J1/J1s Clogging Issues and New Hotend Kit Update

Dear Snapmaker J1/J1s users,

In response to valuable customer feedback and to address hotend clogging issues experienced by some users, we now offer a new type of Hardended/All-metal/0.4mm Hot Ends at Snapmaker official stores. After analyzing support tickets, user testing feedback (special thanks to Masta Bean, SnapSnap, Jeffrey, Vincent, Rob, Dylan, i3sven, Patrick), and survey results, here are the key findings:

  1. Causes of Clogging:
  • Inappropriate print settings. (Common issue: setting the retraction distance value too high)

  • False trigger of the “Failed to Load Filament” error.

  • Extruder drive gears are not aligned/Extruder drive gear set screw is loose.

  • The extruder is clogged.

  • The hot end is clogged.

  • The nozzle is clogged.

  1. Solutions:
  • Changing filament (e.g., the original filament may have absorbed moisture, and certain brands of silk filament may be prone to clogging).

  • Adjusting slicing profile settings (e.g., some filaments may require an increase in printing temperature or a moderate decrease in printing speed).

  • Adding a print cooling fan upgrade.

  • Adjusting the filament-loading structure (e.g., feeding filament from top to bottom, adding a PTFE guide).

  • Replacing the nozzle/heat break/hot end.

  1. Production Issues:
  • Metal debris inside the nozzle.

  • Improper cutting of the Teflon tube inside the hotend (either slanted or insufficient length, leading to gaps in the throat tube).

  • Thread leakage of thermal paste between the heat break and heat sink.

  1. User Innovations: Some users successfully resolved clogging issues by implementing advanced hotend modifications shared on the Snapmaker J1 forum.

  2. New Hotend Kit: We are pleased to introduce a new type of Hardended/All-metal/0.4mm Hot Ends today, with plans for individual left/right hotends and high-speed fan accessories set for release in the coming months (around April). For more information on the new hotend kit, visit:

  1. From January 31, 2024 to February 18, 2024, we surveyed to gather information on the hotend clogging status and specific situations for all J1/J1s users. We appreciate everyone’s active participation and are grateful for the valuable feedback received. The survey garnered a total of 1017 views, with 187 responses, indicating a feedback ratio of approximately 18% regarding hotend clogging issues. Based on the survey feedback, our technical support team will reach out to users who are experiencing challenging hotend clogging or abnormal clogging frequencies through support email, offering appropriate after-sales solutions.

  2. If purchased from distributors: Please contact distributors for assistance directly.

  3. While the standard hotend should suffice for most users, the new hotend kit aims to reduce clogging risks in scenarios like silk PLA and high-speed PLA printing. Users seeking an improved experience with these materials may consider upgrading to the latest hotend iteration:

  • Silk PLA - False clogging during printing.

  • PLA - Tower stringing.

  • PLA - High-temperature clogging (environment temperature around 35℃).

  • PLA - High-speed printing clogging.

Silk PLA: When printing with Silk PLA, we recommend using a printing speed of no more than 100mm/s. The nozzle temperature should be set at 220℃ or higher to minimize the risk of clogging and achieve a better silk-like texture on the printed surface.

  1. Additionally, here are the findings and insights regarding the new hotend:
  • The new hotend effectively reduces clogging frequency, particularly with silk PLA and high-speed printing PLA.

  • While the new hotend addresses certain clogging issues, it may not resolve specific problems caused by various factors. Users have found that adjusting variables such as filaments, slicing profiles, or adding a print cooling fan upgrade can help solve some clogging issues.

  • Some advanced users may not find the new hotend as exciting, especially those who prefer experimenting with the latest technologies like ceramic heating elements.

  • Drawback compared to the current hotend design: The integrated design of the new hotend does not support individual nozzle swapping.

Thank you to all users for your patient reading and active participation! Through your valuable feedback, we have gained in-depth insights into the challenges and needs related to the hotend of the J1/J1s machines. If you have any questions or feedback, feel free to leave a comment or contact our technical support team at any time.



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@Miles @rclarke @nnowak @Sukhvir @kilt_er @hthavana @neetyd @wudecao @splt7190 @hthavana @JohnDoe @i3sven @Mechanikus @Karass3D @3DPrintMunich @SnapSnap @nnowak @Rwide @wfux @evilC @n3dp @Belvis @StePhDen2020 @Kiwirob @Albert @naPS @Pautz @Jaeger @obertini @mehlawlarz @StePhDen2020

I saw discussions in the previous posts about issues related to hotend clogging. Now, we’ve made some updates. If you’re interested, feel free to take a look. Feel free to skip if not interested. Thanks a bunch!

Hi Zoe,

thanks for the information! It is good that Snapmaker finally offers a solution for the clogging issue that is also suitable for “mechanically handicapped” users :wink:

But since these hotends do not allow any disassembly by the user due to their press-fit design, I am however not interested in those. The old variant with its V6 head works perfectly fine here with the Copperhead heat break - and it lets me replace the nozzles just as I like which reduces waste and saves money.

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Gotta side with Mechanikus here. The specs look great but after seeing people here put together a v6 or revo compatible hotend, I’m not sure if a pressed in nozzle is really the upgrade we wanted.

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Very dissapointing…

I see Zoe has been trying to cauterise all the threads on this subject. Is everyone being offered vouchers to get a free replacement? Or is only happening under the table? Are the nozzles not replaceable on the new hot-ends?

@Boxkite In short: yes. Take a look at the picture in the post above, and Zoe also explicitly mentioned it:

“interference fit” is a nice wording for “parts are are mounted using a press-fit”. Unless you have the correct tooling (usually an arbor press and the correct custom adapters) you are likely not able to disassemble that thing without destroying it.

A press-fit is cheaper to manufacture and less time-consuming (i.e. again cheaper) in assembly than a screw seat. Since I never heard of a press-fit being significantly better in heat transfer than a screw seat with a suitable thermal paste, I personally suspect “cost reduction” and “intended sales increase” to be the real idea behind this… if you cannot use standard nozzles, you must buy a complete module if the nozzle of yours is broken or if you want another nozzle diameter.

I find this quite unacceptable. A $2 replacement now becomes an $80 replacement. And if you want to use a different size, that’ll be $99 thank you. And currently only available in pairs, so if you use one nozzle more than the other…

Indeed, see my post further above. IMHO anyone who has the means of doing it is better off with converting his existing hotends.

But the people who are not able to do this now at least have an alternative… better than nothing :face_with_diagonal_mouth:

Hi @Mechanikus @Boxkite,

Thanks for the feedback. As for the integrated design of the new hotend does not support individual nozzle swapping. This is determined by the design principle of the new hotend: the Heat Sink, Heat Break, Heater Block, and Nozzle are integrated into a single unit and assembled using an interference fit technique, minimizing filament oozing and heat resistance. In response to users’ concerns, we will subsequently release individual metal components for the hotend, allowing users who need it to replace specific parts.

@Mechanikus Hi Mechanikus, I understand your concerns. But from what I remember discussing with the engineers early on, the switch from a threaded connection to using the interference fit assembly technique was mainly to improve the consistency and quality control of our manufacturing process. For example, as Zoe mentioned above:

Update:
Additionally, our engineer shared insights into the performance differences between interference fit (press-fit) and threaded connection. Interference fit assemblies have no clearance, whereas threaded connections introduce clearance (filled with thermal grease for heat transfer, albeit with lower thermal conductivity compared to the metal itself).

This shift to interference fit is a new process for our team, which actually means more money and time investment.

I agree that this updated technique will bring about a change in user habits and replacement cost, such as not being able to replace individual components like nozzles/heat break. However, after considering various factors, we still lean towards adopting the interference fit new technique. In terms of after-sales support, on one hand, we will provide the hot end pure metal part as a spare part (approximately $24), and on the other hand, we will continue to offer the original version of the hot end with the threaded connection.

Once I learn more from the engineers, I will continue to post updates here.

3 Likes

Additionally, I’d like to share a bit more information about the performance differences. I believe that some users care about them.

When printing silk PLA, the new hotend allows for larger retraction distances, providing more flexibility in settings. Another key difference is in flow rate. There is an increase in flow rate with the new hotend, resulting in better layer adhesion and reduced chances of filament spreading.

However, we can understand that some advanced users may not find the new hotend as exciting, especially those who prefer experimenting with the latest technologies like ceramic heating elements and who do not like the integrated design and interference fit.

Retraction Distance
Here’s an example when printing silk PLA using 0.8mm and 2mm retraction distance:

Flow Rate
Here’s an example using Sunlu PLA as test material, the original hotend maxed out at 16mm^3/s with a max speed of 200mm/s, leading to average layer adhesion. On the other hand, the new hotend can handle 20mm^3/s with a max speed of 250mm/s, resulting in better layer adhesion and less chance of layers separating.

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Thanks a lot @Jade !

One can indeed easily see that the new hotend solves one of the main issues the old hotend had - it has a longer heat block which does strongly suggest that the too short melting zone of the old design is much better here. Therefore a better flow rate is to be expected - and it is nice that you have confirmed this. :slight_smile:

However, the picture of the threaded connection you shared is little weird and seems much more like “claim-supporting marketing” than reality. The overall shape and material-to-gap ratio of a metric ISO M6 thread does not look like this at all - and the standard thread gap can be further reduced by using a tighter thread tolerance pairing, e.g. an M6-4h thread for the heat break instead if a standard M6-6g.
Additionally, the surface roughness of machined metal was ignored as well. Unless you polish both sides of the press-fit to mirror-finish, this surface roughness and the microscopic air gaps it causes between surfaces that seemingly are in direct contact is the main responsibility for thermal resistance between two adjacent parts.

In case anyone is interested: here is a nice document of a thermal compound manufacturer which nicely shows some more realistic impressions on its first couple of pages: https://www.techpowerup.com/forums/attachments/semikron_application-note_thermal_paste_application-pdf.234191/

Therefore, I stay convinced that the press-fit does not offer any significant advantage in thermal conductivity in this case over a correctly chosen (length and thread tolerance) metric thread with suitable thermal paste, at least unless you invest an awful amount of work/money into surface quality :wink:

Edit: but you are right, the press-fit design will probably yield a more consistent output - since you still mention the old " not enough thermal paste" issue, it seems you did indeed have a very bad time explaining to your workers what “sufficient amount of thermal paste” means… having issues with this so long after production start would probably have made me consider a press-fit was well, unless I wanted to let the users assemble the hotend on their own - which does not fit to what you want to achieve with the J1.
(2nd edit: I just got a pair of new hotends since I took the chance of them having a special price to buy one set of spares - and indeed, there is still next to no thermal paste where there ought to be a decent amount - after more than one year of production :face_with_diagonal_mouth:. Seems to support my theory of a 100% improvement-resistant personnel at the assembly line…)

The only thing I absolutely fail to understand however is why you do not replace that unlucky titanium heat break on the existing design with a copper-stainless-copper bimetal heatbreak. There are so many manufacturers in China that offer this, they surely could make you a 100% compatible replacement… together with a real V6 nozzle to ensure a sufficient melting area the old design would perform almost as good as the new.

2 Likes

Hello, as hundreds of users have already received the new hotends, we are interested in collecting feedback on the J1/J1s new hotends from these users. We’ve sent out an email to users who have received the new hotends in mid-May, but some recipients may have missed it. To ensure we gather ample feedback from users who have utilized the new hotends for a while, we are sharing the survey link here. Your input is highly valuable to us, and we truly appreciate your sincere feedback. Kindly click on the link Product Feedback - J1/J1s New Hotend to fill out the survey and share your experience with the new hotends .

If you have already submitted the survey, please disregard this message.

Welcome to participate in the discussion by following this thread:

My hotend is still on its way but i will give feedback. The only problem i had was with PLA white or rock white/marmor. ABS works fine.

I did fill out the survey. Printed around 1-2000 filament swaps with the filament it didnt like and clogged before (white PLA).
No more clogging. Printed 2 Frogs with 0.2mm and 0.12mm layer height and a couple other parts. Everything looks fine now.
0.4mm retraction and 1mm for filament swap.

I printed the big frogs here:
https://www.printables.com/de/model/469379-multi-color-tree-frog/comments

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