OT: Cutting tile , brick or concrete with a 7 1/4" circular saw?

Spud · Jun 26, 2014

Standard corded circular saw, 7.25" . Milwaukee, Bosch, Porter-Cable,Makita etc...

So is it ok to cut Tile, concrete or brick with it, with appropriate blade ofcourse?

Dry cutting or wet cutting.

-
Makita has a masonry and tile cutting circular saw of 4 3/8" , with a No Load speed of 12,000 or 13,000 rpm.
Their 7 1/4" circular saw for wood is 5800 rpm. Is the Rpm on the Makita Tile saw just a function of it being a small diameter (4 3/8") saw blade and not necessarily because you need high Rpm for masonry and tile?

So for concrete, masonry and tile, one needs high rpm? But angle grinders which are used for cutting these materials are low rpm, about 3500 rpm for a 14" blade on an angle grinder cut-off saw.

Tony Quiring · Jun 26, 2014

Have used correct blade and it works but not tge best.

What is the project?

rbent · Jun 26, 2014

We've got two of these Makita 5057KB 7 1/4" circular saws w/ dust collectors.

http://www.amazon.com/Makita-5057KB-4-Inch-Circular-Collector/dp/B00004YODW

I bought them initially for a project in a plant we were working in, we grooved with a 3/8" wide tuck point blade ~1/4" deep or so for 2,000ft. Worked great. I had two of them built out identical so if one died we could switch them out but never a need to. I've now got that saw cutting 2" deep with an .090" diamond blade through a 3.5" sq prestressed beam of ~10,000psi concrete with two prestress wires in one shot and hasn't had a problem yet.

I think the dust collector works well, but I've never used it in its factory setup. The first one I made a new base to fit my saw guide tracks that had additional brushes to help control dust, and the second setup has it in a box with brushes where the beam passes through so all the dust is contained and sucked out through the saw. Our cheapo dust collector on that is a 5gal shop vac with a cyclone bucket before it.

CalG · Jun 26, 2014

I used the "double insulated" $50 Makita to cut all the soap stone when We did the kitchen counters. (30 lineal feet of counter plus a side board) I purchased the stone "rough" and cut to suit , including the back splashes.

Everything was done wet with the stone slabs supported on a piece of "blue board" ridged foam insulation. With another family member holding the garden hose to flood the cut line, but not flood the saw, operations went smoothly.

But, soapstone is easy...

specfab · Jun 26, 2014

Take note of the difference in diameters you are mentioning; if you run the numbers, you'll find that the 14" and 4.375" blades are running something like 12,000 SFPM, while the 7.25" is a little slower, around 10,500 SFPM. I gave the RPMs a little decrease assuming loaded condition. Long story short, they are generally equivalent for the different diameters.
I used a 7.25" Skilsaw with an abrasive masonry blade to slice up stucco for removal on existing construction when I added the shop onto the house. No requirement for nice cuts in that case, but it worked "OK". If you are doing fancy work, hand-held usage is the lesser choice. I definitely would NOT use a hand-held run-of-the-mill circular saw to do wet cutting. That could lead to some interesting sensations.

specfab · Jun 26, 2014

CalG, you're more trusting of those saws than me :-)

Greenwud · Jun 26, 2014

Depends what you are cutting and how much. A diamond blade cutting concrete has a shorter life if run dry and there is an optimal speed for cutting.
The dust from anything you might cut with such a blade is seriously unhealthy and a wet saw works so much better that it is a no-brainer IMHO. The dust also builds up in the motor and although it may seem to have done no harm, the saw cannot cool properly and lets it's smoke out in protest- this is com experience.
Makita also makes a 7 1/4" wet saw and Hitachi makes or made a 6" wet saw-get one if you have any real work for it.
I'd rather have the Hitachi and have not managed to destroy mine yet.

Spud · Jun 26, 2014

rbent said:
We've got two of these Makita 5057KB 7 1/4" circular saws w/ dust collectors.

Makita 5057KB 7-1/4-Inch Circular Saw with Dust Collector - Power Circular Saws - Amazon.com

I bought them initially for a project in a plant we were working in, we grooved with a 3/8" wide tuck point blade ~1/4" deep or so for 2,000ft. Worked great. I had two of them built out identical so if one died we could switch them out but never a need to. I've now got that saw cutting 2" deep with an .090" diamond blade through a 3.5" sq prestressed beam of ~10,000psi concrete with two prestress wires in one shot and hasn't had a problem yet.

I think the dust collector works well, but I've never used it in its factory setup. The first one I made a new base to fit my saw guide tracks that had additional brushes to help control dust, and the second setup has it in a box with brushes where the beam passes through so all the dust is contained and sucked out through the saw. Our cheapo dust collector on that is a 5gal shop vac with a cyclone bucket before it.

When you say "grooved" , do you mean like a Dado blade setup (only in your case it is 1 blade that is 3/8" thick) on a table saw that cuts a groove/slot/channel ?

gvidas · Jun 26, 2014

I've had good success cutting 1" thick slate slabs with a circular saw. Borrowed a toothless diamond wheel from a tile saw.

Dry cut + respirator + box fan for visibility seemed better in that case, since it was hard to get enough water to truly flush the joint without also flushing the saw, and the toothless diamond blade wasn't clearing the mixture.

Definitely use a clamped straight edge as guide and support both sides of the cut with polystyrene.

Bill D · Jun 26, 2014

I have the little harbor freight wet saw with diamond blade. I used it to cut back stucco. a easy task that it handled well except... Part of the cut was horizontal and tight room meant I had to run it motor down. I could see water dripping from the fan housing. Tripped the GFCI several times with that orientation.
Bill D.

Spud · Jun 26, 2014

CalG said:
I used the "double insulated" $50 Makita to cut all the soap stone when We did the kitchen counters. (30 lineal feet of counter plus a side board) I purchased the stone "rough" and cut to suit , including the back splashes.

Everything was done wet with the stone slabs supported on a piece of "blue board" ridged foam insulation. With another family member holding the garden hose to flood the cut line, but not flood the saw, operations went smoothly.

But, soapstone is easy...

This one? It is 5 1/2" , and costs about $245.
Makita 5005BA 5-1/2-Inch Circular Saw with Electric Brake - Power Circular Saws - Amazon.com

Which one are you referring to?

Motomoron · Jun 27, 2014

One of the few reasons to buy a Harbor Fright tool: You're going to do something abusive to it.

I bought a HF 9" angle grinder and a cheap 9" segmented diamond blade from amazon.com - like $25 cheap.

It blasted through 2 tile-over-mortar bed bathroom demolitions and has cut all the brick/paver/slate I've needed to do for about 5 years.

I do cheat and blow it out at the end of longer jobs, though.

Prior I had a couple pawn shop circular saws w/ grit blades. They're pretty spectacular when they finally die, and are the only tools I've
killed through abuse.

Spud · Jun 27, 2014

Motomoron said:
One of the few reasons to buy a Harbor Fright tool: You're going to do something abusive to it.

I bought a HF 9" angle grinder and a cheap 9" segmented diamond blade from amazon.com - like $25 cheap.

It blasted through 2 tile-over-mortar bed bathroom demolitions and has cut all the brick/paver/slate I've needed to do for about 5 years.

I do cheat and blow it out at the end of longer jobs, though.

Prior I had a couple pawn shop circular saws w/ grit blades. They're pretty spectacular when they finally die, and are the only tools I've
killed through abuse.

No Harbor freight in Sri Lanka

but there are cheapo Chinese knockoff but they are still too much money for what they are , such that for 30-40% extra I get brand name tools. Anyways I am taking a bunch of tools with me when I head over in a few days. I got a new Bosch 9" angle grinder over there but it doesn't have a shroud/guard/base like a circular saw, so that's why I prefer using a circular saw since I can get far more accurate results .

--

So ...

If I am going to flush with water while cutting tile and or concrete and other masonry, how safe are double insulated circular saws? Keep in mind it will be a 110volt tool running off a step down transformer (NOT an isolated transformer) that converts the mains 220-240v to 110-120v.

Big B · Jun 27, 2014

I have an old bottom of the line Craftsman 7 1/4" circular saw that I bought for about $10 for the sole purpose of sacrificing it to a diamond blade. Now about ten years later and one dunking from a flood it just cut about 1" deep for about 6 feet last week. Just can't kill it. I think the blade was about $25 at the big box store.

Big B

Spud · Jun 28, 2014

thermite said:
Surely you aren't using an autotransfrmer or Variac for that great a drop? It probably IS an 'isolatION' (not 'isolatED') transformer as part of the deal.

IF THEN it happens to have a centre-tap on the 110/120 V side.. and you are able to Earth that .. soundly .. each leg presented at the tool could be only 60 VAC above ground. And it is 'A' C so there is a shake-loose chance vs stick-and-fry DC.

There is still, however, the upstream 240 VAC feed somewhere in the area, so I'd certainly use a long extension to get well away from that AND the transformer it enters, elevate, cover, and tape whatever wanted kept dry, and be damned careful with the water.

BTW .. back to that hand-drilling hammer and wedge or chisel I use... certain amount of fly-rock. Eye-protection more than mandatory.

But damned little dust.

Bill

One of these; placed order last week. Should be here next week. It is an autotransformer ; it is specifically made to run American 110-120v tools on UK 220-240v mains. It is 3kv continuous rated. From my research Carroll & Meynell is a respected UK brand of portable job site tool transformers, and their products are Made in the UK.

UK to US Supply Conversion, 3kVA - CM3000/A/US - UK to US Supply Conversion - Products

--

Well yeah I would be using a proper filter cartridge dust mask this time around ; last time I did concrete cutting I just used a basic disposable cloth mask. This time I'll take with me 3M cartridge type mask . Ofcourse I will also use Googles also. Still that concrete dust make it seem like it is snowing heavily , only its grey snow. Such a bloody dust-bowl when I start cutting. That's why I wanna use wet cutting .

Makita does make a little 4 3/8 wet cutting tile saw , the below one , but what is soo different (from a electrical safety standpoint) between it and the 7 1/4 " circular saws used for wood? Other than the: "special cover" & GFCI plug??? Any special electrical additions/modifications you notice in the specs or pdf manual?

Makita USA - Tool Details - 4101RH

Spud · Jun 28, 2014

thermite said:
Spud?

"Priorities', mate.

Yer daft. OCD, even, on the tools and their 'infrastructure'.

You'll jump through dozens of costly hoops to arrive in Sri Lanka a 'subject matter expert', buried in paid-invoices and paperwork, over-equipped with esoteric tools..... and have WAY too little knowledge of the most efficient and EFFECTIVE way to simply get the construction task DONE with minimal effort and harm.

It's basic masonry and wood work. Not a rocketship.

Bill

Yeah I do have OCD , and try for best practices and cringe at shoddy work. Might seem annoying at times but my sis always gets me to hang pictures, minor house renovation, cutting the lawn etc.. cause she says I do it nice while her husband just wants to get it done and isn't concerned with how it looks.

Peter. · Jun 28, 2014

I wouldn't entertain cutting concrete with any type of 'circular saw' such as used for cutting timber, it won't improve your lines and is awkward to use efficiently. Get a normal angle grinder and fit a diamond blade. If the concrete is hard or dust a problem find one of those pump-spray bottles they use for spraying garden plants and have someone direct it at the blade. Don't go mad or the motor will pull in water through the vents.

rbent · Jun 28, 2014

Spud said:
When you say "grooved" , do you mean like a Dado blade setup (only in your case it is 1 blade that is 3/8" thick) on a table saw that cuts a groove/slot/channel ?

Yes. Single 7" diamond blade that is 3/8" of an inch wide at the cutting edge. I think we got them from Delta Diamond.

Big B · Jun 28, 2014

Why on earth would you want to cut such a wide groove in the concrete? The diamond blade that I use in my circular saw is more like 1/8" or 3/16" at most.

Big B

rbent said:
Yes. Single 7" diamond blade that is 3/8" of an inch wide at the cutting edge. I think we got them from Delta Diamond.

rbent · Jun 28, 2014

Big B said:
Why on earth would you want to cut such a wide groove in the concrete? The diamond blade that I use in my circular saw is more like 1/8" or 3/16" at most.

Big B

Tuck point blades are generally used for mortar/grout removal or prep for tuck pointing. We were using it for a process we developed where we wanted a 3/8" wide groove.

OT: Cutting tile , brick or concrete with a 7 1/4" circular saw?

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