Prusa INDX nozzles in early CORE One+ INDX kits were not the hardened steel parts buyers were told to expect, Bondtech has acknowledged. The company, which makes the INDX toolchanger system used with Prusa’s CORE One platform, says the shipped nozzles are nitrocarburized steel rather than true hardened steel.
Bondtech’s admission turns a small materials detail into a practical problem for users who bought the limited Founders Edition kits or early upgrade kits and planned to print abrasive filaments. A nozzle that survives ordinary PLA or PETG is not automatically suitable for carbon-fiber, glass-fiber, glow-in-the-dark, or metal-filled filament. Those materials chew through softer nozzles.
What nozzles shipped with the Prusa INDX kit?
According to Bondtech, the Founders Edition and first batches of the Prusa CORE One+ INDX Upgrade Kit shipped with nitrocarburized steel nozzles. Nitrocarburizing is a surface treatment that gives steel a harder outer layer, but Bondtech’s own batch testing put these nozzles at about 30 to 32 on the Rockwell C hardness scale.
That is harder than brass, which Bondtech says is below 10 HRC, but well short of hardened steel at roughly 55 to 60 HRC. In plain terms: the shipped nozzles are not junk, but they are not the hardened steel parts advertised for abrasive-material duty.
The discrepancy surfaced after a Reddit user posted what was described as a support email from Bondtech founder Martin Bondeus. In that message, Bondeus said Bondtech ran into production trouble when trying to machine the intended material because the cutting tools could not reliably handle the process. He said Bondtech supplied the nitrocarburized version for the time being rather than ship inconsistent parts.
Why abrasive filament is the problem
Bondtech says the nitrocarburized nozzles should work well for most users and most materials. The company also says they will wear faster when used with abrasive filaments. That distinction is the whole fight: buyers of a multi-tool upgrade kit may reasonably expect to print the exact messy composites that make a hardened nozzle useful in the first place.
The INDX system also uses a custom induction-heated nozzle, so owners cannot fix the issue by grabbing a standard third-party replacement. Bondtech says it does not yet have a “concrete solution” and that producing truly hardened INDX nozzles could take months.
Bondtech is asking customers not to return kits while it works on a fix and to use non-abrasive materials in the meantime. The company has not promised compensation, saying it first needs to understand the cost of replacement parts.
How buyers and Prusa are reacting
The timing is awkward for Founders Edition buyers, who received an upgrade kit that requires serious disassembly. Installing INDX means stripping down a CORE One, removing the Nextruder, fitting the INDX carriage, and mounting a rack for eight tool heads. Some early assembly pain was expected; a nozzle-material mismatch was not.
One buyer, identified by Tom’s Hardware as “Daddie0,” created Nozzlegate.com to document complaints about Bondtech’s handling of the issue. He told Tom’s Hardware that his own INDX kit had suffered mid-print crashes and layer shifts before a Prusa firmware update fixed those problems, and that the nozzle news arrived as his two-week EU return window was ending.
Tom’s Hardware reported that Prusa Research said it was surprised by the nozzle issue and planned to issue a formal statement. The INDX kit is a collaboration between Bondtech and Prusa, with the first Founders Edition run aimed at early adopters.
For now, Bondtech has confirmed the material mismatch, the replacement path is unresolved, and owners who bought the system for abrasive filament have the least satisfying option available in hardware: wait.
This story draws on original reporting from Tom's Hardware.
