Concerns are being raised within the 3D printing community regarding the Bambu Lab A1 after a recent video by YouTuber Grant Posner (3D Musketeers) revealed a possible safety issue. Posner has seen an alarming number of A1 printers with charred or melted cases, which suggests that the A1’s AC power distribution board may be operating above normal temperatures, posing a risk of fire. The AC power board uses an NTC thermistor to limit inrush current and is active only while the printer is rapidly warming up. Posner claims this thermistor is being pushed too close to its rated limits.
Posner hosts the popular Print Fix Friday series on YouTube , where he analyzes 3D printing fails and offers practical advice. He told Tom’s Hardware that he has operated his Tampa, Florida-based business for 15 years, offering 3D prototyping, scanning, manufacturing, and printer repair services.
Several subreddits are echoing Posner’s concerns. One user on r/BambuLab reported “my A1 melted” with a photo of a small bulge on the printer's bottom near the NTC thermistor, while another showed a puddle forming on the top of an A1’s case . Meanwhile, Redditors on another thread suggest that Posner simply has an ax to grind with Bambu. A quick check of the 3D Musketeers channel reveals dozens of videos critical of the company.
During a recent 3D Musketeers livestream, Posner examined an A1 printer with a thermal camera and clocked the NTC thermistor at 140° C, which he said was unacceptable for an electronic component.
(Image credit: YouTube video 3D Musketeers)
After doing further research, Posner found out that the NTC thermistor is rated for 200C. He said the real problem is whether the surrounding components and the case itself can also withstand these elevated spikes in temperature that occur while the machine is heating up.
“While the component in question is rated for the temps we have directly measured,” Posner said, “it is clear there are some issues with part quality, consistency, or local power that are causing machines to catastrophically fail.”
Bambu Lab Responds to Allegations
We reached out to Bambu Lab for a statement on the melting A1 printers. A representative was quick to acknowledge the issue, but insisted that failure rates were extremely low (around .052%), directly connected to preventable power surges, and were fixed in Q3 of 2025 when the NTC was removed and the board redesigned. All customers who reported problems with the power board were provided with repairs or replacements.
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