How to tell plunge router bits from non-plunge router bits.

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    Internet Fact Checker
    • Dec 2002
    • 21082
    • Katy, TX, USA.
    • BT3000 vintage 1999

    How to tell plunge router bits from non-plunge router bits.

    Do you guys know your router bits?

    Do you know how to tell a plunge bit from a non-plunge bit?

    A non plunge bit has cutters around the periphery, but not the center. It can enter grooves from the side and cut moving sideways. Click image for larger version

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    A plunge bit has cutters that go all the way to the center of the bit face. It can cut moving vertically as well as sideways.

    Click image for larger version

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    Above see the bar across the center as well as the two edge cutters? Without this bar, when you drive the bit straight down the dead spot in the middle will prevent plunging (just burns) unless you crush the wood. Can't use a non plunge bit on a plunge router to enter a hole vertically... like you would for a lettering template bit or a stopped groove where you have to drop the bit in vertically and then move it sideways. It has to cut its way in on the plunge, then cut on the side when you move it.

    Here is another pictorial anatomy of a plunge bit
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    Note that the following round nose bits are plungeable because the cutters go all the way to the center.
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    Last edited by LCHIEN; 02-06-2021, 11:10 AM.
    Loring in Katy, TX USA
    If your only tool is a hammer, you tend to treat all problems as if they were nails.
    BT3 FAQ -
  • GrumpyDad
    Established Member
    • Jul 2020
    • 165
    • Midwest
    • Ryobi BT3100, BT3000, Sawstop PCS

    Thank you for this article. I have strays that needed clarification.


    • cwsmith
      Veteran Member
      • Dec 2005
      • 2745
      • NY Southern Tier, USA.
      • BT3100-1

      Thanks Loring,

      As usual, you always bring knowledge and wisdom to this forum.

      Thanks and Merry Christmas to you and your family,

      Think it Through Before You Do!


      • leehljp
        Just me
        • Dec 2002
        • 8469
        • Tunica, MS
        • BT3000/3100

        Unfortunately, (or is it fortunately?) I learned that in the school or hard knocks. I have owned a plunge router since the mid '80s and quickly learned the necessities of a full cutting edge around the bottom. But it has only been since Loring posted the thread on signs that I started using brass guides.

        Before that, I made jigs for the base of the router to guide the plunge and cuts.

        That said, My mind has been running wild with templates for plunge and inlays. I started looking at templates and they are expensive and not nearly as creative (wide a variety) as I would like, Then it dawned on me after doing a couple of signs: I have a good Scrollsaw and I can do graphics fairly well on the computer, and size them accordingly - just make my own. I also thought of choosing my own fonts and scroll sawing a set in the perfect size on the Scrollsaw. It would not be difficult to print out the letters the size of the bushing/guides and attach them with spray adhesive to 1/8" plywood to cut out.
        Hank Lee

        Experience is what you get when you don't get what you wanted!


        • Jim Frye
          Veteran Member
          • Dec 2002
          • 1051
          • Maumee, OH, USA.
          • Ryobi BT3000 & BT3100

          When I bought my first router (early 90s), it was a Ryobi R700 plunge router. I didn’t have much money for tools back then and bought router bits from the same mail order house (Trend Lines) that I bought the router. They had an in house line of bits that I used because they were much less than the other bits available. All of the straight bits had the extra cross cutter at the end. Never gave it a second thought until years later when I bought a Bosch straight bit that lacked the cross cutter. Yes, I had been plunge cutting with the old bits for years. They worked well enough that I never considered buying any of those spiral bits.
          Jim Frye
          The Nut in the Cellar.
          ”Sawdust Is Man Glitter”