Fuse 1+ Global Melting

Support & Troubleshooting Fuse 1
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Printer Details: Fuse 1+ 30W, Nylon 12, 50% Refresh, Default Print Settings, -1.5°C Bed Temp Offset, 1900 hours, UPS

I’ve been dealing with global melting issues since early December, and unfortunately, it’s back again. I wanted to share my experience in case it’s helpful for anyone troubleshooting a similar problem.

12/18:
Overheating began fairly early in the print (around 6–8" before the last layer) and escalated from noticeable caking and pitting to full global melting. I ran a bed temp calibration afterward and applied a -1.5°C offset based on FL’s recommendation. I also started using 50% RR powder to address an orange peel effect I was seeing. That seemed to help for a bit, but some pitting and orange peel still persisted.

2/20:
After about 10 successful prints, the melting returned. This time I discovered a scorched quartz tube socket. I replaced the quartz tube frame and tubes, installed a new IR sensor o-ring, and gave everything a thorough cleaning. Once again, things seemed to be back on track.

3/28:
After nine more clean prints, the issue returned around layer 2300. I replaced the recoater motor, build chamber seals, and installed a new optical cassette. Despite all that, the next print melted again—right around the same layer. I then tried a shorter job (~600 layers), which turned out great. At this point, support sent over a new MT board, suspecting a contaminated or faulty pressure sensor. Unfortunately, that didn’t solve it either—the next print failed around layer 1500.

Notably, I haven’t had a print fail before layer 1500, so there’s at least some consistency.

Support has been incredibly helpful throughout, and I’m hopeful we’ve finally narrowed it down…

Possible Culprit: Damaged IR Sensor / Flow Body
After all the overheating, it’s likely that the IR sensor has sustained some permanent damage. The photo below shows the sensor after cleaning off significant laurolactam buildup from a failed print. The small scratches have been there since day one and didn’t seem to cause any issues initially, but at this point, I wouldn’t be surprised if the sensor’s condition has contributed to both the melting and possible wear on other components.

IR Sensor - After Cleaning
IR Sensor - After Cleaning1920×1619 144 KB

This may have been an obvious cause to some, but I hadn’t realized the sensor was in unacceptable condition. To be fair, support had seen photos of it in the past and didn’t flag it as a potential issue either. I’ll be replacing both the IR sensor and flow body this week and am hopeful I’ll be able to share some good news soon!

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Nice to hear that despite recurring errors, it is still possible to continue working with the printer.
In any case, it can’t hurt to replace the IR sensor once with the described errors.

We had to deal with bulges at a certain layer height over a period of time. While the support team initially suspected a temperature error, in the end it was the print bed that came from a faulty batch.
Just in case the problem persists, this might also be worth considering. (Although less likely, as this should not lead to global melting)

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It is great that small jobs can still be run, but it’s odd the global melting only occurs when a print is past ~1500 layers. Replacing the IR sensor definitely seems like a no-brainer.

I have noticed layer bulging getting progressively worse, so I will absolutely be looking into a print bed replacement down the line.

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The “lens” on the IR sensor appears to be germanium with some type of AR coating that is scratched on your sensor. I presume it is some sort of LWIR sensor, and my understanding is these sort of surface defects do not cause too much of a disruption in LWIR. Perhaps its the sensor itself that is faulty? Of course, its possible none of my assumptions are correct because I have no inside knowledge!

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That’s helpful—I didn’t know much about AR coatings or LWIR sensors, so I appreciate the info. I’ll be swapping out the flow body too, since it could be contributing to the issue.

I do wish there were more detailed resources from FL on how all the printer components work together—it would make troubleshooting a lot easier. Have you come across any good resources that go in-depth on how SLS printers function?

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I wonder of something is failing after a set time period of heat exposure. Its happening within a certain number of layers but is it perhaps more tightly correlated to print time? Just thinking out loud.

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I think you’re right that it relates more to the heat exposure than layer height. It doesn’t seem to be failing at a specific height (~2300 twice, ~1500 once). I have a feeling that once 1000+ layers have printed the amount of heat contained in the powder cake is contributing to the melting issue. Maybe the chamber heating is not properly accounting for the temperature measurements from the build chamber.

I am curious as to what the pressure measurements control in the heating process. I’m assuming they
relate to the air exhaust/intake system but I’m not certain. Do you know if the Fuse prints in a pressurized environment?

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I don’t know. Ultimately your best bet is with support, as they have all the data and experience troubleshooting many machines over time. You and I are just poking around in the dark, by comparison. I am interested in what ultimately resolves this issue.

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No doubt. Thankfully support has been amazing from start to finish—they’re the only ones with the experience to get this printer back in action.

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Hi @jmasterson, sorry you’re struggling with this. Thanks for sharing the play by play.

After talking it through with teammates, you likely need to clean your IR sensor and optical cassette. We’d be happy to troubleshoot with you directly by creating a ticket with our support team. This way the team can get your error codes and diagnostics, it’s harder to tell what’s going on with the build chambers.

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Hey @verdugod! Sorry if my post came across as unclear — I just wanted to share a bit of background. I’ve actually had a support ticket open since 3/31, and the team has been incredibly helpful the whole way through! They’ve been quick to order replacement parts right after each print issue, and communication has been great.

I mainly made the post to give others a bit of context in case they’re running into similar issues.

I’ve got a new IR sensor and flow body arriving soon, and I’m planning to start a test print this afternoon. Fingers crossed this gets the printer back in action!

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Out of curiosity, did you try to clean the window on the sensor with alconox? It sort of looks like laurolactam buildup which I think would come off with alconox. Laurolactam is probably not transparent in the LWIR band which is why formlabs is so insistent that the cone and sensor are cleaned so often. I clean mine before every print, unless the prior print is super short.

Does formlabs have anything to say about using alconox on the sensor window? I don’t recall.

Again, me shooting in the dark, just some thoughts.

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I gave that a try and the alconox did the trick—it cleared up the fogginess, which I’m also guessing was from laurolactam.

I’ve been cleaning the sensor after every print, and the cone every few prints. Lately though, since the cone is so easy to clean, I’ve just been doing it every time too.

I know FL recommends alconox for the optical cassette, but I don’t think they mention it specifically for the IR sensor.

Just finished swapping out the flow body—wasn’t too bad at all!

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Great news—I ran a full print job, and it just completed successfully! Looks like swapping out the IR sensor and/or flow body did the trick.

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