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

    Why were you drilling if it’s an existing hole?

    It was not a freshly drilled hole. I would always use the same size bit as the anchor diameter so I remembered that. A 10mm anchor in a 12mm hole would also be very loose which is not the case here.

    I just now drilled a bit more after realising that the anchor should probably be flush with the brick, not the 10mm of plaster layered on top of it.

    You’re using a masonry bit with a hammer setting right?

    Yeah, and in fact it’s not just a hand drill with a hammer setting but a proper ~10kg hammer drill with a shock absorber, a grease reservoir, and STS mounted bits (or whatever they are called). Before I bought this big gear that makes me feel like Rambo, I used a standard drill with hammer setting on poured concrete and it melted one of my bits because it had a weak hammer and spun fast enough to make the bit molten red hot.

    I wouldn’t re-use this thing. This is the cheap type that comes free with things that need to be fixed to a wall.

    Maybe too late to change now but I might consider a different anchor if it fails to hold my bicycle. I ended up drilling 10mm deeper so that I could push the anchor to be flush with the brick (thus 10mm recessed below the plaster layer). I also added a metal shard about the size of a toothpick between the anchor and brick. It’s holding for now but does not feel rock-solid.