I've got some rawlplugs marked 40x8. They're obviously around 40mm long, so you'd think they'd go into an 8mm dia hole. Drill an 8mm hole in the wall, and they're loose in the hole. Are you supposed to drill a slightly smaller hole than the rawlplug, or is my drilling dodgy (ie, bouncing about and making a bigger than 8mm hole), or are the rawplugs wrong?
They're probably meant for number 8 screws. I don't know off the top of my head what the hole size is intended to be. I would progressively try different sizes of hole rather than just jump in and assume the size.
HTH -
You probably need a Number 8 masonry drill which is 3/16in or approx 5mm.
Bah. Bought a set of plugs and fixings from either Aldi or Lidl, so assumed mm measurements. Imperial should f*ck right off, except for when I want to talk in feet and yards...
|I've got some rawlplugs marked 40x8. They're obviously around 40mm long, so |you'd think they'd go into an 8mm dia hole. Drill an 8mm hole in the wall, |and they're loose in the hole. Are you supposed to drill a slightly smaller |hole than the rawlplug, or is my drilling dodgy (ie, bouncing about and |making a bigger than 8mm hole), or are the rawplugs wrong?
I get hold of a plug and choose a drill which is the same diameter as the plug by eye. Any if the plug is then slack, I add match sticks as packing, cutting off the heads and tapering the end first. If the plugs are long, I use Cooks matches. If the screw will not go into the plug I drill out the plug to the core diameter of the screw.
Difficult I'd say because different species of plug are intended to expand in different ways (hence your slack plugs on occasions?) Any rawlplug I've every bought - and I exclude the 'bastard' ones you always get supplied with fittings, which get binned instantly! - specify what size drill you need to use, and I stick to that rigourously.
David
|Dave Fawthrop wrote: |> On Mon, 23 Oct 2006 00:03:08 +0100, "Doki" wrote: |> |> |I've got some rawlplugs marked 40x8. They're obviously around 40mm long, so |> |you'd think they'd go into an 8mm dia hole. Drill an 8mm hole in the wall, |> |and they're loose in the hole. Are you supposed to drill a slightly smaller |> |hole than the rawlplug, or is my drilling dodgy (ie, bouncing about and |> |making a bigger than 8mm hole), or are the rawplugs wrong? |> |> I get hold of a plug and choose a drill which is the same diameter as the |> plug by eye. Any if the plug is then slack, I add match sticks as |> packing, cutting off the heads and tapering the end first. If the plugs |> are long, I use Cooks matches. If the screw will not go into the plug I |> drill out the plug to the core diameter of the screw. | |Difficult I'd say because different species of plug are intended to |expand in different ways (hence your slack plugs on occasions?)
Which I cure with matches
|Any |rawlplug I've every bought - and I exclude the 'bastard' ones you always |get supplied with fittings, which get binned instantly! - specify what |size drill you need to use, and I stick to that rigourously.
I can judge when a screw is holding well enough for the job in hand. This does not always happen when following the rules. Screws as well as plastic plugs differ markedly. Also drills do not always drill the size of hole it says on the shank, depending on the material you are drilling, and the tip of the drill, as I was taught in Apprentice School years ago.
But with my protocol I don't need matches... ;-)
David
Well, you'll still see wood screws sold by the same number system. I dunno how it was derived, but if those sizes were directly quoted in metric you'd have to remember some pretty odd ones. There's a lot to be said for a practical numbering system like that rather than some sanitised universal metric crap which doesn't work as well.
|Dave Fawthrop wrote: |> On Mon, 23 Oct 2006 07:53:38 GMT, Lobster |> wrote: |> |> |Dave Fawthrop wrote: |> |> On Mon, 23 Oct 2006 00:03:08 +0100, "Doki" wrote: |> |> |> |> |I've got some rawlplugs marked 40x8. They're obviously around 40mm long, so |> |> |you'd think they'd go into an 8mm dia hole. Drill an 8mm hole in the wall, |> |> |and they're loose in the hole. Are you supposed to drill a slightly smaller |> |> |hole than the rawlplug, or is my drilling dodgy (ie, bouncing about and |> |> |making a bigger than 8mm hole), or are the rawplugs wrong? |> |> |> |> I get hold of a plug and choose a drill which is the same diameter as the |> |> plug by eye. Any if the plug is then slack, I add match sticks as |> |> packing, cutting off the heads and tapering the end first. If the plugs |> |> are long, I use Cooks matches. If the screw will not go into the plug I |> |> drill out the plug to the core diameter of the screw. |> | |> |Difficult I'd say because different species of plug are intended to |> |expand in different ways (hence your slack plugs on occasions?) |> |> Which I cure with matches | |But with my protocol I don't need matches... ;-)
When everything goes well. IME Sods law applies to rawlplugs as with everything else.
I wouldn't have thought they would mix old imperial drill size with metric length though. And a 5mm plug isn't likely to be 40mm long, more like 25mm.
What colour are they?
That could be the problem! Get some Fischer ones!
. There's a lot to
Well said Sir! The old engineering Number and Letter system of drill bit sizes was infinitely superior to the current Metric system. Same goes for nuts & bolts. Any engineer who used the Witworth system of proportional thread sizes would agree it was far superior to the current systems.
Slatts
The largest plugs I use (brown) take a 7mm bit. I bought a top quality 7mm SDS masonry bit and it has lasted me 5 years and no signs of bluntness! I don't actually possess any other sizes of small SDS bit, so it is always easy to find.
Any bigger than that and I use rawlbolts instead.
Christian.
Utter bollocks. I hate imperial sizes. About 1 billion different units to remember and convert between, with each context requiring another medieval hangover so they can't be compared. Complete faff.
I just wish it was easier to get metric only tapes without all the Luddite bollocks at the top of the tape getting in the way. Measuring off the bottom of the tape is inaccurate. However, I shouldn't grumble as I found those metric only tapes in Tesco someone mentioned earlier. 50p each as well, although the quality isn't up to much, as you might expect.
Christian.
You can order Stabila and others from Germany easily enough. I usually buy a few on trips there if I remember.
8mm hole or 8mm drill ? I'd guess these things were designed for optimal fit in an 8mm hole, once expanded. The actual fit depends on the squashabiltiy of the material and the accuracy of drilling it. If you drilled a cheesy wall with a hammer drill, then it could be well oversize and you might only need a 6mm drill bit. SDS drilling into hard brick will be much closer in size, and needs less expansion to fit.
I wouldn't expect Rawlplugs to be marked for either No 8 screws or a No
8 drill, unless they were the old fibre Rawlplugs, and old stock at that! We still see screws sold as "8s", but plugs care much more about the drill size than they do about the screw you put into them.
I was once stocking up on plugs from Screwfix and noticed their blue ones: which I'd never seen before, so thought I might as well have some in the toolbox alongside my yellow, red and brown ones. However, I've never actually used a single one so far, and having handled them I can't really imagine a scenario where I would do so! IIRC they were no longer than brown ones, which will happily take a No. 10 screw, so I can't see when anyone would use them. As you say, beyond what a brown plug will take it's time for rawlbolts or similar.
David
I'm down to my last 96. Useful when you are using long coach screws which tend to come in larger diameters only.
If the hole is to big,then tightly pack the hole with polyfilla and then insert the plug. :-)
I think that traditional fibre Rawlplugs are the only ones where the diameter of the plug (and therefore hole) is the same as the clearance hole for the screw. Therefore you use a no. 8 plug with a no. 8 drill and no. 8 screw, hence their system for sizing. It has the advantage that you can drill straight through a fixing into the wall, push a plug right through, and then screw into it. The only other way of doing that is using the "hammerfix" type of fixings.
Numbered screw sizes are also used in Europe, they're not peculiarly British. You'll also find good-old inch-based pipe threads over there too (including garden hose fittings, washing machine connectors, etc). Metric hasn't completely taken over :)
Rick
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