Description
Product Overview
When you’re setting a compound slide, scribing a precise bevel on a workpiece, or transferring an angle from a drawing to a surface plate setup, eyeballing it with a cheap plastic protractor isn’t going to cut it. You need a proper precision bevel protractor — one with a calibrated vernier scale, a lockable blade, and a solid stainless body that holds its setting when you tighten the clamp. The Marui Keiki BP-303 is that tool: a full-circle vernier bevel protractor made in Japan to toolroom standards, capable of reading angles to 5-minute (5′) increments across the full 360°. This example shows very little sign of use and presents in excellent working condition, with both the main blade and the shorter acute angle attachment included.
- Full 360° graduated dial with 5-minute vernier resolution — At 5′ increments you’re resolving angles to one-twelfth of a degree, which is the difference between a fit and a rework on precision bevel gears, dovetail slides, and angled fixture work. A standard protractor that only reads whole degrees simply doesn’t belong in this conversation.
- Stainless steel construction throughout — The blade, stock, and dial body are stainless, meaning the reference surfaces resist rust and hold their flatness on the bench. Ground and lapped reference edges are what make an angle transfer repeatable; a tool that corrodes or distorts undermines the whole exercise.
- Adjustable and lockable blade with acute angle attachment — The main blade slides along the stock and locks with a knurled clamp, letting you reach across a workpiece or retract for tight-clearance work. The included acute angle attachment extends the usable range into angles under 90°, covering dovetail work, chamfers, and thread-form verification without a second tool.
- Magnifying lens over the vernier scale — The BP-303 incorporates a built-in magnifier on the vernier window, which is a practical detail that matters under shop lighting when you’re reading 5-minute graduations. Not all bevel protractors include this; it removes the need for a separate loupe.
- Ideal for — setting compound slide angles on a lathe, scribing and verifying bevel and chamfer angles, checking dovetail slides and gibs, setting sine bar and sine plate angles, transferring drawing angles to fixture setups, and verifying ground taper surfaces against a reference.
Condition
(Used — Good Condition / Low Hours, Very Light Wear)
Mechanically, this protractor is in excellent shape. The vernier scale is clean and fully legible, the dial rotates smoothly through its full range, and the blade clamp locks positively without slop or creep. The ground reference edges on the stock and blade are free from nicks, burrs, or visible scoring — the surfaces that actually touch your workpiece are in the condition that matters. There is very light surface patina consistent with bench storage rather than heavy use; no corrosion, no deep scratches, and no damage to the vernier window or magnifier. The original box shows the expected signs of shop storage and age — some exterior wear and marking — but it provides adequate protection for storage and transport. As with any used angle instrument, it’s good practice to verify the zero against a known reference square before committing it to critical work, and to confirm the vernier reads true at 90° and 45° using a precision square and a known standard. There is no reason to expect any issue — this is a precaution, not a flag.
Included:
- 1 x Marui Keiki BP-303 Vernier Bevel Protractor (full instrument with stock, blade, and magnifying vernier head)
- 1 x Acute angle attachment blade
- 1 x Original manufacturer’s box / packaging
- 1 x Original papers / documentation
Not included: No carrying case beyond the original box. No setting master or reference standard.
Brand Information
Marui Keiki Co., Ltd. is a Japanese precision instrument manufacturer with a long-standing reputation in the metrology and layout tool market. Their bevel protractors, squares, and measuring instruments are produced in Japan to standards consistent with the broader Japanese toolroom instrument sector — the same manufacturing culture that underpins Mitutoyo, RSK, and Niigata Seiki. Within the global market, Marui Keiki sits firmly in the professional/toolroom tier: not a budget import, but a working instrument built for accuracy and durability in industrial and trade environments. Japanese-made metrology tools of this class are well regarded in Australian toolrooms for their consistent calibration, quality of finish, and longevity.
Specifications
| Feature | Specification |
|---|---|
| Brand | Marui Keiki |
| Model | BP-303 |
| Type | Vernier Bevel Protractor |
| Measuring Range | 0–360° (full circle) |
| Vernier Resolution | 5 minutes (5′) of arc |
| Blade Length | Adjustable / sliding main blade (refer to manufacturer documentation for nominal length) |
| Acute Angle Attachment | Included |
| Magnifying Vernier Window | Yes — built-in magnifier over vernier scale |
| Material / Construction | Stainless steel body, blade, and stock |
| Blade Lock | Knurled clamp screw |
| Country of Origin | Japan |
| Condition | Used — Good Condition / Very Light Wear |
| Included Items | Protractor body with blade, acute angle attachment, original box, original papers |
| Not Included | Hard carry case, setting master / calibration reference |
Keywords
Marui Keiki BP-303, Marui Keiki bevel protractor, vernier bevel protractor Japan, precision bevel protractor 5 minute, universal bevel protractor toolroom, bevel protractor stainless steel, angle measuring tool machinist, layout tool surface plate, compound slide angle setting, dovetail slide inspection, Japanese precision measuring instrument, bevel protractor Australia
