Choku-ba (直刃) Blade Line

Reference sectionChoku-ba (直刃)—straight-blade wording

Choku-ba combines Japanese wording associated with “straight” and “blade.” In a scissor catalog, it can identify a comparatively straight heel-to-tip line within that maker’s range.

The term does not establish a perfectly straight line, a shared radius, or a national design standard. Preserve the maker’s original wording, exact model, size, market, and dated source.

Reference sectionWhat the term establishes

A product photograph can suggest a line but cannot establish precise geometry without a declared view, scale, and camera correction.

Reference sectionMaker evidence

Joewell’s blade guide compares its straight, ordinary or willow, and bamboo-leaf lines. Inside that maker’s system, the straighter line is described as holding hair more readily, while greater curvature lets more hair move toward the tip. Joewell’s New Cobalt page calls that model “close to a straight line” and associates its capture with detailed cutting.

That documents a relative design intention inside one maker’s range. It is not a cross-brand measurement or a rule for every straight line. Other makers use different names and diagrams, and a model one company calls straight is not automatically the same shape as another company’s choku-ba.

Reference sectionKeep the other geometry fields separate

• Blade line: heel-to-tip path in a declared side or plan view.
• Body cross-section: end-on form of each blade half.
• Edge or grind: the maker-stated working surface, finish, honing, or serration.
• Inner geometry: relief, hollowing, contact lands, pairing, set, and current condition.

Choku-ba fills only the first field when the source uses it that way.

Reference sectionExact-model record

Capture:

1. maker, model, code, size, handed variant, market, and date;
2. original term and maker-supplied translation;
3. full blade drawing or photograph with a declared viewpoint;
4. heel and tip datums, measured zone, and any published dimension or radius basis;
5. section, edge, finish, inner relief, partner blade, and pivot;
6. maker-stated use and limitations;
7. condition, adjustment, and service history; and
8. trial, return, warranty, and qualified service terms.

Leave unpublished fields unresolved. Do not borrow a radius, technique claim, or service rule from another choku-ba model.

Reference sectionSelection checklist

Before treating a straight-line label as a buying recommendation, verify:

1. the exact maker and model;
2. the maker’s blade-line diagram or published radius, including which portion is measured;
3. blade length, width, section, and the construction of both blade halves;
4. the final edge grind and finish;
5. the maker-listed techniques; and
6. capture, release, and tip accuracy on the hair state and motion you actually use.

Reference sectionStraight lines in use

Slide work depends on the complete construction and the motion, not on the line name. A micro-serrated finish deliberately grips hair and is a poor match for a continuous glide, while a polished bevel does not carry that same grip. There is no mandatory pairing of a straight line with any one edge grind, and a slide result on a straighter line depends on hand angle, section control and practice at least as much as on the line.

Technique guidance sometimes describes loose pivot tension on a flat, straight blade as amplifying push-out, on the reasoning that there is little curve to channel the section. That is not established as a general property of the line, and it does not show that a straight line needs firmer tension or loads the hand more than a curved one. Set tension to the maker’s specification, and treat pushed or folded hair as a condition to diagnose on the exact tool.

Reference sectionTrial the complete shear

Line geometry can contribute to contact during closing, but the observed result also depends on section, edge, blade pairing, set, pivot, adjustment, size, handedness, condition, material, task, and operator motion.

Compare exact candidates under the same permitted conditions. Record control, push, fold, drag, effort, noise, and repeatability without assigning the result to the line name alone.

Service routeService boundary

Choku-ba does not prescribe a pivot setting, drop-test target, abrasive, machine, angle, or sharpening direction. Ask the maker or qualified provider how they will identify and preserve the exact model’s line, section, edge, inner relief, pairing, and set, and document the work performed.

Source trailSources and limits

The Japanese trade and maker sources cited here describe relative line vocabulary within their own ranges. None publishes a cross-brand radius threshold, a tolerance, a measurement zone or a technique gate, and no national standard for the term was located. Statements about capture, slide, tension or hand load stay attached to the named model and to the trial that produced them. Line, section, edge, inner relief and pairing remain separate fields to record for the exact shear.