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I was cleaning out my collection of masonry bits and found the two shown in the accompanying picture.

They are from a remodeling project from 20 years ago, but I do not recall where they came from (or why I bought them). I thought at first they might be some kind of mortar rake. Anyone see these before or have an idea what they might be?

enter image description here

isherwood
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Bob Sjoberg
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4 Answers4

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I know this tool as a rotary rasp. Well, it's a drill bit with an integrated rasp, presumably to facilitate quick cutouts in soft materials. They're apparently fairly rare, possibly a short-lived gimmick.

In modern times you're more likely to use a rotary cutter like a Rotozip™, or maybe an oscillating tool.

Here's a more common rasp without a drill tip.

enter image description here

isherwood
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They are "routing drill bits". I have a set that are at least 40 years old. I still have them because they really have had limited use and are difficult to use precisely. They don't work well except possible in drywall.

mikes
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The ones I've got were sold as "drill files" and look almost identical to the picture. The only real uses I've found for them are:

  • slightly opening up holes in thin material (when the increase is less than a step of my step drill).
  • deburring, though I ve got other tools that do a better job of that, especially with access to both sides.

They're not very easy to control so don't give a nice finish.

Chris H
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They’re called side-cutting bits. I recently bought some on Amazon to slightly shift a mis-drilled hole to be about 1/2 a diameter lower

https://a.co/d/3JDLget

Retired GC
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