I've been given the task at work to cut a 1m x1m hole in the factory floor where I work. Judging by the edge of the pad, it is 220 -250 millimeters thick (8-10")

I'm guessing it has the typical rebar mesh inside it as most do. They won't let me hire one of those monstrous petrol-powered brick cutters, I only have an electric hammerdrill, a sledge hammer, chisels and a 9" elec grinder. I'm currently looking for some kind of concrete cutting blade for the 9" that won't shatter when it hits rebar.

Any ideas?

tell your boss to go fuck himself.

thats a quarter of a cubic meter of concrete to mash out with some chisels and a drill.

Grinders do have discs that can cut through concrete but i qouldn't recommend it.

just hire a concrete saw, $60 tops.

tell your boss to go fuck himself.

This. Verbatim.

Your boss is a fucking cunt.

thermite

let's not even start on the health hazards posed by cutting up concrete.

you dont want to breathe the shit in.

The hammer drill should be able to do it. They make long bits for the fuckin things. But, if the hammer drill isn't a Hilti, it's probably not worth the plastic it's made out of. I say measure out the 1mx1m area, drill 4 holes, one for each corner, then drill a bunch of holes along the edges of the 1x1 area close together. You're getting paid either way, right? Other than that, I know hilti makes an electric chipping hammer that would do the job right.

I've used a hammer drill to rip up asphalt before, and although that's obviously quite different, I'd imagine if you did the holes around the perimeter method you could pull this off. After those are done, just start smashing the middle, and when rebar pokes out, chop it up with a metal cut off blade on the grinder. Not really efficient, but it seems like you could manage with what you have.

have any of you tried to remove that much concrete by hand before?

even with a kanga it would take awhile to do.

tell your boss to get you decent tools and protective gear while he is at it.

you need a kanga hammer, a 9 inch grinder with the right discs, face shield, respiratory protection and a concrete saw if possible.

Tell him to either;

a. get fucked
b. get shaped charges

I dont recommend using the angle grinder, especially not a 9"(ive heard stories of them slipping and disemboweling their operator..)

Concrete dust is bad shit ti breath in. The little fragments will hurt/puncture the skin if they hit you. You need to keep the area wet aswell, to minimize the amount of dust/fragments. Im sure your boss can spare $100 for a concrete saw to cut the hole...

Tell him to either;

a. get fucked
b. get shaped charges

I dont recommend using the angle grinder, especially not a 9"(ive heard stories of them slipping and disemboweling their operator..)

Concrete dust is bad shit ti breath in. The little fragments will hurt/puncture the skin if they hit you. You need to keep the area wet aswell, to minimize the amount of dust/fragments. Im sure your boss can spare $100 for a concrete saw to cut the hole...

I suspect he was just fucking with me for the fun of it. On the advice of, I think, everyone in this thread, I did indeed tell him to go fuck himself if he won't get me a concrete saw. He's getting a contractor to come and do it now. (so after a few more weeks he'll probably ask me again after the con tells him to get fucked as well)

Cheers for the advice anyway, that disemboweling thing sounds like fun, I'll have to try that out on him one day.

Cheers for the advice anyway, that disemboweling thing sounds like fun, I'll have to try that out on him one day.

Put grease on the handles ;)

A contractor will have, or have access to, the proper concrete saws. Dont even bother with this.

Tell him to either;

a. get fucked
b. get shaped charges

I dont recommend using the angle grinder, especially not a 9"(ive heard stories of them slipping and disemboweling their operator..)

Concrete dust is bad shit ti breath in. The little fragments will hurt/puncture the skin if they hit you. You need to keep the area wet aswell, to minimize the amount of dust/fragments. Im sure your boss can spare $100 for a concrete saw to cut the hole...

lol nine inch grinders are absolutely lethal.I have seen experienced tradesman lose control of them before. You have to be concentrating 100% and be ready for it to kick.

lol nine inch grinders are absolutely lethal.I have seen experienced tradesman lose control of them before. You have to be concentrating 100% and be ready for it to kick.

Hey, its all in the way you use them.
I have used them for 25yrs & the only accident I have had was when I was putting it back on its shelf & the disc cut a little slot in the back of my left-hand middle-finger knuckle. That was a 4 1/2 inch grinder too.

Normally I use
a 9inch as a cutoff grinder
a 8 inch as a grinder
a 4 1/2 inch grinder

Tips,
Always hold it so that it will jump/pull away from you.

Fasten the guard properly & use it as a rest/lever against the job to make your work easyer.
Dress the outer edge of the disc, as soon as it starts to 'feather'. Flip the grinder over & grind only on the outer edge so as the wear away the feathered part.

Always have a shortish power cord on it so if you have to you can stand on the cord & pull the grinder up so the plug falls out & it stops. (Thats a good use of the first 3 feet of a extension cord as thats where it never gets worn out)

Store them with the disc up top & the handle downwards (The grease inside the head will then flow back down onto the bevel gears & that will keep it lubed. Do that & expect to last years) Don't do that & it may last 9-12 months.
Make a rack on the wall & put the grinder into it, the guard fits inside the rack, which is two bits of angle iron in a V shape.

Unplug the fukker before changing discs! Use the right tools for that job too.

You can wear down the discs & once they will fit in the smaller grinders, take the disc out & put it aside. ie, once 9 inch disc is 4 1/2 inch dia, it should go in the 4 1/2 inch grinder.
I nail a long nail in the wall & put a 8 or 4 1/2 inch disc on it & draw a circle around it. When a disc has worn down enough it goes on the correct nail & its easy to check for size too.
Use a small file & file a small nick in the grinder guard at that same 'change over' diameter.
Its all about 'meters/min', NOT RPM!

Buy the grinder with a 'spindle lock' on it, it should also have a 'over centre lock' on the guard so you don't need tools to shift it.

(also, don't let anyone see this- use the spindle lock & you can bash the grinder disc against the workbench to make it turn around & that will loosen off the disc. Only do that on discs that are fukked. I never told you that, allright!)
------------------

OK, to do the concrete cutting,
Use a dust mask, & safety spec too.
Use the correct disc, its right beside the metal cutting discs in the shop.
Wet the concrete.
Its not gonna make any difference when you hit the steel rebar except you may see sparks then.
You are only gonna be able to get 3+ inches into the concrete. But that gives you something to work too.
A proper cutter would be better, but, your boss. Is your Boss.
Harden up, it builds character.
Make some sort of 'over strike' protection to use when you are bashing the cold chisel with the hammer. Smashing your left first finger where it joins your palm gets to be a pain.
I only have to hit mine once now & it swells up a bit & hurts for days, thats character.

Have fun.

I've been given the task at work to cut a 1m x1m hole in the factory floor where I work. Judging by the edge of the pad, it is 220 -250 millimeters thick (8-10")

I'm guessing it has the typical rebar mesh inside it as most do. They won't let me hire one of those monstrous petrol-powered brick cutters, I only have an electric hammerdrill, a sledge hammer, chisels and a 9" elec grinder. I'm currently looking for some kind of concrete cutting blade for the 9" that won't shatter when it hits rebar.

Any ideas?
electric jack hammer for concrete + grinder for steel rebar= win. You can rent a electric jack hammer for pretty cheapand it will be eaiser to use than a little hammer drill.With the hammer drill you will have to drill alot more holes than just the outline. it would be easiest to just rent the gas powerd concrete saw or what you called a "brick cutter". You know i am not sure but they may have an electic concrete saw.

Using chisels and sledge hammers is just impractical you need a jack hammer for sure.

A boatload of protips, followed by:
(also, don't let anyone see this- use the spindle lock & you can bash the grinder disc against the workbench to make it turn around & that will loosen off the disc. Only do that on discs that are fukked. I never told you that, allright!)

I usually just use the hand, suitably wearing a glove of course, and "chop" down on the exposed part of the disc with the edge of my hand, or the palm (disc held vertical, and to the left side, motor housing held in the right hand, to the right side) to loosen it.
Wouldn't bash it against anything hard though, as the disc might be damaged...

Btw, nice to see some advice from someone who knows their shit.

If he's that much of a dumb ass to get you to do the job.
Has he even though about how the hole will effect the slab structurally?


This whole building is bound to fall down.

I'm assuming it's on the ground floor, shouldn't affect the building at all.

If he's that much of a dumb ass to get you to do the job.
Has he even though about how the hole will effect the slab structurally?


This whole building is bound to fall down.
No it fucking isn't.

If he's that much of a dumb ass to get you to do the job.
Has he even though about how the hole will effect the slab structurally?


This whole building is bound to fall down.

I loled. you have to cut into/jack hammer into the slab in many situations to do repairs on drains and piping.

There is nothing more stimulating than cutting into concrete with a petrol cut off saw.

There is nothing more stimulating than cutting into concrete with a petrol cut off saw.

Jack hammer is fun also. I think an electric jack hammer would be much more suitable for what he wants to do. You would need a seperate blade for the rebar and if you ran into the rebar with the concrete blade on it you will fuck up the concrete blade.

Jack hammer is fun also. I think an electric jack hammer would be much more suitable for what he wants to do. You would need a seperate blade for the rebar and if you ran into the rebar with the concrete blade on it you will fuck up the concrete blade.
Concrete Diamond tipped steel blade would http://www.china-metal-tools.com/products/laser-welded-or-brazed-diamond-saw-blades/concrete-diamond-saw-blade-s.JPG but not a masonry cut off blade, http://www.nortonconsumer.com/Media/Documents/S0000000000000001032/89353%20Masonry%2014in%20CutOff-Blade.jpg
would chop through steel better than a steel cut off blade. (takes a lot more shit than a steel one)

Concrete Diamond tipped steel blade would http://www.china-metal-tools.com/products/laser-welded-or-brazed-diamond-saw-blades/concrete-diamond-saw-blade-s.JPG but not a masonry cut off blade, http://www.nortonconsumer.com/Media/Documents/S0000000000000001032/89353%20Masonry%2014in%20CutOff-Blade.jpg
would chop through steel better than a steel cut off blade. (takes a lot more shit than a steel one)

yeah i am not real educated on the blades. i just asked one of the concrete workers on one of our job sites if his concrete cutter would cut through rebar and he said "the blade on his would have to be changed or it would destroy the blade," it did actually look like the diamond blade but it may have been something else. He said if you bought the right blade though it would work.

Jack hammer is fun also. I think an electric jack hammer would be much more suitable for what he wants to do. You would need a seperate blade for the rebar and if you ran into the rebar with the concrete blade on it you will fuck up the concrete blade.

It isn't easy to attain precision with a jackhammer, you still need to cut out the outline with a concrete saw.

It isn't easy to attain precision with a jackhammer, you still need to cut out the outline with a concrete saw.qft!
keeps the area to be cut out contained.

It isn't easy to attain precision with a jackhammer, you still need to cut out the outline with a concrete saw.

Not with the full power compressed air ones. But the electric ones arnt to messy. Drilling and outline with the hammer drill would be enough. Even if you cut an outline i will still not be perfect and pretty looking when you try to take the slab out by breaking it up. With a sledge hammer and chisel it would take days to break it up and get it out. No matter what you will have to use a jack hamer. Think about it, once you cut the slab it isnt going anywhere unless you break it up into manageble pieces.

I've been given the task at work to cut a 1m x1m hole in the factory floor where I work. Judging by the edge of the pad, it is 220 -250 millimeters thick (8-10")

I'm guessing it has the typical rebar mesh inside it as most do. They won't let me hire one of those monstrous petrol-powered brick cutters, I only have an electric hammerdrill, a sledge hammer, chisels and a 9" elec grinder. I'm currently looking for some kind of concrete cutting blade for the 9" that won't shatter when it hits rebar.

Any ideas?
If my boss ever said that to me? I'd give him a tooth pick and hell him to wipe his ass with it. :rolleyes:

Not with the full power compressed air ones. But the electric ones arnt to messy. Drilling and outline with the hammer drill would be enough. Even if you cut an outline i will still not be perfect and pretty looking when you try to take the slab out by breaking it up. With a sledge hammer and chisel it would take days to break it up and get it out. No matter what you will have to use a jack hamer. Think about it, once you cut the slab it isnt going anywhere unless you break it up into manageble pieces.

An electric one will still be rough. Fuck a drill as a last resort though, cutting the outline and then making as many cuts across as possible is the best way to do it.

I'll take a picture of some concrete boxes I have cut out with a saw and jackhammer, they are pretty neat boxes.

An electric one will still be rough. Fuck a drill as a last resort though, cutting the outline and then making as many cuts across as possible is the best way to do it.

I'll take a picture of some concrete boxes I have cut out with a saw and jackhammer, they are pretty neat boxes.
My point was you still have to use a jack hammer either way.

I agreed with you. lol