Indexable Turning Tool Holders

Indexable turning tool holders are the modern alternative to brazed and HSS lathe tooling. Instead of grinding a single-edge tool by hand, you bolt a multi-edge carbide insert into a holder and index to a fresh cutting edge as soon as one wears — faster changeovers, repeatable geometry, and inserts that simply work harder than HSS ever will. If you're weighing up which one to choose, our Boring Bar Guide: Sizes, Indexable & Selection is a good place to start.

AIMS stocks 391 indexable turning tool holders covering the external, internal and boring combinations Australian machinists actually order — screw lock, pin lock, multiple lock, clamp lock and top clamp systems, in right-hand, left-hand and neutral configurations, from Seco (premium production-grade) and Maxigear (workshop value-grade).

Indexable Turning Tool Holder Selection — Quick Reference

Critical: a tool holder and its insert are one system — the insert's shape, IC (inscribed circle) size and clearance angle have to match the seat machined into the holder. Fit the wrong insert and you get a poor finish at best, a damaged seat or a broken insert at worst. Tool centre height matters just as much: the cutting edge has to sit at the workpiece's centre line — too high and the tool won't cut at centre; too low and you'll get chatter and deflection. Brands stocked for this category: Seco and Maxigear. Companion ranges: indexable inserts, indexable turning & boring, machining.

External vs Internal (Boring) Turning Holders

External turning holders sit in the toolpost and machine outside diameters — turning, facing, chamfering and contouring. Internal turning holders — also called boring bar holders — machine inside a hole, a counterbore or an internal recess. The insert geometry and clamping mechanics are the same ISO family in both cases; the boring bar body is simply longer and slimmer so it can reach inside the work without the shank fouling the bore.

For boring-specific guidance — L:D (length-to-diameter) ratios, anti-vibration bars and finishing strategy — see our Boring Bar Guide.

Lock & Clamping Systems Explained

Screw Lock — a single screw clamps the insert to its seat through the insert's centre hole. Compact, and the workshop default for small-to-medium inserts.

Pin Lock — a pin or lever engages the same centre hole, giving a stiffer hold than screw lock under heavier feeds.

Multiple Lock — combines a pin with a top clamp for the heaviest-duty roughing and interrupted cuts.

Clamp Lock / Top Clamp — a clamp presses down on the insert's top face instead of through a hole. Used for larger or thicker inserts, or wherever a heavy interrupted cut would shock a screw- or pin-locked insert loose.

Reading the Code on the Holder

Indexable turning holders are coded to the ISO 5608 naming convention used across the industry. Read left to right, the code identifies the clamping method, the insert shape, the tool style / cutting-edge angle, the insert clearance angle and the hand of cut, followed by the shank size and insert size. Insert shape letters follow the standard convention — C = 80° rhombic (diamond), D = 55° rhombic, R = round, S = square, T = triangle, V = 35° rhombic, and W = 80° trigon — and all seven of these shapes are stocked at AIMS across this range.

Some real examples from AIMS's own Seco range: MWLNR-10-3A is a Multiple Lock holder for a W-shape (trigon) insert, right-hand cut; SVJCL2020K11 is a Screw Lock holder for a V-shape (35° rhombic) insert on a 20 x 20mm square shank, left-hand cut; CTGPL2525-16 and CSKNL2525M06 are both Clamp Lock holders on 25 x 25mm shanks. Match the code on the box to the code on the insert pack before you order — the geometry has to line up exactly.

Matching a Holder to an Insert — What to Confirm

• Insert shape — C, D, R, S, T, V or W — must match the seat machined into the holder.
• IC size — the insert's inscribed circle diameter (commonly 06, 09, 12) — has to match the holder's seat size.
• Shank size — match your lathe's toolpost. AIMS stocks common sizes through to 20 x 20mm and 25 x 25mm square shanks. Too big and it won't fit; too small and you'll get flex and chatter.
• Hand — right-hand for the great majority of external turning (toolpost on the operator's side); left-hand for back-turning setups and some CNC configurations.
• Clamping method — screw, pin, multiple lock or clamp/top clamp — chosen for the cut, not just the insert.

Brands We Stock

Seco — the premium range across this collection, covering screw lock, pin lock, multiple lock, clamp lock and top clamp holders in steel and solid carbide shanks, for both external and internal (boring) turning. Use where edge life, rigidity and repeatable finish justify the cost — production runs, tighter tolerances, harder materials.

Maxigear — the workshop value range: right-hand and left-hand external turning holders plus a boring bar with holder set, at a lower price point. Suits maintenance shops, jobbing work and trade training environments where a Seco-grade holder is over-spec for the job.

Companion Collections

A turning holder is only half the system — here's the rest of what machinists working this range usually need:

• Indexable Inserts — the carbide inserts that go in these holders.
• Indexable Turning & Boring — our broader turning and boring range, including bars and specialist configurations.
• Cut-Off Blades — for parting and grooving work, which sits outside this holder range.
• Tool Holder Accessories — arbors, live centres and related toolpost accessories.
• Corner Radius End Mills — for shops running a mill alongside the lathe.
• Machining — the full AIMS machining and cutting tool range.

Background reading: Boring Bar Guide (L:D ratios, chatter control), Lathe RPM Formula Guide (surface speed calculations), End Mill Guide (insert grade selection principles that carry across from milling).

Order from AIMS

Not sure which lock system, hand or shank size fits your lathe? Call the Sydney team on (02) 9773 0122, get in touch through our contact page, or send us the job for a quote and we'll match a holder, insert and grade combination to the work you're doing.

Common Questions

What's the difference between an external turning holder and an internal (boring bar) holder?
External holders sit in the toolpost and machine outside diameters — turning, facing, chamfering and contouring. Internal turning holders, also called boring bar holders, machine inside a hole, counterbore or internal recess. The insert and clamping mechanics are the same ISO family; the boring bar body is simply longer and slimmer so it can reach inside the workpiece without the shank fouling the bore.

What do the letters and numbers on a turning tool holder mean?
Indexable turning holders are coded to the ISO 5608 system used industry-wide. Read left to right, the code identifies the clamping method, the insert shape, the tool style/cutting-edge angle, the insert clearance angle and the hand of cut, followed by shank size and insert size. In AIMS's range, MWLNR-10-3A is a Multiple Lock holder for a W-shape insert, right-hand cut; SVJCL2020K11 is a Screw Lock holder for a V-shape insert on a 20 x 20mm shank, left-hand cut.

What's the difference between screw lock, pin lock, multiple lock and clamp lock/top clamp holders?
Screw lock uses a single screw through the insert's centre hole — compact, and the workshop default for small-to-medium inserts. Pin lock uses a pin or lever through the same hole for extra rigidity under heavier feeds. Multiple lock combines a pin with a top clamp for the heaviest-duty roughing. Clamp lock/top clamp presses a clamp over the insert's top face instead of through a hole — used for larger inserts or where a heavy interrupted cut would shock a screw- or pin-locked insert loose.

Can I fit a different brand's insert into my holder?
In most cases yes. Indexable turning is an ISO-standardised system, so an insert of the correct shape, IC size and clearance angle will seat correctly in a holder from a different manufacturer, whether that's a Seco holder or a Maxigear one. What has to match is the ISO geometry, not the brand.

What shank size do I need?
Match your lathe's toolpost. AIMS stocks holders from smaller precision shanks through to 20 x 20mm and 25 x 25mm square shanks, the sizes most common on workshop and light-production lathes in Australia. A shank too big won't fit the toolpost; one too small will flex and chatter under load. Check your toolpost's clamping capacity before ordering.

Right-hand or left-hand — which do I need?
Right-hand holders cut towards the chuck and suit the great majority of lathes, where the toolpost sits on the operator's side of the workpiece. Left-hand holders are for back-turning setups or lathes where the toolpost mounts on the far side of the work — common on some CNC configurations and sub-spindle jobs.

Seco or Maxigear — which should I choose?
Seco is AIMS's premium range — screw lock, pin lock, multiple lock, clamp lock and top clamp holders in steel and solid carbide shanks, built for production environments where edge life and repeatable finish justify the cost. Maxigear is the value-grade alternative — common shank sizes and lock styles at a lower price point, well suited to maintenance work, jobbing shops and trade training environments.