Print once at a time - Failure on UM3E

[dxp 21]

Hello,

 

printing "once at a time" seems tricky: the preview was perfect, but in the end, the last part (in the lower left) was cut in half. The cutting area was even closed with a nice wall! Pics are included as is the 3mf and gcode. The number of extruders was set to 1. I'm not asking for help, just for some hints of how to avoid that. (And yes, these prints are ugly, the TPU95A must be dried.)

There was a thread in 2016 with the "print once at a time" topic, now i'm calling for @nallath or @gr5 🙂 

The printer setting:

UM3E_pUFFER-5er-Gruppe.3mf UM3E_pUFFER-5er-Gruppe.zip

[nallath 1,079]

Well, the slicing preview looks fine. The one reason we could come up with how this happens is that you head couldn't move that far and it just squished the lines there, but that would mean you'd see a fair bit of over extrusion.

[dxp 21]

Well, actually i see no over extrusion... looks like a "healed" cut. The walls are only 2 perimeters by default (which is too thin). But there is no surplus material.

I will reprint the last position to see, if there is a mechanical collision. There is no way for Extruder 1 to reach the entire area of the model, the print is cutted.

After stopping the print, i raised the build plate and moved the head to the print. The head is 1mm away from the chassis. Nozzle 1 is still 1-2cm away from the sliced positions (red vertical line). The right nozzle could help... kidding. Maybe the bounding box is too small?

 

Edited August 2, 2019 by dxp
Reprinted and pictures added.

[nallath 1,079]

Wait, you're printing with the second extruder? I think we never actually tried to see what happens if you do that with one at a time printing...

[dxp 21]

Nope, i used the first/left extruder. In printer settings i set the number of extruders to 1, the remaining one was Extruder 1. (The last picture is irritating, because EX2 is down. I took the picture with a manually raised bed, and the UM was switching to EX2 for unknown reasons.)

 

Seems like the Ultimaker himself re-computed the gcode for printing a model in half 😀

[nallath 1,079]

23 hours ago, dxp said:

Seems like the Ultimaker himself re-computed the gcode for printing a model in half 😀

That would be interesting as there is no code on the machine that can do that. (Here is me hoping that it didnt' suddenly become sentient...)

[dxp 21]

Maybe the Ultimaker was just polite 🙂 There is really no unneccessary material. Just a sharp cut and a wall.

 

Just checked the gCode - all parts have a brim. But: the slide to simulate the buildup cutted all parts at the same time and ignored the once-at-a-time setting. Maybe just a render-thing in cura.

 

This is a render of the gCode with Repetier Host. It shows the correct printing order, but the used area is larger than 200mm... eeergh.

Edited August 6, 2019 by dxp
Repetier host added

[tinkergnome 918]

3 hours ago, nallath said:

That would be interesting as there is no code on the machine that can do that. (Here is me hoping that it didnt' suddenly become sentient...)

 

Actually there is code on the machine that can do that! 🙂

I don't have the Marlin sources of the UM3 at hand, but usually the so-called "software endstops" are enabled.

With other words - it's the normal behavior: the firmware of the motion controller limits all moves to specified boundaries (instead of ramming the printhead into the wall). All moves beyond the limits of the printer are clipped.

http://marlinfw.org/docs/gcode/M211.html

 

On 8/5/2019 at 9:47 AM, dxp said:

In printer settings i set the number of extruders to 1, the remaining one was Extruder 1.

 

@dxp if you do it this way, you have to reduce the maximum x coordinate to 215mm as well.

I guess the normal way is to simply disable the second extruder with the "official" checkbox in Cura. This should be enough to unlock the "once at a time" option (or does this not work?).

 

[dxp 21]

9 minutes ago, tinkergnome said:

All moves beyond the limits of the printer are clipped.

It does look exactly like that! Wow. Soft end stops, how cool is that!

 

10 minutes ago, tinkergnome said:

reduce the maximum x coordinate to 215mm

Oh, x (Width) was left at 233mm. And yes, i deactivated the second extruder AND set the printer to one extruder. Maybe that puzzled Cura.

So, I left x at 233, let the machine have 2 extruders (in printer settings) and deactivated the second extruder at the prepare panel/configurations. That way the option "Once-at-a-time" was available. Then i had to move the most right part 15mm to the left and everything was printable! 🙃

 

Reducing x would help too, I guess. But fiddling in printer settings back and forth is not my cup of tea.

Thank you very much for "tinkering it out", @tinkergnome. And thank you @nallath for your patience!

[tinkergnome 918]

7 hours ago, dxp said:

So, I left x at 233, let the machine have 2 extruders (in printer settings) and deactivated the second extruder at the prepare panel/configurations. That way the option "Once-at-a-time" was available. Then i had to move the most right part 15mm to the left and everything was printable!

 

Great, i assume that's the original / intended way to use this feature. You're welcome! And always stay upright! 🙂