Bore a Clean, True Hole Without Buying a Full Boring Head Setup

When your drilled hole is undersized and your reamer selection stops short, or you need to hit a precise bore diameter that no off-the-shelf reamer covers, you need a boring tool you can dial in with confidence. A quality adjustable boring bar lets you sneak up on final size in controlled increments — no guesswork, no swapping between tooling, no compromise on roundness or finish. The Toyo Seiki 24–32 mm boring tool delivers exactly that: a compact, self-contained boring unit with a 20 mm parallel shank, a graduated adjustment collar, and a brazed carbide cutter — ready to run in any mill, drill press, or lathe with a 20 mm collet or boring head mount. Mechanically sound with a clean, functional body and three spare cutting bits included, this is a capable shop-floor tool at a used price.

24–32 mm adjustable boring range — Eight millimetres of travel in a single tool means you can bore to a precise fit diameter without changing tooling mid-job. Critical when you’re creeping up on a bearing housing bore or an interference-fit bushing seat where a thou either way matters.
Graduated micrometer-style adjustment collar — The knurled thimble and scale on the collar let you advance the cutter in measured increments rather than tapping the bar blind. This is the feature that separates an adjustable boring tool from a single-point guess — you can read your adjustment before you cut.
Brazed carbide cutter — Carbide holds an edge longer than HSS at higher surface speeds and handles interrupted cuts better in cast iron or hard steel. Brazed carbide can be reground, which is relevant here given the spare bits included are already at various stages of regrind.
20 mm parallel shank — Fits directly into ER20 or larger collet chucks, 20 mm boring head adaptors, or a drill press chuck — no Morse taper adaptor needed. Confirm your spindle can accept a 20 mm straight shank before purchasing.
Ideal for — Boring bearing housing seats, bushing fits, and stepped bores on a knee mill or benchtop mill-drill; cleaning up drilled holes to H7 tolerance on a manual lathe using the cross-slide; precision through-bores on a drill press where a reamer size isn’t available.

Condition

(Used — Good Condition / Mechanically Sound, Surface Wear Present)

The body of this boring tool presents well for a used item — the parallel shank is free of significant dings or raised burrs that would prevent seating cleanly in a collet or chuck. The graduated adjustment collar rotates smoothly and the scale markings are legible. There is light surface patina and minor shop wear consistent with regular use, visible on the shank body, but no deformation to the precision bore that carries the cutter. Three spare brazed carbide cutting bits are included; the seller confirms these are in various condition — some have been reground and at least one has chipping present. This is honest disclosure: reground carbide can still cut cleanly if the geometry is maintained, but chipped inserts will need to be reground or replaced before use in a finishing pass. For roughing work, a chipped cutter may still be serviceable. Recommend inspecting each spare bit under magnification, dressing or discarding any with severe edge damage, and verifying the boring diameter against a known-good bore gauge or ring gauge before committing to a final-size pass on a critical component.

Included

1 x Toyo Seiki Adjustable Boring Tool, 24–32 mm range, 20 mm parallel shank
3 x Spare brazed carbide cutting bits (used, various condition — some reground, some chipped)

Not Included

Storage case or pouch
Setting ring / bore gauge for calibration verification

Brand Information

Toyo Seiki (東洋精機) is a Japanese manufacturer with a long-standing reputation in precision machine tooling and metrology instruments — the kind of brand found in professional toolrooms and trade workshops across Japan and exported throughout Asia-Pacific. Japanese-made tooling from this era is generally held to a high standard of fit and finish, sitting in the same respected tier as fellow Japanese manufacturers such as Mitutoyo, RSK, and Showa. While Toyo Seiki may not carry the same global marketing footprint as Mitutoyo, the build quality and material standards of their tooling reflect the rigorous manufacturing culture Japanese precision tooling is known for — a meaningful point of difference over anonymous OEM boring tools of uncertain origin.

Specifications

Feature	Specification
Brand	Toyo Seiki (東洋精機)
Type	Adjustable Boring Tool / Boring Bar
Boring Range	24–32 mm
Shank / Mount	20 mm parallel (straight) shank
Adjustment	Micrometer-style graduated collar with knurled thimble
Cutter Type	Brazed carbide (replaceable / re-grindable)
Construction	Steel body, machined and ground
Country of Origin	Japan
Condition	Used — Good Condition (surface wear, mechanically sound)
Included Items	1 x boring tool, 3 x spare brazed carbide bits (used, various condition)
Not Included	Case, bore gauge / setting ring

Keywords

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Toyo Seiki

Toyo Seiki 24-32mm Boring Tool 20mm

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