GRAPHTEC PEN HOLDER — B6 / C4 / I4 PRINT AND FIT GUIDE
Status snapshot: 13 September 2026
Latest body: B6. Physical B6 testing is pending.

MATCHING PARTS
body_B6_no_nose_smooth_bore_plus_1mm.stl
cap_C4_compact_13_77_trial.stl
insert_I4_compact_10_05_trial.stl

Print only B6 if you already have C4 and I4. These cap and insert files are
unchanged from the matching compact mechanism. Each part has a recessed ID.
I3 and the original larger cap/body are not interchangeable with this set.

WHAT CHANGED
The previous printed body was reported to have holes near the nose root and
insufficient pen reach. B5 is inferred from the latest delivery; the printed
ID was not restated. Removing its small nose let the pen pass through, but
another 1 mm of lowering was needed.

B6 removes that complete 5.51 mm diameter, 3.25 mm long nose. The next ring
keeps its 10.94 mm outside diameter and 4.48 mm length. Inside, a smooth cone
is shifted 1 mm toward the tip relative to the nose-cut B5. The new outlet
is 6.3075 mm diameter, opening to the 10.15 mm barrel passage. The minimum
radial wall in this lower ring is 1.2056 mm. Carriage surfaces, flange
positions, female thread and collet socket are unchanged from B5.

The extra travel is a CAD allowance checked against recorded profiles, not
a physical B6 result. The obstruction in the cut print was not measured.

PRINTING
Units: millimeters. Scale: 100 percent. STLs are already oriented.
B6 body: large screw opening on the bed; smaller outlet upward.
C4 cap: wide grip band on the bed; threaded stem upward.
I4 insert: closed band on the bed; slotted fingers upward.

Recorded B6 slice: Bambu A1 mini / 0.4 mm nozzle / Generic PLA / 0.16 mm layers /
four requested walls / 15 percent infill / 3 mm brim / supports off.
Estimated body time: 40m45s. Estimated body material: 3.03 g.
Body size: 15.84 x 15.84 x 39.46 mm.
Thin sections may not fit four wall loops. Inspect upper contact ledges,
the lower ring, bore and slots after printing; remove brim remnants.

FIT AND HEIGHT TEST
1. Confirm the printed IDs are B6, C4 and I4. Check that the empty thread pair
   turns freely and the insert slots are open.
2. Place the slotted, tapered insert end into the body's seat; the closed band
   faces the cap. Start the cap loosely. Insert each pen gently; do not force
   its writing point or nose through a restriction.
3. Check whether B6 seats consistently in the height tool now that its small
   locating nose is removed. Check stationary carriage seating and clamp grip
   separately. Do not treat an unverified sample as ready for plotting.
4. With the cap loose, use the tool to set the point at the pad while supporting
   the barrel. The old target was 4.18 mm below the removed nose face. Relative
   to B6's NEW exit face, that target is 7.43 mm, with the flange datum unchanged.
   This is a nominal carried-forward target, not a measured B6 fit result.
5. Tighten by hand, test grip and release, and recheck writing height after
   tightening. The cap need not close flush. Record any remaining cap gap if
   tightening stops before grip develops.
6. Record each pen's exact label, passage/reach, tool seating, carriage grip,
   slip/release and final height. Confirm those before a plotting trial.

WHAT IS VERIFIED
B6 is a single closed mesh and passed the recorded support-free slice without
warnings. Its engraving is present in sliced wall paths. Digital checks do
not establish physical print quality, all-pen fit, compact grip or plotting.

I3 passed a user-reported manual pull test in the earlier larger mechanism.
The exact tested pen and companion IDs were not restated, and force was not
measured. I4 changes the insert size/flexure and requires its own physical test.

See https://graphtec.mhilo.com/current-build.html for the illustrated guide.
