Why 5.5mm Sds drill bit?

[Andrew Gabriel]

IME, they go straight through rebar without hesitation. That's not necessarly a good thing - many pre-stressed concrete lintels only have one rebar in them in the first place.

[charles]

oh, I agree they go through, but they aren't much good on brickwork afterwards.

[Grimly Curmudgeon]

For the slightly smaller 5.5mm frame fixers that sparks commonly use to bosh in wiring boxes with.

[The Medway Handyman]

Utter cobblers. The spiral 'side' of the bit only clears the waste, the tip makes the hole.

I've never had an SDS bit go blunt, despite drill thousands of holes a year.

[rick]

yep .. most of my plugs take 5.5 ... though I will often drill out at

5.0 to allow for usual loose hole that results.

[Andrew Mawson]

Dave, I wish that my larger SDS bits were as long lasting as yours seem to be. I have a box of 20 mm to 35 mm sds drill bits that have been used many times on re-inforced concrete and are decidedly smooth where they should be sharp :) Sharpening is easy enough on a diamond or green grit wheel but it's one of many 'round-tuit' jobs !

I agree with your comment about the spiral having no part in the cutting - I have some that are amazingly wasted down !

Andrew

[Dave Plowman (News)]

I'd agree - although they don't get anything like your sort of use here. Ordinary masonry bits in a hammer drill were a different matter.

[Mike Barnes]

IKWYM but I'd say they do go blunt. But they still work well enough when blunt, in a way that simple twist bits and masonry bits don't.

[Dave Plowman (News)]

It's very easy to check for wear on the tip. And it takes a lot of use before it shows - although obviously depending on what you're drilling.

[Grimly Curmudgeon]

You must have one of the fabled everlasting drill bits, then. I keep getting the ones that eventually wear - and I've also drilled thousands of holes with them.

[Roger Chapman]

I suppose it depends to a great extent on what you are drilling into. When I moved to my current address in 1978 my trusty hammer drill would take 10 minutes or more to drill a hole for a wall plug in the stone walls even assuming the masonry drill stood up to the punishment. SDS of course is a different ball game but the drill bits tend not to last. I don't actually count the number of holes I drill but I suspect that my drills last for 100s of holes rather than 1000s. And if you can drill a small diameter hole in a few seconds you do tend to drill far more holes than you would if almost every hole was an epic as used to be the case.

[charles]

and before masonry drills we had to use a Rawltool!

[meow2222]

+1. If its then not tight enough, stick a match in the plug.

NT

[Capitol]

and before that, we used a piece of pipe with the end notched and a club hammer! Great fun on 6' thick walls.

[stuart noble]

Do you carry a box of matches? I light my joints with a blowtorch

[Grimly Curmudgeon]

I lost a 14mm SDS bit the other day. It went in and jammed solid and as it was at the top of a section of ladder I wasn't in a position to get decent access or leverage on it. Fortunately the hole wasn't a vital one-off position, so a new hole got drilled below it and the first new proper application of my new AG took place on the stuck bit.

[fred]

Axminster recommend 5.5mm bits for their red wall plugs