Prusa CORE One INDX Kits Stalled by Nozzlegate Over Soft Steel Nozzles

The Prusa CORE One INDX upgrade has hit a serious snag before most users even got their hands on it. Bondtech, which co-developed the eight-tool-changer INDX system with Prusa Research, confirmed that the nozzles shipping in the limited Founders Edition run are nitrocarburized steel rather than the fully hardened steel originally promised.

That matters because hardened steel nozzles are supposed to survive abrasive filaments like carbon fiber, glow-in-the-dark, and metal-filled plastics without wearing down. The nitrocarburized nozzles Bondtech actually shipped measure around 30 to 32 on the Rockwell C scale. True hardened steel typically sits at 55 to 60, while standard brass nozzles fall below 10. For everyday PLA and PETG, the difference is unnoticeable. Once you start running abrasives, the coating begins to fail fast.

Prusa Research issued a statement on Reddit and by email to INDX pre-order customers, saying the company had decided to hold off shipping conversion kits until the nozzle situation is resolved. INDX kits will now ship in mid-August at the earliest, and Prusa says it will include unspecified extra hardware for free as compensation. Customers who do not want to wait can cancel their orders.

The problem surfaced after a Reddit user shared a support email from Bondtech founder Martin Bondeus. In that email, Bondeus explained that production machining challenges prevented the company from reliably cutting the originally specified hardened steel. Instead of releasing an inconsistent product, Bondtech chose to supply the nitrocarburized version temporarily.

Testing by Prusa engineers showed the nozzles handle up to five kilograms of carbon fiber PETG with little visible wear, but just 100 grams of super-abrasive Ultraglow filament started breaking down the protective layer. The INDX uses a bespoke induction-heated nozzle with no off-the-shelf replacement, so owners cannot simply swap in a standard hardened steel nozzle from another system.

Bondtech says a true hardened steel solution could take months to finalize and is not yet offering refunds or compensation before it knows replacement costs. The company is asking customers to avoid abrasive materials for now.

One frustrated Founders Edition buyer responded by building an entire protest site called Nozzlegate.com. The site tracks complaints and advice for buyers who feel misled by the hardened steel marketing language.

The CORE One itself remains a strong machine, and the INDX toolchanger concept is compelling when it works. This is a supply-chain quality issue, not a fundamental design flaw. Still, early adopters paid a premium for a limited-edition kit, and the lack of a clear fix timeline makes the delay sting more.