Rostock V2 losing layers?

[peterk]

I don't know what is happening with my Rostock Max V2. Very reliable machine. For a large project I have been printing various smaller (1-3 hour) prints. These are fairly simple pieces with 90% infill. My Rostock prints from a Raspi/Octoprint setup, works great - especially since I can see on my computer in the office what's happening in the workshop.

This is what the model looks like:

mount_fasteners-B.jpg (7.28 KiB) Viewed 8061 times

Over the past week I have, without hiccups, printed all the other little parts successfully. But this one always gets stuck. I have 5 misprints like this:

The print seems to lose a layer (it seems always at the same layer) and I end up with this:

The print gets "weird" and then the filament doesn't have anything to attach to and it starts attaching itself to the nozzle.

I am not sure where to continue trouble shooting.

So far I have:
1) used MatterControl and Repetier Host to make gcode, trying various layer heights.
2) since it's around 60F in my workshop I tried raising bed temperature from 80F to 85F. Maybe the filament gets cold too quick, hence the curling.
3) verified the filament diameter
4) checked the gcode file layer-by-layer in Mattercontrol if there is any strangeness - but no.
5) gcode created in Repetier Host prints about twice as fast as Mattercontrol. gcode files created by either software have always worked fine on this printer (only issue is that Repetier Host doesn't like flawed STL files)

so, could it be:
- filament feed is somewhat unreliable? Maybe retraction? After these misprints filament feed works fine when doing a test extrusion.
- filament itself? I have yet to try a different spool
- does the EZStruder need help? I tightened all externally accessible screws.
- are there other issues that could hinder easy filament feed?

The really strange thing is that all other parts printed fine. After I had the first misprint with this part I successfully printed two others and then (assuming that everything was fine) printed the "bad" part with the same spaghetti result.

Yikes, this part is small enough that my Cupcake could do it.......

[rootboy]

Could you post your .stl file please? And any idea as to which layer you are having trouble on?

[peterk]

Attached is the STL file.

As I mentioned, I checked the gcode in Mattercontrol preview and can't see anything strange.
I wonder if there is some combination of feeding and retraction at a particular spot in the print that leads to the filament to get stuck.
I'll also recalibrate and check/update firmware on the Rostock. Maybe print under computer control rather than from Octoprint. Take the extruder apart and clean and make sure the threaded wheel is screwed on tight.

Don't really know.

[rootboy]

It's worth checking out. Try either scaling the part somewhat, or better yet, moving it to a different spot on your bed and print it there.

[peterk]

I think I forgot to mention that I did try to rotate the part on its side. Freaky things happen and the regularity of the breakup may just be coincidence.
My best guess is that the threaded wheel is a tiny bit lose and upon switching from extrusion to retraction and back may just drop enough filament to ruin the print.

[rootboy]

I've got a Max V2, and I had nothing but trouble out of my EZStruder. But mine never did work correctly from day one, and in your case it sounds like it has been working fine up to now. So go ahead and check for tightness. And possibly bump up the current for your stepper in your .config file.

This is what I did for my extruder:

http://forum.seemecnc.com/viewtopic.php ... 23#p106843

[peterk]

I think my V2 is 3 or 4 years old and except for a power upgrade for the heated bed in the form of relayed power directly from the power supply it's stock. Never had a problem.

And now....

I took off the transparent plastic cover today and checked if the scroll wheel was tight on the stepper axle. It is. No wiggle. Left the extruder open and just printed the part that has been giving me so much trouble. It printed out perfectly and I should be overjoyed but I still hate stuff like that.

The only significant differences to the 5 failed prints of the same part:
- it was a balmy day today (70F+ in my shop, last week it was kicking around 60F)
- I re-sliced the part after positioning it slightly off center

[rootboy]

That's interesting. I did a bit of research on your problem and there were a few folks who reported that taking the cover off of the EZStruder seemed to help.

But in any case I know the feeling of finally getting past a print that's being a problem child. Feels great!

[peterk]

We'll see how this develops after the cover is back on - even though I can't see how the cover would interfere.
I am glad that it works again but would have really liked to know what caused it.
Until the next one...

[geneb]

It sounds to me like a slicing error - especially if you got a go print after moving it and re-slicing.

g.

[peterk]

I don't know slicing error. I sliced the part at various layer heights in Mattercontrol and Repetier Host standing upright and lying on its side. Eventually it will pop up again and maybe I can figure it out.

[geneb]

Try using Cura. You won't be sorry.

g.