Infosite about Kobra 2 Pro

Dear community,

as I was lucky and won a Kobra 2 Pro back in September at a giveaway in the sub 3Dprinting, I thought I'll make another infosite about this specific model to give something back to the community.

The site isn't 100% done yet, but I think it's already comprehensive enough to be announced now. I hope it'll be somewhat helpful for at least some of you.

This is the site about the Kobra 2 Pro: https://1coderookie.github.io/Kobra2ProInsights/

If you come across specific infos that are missing, specific mods or e.g. error messages and feel to contribute, just reach out in private using either dm, chat or email. Please don't us a PR at GitHub for that.

As the Kobra 2 Plus and Max are pretty much using the same hardware (up to a certain degree - of course not when it comes down to specific differencies like the bedplate, bedgantry, Y-motor etc), it's also kinda valid for these models (until a kind and reliable user feels to take the effort and provide me with the specific pics of e.g. the according K2Max pics.. ;) ).

If you find the site useful, please consider recommending it to other users to make the community become aware of it - also on different platforms (I personally don't use any other social media so I can't do so).
I don't make any money from the site, so there are no affiliate links, ads or whatsoever. If anybody feels to support my work and help me coping with the costs that occur (e.g. for getting specific parts for being able to provide specific pictures etc): you can do so by donating to my Ko-fi account - every bit helps ;)

I hope my work will help at least some of you.

Happy printing (and tinkering ;) )!

in anycubicby Catnippr

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6mo

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6mo

I don't have a Kobra 2 but I did have a Kobra Neo, and your other site was such an invaluable resource. I'm glad you're continuing with your 3d printing journey in this way, which helps so many people

OP

3

6mo

Thank you so much for your kind words!
I'm glad that my other site was helpful for you, that's the reason I put all that time and effort in this, instead of investing my time in learning how to properly design my own models (what I really need to do as well haha).. ;D

3

6mo

Very cool. Hope to see this grow.

OP

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6mo

Thanks :)

Btw, as for your problem you mentioned ~3 weeks ago ("But definitely can't use the right side of the bed or it's going to be under extruded!"): tram the x-gantry first of all.
Once you've done that, also check the timing belt.
Last but not least also check the height of the z-offset sensor and adjust it if necessary.
Hope it helps..

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6mo

Yeah, I've done all that. I mentioned it in the first comment of that post. Bed was warped. Awaiting a new one. Thanks anyway!

OP

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6mo

I've read that post, but did you actually really tram the gantry in relation to the bed? Like how I described it at the infosite? You need to dismount the anti-backlash nuts for taking off any screw-load of it, loosen those Y-shaped brackets of the gantry for being able to turn them in the correct position and actually tram the gantry and then you rest the gantry on two equal objects to tram it. If you didn't do that, it's most likely the case that the right side is slightly lower and therefore the underextrusion at the right side occurs due to the nozzle being too close to the bed.

2

6mo

Their support had me print a huge dog and didn't even ask to see it; I sent pictures anyway. They determined it was the bed. I mentioned my printer came with bad belts I could see copper through the sides of, they said it wasn't a problem. I stuck to printing on the middle of the bed. Then the Z axis belt snapped. I was wondering about the backlash nuts before all of that and intended to check them. I just didn't know how to open them. I checked to make sure the bearings were centered and everything I could do besides bust those loose and check them out.

I printed a mod that did absolutely nothing to tighten the upper belt so I tossed that. Right now I'm powerless, but I'll definitely be scouering that site when the parts come in. The bed screws felt like they stripped extremely easily so I was also worried that may be the case. Needless to say, I have a lot of investigating to do and I'll keep that in mind when the time comes.

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6mo

The X axis belt is GT-2 6mm, not 8mm.

OP

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6mo

Correct, the Y belt is 8mm. Do I have 8mm for X in there?!? Dammit, then I probably have the same mistake in there for the X pulleys then as I think I wrote that before I even had the machine on the desk..argh.. Thanks, will change it tomorrow asap!

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6mo

I've recently changed my belts so I can give you the lenghts too. X: 790 mm, Y: 770 mm. These are the belt values you need to cut for a good fit. I replaced my Y belt with a 10 mm wide one to have less horizontal play.

OP

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6mo

You're the (wo-)man! Thank you so much!
I assumed it would be the same length like at the Knobra Neo or Go for example, which is ~770mm, but I wouldn't have thought that the X belt is actually longer.
I think I also have the wrong dimensions for the pulleys in there, those aren't 16/5, it's more like 10/5 or even 9/5, so I need to check that as well.
I assume you had to take off the belt tensioners, right? Did you by any chance take pics of them when you had them disassembled..?

OP

1

6mo

Just for clarification: did you measure this between those crimped metal pieces?

1

6mo

Nope, since that's not really useful due the X axis requires a loop made from the belt on the ends.

OP

1

6mo

Right - I forgot about those loops at the X belt, just thought of the Y belt..
So then you measured the length between those crimps for Y and the total length including the crimped loops for X (like from loop-end to loop-end with flattened but still crimped loops, one way so to say - sorry, dunno how to express what I mean, non-native speaker here :( )?

1

6mo

It's okay, no the 770 mm would be the total belt lenght, the length between the crimps would be 750 mm.

OP

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6mo

Ok great, thx a lot! :)

1

6mo

Here is a picture of the original X belt, maybe this explains it better:
https://i.imgur.com/cDDOQAP.jpg

OP

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6mo

Aaaahh, so you really measure the whole belt length! I didn't do so when I measure the length for the Kobra Go/Neo, I measured the length between those crimped ends (and here I would've measured the length including the loops, but not taking the loop itself into account - hope it makes sense), as that's what I personally think is relevant - so it doesn't matter if one leaves like 1cm or only 0.5cm of the belt after the crimped part.
May I use that picture for the infosite then, so ppl can see how it's been measured?

Continue thread...

2

6mo

Wow, your website looks awesome. So many information. I just ordered the printer and was looking for something like this. Now, I'm overwhelmed with all of this. That's some great work you do. Thank you.

OP

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6mo

Thanks for your kind words! Yeah, it's quite a lot to read lol, but at least you have something interesting to read when it's getting dark&cold now, right? ;)
And now that you discovered it even before getting the printer, you'll start out well prepared! :D

SomeImagination9433

2

5mo

Thanks for the useful infos on your site

OP

2

5mo

Thanks :)

Zealousideal_Taro881

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5mo

Love it. Thank you so much.

OP

1

5mo

Thanks, glad you like it! :)

1

5mo

Curious, do you have any recommendations for support settings in Prusa? I've tried many different combinations and still can't get them to come out right. So I've been using other printers for models that rely on supports. Say, if I have a port in the center of my model, the spot where it is meant to "cut out" the port isn't visible and it seems as though it's all a single layer.

They're extremely difficult to remove and finally when I get what I can out, the overhangs still look really bad and you can spot witness marks.

OP

1

5mo

No, unfortunately I don't as I have no clue about support settings in general. :(
Generally speaking, my infosites are more about the hardware and not about slicer settings - there are other people and resources which are much better when it comes down to tweaking slicer settings to perfektion..

Actually, I have a stupid problem myself where I just can't get support to work, I'm always getting an error message (not even talking about the K2Pro..). I was able to get rid of it once, but as I usually try to avoid supports I totally forgot what I did back then and now I just can't figure out again what I have to do to make it work.. But as you're using supports, you may know the solution? Can I send you a screenshot of that message via chat? Maybe you know what I'm doing wrong and what setting I have to change?

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5mo

I can give it a look but I may be just as in the dark as you are. After my last comment, I installed their Prusa-hybrid slicer which lacked many options such as where to place the seam but ultimately by turning them off I was able to get a decent result on my current model.

I've gone through soo many threads here about supports that are always empty in the end. Even waiting months sometimes to check search results again. This is the last flas that I just can't seem to pin down.

By the way, thank you for your invaluable resource. I changed my X axis belt and noticed there was some residue on my bottom rod. I thought it was wearing on it but apparently I got lucky so far. Once I cleaned that a few times with a paper towel doused in alcohol, I applied some Super Lube and my prints have been coming out without under extruding in certain spots. It also helps they've updated the firmware to move in smaller increments now but the rod was definitely my main cause, I'm practically sure of now.

That's another thing I was wondering- rather than purchasing chrome coated rods where it chips away, if stainless steel might help out in this situation.

OP

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5mo

Great, thanks, I'll send you the screenshot in a sec via chat..

So your problem really is something Kobra2Pro-specific then, right? It's pretty weird as I'd expect that those support settings in the slicer shouldn't have anything to do with the printer model..
But I just remember that I came across an answer AC support gave someone in a German 3d printer forum where they listed the commands which aren't supported anymore as they were known to cause problems. I wanted to add that to the infosite but I forgot about it - I'll search for it and will post it in a minute once I found it. Maybe those support settings use a command from those and therefore you're having problems? So maybe check what all of those commands exactly mean () and if you can find them in the sliced gcode-file of that specific model which is causing you problems - at least that's how I'd try to investigate it further if I was you.
Or maybe ask in the Prusa forum..?

Thanks for your kind words - speaking of your x-axis belt, I think I have a mistake in there regarding the size of the pulleys, I need to check that again..

As for the wear&tear of those rods: yeah, that's why I really don't like those SG15 rails..
First of all, try to place the models at different spots of the bed instead of always placing them right at the center of the bed, just to avoid the repeating motion at the same spot(s) as much as you can.
Second, check the position - I think with these bearings it's even more crucial than with the POM wheels to find the perfect position.
As for the rods: I could imagine that regular stainless steel rods might be 'rougher' when no chrome plating is there - but that's just a guess, I don't know that much of these materials. I actually was wondering if softer brass rods might even be better, just cuz we'd have one component then which is actually 'meant' to wear off, but maybe plain stainless steel rods would be a better compromise. But as I said, unfortunately I don't know enough of the materials and I'd assume there's a reason manufacturers choose chrome plated parts. I guess it's cuz wear&tear should be reduced to a minimum - but then it still occurs. Kinda weird imho.. I personally think if I'd use it much more and would aim for the max speeds all the time, then I'd probably swap in regular linear rails..

OP

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5mo

Chatmessage sent.. ;)

OP

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5mo

So this is the convo with that German user and the AC support about the 'malicious' commands. They deactivated them in fw 2.3.9, but maybe anything in there is causing the issues with the supports for you? I didn't check the meaning of each command yet..
``` Many customers have reported that the G4 command will cause the printer to stop.

We skipped this command in firmware 2.39,

Version 2.3.5 does not skip this G4 command.

2.39：

Optimize the problem of printing pause caused by abnormal commands (delete M20, M21, M23-M30, M204, M130M131, M132, M301, M500, M573, G4

G29, M112, M211, M220, M222, M223 commands, modify the M900 setting range, adjust the M8xxx command reading method)

Kind regards, ```

1

5mo

I was reading on your site about rearranging them on the bed in certain spots and that is a good idea but I print a lot of the same models for sale so it's hard to go back and edit things to put onto my printer at times since I run my shop by myself and have to do everything myself. It typically takes me a while to change things up since I keep pretty busy with a thousand things at once.

I apologize for taking a while to get back to you. I've since popped on and commented on random things that haven't taken much thought and planned on coming back to this as I am now.

Yes, my problem is Kobra 2 Pro-specific. I have an Alfawise U20 and two Creality Minis that run Octoprint so I have full control over those models and supports come out great.

I wanted to mention, I jotted down the length of the X-axis belt and it came to 31 inches. It's a 2M6 and you can get 10M for $10 on Amazon. I thought that might be helpful for you to add to your page somewhere. I also used small zip ties in place of crimping and it has worked out great. I tried using a crimp tool I had around and totally mangled it. I only had copper buckles left, so I figured I should take a different approach for the time being, at least.

As for your chat, I'm sorry. I have chat blocked across my network so I don't get any of those messages. If you send it in a direct message I can view it, though!

As for your problem, you're probably way further ahead than I would be at figuring it out. As you know, specifics with each printer can go in a thousand different directions. I'm not even sure what you're running.

I was looking into these rails, not real sure what I should purchase for backup. I'm going to have to take some measurements. But since I didn't have to spin the one I have on it at the moment because the wear wasn't actually chewing into it I didn't get around to it.

Stainless Steel

Stainless Steel

Chrome Coated?

That's an interesting idea, I didn't think of the softness of the metals playing a roll. I'd like to get a spreadsheet together of all of the parts I can source so I can order them in bulk "packs" if need be, POM wheels being one of my main concerns. All of my other printers had rubber or whatever that material is. I guess these are called groove roller wheels. I guess you can tell I'm not too familiar with the terminology of the parts that make up the machines. Oddly enough, outside of the power supply, software is my main focus with these machines most of the time.

OP

1

5mo

Absolutely no problem about the 'delay'! :)

Deactivated chat: aaahh, that's why you didn't answer - I sent you a message there quite a while ago already and you never replied lol

Not sure if I can send an image using dm, but the error message says "supportmaterial_extrusion_width=0.2 mm is too low to be printable at a layer height 0.2mm". I'm using a 0.6mm nozzle with 0.2mm layer height - and I have no clue why that error even says "support_material_extrusionwidth=0.2" being a problem as I don't have set the width to 0.2 with my 0.6 nozzle anywhere..
I tried to change different settings as I didn't find that specific setting being mentioned in that error message, but nothing worked out so far. This is at one of my Neos btw, but the actual printer model shouldn't play a role here..

About rearranging models: ah ok, yes, that's quite unhandy then. I mean, you could upload different files of the same model with the models itself being placed on different locations then while naming the files _1, _2, _3 etc and then just printing them one after another, but sure, that's a bit unhandy as well.
Once Klipper will be available or you make the step and swap out the stock mobo for being able to use Klipper with a different mobo, then you could think about taking advantage of the Klipper feature exclude_objects - might come in handy for batch printing. Just for the back of your mind IF the time of Klipper comes.. ;)

Thanks for the belt length, somebody already reported it a while ago tho. So 31inch is about ~79cm/790mm, right (metric guy here haha)? That's what the other user reported and that's what I have listed in the specs section right now.

As for the AliEx links with the rails and wheels: those all don't fit. I think you'd need 6mm rods (and I'd get chromium plated ones again then), but I didn't measure them yet (same goes for the length). But as described you can always 'push' them out carefully, turn around a bit and put them back in in the first place until it's not possible anymore due to heavy wear&tear.
As for those wheels just search for "SG15" (u-groove), then it should come up with many results.
But: if I was you, means, printing a lot at high speeds with this machine and being 'dependant' on the flawless functionality, then I'd probably think about upgrading to true MGN linear rails tho.
As for the BOM/spreadsheet of spare parts and POM wheels and stuff in general (those 'rubber' wheels at your other printers should be POM wheels as well btw): feel free to reach out directly via email at any time - if I can somehow help you, I will. You can find my email address in the footer of each page of the infosite. That'll be much more comfortable for the both of us than writing here or via reddit's dm.. ;)

1

5mo

I found this thread about your issue in Prusa Slicer.

Exclude Region is a plugin I use often on my other printers and I miss it soo much. I may do some unconventional upgrades on this thing if they don't get their act together with it soon. That AnyCubic Slicer is just awful but it worked for that single print so I guess I'll keep it installed for a while just in case.

I need to jot down some notes on some of these things you said, for sure. SG15 (u-groove).

Alexa tells me that 31 inches is about 787mm for the belt length so the info you have seems to be correct!

My rods are fine at the moment so I have some time, but I'll have to pin it down eventually. Thanks for all of your help. I have your site pinned in my personal Discord server so I can easily find things so I'll keep in mind that your email is there.

OP

1

5mo

THANKS for doing a search about my problem!!
I came across that one as well tho and my problem is that everything set there is >0.6mm as that's my nozzle size. So just as an example: "default extrusion width" is 0.672 there and "support material" is 100% - so I have no clue why PS complains about 0.2 extrusion width and where it comes from.
I then thought it might have sth to do with some Arachne settings, but I checked that and "minimum perimeter width" is set to 85% - which would be 0.5712mm then - so again it's not even close to 0.2mm.
BUT: I just saw "perimeter transitioning filter margin" which is set to 25% - which then would be even smaller than 0.2mm..hmmm..dunno if that is the problem tho, as the the error message clearly states "0.2mm"..

Exclude region is a pluigin for OctoPrint iirc, right? So that would sth different than the Klipper feature I was talking about then.
Btw: ppl are trying to get a native Klipper running with the stock mobo (as that would be quite neat, so one could avoid swapping out the whole mobo then..), I'm keeping an eye on that. As soon as I come across a working solution, I'll add that info to the Klipper chapter at the infosite and most likely I'll do an infopost about that here at reddit as well then.

OP

1

5mo

Btw: you didn't by any chance disassemble the belt tensioner when replacing the X belt, checked the specs of that pulley and took pics of those inner parts..?
If not, no problem, then I'll have to do it once I'll find the time for it.. ;)

1

5mo

Oh, that's unfortunate you've already come across it. Perhaps comment on that thread and they can help you out. I have to admit, I'm just as lost as you are.

Exclude region is a pluigin for OctoPrint iirc, right? So that would sth different than the Klipper feature I was talking about then.

Btw: ppl are trying to get a native Klipper running with the stock mobo (as that would be quite neat, so one could avoid swapping out the whole mobo then..), I'm keeping an eye on that. As soon as I come across a working solution, I'll add that info to the Klipper chapter at the infosite and most likely I'll do an infopost about that here at reddit as well then.

Klipper would be awesome on this thing- ESPECIALLY not having to shell out more cash to get it running.

Btw: you didn't by any chance disassemble the belt tensioner when replacing the X belt, checked the specs of that pulley and took pics of those inner parts..?

Haha! That's funny because actually, I did take pictures and I was going to send them to you for your page! I noticed that you already had a photo of the right side so I only took pictures of the left. I'll email them over once I find where I put them.

Continue thread...

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