[KCMike]

I recently bought a new 30" cooktop however the exisiting cutout is too small. The opening needs to be about 1-3/4" wider. The countertop is 1/4" tile on top of approximately 1" of concrete on steel mesh which is on top of 3/4" plywood. What tool(s) do you recommend I use to make the cut? The cut is about 19" front to back.
Thanks for your help.

 

[Windows on Wash]

Angle grinder with a diamond blade.

You are going to make a ton of dust though so try to get a vacuum equip set up.

 

[Daniel Holzman]

You may be able to cut through everything using a diamond blade on a circular saw. The angle grinder would be used for the corners, or you can probably cut the corners using a diamond or carbide blade on a jig saw. I have cut through concrete block using a diamond blade on a circular saw with no real trouble, just don't try to cut the whole way through in one pass, make say 1/4 inch cuts. As with a grinder, makes lots of dust, so a shop vac would be good, but also wear a NIOSH approved mask, concrete dust is really bad for your lungs.

 

[Windows on Wash]

You may be able to cut through everything using a diamond blade on a circular saw. The angle grinder would be used for the corners, or you can probably cut the corners using a diamond or carbide blade on a jig saw. I have cut through concrete block using a diamond blade on a circular saw with no real trouble, just don't try to cut the whole way through in one pass, make say 1/4 inch cuts. As with a grinder, makes lots of dust, so a shop vac would be good, but also wear a NIOSH approved mask, concrete dust is really bad for your lungs.

+1

A circular saw with a diamond blade would be preferable for the longer straight cuts.

Proper PPE is a must and be prepared to make a mess.

 

[epson]

I have used a rotozip tool to do many a job similar to this and had great results see link below.

http://www.rotozip.com/en-us/CuttingTools/Pages/cuttingtools.aspx?catid=5122

 

[ddawg16]

In case you didn't get the hint.....it will be REAL messy......make sure you put up a curtain between the kitchen an adjacent room. Cover everthing else with old sheets......and toss a sheet on the floor as well....and have the shop vac handy. And I wouldn't use safety glasses....I would use a face shield along with mask....

There is nothing that is going to kill you chemical wise....but the dust can be bad and is not good for lungs....

 

[stadry]

cutting tile's easy but 3/8" of tile on top of 1" conc over wood isn't,,, this calls for step cutting, too,,, comparing the 2 suggested method's, i'm willing to bet on the rotozip as being the least messy for the tile cut but you'd not get the depth needed in 1 pass,,, we have shrouds on 4 & 7" grinders hooked up to 220v vacs & still there's dust,,, i'd pick a 4" diamond blade & grinder for the tile/conc 1st cut followed by 7" circle saw & carbide blade for the 2nd,,, there are shrouds for both but, unless you're a pro, $200 just for shrouds is a large investment for single use,,, if it were me in your circumstance, i'd let this job out to a c-top pro - hire his tooling & expertise - either cutting wet or dry, it's messy

 

[paintdrying]

Have you considered buying a cook top that will fit properly. I am still finding concrete dust from 30 years ago throughout my house. I would at least try a chipping hammer before I put a saw to concrete

 

[KCMike]

Thanks guys for all your ideas. I really appreciate your prompt help.

Have a great day and a blessed and happy New Year!

 

[stadry]

ixnay on the chipping gun even 1 as light as a bosch bulldog,,, conc has no 'grain' therefore it won't cut straight,,, IF you can live w/jagged edges, it wouldn't be a dealbreaker,,, we routinely saw, drill, diamond core, & chip conc for a living - that's what we use for the reply's basis

another note - op already bought the cooktop - i'm sure the suggestion of a smaller top's already been discussed