Bondtech's INDX hardened nozzles are only HRC 30 to 32
Bondtech INDX hardened nozzles measure HRC 30 to 32, roughly half the HRC 55 to 60 the word usually promises. Bondtech has since apologized and pulled “hardened” from its pages. Treat what you own as long-life brass. It handles most filaments and wears out fast under daily carbon fiber work.
Key Takeaways
- The INDX “hardened” nozzles measure HRC 30 to 32, about half of true hardened.
- They are surface-treated steel with a soft core underneath.
- Bondtech has apologized and admits the nozzles are not abrasive-resistant.
- Boxes and invoices that buyers received still carry the word “Hardened.”
- You cannot fit a real hardened nozzle, because the part is proprietary.
What hardness did the Bondtech INDX hardened nozzles ship at?
The shipped nozzles come in at HRC 30 to 32. The number came from Bondtech’s own staff on the company Discord. HRC is the Rockwell C scale for steel. A higher number means the surface resists scraping wear better.
Two days earlier, off duty on Discord, a Bondtech employee had already called the nozzles only semi-hardened. He added that he would not use them for regular abrasive printing. The 3DPCC investigation chained the Discord screenshots, the founder’s support email, and the archived product pages into one timeline.
Why hardened is not the same as through-hardened
Bondtech did try to build a properly hardened nozzle. Founder Martin Bondéus confirmed by email that the team tested a version at about 60 HRC. The cutting tools couldn’t survive machining it, so nitrocarburised steel shipped instead.
Nitrocarburising hardens the outer skin of the steel while the core stays soft. Through-hardening makes the whole part hard, all the way in. A nitrocarburised nozzle therefore beats plain brass, while still wearing far faster than a tool rated for abrasives.
| Nozzle type | Typical hardness | Abrasive filament |
|---|---|---|
| Brass | HRC 0 to 10 | Wears out fast |
| Plain steel | HRC 20 to 25 | Wears quickly |
| Nitrocarburised steel (what INDX ships) | HRC 30 to 32 | Accelerated wear |
| True hardened steel | HRC 55 to 60 | Rated for it |
Sitting at HRC 30 to 32 puts the INDX nozzle closer to plain steel than to a hardened tool.
What did Bondtech advertise the nozzles as?
From the pre-order page onward, the INDX spec table read “Hardened with CHT.” A matching paragraph ran on the Founders Edition, the Development Kit, and the standalone tool listings. It promised steel with zero fear of wear on carbon fiber, glass fiber, and glow-in-the-dark filament.
The word followed the product into the box. Buyers posted photos of retail boxes printed “Hardened” in every nozzle size. Invoices listed “Bondtech INDX Hardened Tool” as a paid line item, and the packing slips said the same.
Every passive tool sold at the same price, so hardened described the whole line. Prusa echoed the claim in its own words, listing hardened nozzles that handle any abrasive filament on its conversion kit page.
How Bondtech edited the claim off its pages
The rewrite started the same day the community found out. The spec table that read “Hardened with CHT” now reads “Steel with CHT.” The tool once sold as the CHT Hardened Tool is now the INDX Passive Tool (Steel CHT) . It’s now described as built from steel, and the abrasives paragraph is gone. A separate hardened tool page from the same period returns a 404.
For days after the news broke, the Development Kit and Founders Edition pages still carried the “zero fear of wear” paragraph. Prusa’s kit page no longer lists hardened nozzles among the INDX selling points either.
What Bondtech said in its official apology
A signed Bondtech statement about two weeks later conceded the point.
The nozzles were listed as hardened and suitable for abrasive filaments. We had this description on our website, and while we intended to produce hardened nozzles, the units shipped with the INDX are not truly hardened.
The statement covers every nozzle in the Founders Edition, plus every nozzle in the first Prusa CORE One+ upgrade kits. It also warns that boxes may still show the “hardened” label, and promises fixed packaging.
On compensation, the company says it has no plan yet and won’t promise pricing it can’t back. A properly hardened INDX nozzle is many months from serial production. Until then, a refund is the only option on the table.
What INDX owners and Prusa buyers should do now
For everyday filament the nozzles are fine. Bondtech lists PLA, PETG, ABS, ASA, TPU, nylon, PC, and polypropylene as safe on the steel nozzle you received. Glow-in-the-dark, metal-filled, carbon-fiber and glass-fiber filaments chew through it.
The founder drew the line at duration: occasional abrasive work is survivable, while long abrasive runs will finish the nozzle off. If abrasives are your daily job, no INDX nozzle on sale is rated for them. On an open hotend, a ruby-tipped nozzle handles that work.
Nor can you solve this with a better nozzle from someone else. The INDX nozzle is the induction-heated element itself, proprietary to the system. A Diamondback or a standard V6-style hardened nozzle won’t fit. Bondtech is the only source, at $55.35 each before tax. Buyers on the Prusa forum thread about the hardening problem worked through the same dead end.
How fast the nozzles wear on glass-fiber nylon is still an open number. Bondtech has promised a hardness profile at depth, plus a figure in kilograms of abrasive filament. Until that lands, budget for these nozzles as consumables that outlast brass, at $55.35 a time.