SDS Hammer Drill how hard to push?

Drill, or chisel?

If it is a heavy device then as far as possible use the weight of the device. If it's just a small one then you may have to push quite hard to get anywhere.

There is quite a "knack" to breaking concrete efficiently. Try to start from an edge, if you can't then try to make an initial crack in the middle (e.g. with a sledge hammer). Assuming it is something like a path laid on earth, get a crowbar under it and try to lift it.

ten inches of concrete over a sewer pipe

For drilling, usually only hard enough that you can feel the bit/chisel "floating" on the air cushion. For chisel for, a bit harder, but not much.

That's hard and fast.

There is no need to be sensitive.

George Miles explained on 30/03/2019 :

Let the weight of the machine do the work - You should not need to push, you just need to steady it and let it bounce. If it stops bouncing, or the bounce seems restricted - you are pushing too hard.

If you start going up and down on the end of the drill you might not be pressing hard enough? Brian

That's quite a lot thicker than I've ever had to break up. What sort of SDS drill do you have? How many joules? Is it a breaker, or just a standard drill?

As far as the drill bit is concerned, you may find it easier to use a spike than a chisel, and just crack chunks off the edge.

Order a couple of spare lengths of salt-glazed pipe now ;-)

If it just domestic stuff, no more than 4-5 inches thick, then use a spade to undermine the edge about a foot or so in, then just give it a whack with a decent sledge hammer. It should just crack and create a calve just like an iceberg.

then just undermine a bit further and repeat.

Unless you have a heavy duty SDS machine intended for concrete breaking you'll be at it for ages.

In that case hire a 9 or 12 inch angle grinder and try and chop lumps out of it. The sledge hammer technique that I mentioned lower down is probably not a good idea :-(

And get the correct diameter and matching plastic connectors.

There used to be two companies, Naylor and Denley ?, whose products were not quite compatible.

If we are talking a 2kg class machine with 2-3J of impact energy, then you are in for a very *long* job. It was a similar job some years ago that prompted me to buy a 15kg machine with 45J of impact energy!

Cutting slots with a diamond disk in a large grinder, may may it a bit quicker to attack, since you then only need the SDS to break out the waste bit between the slots.

For 10" concrete, you are going to need a much bigger angle grinder than that, surely?

I would be starting out by cutting deep slots in a three inch grid with a big angle grinder, then knocking out the individual blocks. That is a

Whatever works quickest ;-)

:-) Yup!

And guarantee the sewer pipe underneath gets broken?