cutting concrete

[jontar]

Never really needed to cut concrete before, but I want to install a sump pit in my garage that never was put in, when it was built 7yrs ago.

I want to cut a rectangle into the 25MPa 4inch slab of concrete, near the center so that water and melted snow drip into the sump rather then drip all over the garage.

What should I use, there is rebar, and I thought of using a 7inch skil saw, with a concrete blade and watering down the floor before cutting to keep the dust down and to help"lube" and cool the saw blade.

Any opinions welcome, as I haven't done this before, but dont want to rent a huge concrete saw just for this small hole.

 

[Bobcat753]

It would be best to rent a concrete saw and small jack hammer. In the end it will be easier and you won't be making more than one cut were a skill saw will take forever. I tried to cut concrete with one and failed. The blade snapped in half and that was a expensive blade.

 

[2oolhound]

I used my tile saw to cut a strip out of the driveway when I had to run a new water line last summer. The tile saw was $70, 4.5" blade and has a water hose attachment. Because of the size it only scores the concrete about 1 3/4" deep but I smashed the rest out with a sledge hammer. The cut stayed even on the top edge but went off any-which-way past the cut. The tile saw has paid for itself over and over. However your job requires a neat job so I think I'd consider renting a big concrete saw and not risk cracking the concrete past the cut.

 

[dogdog]

I just cut a 4 inches ish thick slab with that 7 inch concrete blade (about $12 ) from home depot, on a 7 inch grinder. the hole is about 6X12 for a post with a good SDS MAX 3/4 but and a SDS MAX chissel , sledge hammer, you are all set to go. just draw your box, drill 3/4 inch hole with your drill on all 4 corners and one hole in center. make the 6 cuts. 4 on outer edges of the hole, and 2 cross cut from each corner. break with hammer or your chisel point. make sure you use plenty of water for coolant when cutting. and don't spill water into the grinder. only to the blade. so have a helper. and safety google , ear plugs ,dust mask etc etc and usual safety.

This similar blade mine was black and decker or somehting costed $12, even it says dry cut blade, use plenty water for coolant and lube. I used one of those garden sprayer to have someone spray the water on blade while cutting.

http://www.homedepot.com/p/MK-Diamo...Turbo-Diamond-Saw-Blade-MK-99TWD7-7/100476897


If you are planning to cut say a 10 foot long cuts, I suggest you get a 14 concrete saw (buy or rent) I have done that to get a trench with the TS410 STHIL it's like cutting butter with hot knife. Home depot rents them for about $60 per day plus $40 / day for the 14" segmented blade....If you choose to use the $12 fiber concrete blades , be prepare for lots of dust and pissed off neighbor and do not use water to cool or control dust while the fiber blade is in use. Home depot have 2 brands Bosche and STHIL.

 

[bob15]

Unless the garage floor is already pitched to the center (where you want the sump pump), you're probably wasting your time. Water isn't automatically going to run to a sump pump hole unless the floor was sloped in that direction.

Also, how do plan on covering over the pit/sump pump so you aren't tripping into it or having stuff fall into the hole? Or are you putting a shallow trench?

Gas powered cut-off saw would be the best....but would like to hear more on the project.....

 

[tibwd]

Funny this topic came up. I need to replace an underground water suction line on my pool. 4ft underground, topped by concrete sidewalk slabs. My plan is to cut 14 inch wide path from filter house to pool, remove concrete pieces and dig trench to access/replace line. Concrete has mesh type reinforcement. I did not know if the rental saws cut through the metal? I obviously want the right tool for this job. Cut is approximately 12 ft long. Only need one side cut, other side matches up nicely with the seam of the adjacent sidewalk type pieces. Any recommendations and suggestions? Thanks in advance.

 

[dogdog]

I have the rebar and mesh when I put down my concrete. It cuts through the mesh like butter, but the rebar part will take it slower with plenty of water for lube and coolant.
first you have to be sure about where your pipes are located no??


you can rent the walker if your back kills you, or handheld. I did the 2 cuts in about 90 minutes or so that is not including digging the trench 32 or so inches deep. that took me another whole weekends. about 12 or 14 feet and about 14" wide. suggest you to cut wider if you are going to dig any deeper. drill relief holes across the trench about 3 feet apart. with FAT MAX pry bars. 10 lb or 15lb sledge hammer. The cuts are nice and smooth with no cracks extend outside of the cut area. but the 14 inch concrete saw cuts only about 5.5" or maybe no more than 6" deep.

HandHeld: just get a diamond segmented blade. a little tough for back and hand (vibrations), mine saw is the TS420 or TS410 bought it used from ebay and refurbish my self. but cost less long run on rentals, because I took my time on DIY stuff. but if you know what exactly you are cutting. just rent it for a day $100 or so for the handheld plus the blade, last year when I checked.

The Walker ones:

 

[Hpozzuoli]

Like a hot knife thru butter. Seriously, it cuts great with the hose on it. Makita DPC7321. I was using it to cut steel fence posts with this blade.

 

[Bondo]

Funny this topic came up. I need to replace an underground water suction line on my pool. 4ft underground, topped by concrete sidewalk slabs. My plan is to cut 14 inch wide path from filter house to pool, remove concrete pieces and dig trench to access/replace line. Concrete has mesh type reinforcement. I did not know if the rental saws cut through the metal? I obviously want the right tool for this job. Cut is approximately 12 ft long. Only need one side cut, other side matches up nicely with the seam of the adjacent sidewalk type pieces. Any recommendations and suggestions? Thanks in advance.

Ayuh,.... I'd rethink yer width,....

Diggin' 4' down through, basically a crack is gonna be tough,...

24" ain't alotta room, but doable,... for both diggin', 'n compactin' later,...

For a Rented power saw, buy a carborundum blade,...
Rebar will chew the diamonds off a rented diamond blade,... way to expensive,...

 

[G_P]

Rent a gas powered concrete saw with diamond blade. Hook a garden hose to it. If you are worried about the water making a mess you can make a dam around the cutting area with some towels. if you have a helper they can shop vac up the excess water.

There are dry cut saws available but the amount of dust they generate is amazing and it will coat everything in your shop.

Will this sump pit have a liner and pump in it? or is it just going to be a dirt hole in the floor for water to soak into?

 

[BFHtime]

A ring saw where the movement of the blade only occurs at the circumferance and about an 1 1/2 in from the edge, the center Portion does not move. Less mass to turn and less material in the blade, these have an attachment for a garden type hose to keep the blade wet. Best I have seen for cutting concrete besides those monsters that cut he road, or a water jet. These can be rented, as I have seen them rented.

 

[BFHtime]

Quick search here is an example.

http://www.husqvarna.com/us/construction/products/power-cutters-product-range/k-970-ring/

 

[dogdog]

here's the left over concrete cut with the TS420.