I have a 100 x 75mm fence post and want to cut a notch for a 70 x 45mm rail. If I cut the notch the full thickness of the rail it would only leave 30mm on the post. I'm assuming that's too much. Could I cut half of the 45mm thickness of the rail from the post and half from the rail? That would leave over 50mm on the post.

  • "I have a 100 x 75mm fence post and want to cut a notch for a 70 x 45mm post." I think there is a typo here that makes the question hard to understand.
    – Charles
    Dec 19, 2019 at 2:01
  • I've edited the question, changing the second reference of post to rail. If this is incorrect, reverse the edit.
    – fred_dot_u
    Dec 19, 2019 at 2:14
  • Orient the post so you cut the notch in the 100mm dimension.
    – Solar Mike
    Dec 19, 2019 at 5:54
  • @SolarMike That's a good suggestion but I'm not able to do that for various reasons.
    – user82609
    Dec 19, 2019 at 7:12
  • @jrcollins is that because you have put them in already the wrong way round?
    – Solar Mike
    Dec 19, 2019 at 7:14

1 Answer 1


Based on the understanding that the second reference to post means a reference to rail, your approach is sound. You'll be removing the minimum amount from both components while retaining the maximum strength for both.

Removing half from each means that the rail will be offset in the post and not flush with either edge, which is not particularly a problem, unless the esthetics are critical.

  • 1
    Sorry, I meant notch 22.5mm from both the rail and the post. That would mean the thickness of the rail is halved and over 50mm is left on the post. The outerface of both the rail and post would then be flush.
    – user82609
    Dec 19, 2019 at 3:04

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