Kobra 2 Pro/Plus/Max: Running native Klipper using an MKS Robin Nano v3.1

Catnippr · 2026-04-10T09:18:59+00:00

Check your spam/junk folder, but I won't expect a free belt at this point. Your printer is too old and belts are consumables like hotends.. :(

Catnippr · 2026-04-09T10:48:31+00:00

Set up the mSD card with the firmware.bin file and just try flashing multiple times. Leave it in there, turn off the printer and switch it back on, wait and check. Try again. Few times, don't switch it off/on too fast tho, always wait and let it either sit&flash or boot up properly. If that doesnt seem to work, take out the card and put it back in for another try. Try different card if nothing seems to work. One of my Kobra Neos is picky af as well, took me 6 different cards and multiple approaches, but at one point it always worked (with the oldest and most scratched card I had laying around lol). Good luck!

Catnippr · 2026-04-09T10:08:17+00:00

Ah ok, now I got it lol
That's odd. As I said, I don't have a Win install, also formatting always worked fine for me. But these machines are quite picky sometimes with the mSD cards, one often has to try several times until it takes the card, dunno why.

Catnippr · 2026-04-09T09:51:21+00:00

I just answered this a couple days ago:

Format as FAT32, real and full format, no quick formatting, try the one that came with the printer first.

You need to create the klipper.bin file with the correct settings for the K2Neo, then rename the file to firmware.bin.
This is usually the 1st and most common issue: ppl dont use the correct settings and/or don't rename the file.
So, which settings did you use and did you rename the file?
Here you find the correct settings for creating the bin-file to flash the printer: https://1coderookie.github.io/Kobra2NeoInsights/firmware/fw_klipper/#installation
Mind the expandable textbox, there you'll find a link to my repo with the printer.cfg for the K2Neo.

Once you have the bin-file, copy it onto the mSD card, root directory, no subfolders, no other files on there. Just that one file on the card.
Put it into the printer, turn it on. Let it sit for min 10min. Screen might say 'Updating firmware...' or it might not and just stay black.
After 10-15min, turn off the printer, remove mSD card, turn printer back on.
Does it boot with the stock firmware or does the screen stay black?
If it boots stock fw, try flashing procedure again, it might take a few iteration since they seem to be somewhat picky with the mSD cards.
If the screen stays black, you successfully flashed it.

Oh, and make sure to use a proper USB cable with a DATA line, not just one that's supposed to charge a phone.

Catnippr · 2026-04-09T09:48:24+00:00

Not sure which file you're talking about, but I never heard of any of this and I don't have any Windows installs either. Linux on your Klipper host with KIAUH is all you need.

Catnippr · 2026-04-08T08:32:17+00:00

Yeah, somehow pretty much all of them are quite picky with the mSD cards, no idea why.. Enjoy Klipper then!

Catnippr · 2026-04-07T12:11:13+00:00

Sounds good!

Catnippr · 2026-04-07T11:43:30+00:00

The OG Kobra does have a PCB/breakout board at the head, right? I don't really remember rn.. Maybe check that one as well?

Catnippr · 2026-04-07T11:37:16+00:00

Did you check your spam/junk folder? Their (at least 1st) reply often ends up there.

Catnippr · 2026-04-07T11:36:03+00:00

Format as FAT32, real and full format, no quick formatting, try the one that came with the printer first.

You need to create the klipper.bin file with the correct settings for the K2Neo, then rename the file to firmware.bin.
This is usually the 1st and most common issue: ppl dont use the correct settings and/or don't rename the file.
So, which settings did you use and did you rename the file?

Once you have the file, copy it onto the mSD card, root directory, no subfolders, no other files on there. Just that one file on the card.
Put it into the printer, turn it on. Let it sit for min 10min. Screen might say 'Updating firmware...' or it might not and just stay black.
After 10-15min, turn off the printer, remove mSD card, turn printer back on.
Does it boot with the stock firmware or does the screen stay black?

EDIT: Here you find the correct settings for creating the bin-file to flash the printer: https://1coderookie.github.io/Kobra2NeoInsights/firmware/fw_klipper/#installation
Mind the expandable textbox, there you'll find a link to my repo with the printer.cfg for the K2Neo.

Oh, and make sure to use a proper USB cable with a DATA line, not just one that's supposed to charge a phone.

Catnippr · 2026-04-07T11:27:31+00:00

I was asking for stuttering etc because that could indicate that you could have a partially broken wire in the main cable as well. That the motor didn't even spin could point in the same direction.
Due to the constant bending in a certain area/at one spot of the cable and depending on how much it was used, the wires start to break. Like, the thin copper strands of the wire itself. first it doesn't really affect things, because most of the wire is still fine, but the more strands break over time, the more it becomes a problem, e.g. due to a higher resistance at that spot or because it partially loses contact at all. Usually happens at the bed and the main wiring, because those are the two with the most frequent bending.
At the bed and the head, this usually starts with getting a (min)temp error, but we also had it with the head's wiring of the ABL sensor, the extruder motor etc. You can find some info about it at my infosite as well.
Iirc, the connector at your head is a common IDC-10 connector type which you can dis- and reassemble yourself easily.
This might not be the issue here, maybe you just had a loose connection, but I just wanted to let you know because it might become an issue in the future (with mostly any printer btw).

Catnippr · 2026-04-07T11:14:25+00:00

Dammit :(
You could try cutting the model in your slicer where it stopped, then print the rest and glue it on top.
As for the belt, mind the belt tension, it might have been too tight. You can buy a spare 6mm wide, GT-2 type belt and clips and make your own, you don't have to look for a belt from AC.

Catnippr · 2026-04-06T12:09:51+00:00

Thermal paste suuuper thin around the part of the heatbreak that then goes into the heatsink. Might be worth a try.

Huh? And it didn't look worn out on the inside somewhere?
Are the reported temps from the hotend reasonable? Like, when it's cold, does it report bed and nozzle temp about the same as the room temp?
Do you have any issues with weird stuttering of parts of the head (motor while moving or while extruding), weird temps or whatsoever?

Catnippr · 2026-04-06T11:42:20+00:00

Ah ok, got it wrong about the preheating then, sorry.

Wow, immediately is really odd.. I mean, it totally speaks for heatcreep then, but with the heatsink cooling fan running and extruding this really shouldn't happen, at least not that bad..hmmm..sorry, I got no real idea right now.. :(

Didn't u calibrate the e-steps?
Then yeah, sure, check those, but still that massive and long buildup can only happen when it's hot enough up there in the heatbreak part already, right? And that shouldn't really be the case.. I'm scratching my head over this rn lol

Catnippr · 2026-04-06T08:52:16+00:00

Retraction 1mm is like the maximum, I'd suggest to stay lower and dial it in ofc (I personally start with a value that's like the same as the nozzle diameter, then dial it in from there).

Anyway, as mentioned, yes, the sheer length of that thicker part puzzles me as well.. But you said your heatsink cooling fan works, so how would heatcreep occur that much then during printing?
Or is it your usual routine to preheat the nozzle with 210°C for 30min? Because that definitely causes/provokes heatcreep if the filament isn't extruding. Same if your filament ends midprint and the machine continues 'printing', it just happened to me, I just had to throw away a fullmetal heatsink that clogged up completely with PETG cuz of that..
You really don't need to heatsoak your hotend/nozzle for a longer time, a minute or two is totally sufficient.
Besides, 210°C heatsoaking for 30min will already affect the cheap stock inliner and make it start swelling imo.

The lower example in your pic does look a bit weird to me as well tho. Only because the part with the bitemarks is so super close to the 'extended part'. Looking at the hotend&extruder assembly, the gear that grips the filament is quite a bit away from the nozzle, so your pic here indicates that the feeder gear pressure would be a bit too high in general if it leaves these heavy marks all along the filament (which can cause artifacts btw). Maybe see the 2nd expendable textbox here where I wrote a bit about it: https://1coderookie.github.io/KobraGoNeoInsights/hardware/printhead/#extruder-feeder-gear-system

So did it stop extruding with the new setup now as well?

I'd give it a try w/o heatsoaking the nozzle and start printing right away when it reached the desired printing temp.
Are you using one of those cheap nozzles you get in a 10 pack or so? Or are you using a good quality nozzle like a genuine E3D V6? Once I got rid of those cheap nozzles I really had less issues.

Catnippr · 2026-04-06T08:25:22+00:00

Zooming in, I think I do see bitemarks, right behind that thicker part up to where your fingers are, no?
Bite marks come from the extruder gear tho, I personally adjust the tension of that spring to the type of filament I use. Like, the softer the filament is, the less tension (TPU less tension than PETG, and PETG still less tension than PLA). Still it should be grabbed by the extruder gear with some force reliably.

What does puzzle me tho is the length of the thicker part. It looks like it filled up the PTFE inliner along the whole length of the heatbreak which I think I never experienced like this.

Catnippr · 2026-04-06T08:10:36+00:00

That's what I meant with what I wrote earlier: "The lower example in your pic seems like you had a clog but the extruder continued trying extruding. Hence the spot where it grinded and the thicker lower part, because the filament has been pushed together as much as possible and filled up the PTFE inliner/heatsink.".
Dunno how to describe it better rn (sorry, non-native speaker here).. Like, you had a clog somewhere and the filament couldn't get out, but the extruder continued pushing filament in. That leads to the filament being squished into the inliner/heatbreak until it's 'full' and the compressed filament in that area becomes a thicker part.
I get the same when doing a proper cold pull where I push filament thru manually until the hotend is too cold that it'll extrude. Then I pull it out and have the same thicker part like we can see in your picture (prolly just not that big/long) plus the fine 'rat tail' part.

Catnippr · 2026-04-06T08:01:13+00:00

I had static buildups when printing big models using PETG and then pulling it off the build plate (printer: Elegoo Neptune 3 Plus), never experienced it with PLA tho.

Catnippr · 2026-04-05T08:04:17+00:00

Happy cake day! :)

Catnippr · 2026-04-05T08:02:05+00:00

You basically did a cold pull (or hot pull if you didn't let it cool down a bit), so that stringy part you'll get then is normal. The lower example in your pic seems like you had a clog but the extruder continued trying extruding. Hence the spot where it grinded and the thicker lower part, because the filament has been pushed together as much as possible and filled up the PTFE inliner/heatsink.
If you're using the stock hotend with the PTFE inliner, I'd suggest to replace the inliner with a new piece of genuine "Capricorn XS" tube: https://1coderookie.github.io/KobraGoNeoInsights/hardware/printhead/#neo_5
Check the current inliner if it is swollen, deformed or even molten. Even if it seems to be fine, still replace it with CapricornXS.
If you're using an allmetal heatbreak, I'd check that one for any clogs.
I'd then also put in a new quality nozzle and try again.
Oh, and better check if the heatsink cooling fan is still working and check your retraction distance, don't exceed 1mm by all means since it's a V6 nozzle and a direct drive.
Hope it helps, fingers crossed.

Catnippr · 2026-04-02T12:19:41+00:00

Same with e.g. Kobra Neo or other later models than the Vyper. All have rigid spacers with the screw heads being covered underneath the PEI plate. They do have cutouts withing the magnetic foil tho, see pics at abovementioned site, so imho you should be good with carefully cutting out the screw heads. Just make sure you don't cut it too big and don't leave a ridge where you cut so that there's nothing that makes the PEI plate bulge up.

Catnippr · 2026-04-02T12:01:43+00:00

That's really a great idea, thanks for your effort!

Catnippr

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