Choosing size for masonry drilling

FreshlyCutFlowers

My last thread got helpful replies so trying again even though this seems more basic but I have no idea what I'm doing..!

I've acquired an 18v bosch sds drill machine and 4mm - 8mm drill bits for masonry. Screwfix also said I needed plugs (got rawlplugs), 5mm, 6mm and 7mm.

The screws that came with my child safety gate don't say size and from what I understand you don't necessarily want the drill and screw size to be the same anyway..?

How can I choose the right drill bit and plug for my screws?
The gate needs 4 holes on each wall and slightly terrified I'll end up with a bunch of unusable holes if I do this wrong. 

southcoastrgi

5.5mm drill
red plugs
8x 1 1/2" screws 

Alter_ego

Plugs are often marked with the correct drill size

FreshlyCutFlowers

southcoastrgi said:

5.5mm drill
red plugs
8x 1 1/2" screws 

Thanks! However I don't know my screw size. I only have the ones which came with the gate.

Alter_ego said:

Plugs are often marked with the correct drill size

Makes sense. My yellow plugs say 5,the reds say 6 and the browns say 7. When I was searching online earlier I found threads where they discussed that the marked size of the plug was 'too loose' for the screws? 

grumbler

Alter_ego said:

Plugs are often marked with the correct drill size

So they often are with the screw diameter they suit.

E.g. https://www.screwfix.com/p/rawlplug-uno-wall-plug-7-x-30mm-300-pack/89068 -"Suits Screw Diameter 4-6 mm"

FreshlyCutFlowers said:

I understand you don't necessarily want the drill and screw size to be the same anyway..?

They hardly ever can be the same size.

The screw size is the outside diameter of the thread

Alter_ego

If the plugs seem "Too loose" for the screws, it's probably screws are too small for the plugs.

FreeBear

Tip when using wall plugs on plastered masonry walls - Tap the plugs 10-12mm in so that the bulk of it expands in to the brick rather than the plaster. This will give you a much more secure fitting and the plaster won't crack around the hole.

If you ever remove the screw and want to fill the hole, you won't have to worry about digging the plug out or driving it deeper in to the wall. Just whack some filler in, sand smooth, job done.

Most packs of wall plugs come with a little guage that indicates what size screw is suitable and the drill diameter to use.

Use a small drill (say 3mm) to drill a pilot hole, and then go in with the right size drill. Trying to drill a hole first time without a pilot hole often produces an oversized hole.

Norman_Castle

Anything like this? The plastic strip in the middle has holes to measure and embossed markings giving screw and drill sizes.

FreshlyCutFlowers

Thanks all. I'll give it a go go this weekend.
Can I use these screws or should I drop by screwfix again? 5.5 drill for comparison. 

grumbler

IMO this screw requires a bigger drill bit.

Norman_Castle

Is there a screw size gauge with your plugs?