learn me cutting concrete blocks

im building a retaining wall. got it far enough along to the point where I need to start cutting blocks where they meet the house. I will also need to trim the top stones to fit the curvature of the wall.

heres what the blocks look like, they are 4x6x12 or so.

so from what i gather on the internets and youtube, ill need a chisel, hammer, and circular saw with diamond cutting blade. and a good mask to not breathe in concrete dust. I am thinking I wont cut all the way through but just score the blocks then use the chisel and hammer to split them. does that sound about right?

I'm picking up a chop saw and 12" masonry blade today to finish my paver walkway.

rent a big wet saw at HD? no dust, make quick work of things. i cut wet whenever possible with a diamond blade. usually with an angle grinder and a turbo blade, it cuts like butter.

How many blocks do you need to cut, and how much are you willing to spend?

You can get a masonry blade for your circle saw, which is probably the best combination of cheap and quick for this job. Masonry cutting discs for an angle grinder will also work and will be cheaper than a circle saw blade, but that will be tedious for this job.

If you want an excuse to buy a new tool you could pick up a Horrible Freight chop saw (the black one), and the blade that comes with it will suffice (barely) if you only need to make a handful of cuts. If you want a new tool and you want to spend some more money, buy that black chop saw and then pick up a real masonry blade for it - the blade will cost as much or more than the saw, but it will cut bricks and blocks like butter.

The black HF chop saw with a Rigid masonry blade was the setup I used for my brick oven build, but I had to make a bunch of cuts so the investment was worthwhile. The saw is borderline decent, and a good blade pushes it into "OK" territory.

If your local box store rents a wet saw big enough for those blocks, that's another way to go. Might be overkill if you only need to make a handful of cuts.

I'd probably recommend a masonry blade for a circular saw in this case. Score one side and break with a hammer/chisel, or saw through from both sides.

And honestly, if you're working outside I wouldn't worry excessively about the dust. A regular mask will suffice.

Nice wall. That's going to look good when it's done.

Thanks!

I need to do at least 12-15 cuts on the large blocks, then maybe an 2-3x as many cuts on the top stones which are maybe only an inch and a half thick, but 8x12 or so and rectangular.

I do have a mitre saw (in fact its new in the box still), 14 amp ryobi 10 inch. Its basically the model previous to this one... http://www.homedepot.com/p/Ryobi-14-Amp-10-in-Compound-Miter-Saw-TS1344L/100634340#.UeF27tI3suA

Ive had it for a few years not used, i thought it was a smaller saw until i checked just now. It was a gift, seems like its a nice saw but I don't think it will actually cut all the way through the blocks. Sooo....just get a masonry blade for it, cut what i can on the blocks and then snap em apart with a chisel and hammer? I wouldnt be able to get a nice even score on the block though since it works more like a chop saw though...

Im not opposed to buying a circular saw or table saw. we've been talking about it for months as it would come in handy for other projects. i think ill be doing a patio behind the house at somepoint too so there will likely be more block cutting involved eventually.

I used a masonry blade in a circular saw, no chop saw. Worked OK but keep it straight. If it kicks back it kicks hard and tries to eat you.

I understand water helps, but water and electricity?

Do not use a new miter saw to cut masonry. If you cut dry, the abrasive dust will do bad things to your motor, bearings, and guides. If you cut wet, you are asking to get electrocuted, or gum up the rails with muck.

That saw was not designed to cut masonry.

Wet saws run at a slower speed, and have sealed electrical components.

I just did a similar wall. Hammer and chisel works fine, or a masonry blade in a skillsaw.

Go to HD rental and ask for a masonry saw. It'll make quick work of it. If you mark your pieces, you'll only need for a couple hours.

wall looks great.

Thanks, i definitely do not want to berkeley up the mitre saw, we will look into a rental

I used a skill saw with a masonry blade for similar work and it did fine. Set it to full depth, cut, flip it over, and cut the other half. Don't ruin a good doing this, buying a dirt cheap model that's basically throw-away is the way to go here. And it goes without saying, but wear the appropriate eye/ear protection, along with a mask for your mouth and nose...

Score the block all the way around where you want to cut it. This can be done with a diamond blade in a 4" grinder or with a chisel and hammer. After you score it all the way around, lay it face down and take a 4" masonry chisel and whack that bastard from the back like you want to kill it. It should split right on your line. Or rent a 14" cut off saw and buy a $100 diamond blade. My company installs these wall every day and we use the cut off saw to score the blocks, then split with the chisel to save $$$blades$$$.

Do it like a real mason and rent a target saw?

spriteracer wrote: Score the block all the way around where you want to cut it. This can be done with a diamond blade in a 4" grinder or with a chisel and hammer. After you score it all the way around, lay it face down and take a 4" masonry chisel and whack that bastard from the back like you want to kill it. It should split right on your line. Or rent a 14" cut off saw and buy a $100 diamond blade. My company installs these wall every day and we use the cut off saw to score the blocks, then split with the chisel to save $$$blades$$$.

bingo

Masons have been building walls for 10's of thousands of years.

Power tools to do the cutting have only existed for the last few decades.

You guys are wimps. Hammer and chisel is cheap and easy.

SVreX wrote: Masons have been building walls for 10's of thousands of years. Power tools to do the cutting have only existed for the last few decades. You guys are wimps. Hammer and chisel is cheap and easy.

Masons are amazing. I saw a guy split these silly things easier than I pour a glass of milk. I haven't done it that well, but I agree that it's typical to watch the guys chisel them in half, and it's very quick and accurate.

It's really not that hard, but most people do it wrong.

spriteracer wrote: After you score it all the way around, lay it face down and take a 4" masonry chisel and whack that bastard from the back like you want to kill it.

This ^ is incorrect.

Masons are masters of conserving energy and fluid motions. They don't whack the E36 M3 out of anything.

Plus, masonry breaks. Severe blunt force does nothing but encourage blow-out, which makes random (not straight) break lines through the unit.

Masons choke their hits. They try to hit the exact same point repeatedly with a pointed instrument (brick hammer) as a sharp surface rap, which encourages micro fault lines to develop in the unit where they want it to break. It's like a woodpecker hit, not a battering ram. Like place hitting a bunt, instead of swinging for the fence.

I will admit that those 1 1/2" cap blocks are more difficult. They are denser, and more brittle. They don't like to break cleanly. When I did mine, I wanted nice pie-shaped cuts in the cap blocks to follow the curves of the wall. I used a 4" grinder with a diamond blade to score them.

Nothing will do a nicer job then a wet saw, but it comes at a pretty high cost, and it's not finished woodworking. It really doesn't have to be perfectly cut to look wonderful.

12" diamond blade in a 2 stroke concrete saw and a hose. Done.

Appleseed wrote: 12" diamond blade in a 2 stroke concrete saw and a hose. Done.

And around here (Frederick, MD) you can rent one for $65 a day.

I work at HD rental

You can rent a "paver saw" for about $60/24hrs. Makes nice work. For my money, though, I prefer the cold chisel and hammer idea since it leaves a rough edge that matches the rest of the wall. Use a 5-lb BFH and score all 4 sides, then set it on one of those scores and whack it.

Like this:

I've done it before with nothing but a 3/4" and 3" chisel and a engineer hammer. Sometimes both halves wont be useable and you'll need to do some cleanup to get one good half, but it works. Score and split.

Don't use a good saw, if you're going to use a circular saw. Buy a $35 one and if it survives the cool, if not still cheaper than the rental.

I thought that you used a hydraulic or screw-drive cutter for blocks,
but I don't see anything available at any US rental places.

FWIW, I bought a handheld tile saw at Lowes a few years back. I LOVE having access to a dedicated wet saw, it even has a hookup to the hose. While is is meant for tile, I have used it to cut block and concrete with different blades. It would be easy to score your block with, and under $100. I have tried an angle grinder, but the dust (or mud) really kill the motor fast.

Wax on, wax off,

Toyman01 wrote:

Like a BOSS.