rawl bolt specification

[sm_jamieson]

Am I correct in saying that the rawlbolt specification screwfix use is ( thread x maximum fixture size), e.g. M12 x 60 can fix 60mm thick fixture. It looks like that from the pictures. The B&Q ones appear to be (thread x length of bolt) and the back of the pack tells you the fixture size - since the bolt is usually 50mm, in B&Q, M12 x 110 is needed for a 60mm fixture. Does this sound correct ? (Good news: a local screwfix counter has just opened (Nuneaton)) Thanks, Simon.

[Andy Hall]

it's the fixture thickness in Rawlbolt specs.

If you are looking at these kind of fixings, then I've found that injection fixings are a much better solution.

- There is not the issue of the fixing not gripping properly if the hole is not quite right or the material a little crumbly

- You can have whatever length you like

- *Very* sturdy fitting.

[sm_jamieson]

I gues this is resin and threaded studs.

Re screwfix rawlbolts, any guidelines to the size of hole used with a certain thread i.e. is it always for example 4mm more than the thread, so M12 would need a 16mm hole ? Simon.

[Andy Hall]

Exactly. Holes for these are always bolt size + 2mm and it's non critical within reason.

It varies. There are charts on the Rawlplug web site showing that for Rawlbolts, the hole is 0.5 to 2mm more than bolt size. I found it to be fairly critical which is one reason I don't use them any more. Slightly too big and the fitting grip is weakened a lot.

[sm_jamieson]

Which resin studs do you use ? Simon.

[Andy Hall]

Various ones.

Screwfix do an own brand zinc plated type.

Fischer do passivated ones similar to the yellow appearance of Rawlbolts - also available from Screwfix. They also do stainless steel if you want that.

All are in various lengths and sizes, or you can even buy 1 metre lengths of rod and cut it - frankly I can't be bothered. There are nuts and washers with the packs.

For resin, I started using the Fischer type with the screw in base that has a mix of plain resin and resin with mortar. e.g. Screwfix 80157. These are quite viable for small to medium projects.

I then had a project where I needed to fit over 200 fixings. At that point, I invested in one of Fischer's special purpose guns (Screwfix

35237). The cartridges for this are about half the price of the screw base ones, so it was worth it.

There are also resin sleeves. These are used if you are fixing into a hollow block or a brick with holes through the centre. They retain the resin around the stud.

The important thing is to make sure that the hole is clean of dust. Needless to say, Fischer sell some gizmos to do this. I found that a vacuum cleaner and/or an air jet is perfectly adequate.