Drill long small hole in cavity wall

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Usually the questions in the building section are about how to core drill large holes so I thought a 6mm hole for some ethernet cable I'm planning to run wouldn't be that difficult. Until I realised that 300mm plus drill bits don't go down to 6mm.

What is the normal/usual way to drill a hole for ethernet cable (without rj45) in a cavity wall? What drill bit size ? And are long sds drills more likely to snap than regular ones? ALso when a store says a bit is "300mm" long does that include the whole thing including what you can't use as it fits into the drill?
 
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Until I realised that 300mm plus drill bits don't go down to 6mm.

I have a 6mm masonry drill bit which is 600mm long. Useless for pushing a cable through after ,because the cable gets stuck, even in a solid wall. For a cavity wall, impossible. I only use it to reduce breakout on the exit wound, then expand the hole to what size I really want.

What drill bit size ?

8mm would be the absolute minimum, but you need an old wire coat hanger or similar to tape it to, to push it through. A 10mm hole will save you a lot of grief.

And are long sds drills more likely to snap than regular ones?

SDS drills are stronger than non-SDS.

when a store says a bit is "300mm" long does that include the whole thing

They mean the whole thing, so you need to knock off a few centimetres for what goes in the chuck.

SDS drill bits have a 60mm unusable shank. That's how come 460mm is a very common size for SDS bits, because 400mm "working length" will be long enough for most normal solid and cavity walls. (often incorrectly labelled as 450mm on eBay/Amazon/etc, so search for both)
 
Many thanks indeed for your reply and all makes sense but regarding the SDS isn't the bit under more stress because its being hammered&torqued through the brick? Ahh, or are you saying the SDS bits are stronger to compensate so that would be the ideal choice?
 
the SDS bits are stronger to compensate so that would be the ideal choice?

Yes, they are made of a stronger steel. They don't flex as much as the cheap, shiny, non-SDS bits you might find in B&Q.

The last SDS bit I broke was a 20mm, 460mm one that was 20 years old and had seen serious punishment. You would think the weak point of a chunky SDS bit would be the shank, because it is only 10mm, regardless of the drill's actual diameter. But no, the TCT part in the tip split in two after pounding away at reinforced concrete for 20 minutes.

You really won't break one going through a normal cavity wall. (Unless you buy a Silverline one or other similar made in China type crap). You want Bosch/Makita/Dewalt/Heller/Irwin Speedhammer ideally.
 
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Yes its much appreciated certainly by me and hopefully by others wanting to know the same thing.
 
And no shortage of buyers in all that time :LOL: :LOL: :LOL:

Indeed. I get so annoyed when I pop into Toolstation to buy something only to discover that it is branded as Silverline. Why don't they fess up in the catalogue rather than wasting customers' time.
 
Indeed. I get so annoyed when I pop into Toolstation to buy something only to discover that it is branded as Silverline. Why don't they fess up in the catalogue rather than wasting customers' time.
Shame.
 
I've managed to burn-out my fair share of SDS bits, but it's pretty much always been 5,5mm bits drilling into stuff like granite or very dense concrete. The only ones I've physically broken have been bigger diameter (12mm and over) bits drilling into (again) very dense concrete. My tally is three broken bits since 1981. But I don't buy cheap bits on the grounds that they can bend too easily, they can break easily and they drill far slower (and thus heat-up more, which in turns means that they shed more tips, etc) than better bits. The premium bits also tend to be better designed with patented flutes, more flutes, etc to give better performance. There is a world of difference between using a cheap Silverline 2-flute SDS bit (i.e. one with a single piece of carbide going straight across) and, say, a Heller Trijet 3-flute bit. Chalk and cheese (and 30% or more faster, to boot)

On the drill front, up to 350mm through a wall and I use a 10mm Armeg Cable Guide drill bit which has a hole drilled through it so that you can thread a cable through the hole and pull it through by simply withdrawing the drill from the hole. They do bigger ones such as a 16mm diameter x 600mm as well

Armeg Cable Guide Drill  001_01.jpg

Of course, Armeg aren't just good quality bits (some quite innovative) - they're also British
 

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