Prusa CORE One INDX Kit Delayed After Bondtech Nozzle Controversy

What happened

Bondtech, the company behind the INDX toolchanger system for the Prusa CORE One, admitted that the nozzles shipped with the Founders Edition kits do not meet the hardened steel standard advertised. The nozzles are nitrocarburized steel, which gives them a hard outer shell, but they fall well short of the 55 to 60 Rockwell C rating expected of fully hardened steel.

Prusa Research responded by pausing INDX shipments until mid-August. The company emailed all INDX order holders with an update, offered extra hardware for free, and gave customers a window to cancel if they wanted. A statement on Reddit said Prusa preferred to wait for clarity rather than ship kits while the nozzle question remained open.

The numbers behind the failure

Bondtech batch-tested the nozzles and reported hardness around 30 to 32 HRC. A standard brass nozzle sits under 10 HRC. True hardened steel lands at 55 to 60 HRC. The difference is not cosmetic. Abrasive filaments like carbon fiber, glass fiber, and glow-in-the-dark PETG will eat through the treated surface faster than expected.

Prusa engineers tested the nozzles internally. After five kilograms of carbon fiber PETG, wear was barely visible. After just 100 grams of super-abrasive Ultraglow filament, the protective coating began to fail. For users who bought the INDX specifically to run engineering materials, that is a problem.

Where the blame lands

The issue is not that Bondtech chose a softer nozzle. Nitrocarburized steel is still tougher than brass and works fine for most materials. The issue is the marketing. Promotional materials called the nozzles hardened steel, and customers paid a premium for that promise. When a Reddit user leaked a support email from Bondtech founder Martin Bondeus, the backlash became impossible to ignore.

Bondtech said it encountered manufacturing challenges that prevented reliable machining of the harder material. Rather than release inconsistent products, it shipped the nitrocarburized version temporarily. The company has not set a timeline for truly hardened nozzles, suggesting it could take months. It is also not offering compensation until replacement costs are known.

The customer reaction

The delay hit Founders Edition buyers hard. Many had already waited months for the limited 1,000-unit run, and the INDX installation is not trivial. It requires stripping down a CORE One, removing the Nextruder, mounting the INDX carriage, and installing eight tool heads. One customer, frustrated enough to build a protest site, launched Nozzlegate.com to track complaints and advise buyers on their rights.

Swedish consumer law gives buyers a two-month window from the announcement to claim a partial or full refund. After that, the path gets harder. Bondtech has asked customers to hold off on returns and simply avoid abrasive materials for now.

What to do if you own an INDX kit

If you have not opened the kit, you can cancel your order. Prusa is accepting cancellations through mid-August. If you already have it installed, stick to non-abrasive filaments until replacement nozzles are available. Carbon fiber PETG is likely safe for moderate use, but anything with glow-in-the-dark additives or metal flecks will accelerate wear.

The INDX nozzle is a custom induction-heated design with no off-the-shelf replacement. That means there is no easy workaround until Bondtech solves the manufacturing problem.

The bigger picture

The CORE One is still a strong printer, and the INDX concept is promising. But this episode is a reminder that early adoption carries real risk, especially when a supplier quietly swaps materials and hope no one notices. Prusa's decision to pause shipments is the right call, even if it frustrates the customers who waited longest.