Drilling masonry for shelf supports


Hi,
I'm trying to put up some supports for small shelves, I've got a set of screws/wallplugs (brown). I forget what size they are, but I know I need a 7mm drill bit to accommodate the wallplugs. Do I need to pilot drill the hole first, and if so, what size(s) would you recommend starting with/stepping up through? The walls are about 1 inch plaster, then brick, which means that my hammer drill chews a huge hole in the plaster, and then struggles with the brick. I'm going out tomorrow for some new masonry drill bits, any suggestions as to make/type? (My drill is a chuck-key type).
Can anyone advise, or point me towards a decent guide to doing this without ending up with a hole I can stick my head through?? Thanks a lot!
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In my opinion (I know others may disagree) that's *way* too big. For anything except huge weights yellow (4mm) or red (5mm) will be absolutely fine.

forget about masonry bits in a 'conventional' hammer drill. I have an (oldish) Stayer SDS and it drills holes in even very hard engineering bricks incredibly fast. You can get a cheapo (but still quite effective) SDS drill for only 30 pounds or so nowadays.
--
Chris Green

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What's the difference between an SDS drill and a "normal" one?
I picked the brown plugs as the screws looked about the right length to go through the wood shelf supports, and have a decent amount going into the wallplug as well. I'm going to be using the shelves for storing power tools, tins of paint etc., and I wasn't sure if the smaller screws/plugs would be enough.
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mentalguy2004 wrote:

A bit like the difference between driving to downtown Baghdad in a tank compared to driving down in a hearse. No one that has used an SDS drill will ever want to use anything else..

child. I use the biggest fixings that will go through the holes in the shelf brackets. It is easy to end up with an incredible amount of weight on a shelf..
-- Sue
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weight on the shelf that is). What *may* happen is that fixings can pull out, preventing this is much more to do with having the right sized holes with the right sized plugs and the right sized screws.
Even ordinary mild steel has a breaking strain (in most modes) of something like 40 tons/sq.in. Thus a single 5mm screw would have a breaking strain of something like 1.2 tons even if it was made of mild steel, in reality most modern screws are stronger than that. So, as I said, forget about the screws breaking.
The important thing is to drill holes such that your red (or whatever) plugs are a snug fit and then use screws that are a tight fit in the plugs. I use either 3.5 or 4mm screws in yellow plugs and 5mm screws in red plugs. You should then have a fixing where the screw won't pull out and ultimate failure is limited by the screw's strength.
I only use larger plugs when a hole has become enlarged or, possibly, in really soft material.
--
Chris Green

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Palindrome wrote:

-------------------------------------------------------
"No one that has used an SDS drill will ever want to use anything else.."
Not quite true Sue. SDS has its place in the wider look of things, but sometimes a good, old fashioned hammer drill (or even one without a hammer) is better - especially on cost if you only use it once-in-a-blue-moon or on purely light, domestic work

That's a little 'overkill' there really. Even a couple of 1" or 11/2" x No7 or No 8 steel screws used in a common or garden shelf bracket will withstand a huge shear load - and there are far more instances of things falling off a shelf because of poor stacking, than shelves collapsing because of inadequate fixings.
Tanner-'op
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Tanner-'op wrote:

I can only think "on cost" - but, even then, that doesn't stop the user from /wanting/ to use an SDS drill :)

shearing. The larger diameter and the longer the plug (within limits), the less load per unit area being placed on what may easily just be plaster and mortar. Smaller screws for the bottom of the bracket, which only has to take shear, is fine - but I do go for "overkill" for the screws at the top, which are in tension as well as shear.
However, each to his or her own. It really does depend on what the shelf is being fastened to and how deep the plaster is at that point. -- Sue
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mentalguy2004 wrote:

No, you don't really need a pilot hole for a drill of this size.
The walls are about 1

Possible four problems here (or a combination):
1) The tungsten drill bit is blunt - or of poor quality.
2) The drill itself is slightly bent thus inducing a 'wobble' effect.
3) You are starting the hole with the drill on the 'hammer' setting.
4) Your drill is not 'man-enough' for the job (especially if it's a 'cheap' cordless one).
The solutions are obvious:
1 Change the drill bit for a good quality new one.
2 Start the hole with the drill 'off' the hammer setting until the hole is started and just below the surface - and then apply the 'hammer', and push the drill with an even pressure - letting the drill bit do the work - and occasionally pulling the drill out of the hole to clear any build up of dust - especially if the wall is a bit on the damp side.
3 Get hold of a good quality cordless drill - or better still (in my opinion) a good quality 'wired' one.
Hope this helps mentalguy2004
Tanner-'op
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Hi, thanks for the advice.... I'm using a corded drill, I'm not sure of the speed but a couple of years ago it was one of the better ones, not a Lidl special!
Im buying some good quality bits tomorrow, hopefully that'll make the difference.
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brick. The problem with drilling through plaster into bricks is that you don't know where on the bricks the drill point will hit it, so if you drill into the edge of the brick, it can push the drill to one side, elongating the plaster hole, so sometimes a pilot hole can help, but not very often in my experience.
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On Thu, 10 Jul 2008 23:08:16 +0100, "Harry Stottle"

I usually use a 3mm pilot drill just to get started. It's easier to see your mark. Especially if your eyesight is getting a bit iffy :(
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To restore balance to the world mentalguy2004 wrote in b4vdk.209183$ snipped-for-privacy@newsfe17.ams

Don't knock Lidi or other cheapo tools- I have a 3 year old DEWALT 12v (about 240 at the time) where as the new line of 18v cheapo are better .Names is not always the best ,you have to compare like for like.Then there's the out lay- if you are only going to use a tool 3 times a year is it money well spent to spend 100+ on a tool just to have it sitting on a shelf.
Chris
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Joker7 wrote:

Yes, IMHO, buying quality tools is money well spent. They do a better, easier and safer job on day 1 and are still doing that 20 years later. If you only need one once in a blue moon, hire a quality tool when needed.
My electro pneumatic hammer drill is the whole dog and its puppies. Because it is effortless to use, it is easier to control and thus a lot safer. It is now decades old but works like new. The case even still works like new.
-- Sue
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To restore balance to the world Palindrome wrote in 4hwdk.195861$ snipped-for-privacy@fe10.news.easynews.com

As I said Sue like with like. Of my experience witch is not a lot with the lower end ,if you are only going to need a tool a couple of times a year- I would not spend heap on power tools to hang a shelf or two.Hiring is good but can make a job expensive.
Chris
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