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This question is about core drilling in granite.

The pic below shows a granite formation that had core drilling performed on it.

Is it possible to ascertain the RPM of the drill that drilled the core in this piece of granite, given the following info about the striations* in the core:

  1. Thread angle
  2. Pitch
  3. Pitch diameter
  4. Major diameter
  5. Minor diameter

enter image description here

Mars Sojourner
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  • Given https://www.diamondtoolstore.com/products/diamond-core-drill-bit-for-granite-wet and they recommend the angle grinder with variable speed then what do you think? – Solar Mike Apr 10 '23 at 18:55
  • No. Different drill materials and geometries behave differently at different RPM. It's already virtually impossible to do so with a uniform piece of material, let alone something like granite. – DKNguyen Apr 10 '23 at 19:13
  • I think you would need the feed rate – Tiger Guy Apr 10 '23 at 19:15
  • @TigerGuy Well feed-rate in terms of depth per revolution is obtainable from the striations. Feed rate in terms of depth per time, which you can't obtain, is what you would need for RPM, and more importantly surface-feet per minute. – DKNguyen Apr 10 '23 at 19:17
  • @DKNguyen You said, "...the feed-rate in terms of depth per revolution is obtainable from the striations." Can you give the formula? I will figure out the math. – Mars Sojourner Apr 14 '23 at 17:13
  • Feed rate is how much the cut is advanced per revolution. The distance between in the striations is the depth advanced per revolution. That's assuming consistent feed rate which it might not if it was advanced manually and not by automated mechanism. – DKNguyen Apr 14 '23 at 18:40

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