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best router bit for through cutting?

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  • best router bit for through cutting?

    I'm making a circular mirror and will be using a router compass to cut the frame to shape. When I did this before, I used a cheap straight cutting bit which took many passes and burned the wood. I'm going to buy a new bit for my next mirror made from cherry. Should I go for a good quality sraight cutting bit or one of those spiral bits? If so, what diameter would be best? I'll likely be purchasing a Freud bit since HD is close to me.

  • #2
    If you are cutting close to the shape with a jig or band saw and then using the router compass to trim to exact shape either bit would do the job. If you are plowing the bit through the center of the cherry to make the shape I would go with the spiral and a 1/4" diameter either up or down spiral just make sure the visible surface is on the appropriate side of the bit. If you are making a few of these you may want to think about making an MDF pattern and then you could cut to rough shape with a jig saw and use a pattern bearing bit to cut to exact shape.


    • #3
      Upcut spiral for through cuts - and I would still take it in a few passes. If you find an upcut leaves the surface edge a little rough, make your first pass 1/16" to 1/8" deep with a downcut spiral then switch to the upcut. This technique is particularly useful if you're ever cutting veneered material. These really want a plunge router.

      If you use a pattern bit, you'll be wanting the router table mounted for best results. This is the only method I would use with a fixed base router.

      Most of the circle work I've done has been for speakers with a homemade circle jig.

      If you are cutting the middle out, you'll not be able to cut through 100% your last pass - though I find I can throughcut just fine if I leave only a few 1/8" wide sections of the last layer un-cut, then flip the finished piece, snip through the tabs, and use a flush-cut bit to smooth them to the rest of the hole. This is only viable if you make multiple passes, but if you don't do this, you stand a huge chance that the center waste will wobble and make a non-round cut, or worse.