Capto interface: the versatile standard for combined turning and milling
Where ISO, BT, CAT and HSK all rest on a circular taper shank, Capto uses a flat-seated polygonal geometry. It is the only system designed from the outset for turning, milling and drilling on one interface.
A polygonal geometry built for versatility from the start
TLDR: A polygonal form combined with a flat seat, standardised as ISO 26623, designed from creation to serve turning, milling and drilling on the same machine.
Developed and launched in 1990 by Sweden's Sandvik Coromant, the Capto interface differs fundamentally from the other standards in its geometry. Where ISO, BT, CAT and HSK all rest on a circular taper shank, Capto uses a polygonal form with a flat seat, now codified by ISO 26623.
The design handles torque transmission and centring simultaneously, with solid axial positioning and high torsional resistance. Its distinguishing claim, made from the design stage: it is the only toolholding system conceived for every type of machining on one interface, rather than built for one use and adapted afterwards to the others.
Why Capto took hold on multitasking centres
TLDR: On a turn-mill centre, where one turret takes tools of very different natures in succession, Capto's native versatility avoids multiplying interfaces and simplifies tooling management.
The rise of multitasking centres, able to perform on one machine what previously needed several stations, created a specific need: an interface able to take a fixed turning tool, a driven milling spindle or a drilling tool without changing mechanical standard.
That is precisely Capto's ground. Its versatility avoids multiplying interfaces on one turret and simplifies tooling logistics in the workshop — which explains its growing presence on modern CNC lathes and multitasking centres, alongside HSK interfaces, which are more specifically oriented towards high-speed milling.
What sets Capto apart
- Flat-seated polygonal geometry, as against the circular tapers of the other interfaces
- Native versatility — turning, milling and drilling on one interface, with no adaptation
- Several standardised sizes, C3 to C10 depending on the maker, covering a wide power and torque span
- Growing adoption on multitasking centres, alongside HSK standards on dedicated milling spindles
When to favour Capto
Capto is at its best on machines combining several processes at one station: turn-mill, multitasking centres, and more broadly any application where tooling flexibility matters more than specialisation in a single process.
For a machine dedicated exclusively to high-speed milling, HSK remains the most widespread and best documented standard. For a conventional lathe with no need for versatility, the ISO, BT and CAT standards are amply sufficient, and cheaper both to buy and to maintain.
Frequently asked questions
Is Capto compatible with HSK, ISO or BT?
Not directly: its polygonal geometry is incompatible with the circular tapers of the other standards. Adapters exist for some configurations, to be checked case by case.
Which Capto size should I choose?
It depends on the power and torque your machining requires. Several standardised sizes exist — a technical review settles the right reference.
Is Capto restricted to Sandvik machines?
No. Although developed by Sandvik Coromant, Capto is now an open standard used by many machine builders and tooling manufacturers.
Can a Capto spindle be converted to another standard?
Sometimes, depending on the spindle design, but it means heavy work. Contact us for a feasibility review before committing to anything.
Do you work on spindles and turrets with Capto interfaces?
Yes. We diagnose and overhaul these assemblies on the same footing as spindles with conical interfaces.
Expertise on Capto-equipped spindles
We diagnose and overhaul spindles and turrets with Capto interfaces, including checks on the polygon and the flat seat, on which centring accuracy directly depends.
Our teams are available from our sites in Beaurepaire (France) and Lussery-Villars (Switzerland).
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