I used a 10mm masonry bit to drill for a 10mm plastic anchor like that pictured. The anchor spins freely in the hole, which I think is expected. I thought I read somewhere that the screw size should be 2mm less than the anchor. Thus 8mm for a 10mm ø anchor. But an 8mm screw is fat enough to rub sides of the anchor as it is inserted because I suppose the anchor is only 1mm thick at the opening. The guy at the shop confirmed that 8mm is too big. He said a 6mm screw matches and sold me those. After installing and loading, the anchor started to pull out.

Do I need a 7mm ø screw? Odd sizes get decreasingly common above 5mm. Yet 10mm sleeves are very common… so it’s not adding up.

I would like to have a reliable PDF chart of bore,anchor, and screw sizes – in metric. It seems there are plenty of such charts for Imperial/English units, like these:

I’m not sure what a “#10” screw or anchor is. Does that refer to the metric size despite being in an imperial system.

  • diyrebel@lemmy.dbzer0.comOPEnglish
    0·
    6 hours ago

    Plastic ribbed anchors will work on concrete/brick/masonry (though I assume only solid brick, which is what I have).

    The difference is load. One of the charts I linked gives a quite low load rating for plastic anchors compared to metal ones. I think they have incorporated a big safety factor but in any case I am below the load limit.

    Worth noting that pro scaffolding installers drilled holes in my brick and used this same shape of ribbed plastic to secure scaffolding that workers’ safety depends on. Those were very long 12mm anchors IIRC.