Cutting concrete with circular saw

[markdem]

Morning,

I need to cut a 40mm deep trench in a concrete slab. Is there anything wrong with putting a diamond blade on a circular saw? It looks like the perfect tool as I can set the depth of cut.

The only issue I see is I need to make the cut dry, but I have a dust extractor so I can move the dust away..

Can anyone see any other issues in doing this?

Thanks

[BobL]

No dust extracting can outcompete the circular saw's motor cooling fan which will such some fine dust into the motor and you will reduce the life of the saw.
I'd recommend hiring a proper concrete cutting saw.

[jack620]

I agree with Bob. Hire a wet saw. No dust extractor can keep up with the dust generated by a concrete saw.

EDIT: just noticed you need to make the cut dry. I that case ignore my previous advice. Maybe buy a cheap powerful circular saw like an Ozito and expect to kill it.

[markdem]

Thanks for the reply.

This is my old $90 GMC that us used to cut dirty sleepers coved in soil.. I have had it since Bunnings sold GMC and to tell you the truth, if the old girl dies I will not be disappointed..

Besides that, is there any other reason this should not be done?

Problems with a proper saw are;

1. It is inside the house so I would like to avoid petrol.
2. It has very limited space so a walk behind is out of the question. Even a hand held concrete saw will be hard and I will probably need to hold it in a very bad position.

Thanks again.

[jack620]

I've dry cut a brick wall inside a house. It's a nightmare. The volume of dust is enormous. It quickly fills the room and visibilty reduces to near zero. If it has to be a dry cut, maybe something with a proper dust port like this:

DEMOLITION SAW - 230MM (9IN) ELECTRIC DUSTLESS (DRY CUT) for Rent - Kennards Hire (https://www.kennards.com.au/for-hire/saws/demolition-saws/demolition-saw-230-mm-9-in-electric-dustless-dry-cut)

Might be the best $120 you've ever spent:

[markdem]

That's perfect. Seems nice and easy to use and should fit in the space I have.

Thanks

[Beardy]

The short answer is yes you absolutely can do it and I have done it as well.
The bigger problem is the dust and it finds its way into everything in the house so you either create a spray booth type enclosure with plastic to minimise the cleanup or the preferable choice would be hire the Kennards saw which will do a far better job and cost the same as building the dust enclosure

If you are creating a trench for a conduit or pipe you can hire a twin blade chasing saw as well

When I used to do it years ago there were not any other options

[malb]

From Kennards description, the Hilti only has a dust shroud to connect to a vacuum, so it is not a self contained dustless option, and I understand that the original poster said that he doesn't have room there for a vac unit. Even if he did, there is a fair chance that the concrete dust would take leave residue around the vac motor that would take out it's bearings in fairly short order.

[ian]

Kennards also have a Makita option
SAW - DIAMOND 125MM (5IN) for Rent - Kennards Hire (https://www.kennards.com.au/for-hire/saws/saws-other/saw-diamond-125-mm-5-in)
includes a dust bag to collect most of the dust

I've been happy the few times I've used mine

worth looking into

[Bushmiller]

MD

Why do you need to cut the concrete dry?

If it is because of the proximity of electricity, I have cut concrete and slate with both a 9" angle grinder and a circular saw. I rig up a water bottle (2L juice bottle) with a small bore plastic tube out of the lid and start the flow by syphoning and then setting the bottle at a suitable height. The tube is directed to the blade through a hole in the guard and serves the dual purpose of cooling the blade and suppressing dust. Actually the diamond blade seems to last for ever with water cooling as heat is the enemy.

While the horrified among you pick yourselves up off the floor at the thought of electricity and water in close proximity, I should point out that I mount an in-line circuit breaker at the plug end of the power tool. I cut the slate for the whole floor of a house using this method. Also I would add that a saw or angle grinder has never tripped the circuit breaker (important to activate the test button to ensure it works correctly before embarking on your project). I did try to find it to take a pic of the device, but it has gone temporarily AWOL and I could not find any thing similar after a quick glance on the net.

On the positive ( ooops, a pun) side while looking I did find an axe head and some garden hose fittings I didn't know I had. :rolleyes:

Regards
Paul

[Pagie]

I have one of the Makita 125mm saws for 20 odd years and have cut hundreds of bricks with it. It need s a new dust bag now, must see if I can find one. I have worn out quiet a few blades

[wood spirit]

If doing this dry for a small job. Mask up well and use a disposable saw. And a dry cut diamond blade. Saw might still be OK - but don't use Ya good one just in case.

[rambunctious]

MD

Why do you need to cut the concrete dry?

If it is because of the proximity of electricity, I have cut concrete and slate with both a 9" angle grinder and a circular saw. I rig up a water bottle (2L juice bottle) with a small bore plastic tube out of the lid and start the flow by syphoning and then setting the bottle at a suitable height. The tube is directed to the blade through a hole in the guard and serves the dual purpose of cooling the blade and suppressing dust. Actually the diamond blade seems to last for ever with water cooling as heat is the enemy.

While the horrified among you pick yourselves up off the floor at the thought of electricity and water in close proximity, I should point out that I mount an in-line circuit breaker at the plug end of the power tool. I cut the slate for the whole floor of a house using this method. Also I would add that a saw or angle grinder has never tripped the circuit breaker (important to activate the test button to ensure it works correctly before embarking on your project). I did try to find it to take a pic of the device, but it has gone temporarily AWOL and I could not find any thing similar after a quick glance on the net.

On the positive ( ooops, a pun) side while looking I did find an axe head and some garden hose fittings I didn't know I had. :rolleyes:

Regards
Paul


Ha Ha Ha Me too.
At the moment my sparky mate has my 9" grinder with diamond blade cutting bricks and concrete.

[Bushmiller]

I went looking for some welding rods, which I didn't find, but I did find the in-line circuit breaker:

526505526506526507

I tested it and it works perfectly. I know that I first used this device around 1993/94 so it is nearly thirty years old. Probably time for a new one that will be better.

Regards
Paul

[ErrolFlynn]

At the moment my sparky mate has my 9" grinder with diamond blade cutting bricks and concrete.

I've cut small sections of concrete using an angle grinder. Replace the 'metal' disk for one marked 'stone' and it will get through it like a hot knife in butter. Plenty of dust. Do it in stages. The disks aren't expensive.

[ian]

I've cut small sections of concrete using an angle grinder. Replace the 'metal' disk for one marked 'stone' and it will get through it like a hot knife in butter. Plenty of dust. Do it in stages. The disks aren't expensive.
Plenty of dust is one way to give yourself a case of silicosis.

Far, far better to use the dust bag on the Makita diamond saw to collect as much of the dust as possible.

Even better is a fully ducted saw connected to a proper dust collector.