 S185 ; wait for temperature to be reached
G90 ; use absolute coordinates
G21 ; set units to millimeters
G92 E0 ; reset extrusion distance
M82 ; use absolute distances for extrusion
G1 Z0.250 F7800.000
G1 X85.390 Y85.770

When you press Z +10 in Pronterface does the Z axis move up? After pressing +10 can you press -10 and have it go the opposite direction?

If it moves the wrong way and does not move the opposite direction when -10 is pressed it is because the endstop pullups need to be inverted.

If it moves the wrong way when you press +10 and the opposite way when you press -10 you need to invert the direction of the axis in the firmware (or unplug the motor and plug it in the opposite way around [with the power unplugged]).

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

No problem controlling axis in pronterface. Goes up and down when asked to. Also endstops work as well. I tried kisslicer to rule out problems with pronterface and it works without problems. I must be missing something simple.

What do you get if you type M114 after homing?

What happens if you then type G1 Z0.250 F7800.000 ?

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[www.hydraraptor.blogspot.com]

Hi, when I deleted line by line in the gcode, I noticed that this line G1 Z0.250 F7800.000 was the one that caused my print to go crazy. How do I get rid of it in settings or do I just manually edit the gcode? Thanks.

That is the move that lowers the nozzle to just above the bed so you can't get rid of it. The feed rate is crazy for Z but the firmware should cap it. Seems like a firmware bug or a firmware configuration problem.

Mine starts with G1 Z0.250 F9000.000, which is even faster but it doesn't cause a problem with Marlin as I have Z max feed rate capped to 4mm/s, which is only F240.

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[www.hydraraptor.blogspot.com]

Is it weird that this line causes my machine to move in the opposite direction? I don't mind the speed just the wrong direction. Everything homes in correctly and moves correctly. Where should I look to correct this error?

Where does it actually home to? I.e. do you home Z to the top or the bottom?

I repeat: "What do you get if you type M114 after homing? "

That tells you where it thinks it is, which might give a clue to why it goes the wrong way.

What happens if you type G1 Z0.250 F240?

Marlin seems to work for everybody else so it is more likely a configuration problem than a bug.

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[www.hydraraptor.blogspot.com]

I've got the same problem.
get X:0.00Y:0.00Z:0.00E:0.00 Count X:0.00Y:0.00Z:0.00 after typing M114
Typing G1 Z0.250 F240 nothing happens if the Z is homed. If not it moves to the homed position
Object was sliced using slic3r ver 0.8.5
Marlin v1.0 rc2
Ramps 1.4
ububntu 12.04