Various problems with Kossel Mini

Hi Everybody,

some time has passed since I finished building my Kossel Mini (according to the BOM of builda3dprinter.eu). I'm using a Rumba Board with DRV 8825 stepper driver an 1/32 microsteps. Everything works fine, except of two things:

I can't Autolevel my Kossel Mini. I kept the Firmware nearly the same as written in [www.builda3dprinter.eu]. I only updated the rod length, default steps per axis and defined the the Board to 80 (Rumba Board). I deactivated the min X and Y endstops. In my opinion the the autolevel probing g29 should work fine, but after deploying the probe it tries to probe nearly 100mm above the surface and going up the z axis per every step: [www.youtube.com] (retracting the probe works fine). Before I start Autoleveling I'm homing all positions with G28. The Endstops working fine:

x_max: TRIGGERED
y_max: TRIGGERED
z_min: TRIGGERED
z_max: TRIGGERED

And this with an active probe:

x_max: TRIGGERED
y_max: TRIGGERED
z_min: open
z_max: TRIGGERED

I've written the following values in the pins.h

#define X_STEP_PIN 17
#define X_DIR_PIN 16
#define X_ENABLE_PIN 48
#define X_MIN_PIN -1
#define X_MAX_PIN 36

#define Y_STEP_PIN 54
#define Y_DIR_PIN 47
#define Y_ENABLE_PIN 55
#define Y_MIN_PIN -1
#define Y_MAX_PIN 34

The second issue is the printing of large items:

Every small prints are working fine (even without autoleveling) e.g. the easter bunny, the Makerbot bot or the frog, but when I start larger prints like a vase, it kills the print after a few layers. The extruder can't extrude any further material and last night the printer kept 2-3mm above the surface, but the printhost has shown layer 250+.

I've tried several programs, Cura, Kisslicer, Slic3r, pronterface + Printhost. The Hotend is cooled by a fan, might it be possible that it's a little bit underpowered? It's a 40x40x10mm 12V Noiseless fan with only 3800upm. (http://www.amazon.de/Noiseblocker-BlackSilentFan-XM2-L%C3%BCfter-40x40x10/dp/B002DFZQBI/ref=sr_1_4?ie=UTF8&qid=1393325442&sr=8-4&keywords=40x40+12v+fan)

The Fan will be activated after Layer 1 and starts with 60% and going up to 100% in 5% steps every layer.

Does anyone can help me solving these issues?

P.S. sorry for my bad english

I guess it's a problem with the probing-switch. Check if the triggered / open - states are correct. IIRC, the endstop should be triggered when the probe is deployed, and open when it hits the ground (and open when the probe isn't deployed of course). Or maybe it's the other way around. I remember having the same problem, when the endstop was inverted.

I ran into this issue with a Kossel-derivative that I built some time ago. Two things were causing the problem:

1. The endtop logic for the probe was inverted from what it was supposed to be. So the probe thought it had hit the bed right after it had deployed, and then would only move in the +Z direction.
2. The distance that the probe will descend from Z max (home) position before attempting to probe is hard-coded in Marlin. If your printer is taller than the printer that Johann had written the auto-leveling code for, you may need to increase this value. Scratch that, this has been changed. The probe will now try to descend to Z = -20 after the auto-deploy, which should occur at Z = 50. If your probe deploy is happening higher than this then there is something else weird happening. I would assume that your Z home offset is correct if you can print properly without using auto-level, so I'm not sure where the issue would lie.

The first thing is to get your endstop inversion correct, after which we can see if other problems still exist.

Quote
Xhnnas
but when I start larger prints like a vase, it kills the print after a few layers. The extruder can't extrude any further material and last night the printer kept 2-3mm above the surface, but the printhost has shown layer 250+.

What do you mean it kills the print? Does the extruder jam up, does it strip the filament, or does it simply stop trying to extrude? Does your host program show any errors?

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By coincidence I have just posted with the exact same issue - mid air probing.

My probe is set up so that when the probe is deployed ie below the extruder M119 reports open. When the bed is hit M119 reports triggered. I assumed this was correct. Maybe not.

If anyone has the definitive answer I would be grateful. Btw the probe switch is wired Normally open so it's closed when the probe is deployed. It's connected to the Z min input on my Rumba (another coincidence ?)

Andy

Mine probes beautifully, but I am using RAMPS 1.4. My problems start after that (another post).

Len, how is your switched wired and configured

Andy

So, one year later, Xhnnas, you're still having that issue? Or you forgot to post how you solved it? ;-)