Which Drill for RSJ ?

I's suggest you try decent cobalt bits, and do it in stages, starting small and working up to 12mm, lubricating the bit as you go.

You want an SDS drill - maybe the refurb Erbauer one.

Are you sure about drilling 9 large holes in an RSJ? Will it still work as an RSJ after that? Are you hitting rebar and drilling through it? This is scary stuff if there's any weight on the RSJ.

Sorry, I assumed a concrete RSJ. Maybe, you should say what it's made of.

Rolled Steel Joist?

While my drill could probably go this slow, I don't know if it would like a lot of force applied to the bit while doing so. The battery drill might have more torque than my old drill can manage.

"How to drill through steel beams..."

Paul

Yes even my old B/DO with two gears and a variable speed on the trigger can drill that type of steel etc. It just needs a lot of patience. I often chuckled when people said, it can't be blunt its HSS. Brian

You are probably right, but people do use RSJ to refer to any type of joist. :)

RSJs are usually fairly easy to drill. Any drill that has the torque will work, but 12mm needs quite quite a lot of torque if you try in one go. Use cutting oil (although any oil is better than none) and make sure you use decent, sharp, drill bits - not Chinesium. Re bits: DeWalt "extreme for metal" are excellent but quite aggressive - probably worth the investment for this job. Alternatively, start small and work through the stages to get to 12mm, or use a step drill.

Battery drill will be fine. If you use a bit of cutting oil, and to make life easier drill in steps - go through with a 1/4" first, then open it up to 1/2". Keep plenty of pressure on the bit so that it keeps cutting.

Nope, not for drilling a steel RSJ.

RSJ = Rolled Steel Joist. Fukinada

No they don't.

If its a concrete lintel they call it a concrete lintel. its an old oak joist they call it an old oak joist.

Every time I see someone drilling an RSJ on grand designs, they seem to be using one that sticks hard to what is being drilled with a powerful magnet. Are these hireable ?

Only the clueless ! (and they are UB's or UC's these days anyway and have a different profile compared to the RSJ of decades past.

Yes, but I wouldn't have thought it was worth doing so for 12mm holes

I was in steelwork for most of my working life and it was always called RSJ for Rolled Steel Joist Channel for Rolled Steel Channel Angle Iron for Rolled steel angle Stanchions for vertical steel uprights (in a building) Girders for horizontal steel beams etc

Use either a cobalt or HSS drill. I've drilled many a hole in steel.

Err, no you don't, SDS drill are for drilling concrete not steel!