Concrete screws- use of -how to.

[jonw1664]

Concrete screws are very fussy on drill bit size, I seem to remover I used 5.5mm and 6.0mm or could’ve been 6.5mm

The screws are 7mm diameter and the pilot hole size depends on the material hard brick or concrete go a 0.5mm bigger.

If they are too tight you can end up with three quarters of the way in and they won’t go in or back out

A bit back I had window fitters come in, replaced the old windows for new pvc dg. A month or so after, i was in one of the storage rooms(usually referred to as 'bedrooms' in normal houses), and in it i discovered one of the firms workers had left behind a stanley fatmax screw box containing a range of big what are concrete screws - 80mm,100mm,120mmx7.5mm and about 100 of each.

Naturally I was keen to return them to the company,, but ahem...seems to have slipped my mind, and as the windows were really expensive, and the fact nobody bothered to come to claim them, i seem to have been left with them.

So anyway. How do you use this type of screw ?

I dont remember them pre-drilling any holes, but they might have, so are they a type that needs a pre-drilled hole, or can you blast them straight in, maybe using an impact driver. It's a large Torx bit. Standard sharp point, no drilling notch in the end of it meaning possibly they need pre drilled, but if they are to be pre drilled, then why the sharp end point ? or is that just standard and nothing to be inferred from it.

Im sure they would also work for timber, maybe for outdoor use. So they'll always have a home somewhere, and it is a rather nice stanley kit box,im sure that will also come in handy.

rhe real beauty o these screws is fixing battens /boards to masonry walls, line up the timber where you want it, use a 6mm multi-material drill bit, drill through fixture and wall, insert screw with impact driver, job done. Saves a massive amount of time versus the traditional rawlplug approach. I have used very successfully on brick, block and even stone

 

[RobinBHM]

The problem with concrete screws is if the brick is hard and the hole is a tad small….you drive the concrete screw in, it’s get to,about 3/4 of the way in and it won’t go in or out.

The secret is if you feel it getting super tight, back it out and drill hole with 0.5mm bigger drill

 

[Phil Pascoe]

The problem there is you can't (?) get masonry bits in 1/2mms. I remember having a sod of job with holes in granite.

 

[HOJ]

The problem there is you can't (?) get masonry bits in 1/2mms.

I have a selection of SDS bits from 5, 5.5, 6, 6.5 to 7mm, depending on what it I'm fixing to, especially soft brick I start with a 5.5 first and see how well they bite.

Fitted a new Plastic door on Monday for a client and stuck with the 5.5 bit size.