Which Drill for RSJ ?

[Rob H]

RSJ is Rolled Steel Joist

[John J]

Get a Dormer drill bit and use with cutting compound at the correct speed.

[Animal]

folk have said most of it, but 1 more thing: a carbide tipped multimaterial bit is the best option. These have twist drill geometry vut with TCT. Steel bits like hss or cobalt are a variable bunch & might or might not manage it.

[chop]

They do fine when you use a good drill and use it properly.

[The Natural Philosopher]

What you want is torque, a drill bit hardened beyond the mild steel of the RSJ, and a bit of lubrication, and some time.

What mechanism is used to hold the drill in the chuck is irrelevant.

[Animal]

and a bit geometry capable of drilling steel. SDS bits are not, they are blunt stone crushers.

[nothanks]

Errr, I don't think you meant to suggest "cutting compound" - unless you sell drill bits, of course ;-)

[The Natural Philosopher]

Joke is on you

[Andrew Gabriel]

Builders cut several holes in RSJs where they bolted together for my brother's house. I didn't see them do it, but the circular cutouts were laying around afterwards, so it must have been some type of metal core borer, not a twist drill bit.

Andrew

[charles]

Tank cutter?

[soup]

Concrete ~ RSJ .Doesn't compute.

Maybe, you should say what it's made of.

Well as an RSJ is a rolled steel joist perhaps it's made of steel.

[Andy Burns]

Quite common to use annular cutters with magdrills, with lubrication drip-fed through centre of cutter

[Animal]

that's lube, not really cutting compound.

[Tim Lamb]

Yes. They still need an initial hole to support the cutter.

On a multi-hole job I do the pilot holes first to save on tool changing aggravation.

>

[Paul]

Even WD-40 gets honourable mention.

Paul

[Animal]

according to that air & water are cutting fluids :)

[Rob Morley]

Mag drills - useful if you want to make larger holes in thicker steel but a bit OTT for half inch.

[John Rumm]

While many will use the term lintel - I find it less common for people to actually specify the type unless they are better informed than the average man on the Clapham omnibus.