What pilot hole size is for 6.5mm diameter self tapper pan head screw? For TV mount.

Forums › Home Workshop DIY › What pilot hole size is for 6.5mm diameter self tapper pan head screw? For TV mount.

Huchiz

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#177782 14-Aug-2015 01:02

I'm relocating the TV mount installed by the previous owner. The mount uses 3 6.5X60mm self tapper pan head screws with Philips drive. （I measured the screw size by myself, so that's the rough number.)

So for the new location, how big the pilot hole I should drill into the stud? To mount a TV is so far the most risky home DIYs I have ever done. Would like to play safe. :-D

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#1365993 14-Aug-2015 04:16

I wouldn't go any bigger than 5 mm. To play it safe, drill an experimental hole in a spare block of wood and check how tight the screw fits.

Bung

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#1366006 14-Aug-2015 06:55

Rubbing the screw thread against a block of soap fixes tight.

frankv

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#1366018 14-Aug-2015 07:07

Just checking... you say "self-tapping" and also "stud". So you're going to mount a TV on the wall of your house? In which case, do you have actual wood screws, or self-tapping screws, which are quite different?

In either case, 6.5mm seems to be very large.

Bung

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#1366043 14-Aug-2015 07:39

6.4mm (1/4 inch) is not large, TV brackets often use 8mm coach screws.

JayADee

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#1366044 14-Aug-2015 07:46

With something that important I agree with a test in a block of scrap! What I usually do is put the bit behind the screw or vice versa, eyeball them and choose a bit slightly smaller than the outside threads of the screw. I also roll both between my fingers together to get a feel for the size difference. Then because we have rimu nogs if I need the hole a tad bigger (hard to screw into rimu or tawa) I'll just reem it out a bit by inserting the bit and pulling it out again a few times with the bit running to enlarge the hole. I also prefer to use a manual screwdriver.

1eStar

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#1366047 14-Aug-2015 08:03

Hold the screw and a drill bit up to the light and eye ball them. Put the drill behind then infront of the shank. If the diameter of the drill is less than the shank, you'll have a hard job driving the screw. If the diameter of the drill is bigger than the threads, it won't hold anything. With soft timber like pine you can get away with the pilot size less than the shank. But hard wood you often get close to the OD to be even able to drive by hand. As suggested, soap or candlewax are good lubricants.

Edit: autocorrect fail

Fred99

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#1366077 14-Aug-2015 09:07

Unless it's an old house with rimu framing, I wouldn't drill a pilot hole at all, except perhaps a 1.5 or 2mm hole to check you've got it centred on the stud.
Pilot hole for rimu because it's so hard that you risk breaking the screw, but 4mm pilot hole should sort that.
I'd dump the pan head self-tappers and get some hex drive self-drilling tek screws of appropriate size, and a driver bit for them (only a few $)
The self tappers that were used probably came with a kit with the bracket, and were probably intended to be used with rawl plugs for fixing into concrete walls, not for fixing in to timber.
Posi/phillips head screws for secure fastening of hardware to timber are an abomination, even worse when they're not the right type of screw. Throw them out, and do it properly.

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DarthKermit

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#1366078 14-Aug-2015 09:08

You didn't mention how large and heavy your TV is. Some of these 75+ inch behemoths that are available now are very heavy.

Jaxson

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#1366093 14-Aug-2015 09:29

DarthKermit: You didn't mention how large and heavy your TV is. Some of these 75+ inch behemoths that are available now are very heavy.

And vice versa, in that the LCD TV's are very light in comparison.
Plasma had real glass on the front which added to the weight there also.

Huchiz

221 posts

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#1366167 14-Aug-2015 11:06

frankv: Just checking... you say "self-tapping" and also "stud". So you're going to mount a TV on the wall of your house? In which case, do you have actual wood screws, or self-tapping screws, which are quite different?

In either case, 6.5mm seems to be very large.

I'm no expert. This is the screw. Please advise.

ubergeeknz

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Vocus

#1366168 14-Aug-2015 11:07

That's not a wood screw. It'll work but it's not really the right screw for this job.

DarthKermit

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#1366218 14-Aug-2015 11:17

What Fredd99 mentioned above is a better choice. They look like this:

and come in various lengths from about 20 mm to 100 mm. I wouldn't skimp on the length that you use.

Huchiz

221 posts

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#1366223 14-Aug-2015 11:23

Fred99: Unless it's an old house with rimu framing, I wouldn't drill a pilot hole at all, except perhaps a 1.5 or 2mm hole to check you've got it centred on the stud.
Pilot hole for rimu because it's so hard that you risk breaking the screw, but 4mm pilot hole should sort that.
I'd dump the pan head self-tappers and get some hex drive self-drilling tek screws of appropriate size, and a driver bit for them (only a few $)
The self tappers that were used probably came with a kit with the bracket, and were probably intended to be used with rawl plugs for fixing into concrete walls, not for fixing in to timber.
Posi/phillips head screws for secure fastening of hardware to timber are an abomination, even worse when they're not the right type of screw. Throw them out, and do it properly.

I will go to mitre10 bunnubgs this weekend, hopefully will talk to some knowledgeable staff.

So you say I better choose another kund of screw? Please see my uploaded photo. thanks.

ubergeeknz

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Vocus

#1366233 14-Aug-2015 11:38

DK has posted an appropriate type of screw above. I believe they're commonly known as lag bolts(at least if they are bigger, they are). Just drive with a socket but not too hard, you can break them, if you're needing a lot of force back it out, drill a bigger pilot.

Huchiz

221 posts

Master Geek

#1366234 14-Aug-2015 11:39

DarthKermit: You didn't mention how large and heavy your TV is. Some of these 75+ inch behemoths that are available now are very heavy.

It's a smallish 40 inch, weights about 11kg. Previous owner had a last generation 32 inch on the mount. I checked that ccfl 32 LCDs are about 9-10kg. So I think weight shouldn't too demanding.

My concern is that the mount has a narraw base which will only attach to 1 stud. There are three screw holes s on the base from top to bottom, with slightly off center to left and right. There is plenty of space between each holes. Im thinking of drilling a new hole jist below the top hole, make it 4 screws, to make it stronger especially on the top side.

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