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I am trying to install these hooks to hang some plants. https://www.amazon.com/gp/product/B08BKSXSMZ/

They say to use a 15/64 drill bit to pre-drill when using the wall anchors. However, I will be installing into a ceiling stud. So I don't need the anchors (I think). How do I figure out what size drill bit to pre drill with? Do I just use whatever is small than the screws?

Alternatively, should I just go and buy my own screws since they will likely be better quality?

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    Pre-drilling is not a waste of time here because at least one of the screws will be near the edge of the board, and you certainly can get all three screws into wood. For that reason alone it's worth doing or the screw can either split the edge off the board or simply deflect off it. Comment-answers flagged for deletion.
    – isherwood
    Jul 24, 2023 at 12:51
  • Bear in mind that the fittings provided both accept the full length of the screw (30mm, 1.18 inches). If you are drilling through a drywall ceiling into a stud, the drywall part is not holding anything up, so you only have about half of the screw length into wood. I would upgrade to at least 40mm/1.5 inch screws. Jul 24, 2023 at 17:03

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Here is a DIY method to determine the pre-drill size.

Hold the screw and find a drill bit and hold it over the screw (parallel) that visually covers just the body (the inner part) of the screw.

You must fully see the screw threads on both sides.

Next choice depends of the hardness of the material you drill into. For a soft material, use the next smaller drill bit.

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    This guy gets it. I was trying to figure out how to put this into words and @Ruskes already got there.
    – RQDQ
    Jul 25, 2023 at 1:34
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    and if your eyesight is not great, step down 1 size. Pilot holes too large is worse than too small.
    – Nelson
    Jul 25, 2023 at 2:36
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Alternate "empirical" answer: take a drill bit that is about a quarter of the diameter of the largest part of the screw (either the straight part just under the head, or the threads themselves) and use that.

Drive the first screw. If you struggle to turn it, drill again with the next size up. This method gives you the right size of pilot hole regardless of the type of wood you are drilling into.

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Like STS1SS said you really could get away without predrilling at all since your chances of splitting a joist/rafter with a screw that size are very low.

However I normally still predrill any non self drilling screws. For pine I will use basically Ruskes method but I will go 2 or 3 sizes down not just 1. The dimensional lumber in your ceiling is going to be either pine or fir and they can be very soft so if you drill too big of a pilot hole it can be very easy to strip the hole out.

I think it's also worth noting that the size of the base plate on those hooks will make it difficult (not impossible) to get all 3 screws into wood. It looks like if you can perfectly find the center of your stud you can easily get 1 screw in the middle and then drill the other two inward at an angle to ensure they bite.

Personally I would line it up so that two screws go into the center of the stud and the third screw goes into a drywall anchor. If you angle the screws into the plate they wont sit flush when tightened and might stand out.

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  • +1 for pointing out that not all three screws are going to go into the stud. The awful Amazon description isn't clear on the distance between the holes, but I would do the same as your suggested to be sure you're getting two screws in the stud. Otherwise you'll probably end up with one in the stud and two not doing anything on the edges. Jul 25, 2023 at 14:34
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If you're going to attach to a ceiling joist, don't use those hooks you linked. It will be significantly easier and at least as strong to use a hook with a single screw into the center of the wood.

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What Ruskes said...

But to directly answer your question; the screw size recommended in the docs is for the drywall anchors. If you anchor into a stud, you don't really need to pre-drill. Pre-drilling serves a couple of purposes: first to prevent the media you screw into breaking out, and second to provide a good surface for the drywall anchors to gain purchase (grab). You aren't using the drywall anchors, so you have to consider the first reason. Because you aren't worried about breakout (tearing the stud) it becomes unnecessary.

Don't worry about it.

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