Carmex · Tiny Tools 2025

Bores down to
0.3mm.
Nothing gets closer.

Seven precision tool families — boring, threading, grooving, multi-task, broaching and more — all built around a single principle: make extremely small features repeatable in high-volume production. Used by F1 teams, aerospace primes, and Swiss-type turning specialists who can't afford a second chance at a part.

Min Bore: 0.3mm Tolerance ±0.025mm Star Swiss Compatible Through Coolant 4 Carbide Grades
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0.3mm
Minimum bore diameter
MTR boring bar series
±0.025
Grooving tolerance
MGR / MKR series, mm
7
Tool families
One system, all operations
4
Carbide grades
K20 · BXC · BMK · TNX
Who runs this tooling

Built for the
tightest tolerances in production

When your component has features under 1mm, material removal is measured in microns, and scrap is counted in £10,000s of lost production — this is the tooling the world's best shops reach for.

🏎
Formula One & Motorsport
Titanium suspension components, hydraulic manifolds, gearbox housings. Parts run in batches where a single out-of-tolerance bore can ground a car. Carmex has been the choice of F1 supply chain machinists who live on sub-millimetre features.
In-house F1 supply chain use
✈️
Aerospace & Defence
Fuel injectors, actuator bores, and flight-critical fastener features in Inconel, titanium, and hardened steel. The CBR chip-breaker bars with internal coolant were built specifically for long-run stainless and super-alloy work.
AS9100 supply chain
⚕️
Medical & Implants
Bone screws, implant threads, and surgical instrument bodies. MIR threading bars handle full ISO, UN, ACME, and BSP profiles from 3mm bar diameter — ideal for Swiss-type production of tiny implant components.
ISO 13485 machining
⚙️
Swiss-Type & Micro Turning
Star, Citizen, Tsugami, Tornos — the SIM 22S and SEMK holders are engineered specifically for sliding headstock machines. X and Y-axis turning configurations, square-shank holders for stationary tools, all with the repeatability Swiss-type production demands.
Star machine specialists
Toolholders

Every insert has
a matching holder

All Tiny Tool inserts are linked to the holders that fit them. The full holder range — SIM 22S for Star Swiss machines, SEMK / SEMV / SEMR square-shank configurations for stationary tools on sliding headstock lathes — is available alongside the cutting tools. When you're buying inserts, the right holder is one click away.

SIM 22S — Star Swiss SEMK Square Shank SEMV Configuration SEMR Configuration
The numbers that matter

Precision you can put on a drawing

0.3mm
Minimum bore diameter (MTR)
±0.025
Grooving tolerance — MGR / MKR (mm)
Seven tool families

Every small-hole operation,
one system

From a 0.3mm boring bar to a full-radius grooving insert to an internal hex broach — if it's a small-feature operation, there's a Tiny Tool for it.

MTR
Miniature Boring Bars
  • Min bore 0.3mm
  • Bar Ø range 3–10mm
  • Neck lengths L1–L40
  • Grades K20 / BXC / BMK / TNX
  • Feed (rec.) 0.01–0.03 mm/rev
CBR
Chip-Breaker Boring Bars
  • Grade TNX
  • Coolant Internal through
  • Chip control Advanced geometry
  • Materials Stainless & super alloys
CMR
Multi-Task Bars
  • Operations Bore + turn + face + chamfer
  • Pilot hole Not required
  • Grade BMK
  • Flute Through-coolant spiral
MIR
Internal Threading
  • Profiles ISO, UN, NPT, ACME, BSP, BSW+
  • Types Partial 55°/60° + Full
  • Min bar Ø 3mm
  • Includes Trapez DIN103, MJ, UNJ, BSPT
MGR
Internal Grooving
  • Width range 0.5–3.0mm
  • Tolerance B±0.025mm
  • Applications O-ring, snap ring, retaining
MKR
Full Radius Grooving
  • Tolerance R±0.025mm
  • Profile Full radius insert geometry
  • Use case Curved-base groove profiles
MVR
Deep Face Grooving
  • Coolant 2× bore channels
  • Application Deep radial face grooves
  • Advantage Dual coolant = chip flush
HK Broaching

Internal hex
from a CNC lathe

The HK broaching system creates internal hexagon keyways in blind and through-holes — directly on a CNC turning centre, no separate broaching machine required. Purpose-built for precision instrument bodies, valve components, and miniature fixings where an internal drive is part of the design.

⬡
Blind holes
Full-depth keyway in blind-bottom bores — no exit relief required.
⬡
Through holes
Standard through-bore broaching on any CNC lathe with C-axis or Y-axis capability.
🔄
No broaching machine
Machine the part and cut the keyway on the same turning centre — no second setup, no separate press.
⚙️
CNC-driven
Runs off the machine's C or Y axis. No specialist broaching knowledge required — just a tool path.
Substrate & coating

Four carbide grades.
Every material covered.

Each grade is matched to a specific material group and operation type. Run the right grade and you'll hit the feed and speed numbers in the cutting data. Run the wrong one and you'll know about it within the first component.

K20
General purpose carbide
Uncoated fine-grain carbide. The workhorse grade for cast iron, non-ferrous, and general-purpose boring applications. Used across the MTR boring bar range.
K · N · H groups
BXC
PVD-coated, steel turning
PVD TiAlN coated grade for carbon and alloy steels. Delivers longer edge life on the small-diameter boring bars where insert wear accelerates fastest.
P · M groups
BMK
Multi-layer PVD, multi-task
The grade specified for CMR multi-task bars. Multi-layer PVD coating handles the variable cutting conditions of simultaneous boring, turning, and facing in one pass.
P · M · K groups
TNX
Stainless & super alloys
Specified for CBR chip-breaker bars. Nano-layer PVD coating with high toughness substrate — built specifically for the work-hardening and heat-generation characteristics of stainless and Inconel.
M · S groups
ISO material groups

Cutting data for every ISO group

Full cutting data tables in the catalogue cover all six ISO groups. Recommended starting point: 0.01–0.03 mm/rev feed on boring operations.

P
Carbon & Alloy Steel
M
Stainless Steel
K
Cast Iron
N
Non-Ferrous / Aluminium
S
Super Alloys & Titanium
H
Hardened Steel
Quick-reference specifications

The numbers on the drawings

Parameter Specification
Min. bore diameter 0.3mm (MTR series)
Boring bar shank Ø 3mm – 10mm
Grooving tolerance B±0.025mm (MGR / MKR)
Recommended feed (boring) 0.01–0.03 mm/rev
Threading profiles ISO, UN, NPT, ACME, Stub ACME, Trapez DIN103, MJ, UNJ, BSP, BSPT, Whitworth
Groove width (MGR) 0.5mm – 3.0mm
Toolholders SIM 22S (Star), SEMK / SEMV / SEMR

The Tiny Tools range was designed around one constraint: everything has to work at diameters most tooling systems can't touch. The 0.3mm minimum bore on the MTR series isn't a marketing figure — it's the point at which the bar geometry was engineered to remain rigid enough to hold tolerance under real production cutting conditions.

The ±0.025mm grooving tolerance on MGR and MKR inserts is a manufacturing spec, not a best-case figure. It means your O-ring and snap-ring groove dimensions are defined by the insert, not by operator feel or machine compensation. For high-volume Swiss-type production, that consistency is what keeps parts in tolerance across a full shift.

Full cutting data for all ISO material groups — starting speeds, feeds, and depth-of-cut recommendations — are in the catalogue. Every insert links directly to its matching toolholder range, so you can spec the complete setup in one place.

Engineering details

Why this tooling performs
where others don't

🌀
Through-coolant spiral flute (CMR)
The CMR multi-task bar combines a spiral flute geometry with internal through coolant. The spiral drives chips out of the bore while coolant reaches the cutting edge — critical when you're boring, turning, facing, and chamfering in a single pass without a pilot hole.
💠
Two-bore coolant on MVR deep face grooving
MVR deep face grooving bars carry coolant through two separate bores to the cutting zone. Dual coolant means consistent chip evacuation from deep radial grooves where a single flood-coolant stream can't reach. The result is fewer interrupted cuts and a cleaner groove floor.
🔷
No pilot hole — CMR multi-task entry
The CMR bar enters a blank bore and machines it to final diameter while simultaneously turning the OD, facing the shoulder, and chamfering the entry — all in one tool path. No pre-drilled pilot hole needed. Reduces cycle time and the number of tool changes on Swiss-type and multi-spindle machines.
🧲
TNX nano-layer PVD for work-hardening materials
Austenitic stainless and Inconel work-harden rapidly under the cutting edge. TNX's nano-layer coating structure maintains a sharp edge longer under these conditions than conventional PVD grades — reducing edge build-up and the surface tearing that scraps medical and aerospace components.
📏
Neck length range L1–L40 (MTR)
40 distinct neck lengths on the MTR boring bar family means you can match the tool to the actual bore depth of your component rather than running excess overhang. Less overhang means less vibration at sub-millimetre diameters — and that directly translates to surface finish and dimensional stability.
Why Protool

We hold stock.
We know the tooling.

01
Same-day dispatch on stock items
Order before 4:30pm and it leaves the same day. We hold Carmex Tiny Tools from stock — not drop-shipped from a European warehouse. When a Star machine is down waiting on a boring bar, same-day matters.
02
Technical support from machinists
The people answering the phone at Protool have run these tools on machines. If a CBR bar is chattering in your Inconel bore, we know what to change — because we've fixed that problem before. Not a call centre. Not a catalogue reader.
03
F1 supply chain experience
Carmex Tiny Tools have been running in Formula One supply chains. We know the documentation requirements, the first-article expectations, and the lead-time pressure that comes with motorsport manufacturing schedules. We work to those standards.
04
Full catalogue — not cherry-picked lines
We carry the entire 2025 Tiny Tools metric range — all seven tool families, all four carbide grades, all holder configurations. You won't find a gap in the range that forces a second supplier into the mix.
05
Cutting data support included
Not just a box of inserts. We'll work through the cutting data with you — speed, feed, depth of cut, coolant strategy. The Carmex catalogue has full tables for every ISO material group. We help you read and apply them.
06
Account pricing for regular buyers
Running Tiny Tools at volume? We set up account pricing that reflects it. No negotiating individual orders — just consistent pricing tied to your actual usage, with invoicing terms that suit a production shop.
Common questions

Questions we get asked
before a first order

The MTR miniature boring bar series reaches a minimum bore diameter of 0.3mm. At that diameter the bars are running at feeds of 0.01–0.03 mm/rev. The catalogue lists neck lengths from L1 through L40 — you match the neck length to your bore depth to minimise overhang and control vibration. For reference, the shank diameters run from 3mm to 10mm depending on the series.
The SIM 22S series is designed specifically for Star Swiss-type lathes, covering both X and Y-axis turning configurations. For stationary boring and turning operations, SEMK square-shank holders are the standard configuration — compatible with SEMV and SEMR variants. If you're setting up a new Swiss-type application and want confirmation on which holder fits your machine's tool station, contact us with the machine model and we'll specify it directly.
The MIR internal threading bars cover a wide range: partial profile 55° and 60° (for turning any pitch in that angle), and full-form inserts for ISO metric, UN, NPT, ACME, Stub ACME, Trapez DIN103, MJ, UNJ, BSP, BSPT, and Whitworth. Minimum bar diameter is 3mm. If you're machining instrument bodies, implant components, or hydraulic fittings — most of the thread standards you'll encounter are covered.
MGR is the standard internal grooving bar — produces parallel-sided grooves (O-ring profiles, snap-ring grooves, retaining features) in widths from 0.5mm to 3.0mm with a B±0.025mm width tolerance. MKR is the full-radius grooving bar — the insert has a curved bottom geometry that produces a groove with a full-radius floor, toleranced at R±0.025mm. Use MGR for flat-bottom grooves, MKR where the drawing calls for a radius base — typically curved-profile sealing features.
Yes. The CMR is designed to enter a solid billet or casting without a pre-drilled pilot. The through-coolant spiral flute geometry clears the entry cut progressively — boring the ID, turning the OD, facing the shoulder, and chamfering the entry in one tool path. The grade is BMK with a multi-layer PVD coating to handle the varied cutting conditions of that combined operation. It reduces cycle time significantly on Swiss-type and multi-spindle machines where tool changes are the biggest constraint on cycle time.

Ready to run Tiny Tools?

Get the 2025 metric catalogue, request a sample bar, or talk to us about setting up account pricing for regular orders. We hold stock and we know the range.

View Full Range Download Catalogue Talk to Technical