After two months of unsuccessful prints on our nearly one-year-old Formlabs Fuse 1, I wanted to share my experience and continue documenting it in order to connect with other users facing similar issues.

Since mid-May 2023, we have been encountering significant problems with severely overbaked prints. This has reached a point where post-processing becomes either too challenging or even hazardous. All our prints have failed quality control or had to be aborted due to the powder within the entire build chamber overbaking, resulting in parts that are inaccessible. When we eventually manage to break apart the powder with great effort, the parts exhibit marks or cracks on their surfaces, and some even break in the process. Prior to this issue, we experienced smooth sailing with only a few minor glitches while printing the same types of parts for almost 10 months.

Our workspace is a self-contained room within a clean, clinical environment, maintained at a constant temperature with air conditioning and a dehumidifier. The powder refresh rate is set between 25-30%, and we have carefully sifted the powder, removing any impurities to ensure high-quality powder. Due to the curved nature of our parts, we average a packing density between 10-15%, rarely lower.

Despite engineers conducting recent tests and providing support at our facility, we have encountered more print failures and part replacements (heaters and quartz lamps), leading to circles of confusion in the diagnosis. These issues, coupled with the two months of downtime and the need to outsource to expensive third-party bureaus under urgent lead times, have incurred substantial costs. Another month of this situation and the expenses would exceed the price of a new 3D printer.

Regrettably, Formlabs analysts attributed our failures to packing at 2% density, which clearly indicates they did not thoroughly review our print history. The only instance we used 2% packing density was for a small part with minimal z-height, allowing the on-site engineer to quickly observe our problem. In contrast, Formlabs’ engineer stated that the recommended packing density is around 30%. Knowing this information from the beginning might have raised concerns, especially considering we sent our parts for sampling and viability checks before deciding to purchase the printer.

Most recently, as of last Friday (June 30th), we observed a slight improvement in the overbaking of PA12 by using 100% fresh powder and thoroughly purging the hopper of debris while reducing the temperature to -3 degrees. However, we now face a new issue of severe warping. Both Formlabs’ optics test and our own assessment resulted in failed parts. By addressing our original problem, we seem to have introduced another one. Moreover, lowering the temperature compromises the optimal strength of PA12, which raises concerns about future part failures.

The complimentary powder provided by Formlabs is insufficient given the significant time wasted dealing with these issues. Additionally, the strain on our printer shown by the browning of the quartz lamps accelerates the wear of a soon-to-be-out-of-warranty equipment. The absence of a backup support plan, such as a loan printer, adds to our frustration. We are reluctant to conclude that this technology has a lifespan of less than a year, but the release of the Fuse 1+ shortly after our purchase, with upgrades to most hardware, possibly supports this notion.

In summary, after a positive 10 months, the 2 months of failed printing is unacceptable and severely compromises the ability of our business to scale. We hope Formlabs sorts this matter once and for all and turns our gaze away from alternative SLS/MJF technology providers.

supporting article: LEADNAV Fuse 1 Down - She's DEAD - UPDATED! - #9 by LEADNAV


If your prints is “overbaked” as you call it then the softcap on the laser should trigger as it triggers at 40 degrees celsius. Our laser just gave up and the printer has been running extremly hard. Almost 24/7 for the past 15 months give or take holidays, weekends etc.

We have had to “so far” replace heater, quartztubes, optical cassettes etc and now the laser has to be replaced. Other than that it goes like clockwork. And we use Nylon 12 GF at a refreshrate 50%.

And just as @LEADNAV we have had trouble with the Fuse1+ aswell but the past 2 weeks the Fuse1+ is running like clockwork with 50% refreshrate. (knock on wood)

It took 6 months to get it running as intended but here we are finally.

How long it will run without issues remain.

Cheers and have a great summer.


As far as we can see, we’re also having thermal related problems with PA12 at the moment. After receiving a replacement build chamber, it looked like the gasket was leaking. While printing there appeared some ‘gaps’ in the powder bed. One time print was aborted by PrintWatcher.
Because there is not much powder below the BC in the printer, Formlabs thinks it is a thermal related problem.

Together with Formlabs support I am running some temperature finetuning prints at the moment. We tested at -2, -1, 0, +1 and +2 degrees Celsius. Latest information is that even -2 is too hot.
For your information; we’re running this tests on a one month old Fuse 1+ printer. MOTEMPBO Circuit board has been replaced in order to rule things out.

Since I am almost daily in contact with Formlabs support, I must say they are wel willing to help. The fact remains that al the testing has to be done on-site, which takes enormous amount of time. So I also become sometimes being frustrated about the policy and way of how to solve problems.

I use a core temperature gauge to measure the inside temperature of the cake, it alsmost doubles the temperature shown on the sift.
For parts that are sensitive to warping, I wait till the inner cake temperature is below 30 degrees Celcius. Takes me 24h longer but results are better.

I am thinking to add a part at the top of each print (like a lid) to avoid fast temperare drops at the cake top, and therefore warping.

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Thx for posting your findings, Much appreciated. I think i will have to try the same with a tempgauge when i get back from holiday.

Cheers and i´ll post here once i´ve tried it. I have had a sispicion that the temps are off.

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