OR2-C2 SMALLPIPE REEDS - FIXED HEEL ANCHOR AND MOVABLE BRIDLE
Local correction, 19 October 2026. Keep OR2 bodies and their matching longer tongues together.

WHAT CHANGED
The heel O-ring remains anchored in its groove, centred 3 mm from the screw end. The second O-ring is now a movable bridle on a continuous 8 mm bed, from 7 to 15 mm along the body. There is no narrow groove trapping this second ring. Start its centre at 11 mm; the supported centre range is 8 to 14 mm. This gives 3 mm of adjustment each way and increases starting ring-centre spacing from 5 to 8 mm.

The OR2 tongue blank remains 3 mm longer than OR1. This source-clearance correction lengthens the body further while retaining the seating interface. The source-clearance correction extends only the plain land and bore before the spigot. Default total body lengths are now Tenor-L17:47.55 mm; Baritone-L21:52.45 mm; Bass-L27:64.45 mm. OR2 tongues, slots, bridles, rings and10 mm seating interface are unchanged. This revision changes the working bore and screw chamber as described below. The exact pre-OR1 tip-to-socket-mouth gaps are9.075001 mm /9.975196 mm /15.975050 mm in tenor/baritone/bass order. These are copied geometric clearances, not a new airflow measurement. The longer internal passage may require retuning in the actual drone. The other length options remain in the schedule. Select one body and matching tongue for each drone; these alternatives are not all required for one set.

ASSEMBLE
Use two 7.5 mm inside diameter x 1 mm section NBR 70 Shore A O-rings per reed. Protect them from sharp edges and screw threads. Put the fixed heel ring in the groove centred 3 mm from the screw end.

Centre the matching tongue on the flat, with its heel starting 1.5 mm from the screw end. Its full width is 3.4 mm. Overall blank length is L + 10 mm. The template mark at 10 mm from the heel identifies the NOMINAL forward bridle edge, not a cut line. That edge lies at 11.5 mm on the body when the bridle centre is at 11 mm. Keep the complete slot covered and the free tongue clear of loose material.

Place the movable bridle centre at 11 mm on its continuous bed. Inspect for twists and unequal pressure. This ring holds the tongue while allowing you to adjust its working length; the fixed ring keeps the heel anchored.

ADJUST THE BRIDLE
Leave the heel anchor in its groove. Move only the bridle, in small increments, keeping it square around the body. Move its centre towards 8 mm, towards the screw end, to lengthen the geometric free span. Move towards 14 mm, towards the blade tip and seating end, to shorten that span. Do not exceed this centre range. The complete nominal 1 mm ring section has at least 0.5 mm of bed margin at either limit.

L is the nominal geometric free span at the starting setting. Across the allowed travel it changes from L + 3 to L - 3 mm, measured from the forward ring edge to the blade tip. It is not a guaranteed acoustic vibrating length or pitch. Make one small change, play the actual drone, listen and record it before changing anything else. Check response, pressure demand and cut-off. Recheck the other drones and the chanter when bringing the set together.

The air slot begins at 15.5 mm from the screw end and finishes 1 mm behind the blade tip. Even at the furthest tipward setting, the complete ring envelope remains 1 mm short of the slot. Check that your actual print, tongue and ring preserve this relationship; do not slide the bridle over the slot or off the supported bed. Use the saved model/diagram to identify which way is screwward and which is tipward, rather than relying on a Highland reed's orientation.

TONGUES AND SANDING
Cut-sheet and flat printed PLA blanks remain options. Use the matching OR2 blank or template; OR1 blanks are 3 mm shorter and must not be silently substituted. Print SVG at 100%, no fit-to-page scaling; DXF units are millimetres. CUT is the outline and MARK_NOT_CUT is the nominal bridle-edge reference. Thickness options remain 0.3, 0.4 and 0.5 mm.

The viewer's formed blade and 0.25 mm opening illustrate assembly and bridle travel. The supplied print blank is flat; choose and voice its material in the actual drone. PLA response and retained opening depend on the print and material. No heat-setting recipe is specified. If sanding the tongue, remove it for controlled finishing, work in small steps, preserve the heel/slot coverage, clean it and refit before listening. Reject cracked or flaking material.

SCREW, BORE AND SEAT
Use a user-supplied M5 x 0.8 x 6 mm flat-point stainless socket grub screw with a2.5 mm Allen key. The3.5 mm working air passage continues through the tenon. The larger screw chamber is8.5 mm deep, with a nominal4.2 mm printed pilot. The screw belongs only in that chamber: start with its accessible end1 mm recessed; the illustrated recess range is0-2 mm. Its6 mm length then places its inner tip6-8 mm from the body end, clear of the3.5 mm passage beginning at8.48 mm. Do not advance it into the smaller passage.

A separate cutting tap is optional. Work the stainless screw gently and squarely into the PLA pilot by hand, supporting the body. Back it out to clear debris. Check that it adjusts with useful friction, holds its setting and seals. If the print is split or stripped, discard it and retry the body at a fractionally increased print scale; recheck screw grip and seating wrap because scaling enlarges the tenon too. This is a fitting option rather than a guarantee for every print profile or screw.

If strings or bore roughness need hand-cleaning or hand-reaming, remove the screw and approach from the screw end through the larger chamber. Use a3.5 mm tool for the working passage, work gently and support the body; do not load the free tenon. Remove debris before fitting a tongue. Do not drill out the thread chamber to the screw's5 mm major diameter. Printed dimensions and tool alignment still need inspection.

The6.5 mm spigot and10 mm insertion remain matched to the source7 mm socket. Fit the wrap without forcing the reed and keep the bore mouth clear. Nominal tenon wall is1.5 mm on the straight section and1.1 mm where the outer bevel and bore lead-in meet. The finished M5 thread-root envelope leaves about0.77 mm beneath the flat in the screw chamber. These are distinct locations, not a universal PLA strength rating. The owner accepts the tenon dimensions for this adjustable platform; do not increase its size merely because bought smallpipe-reed tenons can also be vulnerable.

PRINTING A SMALL BATCH
Printing several bodies together, layer by layer, gives each part longer to cool before the nozzle returns. Use sound, well-bonded walls and inspect the slicer paths around the bores. Tune temperature, retraction and travel for your PLA and printer so inter-part moves do not leave strings inside the openings. More cooling time does not itself prevent stringing. No universal temperature or retraction value is specified. Check a first small batch before making more.

CHECK AS YOU PLAY
The saved geometry checks establish the bed, travel, slot coverage, nominal hardware clearances and installed positions. Actual ring friction/retention, tongue pressure, airtightness and musical response still depend on the parts you make and their setup. Recheck the bridle and tongue after playing and over time. Keep a record of body/blank label, material, thickness, bridle position and screw setting.