what drill bit size for an anchor bolt?

Andy From Sligo

i cannot believe i am asking this question because i suppose it should be one of the easiest things in the world . I picked up a 6mm anchor bolt (never used one of these before , or if i have it would have been years ago) , then I went round to the shelf where the masonry drill bits are and I picks up a 6mm masonry drill bit but i offer up the 6mm anchor bolt to the 6mm masonry drill bit .... but it looks like if i drill a hole into a cement block with the 6mm masonry drill bit it wont make a big enough hole for the 6mm anchor bolt to even fit into ... so am i missing something here , do you need a bigger masonry drill bit, like 8 or 10mm to fit a 6mm anchor bolt into a wall?

kieran.

Andy From Sligo wrote: »

i cannot believe i am asking this question because i suppose it should be one of the easiest things in the world . I picked up a 6mm anchor bolt (never used one of these before , or if i have it would have been years ago) , then I went round to the shelf where the masonry drill bits are and I picks up a 6mm masonry drill bit but i offer up the 6mm anchor bolt to the 6mm masonry drill bit .... but it looks like if i drill a hole into a cement block with the 6mm masonry drill bit it wont make a big enough hole for the 6mm anchor bolt to even fit into ... so am i missing something here , do you need a bigger masonry drill bit, like 8 or 10mm to fit a 6mm anchor bolt into a wall?

https://www.hilti.ie/medias/sys_master/documents/hcf/ha4/9485214547998/Instruction-for-use-HSA-M6-101x120mm-Instruction-for-use-PUB-5120662-000.pdf

twowheelsonly

Is it an M6 anchor by any chance ?? If so then a 12mm bit.

M6=12mm, M8=14mm, M10=16mm, M12=20mm, M16=30mm

Potentially start down a size just to be sure it's not too big but some hammering may be needed if you do.

kieran.

You need to thump it in. If in doubt contact the supplier of the expanding anchor.

punisher5112

I thought it's on the side of it what size.

1874

I was sure Id bought anchors which had the drill diameter marked on the anchoring section required for the bolt.


That said,you could get a tape measure/rule and measure the diameter of the bolt, drill slightly less than that as excess material might come out of the drilled hole, widen the hole slightly as needed.

Now I have to go dig out an anchor bolt from the shed tomorrow to check

Andy From Sligo

thanks all, i remembered it had the numder 6 stamped on the shaft ... but I dont know know if it was 6mm or M6 stamped on it - do they mean the same thing 6mm?

SteM

Andy From Sligo wrote: »

thanks all, i remembered it had the numder 6 stamped on the shaft ... but I dont know know if it was 6mm or M6 stamped on it - do they mean the same thing 6mm?

That was answered in the 3rd post. M6 is 12mm.

Fine Cheers

AFAIK 6mm anchor bolt = 6mm drill bit as already stated. Only one way to find out !
Should be on bolt packaging but i assume you don't have it.
If mass concrete probably will be a bit tight but blockwork generally loosens up a little.
I try to go with masonry bolts / screws but I guess it depends on the end use.

CoBo55

Ah stop lads this has to be a wind up:cool::cool:

Cerco

Andy,
Are you looking at the diameter of the bit instead of the tip?
Okay but just in case as I know someone who made that mistake before

The Mulk

a quick guide, there's similar ones for RAWL plugs too.

First 3 lines on the first table

https://www.ssianchoranddrill.com/Safety-Bolts-Expansion-Anchor-Systems-Simpson.html

cruizer101

Just to explain a bit better as I think some here are assuming some prior knowledge.
The M numbers M5, M6, M8 etc refer to the metric thread size.
So an M6 bolt has an outer thread diameter of 6mm, that is the diameter of the round bar before threads are cut.
An M6 anchor has an M6 bolt and so the anchor part itself has to be a bigger.
So you may have seen M6 and thought the anchor itself was 6mm but it is actually 12.
They often will have what size to drill on the side of them but not always, in which case you can google it.

1874

cruizer101 wrote: »

Just to explain a bit better as I think some here are assuming some prior knowledge.
The M numbers M5, M6, M8 etc refer to the metric thread size.
So an M6 bolt has an outer thread diameter of 6mm, that is the diameter of the round bar before threads are cut.
An M6 anchor has an M6 bolt and so the anchor part itself has to be a bigger.
So you may have seen M6 and thought the anchor itself was 6mm but it is actually 12.
They often will have what size to drill on the side of them but not always, in which case you can google it.

I dont know why anyone would do that (google it) when they could just eyeball it, ie

Measure it OR gauge it (estimate it)

air

Consider using concrete screw bolts next time - better pull out strength, can be easily removed if required and require a smaller hole than expanding anchors.

Edit - they can also be installed far closer to the edge of a piece of concrete without it cracking like it would with an expanding anchor.

https://www.screwfix.ie/p/dewalt-hex-head-blue-tip-2-screwbolts-6-x-60mm-50-pack/351ht

punisher5112

air wrote: »

Consider using concrete screw bolts next time - better pull out strength, can be easily removed if required and require a smaller hole than expanding anchors.

https://www.screwfix.ie/p/dewalt-hex-head-blue-tip-2-screwbolts-6-x-60mm-50-pack/351ht

These are great indeed.

Andy From Sligo

Cerco wrote: »

Andy,
Are you looking at the diameter of the bit instead of the tip?
Okay but just in case as I know someone who made that mistake before

yes i didnt take into account that the tip of the masonry drill bit is wider - so when they say its a 6mm masonry drill bit , is it the tip of it thats 6mm and not the shaft bit? (I know i'm useless when it comes to these things! )

Andy From Sligo

with these fittings , what happens if at the exact point you want to drill into the rendered wall that at that point its got mortar instead of brick/block? - obviously for them to work properly you want to be drilling into the block/brick part

Fine Cheers

Yes you'd want to be avoiding mortar joints as you just won't get the grip.

Andy From Sligo

Fine Cheers wrote: »

Yes you'd want to be avoiding mortar joints as you just won't get the grip.

yes thats what i was thinking but any workarounds if your fixing cannot avoid the mortar part?

anything like dries as strong as brick but in cartridge gun form?

air

You're wasting your time trying to fix into a mortar joint, even if you use a suitable chemical anchor or similar, half of it's surface area will still be in contact with more mortar which will mean it will not achieve it's full strength.

You could drill another hole in whatever it is you're trying to fix or move it slightly if possible.