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Bottle Neck Diamond Core Drills 6mm x 2.35mm

Eternal Tools
  • 2.35mm Shank to fit your Dremel type drills (or 3/32") and Flex Shafts
  • 6mm diameter

These unique Bottle Neck Diamond Core drills are so called because of the 2.35mm shank, allowing you to use them on your jewellery, craft and hobby projects in your pendant drill or Dremel type rotary drill (You will need a Dremel Multi Chuck to hold these drill bits). For use on glass, stone, gemstones, enamel, ceramic, porcelain, bone, shell, glazed pottery, tiles and more. If you require similar drill bits in larger sizes why not take a look at our range of Thin Wall Diamond Core Drills.

Read on for usage information and technical specifications.

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Need to use a large core drill to drill a hole? Don't like having to use a heavy household drill on your delicate jewellery and craft projects?

With a year of research and testing we have come up with the solution to your problem with these, the most popular sizes of large diamond coring drills, but with a 2.35mm or 3/32" shank. This means you can use these core drills in your Dremel hobby type drill or a pendant drill, making it lighter and easier to drill holes in all your hard materials.

So, whether you're a jeweller, glass artist, crafts person, hobbyist or scientist, these core drills have been designed with you in mind to make your life easier, so give them a try!

For use on...

  • Glass, mirror, enamel
  • Stone, gemstone, rock, pebbles
  • Ceramic, mosaic, porcelain, glazed pottery, tiles
  • Bone, fossil, shell

In order to get the best from our Bottle Neck Diamond Core Drills and To find out how to drill through glass, shell, stone, glass bottles, pebbles and more, have a look at our Tutorials section on our blog plus take a look at the tool review for these core drills.

How to Use Our Bottle Neck Diamond Core Drills:

  1. Use with plenty of cold water (changing the water if it becomes cloudy)
  2. Use on a slow speed (we recommend 5,000 rpm)
  3. Use with very little pressure

Disclaimer. Using rotary tools near water has never been, to the best of our knowledge, endorsed by any of the rotary tool manufacturers. If you do choose to drill near water or with attachments under water connected to your drill then you do so at your own risk. Please be aware that mixing electricity and water can be very dangerous.


Diamond grit is precisely electroplated onto a steel 2.35mm shank

Diameter: 6.0mm

  • Overall length: 50mm
  • Diamond tip length: Approx 4.5mm
  • Shank: 2.35mm
  • Inner Diameter: 4.0mm
  • Wall thickness: 0.75mm - 0.85mm

Questions & Answers

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Other questions and our answers

Will these bits fit the Dremel 4000-1/45 ?

Richard Williams

The Bottle Neck Diamond Core Drills have a 2.35mm shank so you can use these in your Dremel 4000 so long as you have a Dremel Multi Chuck.

I want to get a cylinder core out of stone. Is this possible?


Thanks Marianne, a good question. Yes, this certainly is possible and we have lots of customers who use them for just this purpose. However, please note that the diamond core drills are intended for drilling a hole rather than extracting a core so we cannot guarantee the precision of the cylinder.  Take a look at the technical tab to find out the internal diameter of the diamond core drills so you know which size to order. 

Do you have something that will bevel around the area of glass where I’ve just drilled my hole please? Thanks

Sara Pringle

We have a wide range of diamond files perfect for this (try the 600 grit medium diamond files) or you could try  smoothing it with a diamond hand pad. If you want to go further and create a smooth, shiny finish, then we have various polishers and abrasives that will do this.

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