I am attaching curtain rail holders into a wall for installing a door curtain. I have drilled four holes (two for each bracket) with diameter 6 mm and depth 50 mm, in a wall which appears to have ~12 mm plaster followed by brick or concrete (I was only able to continue drilling beyond 12 mm with a hammer drill). I bought these anchors into the hole, but when I try to insert the screws, the first bit works fine but I am unable to screw them in completely; as I progress there is more and more force required to continue screwing, but for the last 5 mm I am damaging the head rather than making the screw enter. When I insert the screw into the anchor outside the wall, it goes in almost completely but breaks open the end of the anchor and widens it. Inside the wall there is no space for it to do so; I suspect this is why I can't strew them in completely? The anchor package illustrates a hammer (apparently it is a "hammer-in plug") but part of the curtain rail holder is in the way, so we can't completely hammer it in either.

Do I have the right anchors/plugs and screws for this job? Initially I had the hole 6 mm wide and 40 mm deep. Based on advice I deepened it, now it is 6 mm wide and 50 mm deep. Does it need to be wider than 6 mm?

Mounting with plug and screw

Wall with plug



  • Mounting bracket, inner diameter: 4.81 mm
  • Screw cylinder (smooth part): 4.29 mm
  • Screw head: 8.8 mm
  • Plug: 5.82 mm
  • Plug head: 9.32 mm
  • Plug with screw inside (outside wall) expands to: 9.2 mm
  • Show us some pictures of the hole and the anchors
    – Jeff Cates
    Commented Feb 11, 2017 at 21:28
  • It sounds like the drill bit is under sized for the anchor.
    – Ed Beal
    Commented Feb 12, 2017 at 3:31
  • @EdBeal The anchor fits but someone else told me the hole should be deeper than the anchor, we will try that today.
    – gerrit
    Commented Feb 12, 2017 at 10:46
  • @JeffCates I have added some photos.
    – gerrit
    Commented Feb 12, 2017 at 12:07
  • I'm unclear how your bit is spinning in those screws. Torx screws hold a bit extremely well. Yous should almost break the screw before it strips, unless your holes isn't deep enough. Are you using the correct bit?
    – isherwood
    Commented Feb 12, 2017 at 12:15

1 Answer 1


I was using the wrong kind of plugs/screws. The plugs I was using were hammer-in plugs and the screws correspondingly. Those were not designed for the task.

I bought this package of plugs and screws instead and now all is good.


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