Head Tube Reaming and Facing Cutter

The 1694 head tube reamer and facer does two operations in one pass: it reams the head tube bore to the headset cup diameter, and it faces the head tube ends square to that bore. Both operations happen on the cutter; the cutter is the single working face the headset cups will eventually press onto. The 1694.1 is the spare / replacement cutter, ordered when the original has worn through enough headset preps to need refreshing.

What this piece does

The 1694.1 is a hardened-steel cutter head sized to 1 1/8″ head tubes, machined with multiple cutting teeth around a bore-and-face geometry. Mounted on the 1694 reaming-and-facing tool body, the cutter sweeps the inner bore while simultaneously cutting the outer face square to that bore. The two surfaces come out machined to the same reference; that's the load-bearing geometric guarantee the headset bearings will live on for the life of the frame.

A workshop running the 1694 already owns this cutter as part of the bundle. The 1694.1 is the order placed when a busy production bench has chewed through the original cutter, when the cutter edge has rounded to where it produces chatter rather than clean cuts, or when a small set of build-side cutters lets a mechanic keep working while one set goes out for resharpening (depending on workshop policy).

Compatibility

• 1 1/8″ head tube bores
• Mounts on the Headtube Reamer and Facer 1694

Specs

• Bore range: 1 1/8″ head tubes
• Material: hardened steel, multiple cutting teeth
• Function: combined ream-and-face cutter head for the 1694
• Made in Slovenia by Unior

Includes: One 1694.1 cutter.

Made in Slovenia, since 1919

Unior has been forging hand tools in Zreče since 1919, and is the official technical partner of multiple World Tour and downhill teams. The 1694.1 cuts two surfaces with one set of teeth, which is the design move that makes the headset bearing seats come out coplanar. Two separate operations (separate bore cutter, separate face cutter) would risk small misalignment between bore and face; a single combined cutter eliminates the risk by reading the same setup for both cuts.

Pro tip from our mechanics

Carbon head tubes change the rules. Carbon frames don't get faced; the layup is the reference surface, and cutting it removes structural material. The reaming pass, on the other hand, is sometimes the right call on a carbon frame: many carbon head tubes use bonded aluminum cups that can ship slightly out of round, and the 1694 with the 1694.1 cutter is the tool that brings the cup bore back to round. Steel and aluminum head tubes get the full ream-and-face treatment; carbon frames get reamed at the aluminum cups only, never faced.

Chatter marks are the diagnostic that gets the 1694.1 swapped out. A sharp cutter leaves both the bore and the outer face smooth on the first pass; when chatter shows up on a head tube job that ran clean a month ago, the cutter has lost its working edge. Resharpening isn't a workshop operation for cutters at this geometry, so the chatter cue means order a replacement. Chip-shape on the swarf is the earlier signal that the same wear is coming, but chatter is the one that ends the cutter's working life.

Inside the broader build, the cutter's role is the bridge from a raw frame to a frame the headset can press into; the full sequence (when to ream, when to face, what to do with carbon, and what comes after) is in our Tech Tips: Frame prep: head tube, crown race, and star nut work →