Copic Multiliner / independent holder experiment

A screw-adjusted grip for your pen.

The end fitting presses a removable, slotted insert into a taper. Its four fingers close around the barrel while the holder locates in the carriage.

CONCEPT 01 · UNTESTED BENCH PROTOTYPE
Exploded cutaway with blue screw cap, amber slotted collet and teal holderExploded view · body sectioned to reveal the socket
Three parts, one adjustable grip

A split-collet mechanism

1. Screw in the end fitting

The hollow cap clears the barrel. Its threaded stem pushes on the closed band of the insert.

2. Close the slotted fingers

The tapered ends move into the body's matching seat and bend inward to grip the pen.

3. Keep the carriage interface

The 13.30 mm insertion body and the 14.50 mm collar remain. The enlarged collar ends exactly 3.20 mm below the flange.

This is an interpretation of the supplied drawing. The threaded cap, clearances and finger dimensions are new trial geometry.

9.75–9.85 mmmeasured barrels to test
18.00 mmproposed maximum outside diameter
+22.70 mmadded height above V14's entry

The grip, in section

The relaxed gripping bore is 10.25 mm. The geometric estimate is 1.14–1.43 mm of cap travel to reach the measured barrel diameters; actual printed fit and bending will change that travel.

Threaded end fittingTightening pushes the insert toward the nib.2.40 mm pitch · custom thread0.25 mm radial clearance; about 2.8 turns engaged.Four slotted fingers10.25 mm relaxed gripping bore; 14 mm insert.Tapered seat · 9.93°Nominal closure travel: 1.14–1.43 mm.14.50 mm clamp contact collarMaximum depth below flange: 3.20 mm.13.30 mm insertion bodyOpen bench sample ends here; full nose is pending.18.00 mm OD3.20mm maxRadial section through finger material. Relaxed geometry shown; bending and pen nose are not simulated.
The main tradeoff is height. The loose cap reaches 30.70 mm above the flange. Confirm that this 18 mm-wide head clears the machine throughout carriage movement before integrating it into the full holder.
Assembled cutaway with charcoal pen barrel inside the collet and threaded cap

Set height with a jig.

The full Graphtec manual shows the holder seated in a separate height adjustment tool. With the fitting loose, the pen is inserted gently until its tip reaches the bottom datum, then the fitting is tightened.

A jig for our holder would put that datum 33.12 mm below the flange contact face, using your target rather than a dimension from the manual. Hold the barrel during tightening, avoid intentional nib deflection and recheck the height afterward.

A matching jig has not yet been modeled. Read the full manual findings.

Release needs testing too. Unscrewing the cap removes pressure but does not pull the insert out of the taper. The fingers must relax, or the pen and insert must withdraw together by the barrel.

The charcoal shape shows only the 9.85 mm barrel envelope. The old nose cone is retained for context; final universal nose geometry still needs three axial measurements.

A small bench test comes first.

The three prototype STLs are already oriented for printing: body mouth down, collet closed band down, and wide cap face down. The open bench body tests the grip independently of the unresolved pen nose.

Three bench parts in their exported print orientations

Left: open bench body · Center: slotted collet · Right: threaded end fitting. Flat lower faces sit on the bed.

PartLayersEstimated materialSteepest downward slope*
Open bench body1923.38 g45.0°
Slotted collet871.00 g1.7°
Threaded cap921.87 g45.0°

*From vertical, excluding the bed contact surface. All three meshes are closed and connected. All three Bambu Studio slices succeeded with supports off and no support toolpaths. This is a geometry and slicer check, not a physical print or grip test.

Test profile: A1 mini · 0.4 mm nozzle · Generic PLA · 0.16 mm layers · four requested walls · 15% infill · 3 mm outer brim. Thin walls may have fewer perimeter paths than requested.

Download bench test kitBlender assemblyDimensions & test notes

What the first test should answer

  1. Do the empty threads turn freely by hand, without forcing them?
  2. Do both measured barrel sizes slide when loose and hold before the cap bottoms out?
  3. Does the insert release after tightening, and survive repeated cycles without cracks or permanent set?
  4. Does the added upper head clear the carriage? After that, complete the nose geometry and check writing height.

The insert has no measured holding-force, fatigue, creep or universal-fit rating. Keep this as a bench experiment until those fit and release checks pass.