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Extension socket MK 4 / 3
Extension socket MK 4 / 3 is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
Delivery and Shipping
At Krollit, we guarantee a safe and reliable shipping process. Orders are handled with the utmost care and traceability until delivery.
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Upon delivery, always sign the delivery note with the words “subject to inspection” to allow for proper handling of any irregularities or discrepancies in the product.
Our goal is to ensure you receive prompt service and a worry-free shopping experience.
Extension socket MK 4 / 3
Description
Morse taper extension sleeve MT 4/3 — MT 3 tool holder in MT 4 machine spindles. Fully hardened, internal and external taper ground according to DIN 2187. Made in Austria by Bernardo; Krollit has been the official distributor in Italy since 2007.
- External taper: MT 4
- Internal taper: MT 3
- Standard: DIN 2187
- Processing: Fully hardened, ground taper
Logistics
Original spare parts available with 3–5 working days shipping. Customer support in Italian available.
Technical specifications
Technical Specifications
| Specification | Value |
|---|---|
| External taper (machine) | MT 4 |
| Internal taper (tool) | MT 3 |
| Standard | DIN 2187 |
| Processing | Fully hardened, ground taper |
Warranty
Warranty terms and support procedures are available on the dedicated Krollit page.
View Krollit warranty termsFAQ / Frequently asked questions
Frequently Asked Questions
What is a MT 4/3 extension sleeve used for and when is it necessary?
The MT 4/3 extension sleeve has an MT 4 external taper (fits into the machine) and an MT 3 internal taper (holds the tool). It allows you to mount tools with MT 3 Morse taper shanks on machines with MT 4 Morse taper spindles — the larger number is the machine taper, the smaller is the tool taper. The extension sleeve allows the smaller tool to fit into the larger spindle, maintaining DIN 2187 concentricity.
Difference between an extension sleeve and a reduction sleeve?
An extension sleeve takes a smaller taper (tool) into a larger spindle (machine): MT 4/3 → the machine has MT 4, the tool has MT 3. A reduction sleeve does the opposite — it takes a larger taper into a smaller spindle. They are not interchangeable. Always check which one you need before purchasing.
How do you remove the sleeve from the Morse taper spindle?
With the ejector pin (drawbar) that slides into the spindle hole: insert the pin from the opposite side and strike with a hammer. Alternatively, use the flat extraction wedge inserted into the spindle slot. Never force it with improvised tools — the Morse taper is self-locking and lateral force can damage the spindle.
Delivery times?
Original spare parts available with 3–5 working days shipping. Customer support in Italian available.
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