# OT: Cutting Concrete for Drainage System



## JustJoe (Oct 26, 2012)

I need to cut across my driveway (30 year old cured concrete) to install part of a drainage system that looks like this:










I'm cutting at the expansion joint so one side is done (yea!) so I just need to cut off a piece about 1.5" wide x 3" deep x all-the-way-across-the-driveway. I have a 4.5" angle grinder, but I don't think the blade will cut deep enough. I have no hammer drill. I won't be renting tools.

Can I take one of these cheap HF chop-saws and remove the blade portion from the base and use it freehand? 









If it's possible to remove the base and use it freehand I can put one of these 14" diamond blades on (they sell this blade, advertised as for "cured concrete" but I didn't see a saw it was designed for?)










The cut can go medium-slow, I don't care if it takes an hour instead of 5 minutes. I don't care if it has to be done dry and creates a noxious cloud of cement dust that blacks out the sun for most of southern AZ (I"ll wear one of those 39 cent dust masks and a pair of cheap sunglasses.) It has to be reasonably clean - the driveway is already cracked in places so this isn't a beauty contest, but I don't want to be breaking giant chunks off either, just straight enough that I can drop the drainage channel in and set with a bit of premixed concrete on the sides/bottom.

Is it do-able under those conditions? Has anybody else ever taken a cheap cut-off saw and chopped off the base and gone free-wheelin down the driveway?


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## patron (Apr 2, 2009)

sounds risky to use that saw freehand
without a base on it

i have just rented the saw
it doesn't take much time
(under most rental places time deal)

be safe
whatever you decide
that saw on the loose could be very dangerous
with the torque and binding it might cause 
in a freehand operation


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## Acelectric (Mar 17, 2013)

I have used one of these blades on a circular saw to cut concrete and it worked surprisingly well. It may not cut all the way through the concrete but deep enough for you to break it out of there. At the surface it will look just fine.


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## robertb574 (Jan 12, 2011)

It looks like you would have to modify the guard too, to get the depth you want. There may be other things that need modifying too. How thick is your driveway? After cutting the side, will it still be attached at the bottom. How do you plan on detaching it from the bottom?


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## JustJoe (Oct 26, 2012)

Patron I'm near a small-town with one source and the price they want for a days rental is not much less than me buying my own tools. I'm not renting. But I will try to keep it safe.
Robert - It's gotta go about 3" deep and I'm cutting the line about 2" from the expansion joint anyhow so once I cut the line deep I can chip off the piece easy enough - if that parts ugly it doesn't matter because I can fill with concrete. I haven't tested to see how deep the driveway is, probably 4" or so. 
Acelectric - Thanks for that tip. for $14 it's worth a quick try. my cordless dewalt saw would probably die if I tried it, but I've got grampas old all-metal powerhorse sitting around here somewhere. I'll have to dig it out.

thanks
Joe


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## MarkDavisson (Apr 26, 2009)

I second acelectric's suggestion of using the circular saw. Take it slow. A 7" blade should get you very close to the 3" depth you are needing


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## GrandpaLen (Mar 6, 2012)

*"Can I take one of these cheap HF chop-saws and remove the blade portion from the base and use it freehand?"*

*NO!!!*

...think DANGER, LOTS OF BLOOD, SEWING FINGERS, HANDS AND LEGS back on.

Work Safely and have Fun. Grandpa Len


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## JustJoe (Oct 26, 2012)

Well I've got the HF 20% off coupon, so the money I save should pay the health insurance deductible 

I bought the 7" diamond blade that Acelectric recommended. i went to put it on the dewalt cordless saw just to see what it could do, and that saw is a 6". So I dug out grampa's old skilsaw. It is a 6.5.

I'm not making another trip into town today, so this project will have to wait until next week when I can swing by lowes and pick up their cheapest ($39) 7" circular saw.


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## Jim Jakosh (Nov 24, 2009)

If you have that chop saw, what if you took it apart and made it swing out instead of in and then use the base it has for a plate to ride on the surface of the concrete to give the saw some stability. Have the base running ahead of the blade and use water on it. It will muck up the chop saw a lot but if you wash it off and dry it you might be in business. I have used one for cutting blocks sitting on the base and not clamped in. You just go slow and careful.

I would not use it free hand without a support on the surface of the concrete.

Also, I have used a 7 1/4" Skilsaw with a concrete blade in it to score concrete to cut out a box in the floor. It was real dusty but I went in about 1", drilled some holes in the middle and busted it all out. I filled it with concrete whenIi was done putting in a cleanout.


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## JustJoe (Oct 26, 2012)

I ended up getting the cheapest circular saw Lowes had ($36) and the $12 diamond blade and it's working nicely. For that kind of money at the tool rental place I might be able to borrow a screwdriver or two. 
The first 6" took an hour because the blade would cut a bit and stop spinning. I thought it was because I only bought the 12-amp saw (3 gerbils on a treadmill) and was thinking I should have bought the 15 amp (3 gerbils, one hamster on a treadmill). Then I figured out it just wasn't tightened on the arbor. Fixed that, and it cut right across all 10' to not quite 3" deep in just a few minutes. Cold chisels and a hammer break off the bottom bit. I've got the 10' cut made, about 7' of the expansion material dug out, and 4' completely chipped away. So I've only got 3' of digging the expansion wick, and 6' of light chippnig to go. Another hour or so and I should have it all ready to set the drainage in place.
thanks for the suggestions.


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## GrandpaLen (Mar 6, 2012)

Well done and Safely too.

Work Safely and have Fun. - Grandpa Len.


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