Extensions
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Core bit extensions for deep core drilling
An extension is fitted between the spindle and the drill bit, increasing the drilling depth by its own length. A core bit with a working length of 450 mm, when used with a 500 mm extension, drills to a depth of around 950 mm, passing through insulated external walls, foundations and ceilings in a single pass, without the need to reposition the drill or start from the other side.
M16 from 32 mm, 1 1/4" UNC from 52 mm
| Extension | Lengths | Thread | For core bits | Tool |
|---|---|---|---|---|
| Extension 1 1/4" UNC | 100 / 250 / 500 mm | 1 1/4" UNC | from 52 mm | 202 series and stand-guided |
| Extension M16 | 180 / 280 mm | M16 | from 32 mm | DKB102/H, M16 core bits |
The minimum diameters are determined by the wall thickness of the extension: a core bit must fit inside the extension tube to allow space for the core. The 500 model is most effective in a drill stand, such as the KBS352/XL-PRO with a 1600 mm stroke.
Lengths 280 to 500 mm
180 mm is sufficient for internal walls, 280 mm for external walls and ceilings with M16 core bits. The 1 1/4" UNC spindle offers 100 mm for compensation, 250 mm for standard walls and 500 mm for foundations. Extensions can be combined, but each connection adds a little more imbalance, so use them carefully and with a steady hand. Copper rings between the spindle, extension and core bit prevent the threads from seizing up after drilling.
That’s why you should choose extensions from Kernlochbohrer.com
The threads and diameters are compatible with our core bits and equipment. Over 5,000 professionals trust us, and we are Trusted Shops certified. We’ll work out the length your wall requires with you over the phone, by email or via WhatsApp.
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Do you have any questions or would you like some professional advice? You can contact us in person, by telephone, by email or via WhatsApp.
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