A hardware experiment by mhilo
A pen holder.
One iteration
at a time.
The I3 insert holds through a manual pull test. Now the B6 body tackles pen clearance and writing height, bringing the fit and adjustable grip into one compact assembly.
In development / Updated
Assembly preview · enable JavaScript for the 3D view
Pen: measured 1.0 profile · shortened barrel for clarity
Small tolerances.
Real ink.
A 3D-printed adapter for using Copic Multiliner pens in a Graphtec plotter.
The aim is a holder that seats in the carriage, keeps the pen steady, and puts the writing point at the right height. It started with a snug-fitting body. New pen measurements and carriage tests have turned it into a series of small, focused prototypes.
Those two paths are now coming together. A smaller screw mechanism fits a newly measured PHP31 shell, while each body revision works through the pen passage and height-setting tool.
Fit the carriage
Seat the flange and reach the clamp without catching on the metal throat.
Hold the pen
Accommodate different pen shapes while keeping the barrel from sliding.
Set the height
Establish a repeatable writing-point position before a complete plotting test.
Each print asks
a smaller question.
From isolated carriage and nose samples to the combined B6 body. V identifies fit samples; B, C, and I identify body, cap, and insert.
V09–10Start with a working printThe solid-holder baseline
V9 provided a successful print. V10 adapted that profile for the measured 1.0 pen shaft, widening the outlet to 2.65 mm while retaining the 10.05 mm barrel bore.
Lesson: A successful earlier print establishes a starting point; each new pen still needs its own fit check.
V11–12Let the holder seatClear the carriage, then check the clamp
V11 removed a protruding ring and shortened the holder by 7.12 mm, using the measured pen projection to target a 33.12 mm flange-to-writing-point distance. V12 reduced the mounting cylinder to 13.30 mm.
Result: The narrower body passed through the carriage, but the clamp did not grip beneath the flange.
V13–14Find the contact zoneA collar, with a hard depth limit
V13 added a local 14.50 mm collar to reach the clamp. A new measurement showed that the enlarged section could extend only 3.20 mm below the flange before hitting the metal throat. V14 shortened the collar to that limit.
Lesson: Passing through the opening and being held by the clamp are separate tests. A short clamp sample makes those checks cheaper.
V15Make room for another penIsolate the barrel fit
A second barrel measured 9.85 mm, compared with the earlier 9.75 mm. An 8 mm-long gauge increased the bore to 10.15 mm to test clearance without printing a whole holder.
Status: A fit gauge was exported. A complete universal holder was not established.
V16Measure a working referenceRevisit the carriage profile
Measurements from a working PHP-31 holder informed a new carriage sample: an 11.93 mm neck, 13.96 mm main body, and 10.90 mm lower section.
Correction: The clamp-contact band was inset where it needed to project outward. V18 superseded this arrangement; V16 was not a confirmed carriage-fit pass.
V17Test the shared nose shapeEntry confirmed; projections recorded
The 15.50 mm sample isolates pen entry and nose clearance. All three pens reportedly enter the opening. Later tip projections were 5.41 mm for 0.5, 5.64 mm for 1.0, and 4.69 mm for the pen reported as 0.05.
Still to clarify: Earlier notes used 0.005 instead of 0.05. The 1.0 measurement also needs a datum recheck. These are nose-sample results, not a common writing-height or retention pass.
V18Raise the clamp bandA corrected carriage-only test
V18 puts a 13.96 mm collar above an 11.93 mm throat, reversing the earlier nominal diameters. Its 2.23 mm collar stays within the 3.20 mm depth limit.
Status: The labeled gauge passed digital checks; physical carriage fit remains unconfirmed. Later PHP31 measurements informed the separate B4–B6 shell.
Path B / Adjustable grip
A grip that
holds its own.
A screw cap pushes a slotted insert into a tapered seat, closing the fingers around the barrel. The original parts assembled, but the pen slipped. V2 ridges helped fingers turn the cap; the earlier insert still did not hold.
I3 is the first successful grip baseline. With a smaller 10.05 mm gripping bore and relieved fingers, the latest tested print tightened more easily and resisted the maker’s strongest attempted hand pull.
This is a qualitative result for that assembly. The tested pen size and companion part IDs were not restated; no measured pull force, durability, or plotting result is claimed.
Explore the original mechanism
First the cap. Then the insert.
The ridged cap improved hand grip. I3 addressed the insert’s clearance and flexibility. The newer compact C4/I4 mechanism changes size again, so it needs its own physical grip test.
I3 and I4 are different parts. I3 does not fit the B6 socket.
Bringing the
pieces together.
The newer PHP31 measurements led to a compact body and a matching C4 cap and I4 insert.
B4Fit a more compact shellA new mechanism, with new checks
The measured upper shell could not safely accommodate the earlier larger thread. B4 introduced the smaller C4/I4 mechanism. Its wider custom nose then proved incompatible with the height tool’s locating feature.
Lesson: B4 is superseded for height-tool fitting. The successful I3 test does not validate the smaller I4.
B5Keep the locating noseThe passage becomes the next problem
B5 restored the 5.51 mm × 3.25 mm nose and revised the internal steps. The subsequent print report described holes near the nose root and three pens that would not reach the tool’s pad.
Bench feedback: Removing the small nose from that print let the pen pass, but another 1 mm of lowering was needed. B5 is inferred from the latest delivery; the printed ID was not restated.
B6Open the passageLatest printable body · physical test pending
B6 removes the small nose and replaces the next ring’s stepped interior with a smooth cone. That lower bore moves 1 mm toward the tip compared with the nose-cut B5. The carriage surfaces and C4/I4 socket stay the same.
Prepared: A labeled, closed mesh and a support-free slice. The additional travel is a CAD allowance; pen reach, tool seating, compact grip, and plotting still need physical checks.
See B6, its matching parts, and the test planThe grip works.
The fit comes next.
I3 passed a manual grip test. The latest B6/C4/I4 assembly is a new physical trial, not yet a validated universal plotting holder.
Reported physical results
Useful steps
at the workbench.
- All three pens entered the V17 sample’s opening, with individual tip projections recorded afterward.
- V2 ridges improved hand grip on the cap.
- The I3 test tightened more easily and held through the strongest attempted hand pull.
- Removing the small nose from the previous body let the pen pass through; more downward travel was still needed.
Still being resolved
Reach, seat,
grip, then plot.
- B6 needs a physical print and a reach check with each pen.
- Removing the locating nose changes how the holder meets the height tool; repeatable seating must be checked.
- The compact C4/I4 grip needs its own hold-and-release test.
- Carriage fit, writing height, durability, and a complete plotting run are not yet established for B6.
Mesh and slicing checks describe the digital model and toolpaths. Physical grip, repeatable writing height, and full plotting performance require their own tests.
The next print,
clearly labeled.
B6 uses the matching C4 cap and I4 insert. Reuse those parts if already printed. The older I3 insert belongs to the larger grip mechanism.
Read the current test notes before printing. Parts are supplied in millimeters and in their intended print orientations.
B6 fit and height guide