Cutting a circle with a router

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  • LCHIEN
    Internet Fact Checker
    • Dec 2002
    • 21104
    • Katy, TX, USA.
    • BT3000 vintage 1999

    Cutting a circle with a router

    Cutting a 6-1/2" circle in 3/4 thick material. GOing to do 8 of them.
    Using a homemade circle jig - a piece of wood with a 1/4" pivot hole and a 1/2" hole for a 1/2" template guide busing in the router base. Holes separated 3-1/8" (radius less half a bit width)

    Going to use a router with a 1/4" spiral carbide bit. FROM EXPERIENCE i know that if you try to take too deep a cut with these they will break. So I usually take 1/8" per pass.

    A: Should I cut all 8 workpieces at one depth and then 8 times at the second depth etc swapping all eight workpieces 6 times. I could use the fixed base since I only have to change depth of cut height 6 times.

    or

    B: Should I cut each board making 6 passes and then change boards? I would use the plunge router because I have to make 48 total height changes.

    I know I did this before but I don't recall how I did it.

    Workpieces are panels 11" x 33"

    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 - https://www.sawdustzone.org/forum/di...sked-questions
  • twistsol
    Veteran Member
    • Dec 2002
    • 2912
    • Cottage Grove, MN, USA.
    • Ridgid R4512, 2x ShopSmith Mark V 520, 1951 Shopsmith 10ER

    #2
    I would have to say neither. It is far faster to cut them carefully with a jigsaw and then trim them with the router than to do 6 passes with the router. If you own a bandsaw, setting up a circle cutting jig would faster still.

    If I were to do it strictly with the router, I'd grab a 1/8" shim, set the router so it touches the surface to be cut and then drop the depth stop rod onto the turret with the 1/8" shim between the rod and the turret . Remove the shim and plunge to make your first pass. For each subsequent pass, lock the router at the full plunged depth and reset your depth stop by adding the shim and repeat the process. I guess that would be Option B.


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    Chr's
    __________
    An ethical man knows the right thing to do.
    A moral man does it.

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    • LCHIEN
      Internet Fact Checker
      • Dec 2002
      • 21104
      • Katy, TX, USA.
      • BT3000 vintage 1999

      #3
      Bandsaw out of the question. Need the hole (unbroken), not a circle and the workpiece too big.
      jigsaw, maybe. Followed by a router and template.
      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 - https://www.sawdustzone.org/forum/di...sked-questions

      Comment


      • leehljp
        leehljp commented
        Editing a comment
        "jigsaw, maybe. Followed by a router and template." That is what I would probably do.
    • dbhost
      Slow and steady
      • Apr 2008
      • 9256
      • League City, Texas
      • Ryobi BT3100

      #4
      If it were me, and mind you I can be an idiot, I would do one disc at a time, one depth at a time. And yes, do not take off more than about 1/8" per cut. It'll take a while, but you, your router bit, and your work piece will be better off for it. That is actually why I went from 1/4" to 1/2" shank bits in the first place.. And now partially back out of necessity.
      Please like and subscribe to my YouTube channel. Please check out and subscribe to my Workshop Blog.

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      • LCHIEN
        LCHIEN commented
        Editing a comment
        " I would do one disc at a time, one depth at a time" not clear

        One disc at a time, running thru all depths and finishing before going to the next disc?

        or one disc, one depth, then 7 more disc at that depth then repeat 8 disks at the second depth. and so on?
        Last edited by LCHIEN; 04-22-2024, 01:49 PM.
    • LCHIEN
      Internet Fact Checker
      • Dec 2002
      • 21104
      • Katy, TX, USA.
      • BT3000 vintage 1999

      #5
      I decided to use the plunge router - its made for incremental passes; it has that stepped turret - and didn't want to be shuffling the workpieces 48 times.
      Went pretty smoothly.
      Observations:
      • My circle jig is pretty beat up. May have to "splurge" and "buy" a new one. J.K. its a piece of scrap wood. Does have a lot of holes in it.
      • Router worked fine. I like the Bosch Quick change template guides
      • I thought I was clever and used a flattened corrugated cardboard box as the backing instead of sacrificing a good piece of panel wood.
      • I got 8 free wheels I need to find a project for.
      • I had moment of panic when I pulled a set of brand new spiral bits and they were all too short... apparently 1-1/2" overall length. Fortunately I found a 2" OAL one in my box of bits that did the job.

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      Last edited by LCHIEN; 04-25-2024, 12:02 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 - https://www.sawdustzone.org/forum/di...sked-questions

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