Drilling Through Manhole Cover Update Fao Builder Please

[woofgang]

Thanks for your advice. Bricks are now lifted and relaid loose with drainage gaps. I tried drilling holes in the base of the cover (its solid, not mesh..it blooming would be!) but the bit wouldn't bite. Its a decent quality bit, Black and Decker, for drilling metal and the drill is a mains powered De Walt with plenty of oomph.

Do I need to buy a better bit and if so what please? or am I doing something wrong?
Many thanks

[Old_Geezer]

Cast iron can be tough. Yes I think new bits might well help. So might trying a pilot hole first ? I'm unsure what qualifies as better though. I tend to go with the thought that you get what you pay for, and invest in the dearest in this sort of situation, even if there is a chance I'm being ripped off. Would a centre punch make an impression in the cast iron ? If the issue is the bit slipping it may be worth a try.

[Old_Geezer]

Not that I have bought them but I know the TV sales channels (well at least one of the major ones) sometimes boast of some kind of drill through anything super bit. Could be just marketing guff though.

[New Judge]

Be careful with a centre punch on cast iron. It can tend to be a bit brittle.

[woofgang]

Its not cast iron, at least I don't think so. The shape appears to have been made by bending the metal, not casting it.

[Old_Geezer]

Ah, you have no excuse then ;-)

[heathfield]

I'm thinking a centre punch and smallish drill bit to start the holes might be the answer. The metal is probably galvanised and this can act something like a lubricant so the bigger bit skids about instead of biting in. A few blows on the punch to make a decent dent might help. But as the Judge says, beware the punch doesn't shatter

[The Builder]

Sounds like galvanised steel, Woofters.

I agree with a pilot hole first. It really does make it easier. A brand new 4mm drillbit for steel, followed by a 6 or 7mm bit. Then maybe a 10mm to finish.

Grip the drill very tightly in case the bit catches in the steel and tries to wrench your arm off.

What diameter bit are you trying with?

[Old_Geezer]

Oh and maybe stand on the workpiece or if it grips & turns you may get a nasty bruise on something !

[woofgang]

thank you Builder. I just went in with the biggest diameter drill first. Will try starting with a small one...and yes not new. Thank you all for your input :-) Will report back.