concrete grinding

[T77911S]

I have a small area of concrete I need to grind. 60x4 inches and about 1/4 in thick. I can hammer drill some of it but need to smooth it after that.
I am looking at 2 diamond bit grinder pads. One is 7in low speed and the other is 4.5in hi speed. Which speed do you think cuts better?
I am thinking slow speed cuts better. About $10 price difference.

[NY65912]

We use this machine to level out the area that pipe hangers are to be installed on tunnel walls. Yes, I know it's overkill for your application. I'll take a look at the grinder and see what rpm it functions at.

https://www.us.hilti.com/cutting%2c-sawing-%26-grinding/cutting-%26-grinding/diamond-grinding/369388

[T77911S]

i was looking at these 2.

RIDGID 4 in. Double Row Diamond Cup Wheel-HD-AWD40 - The Home Depot

RIDGID 7 in. Blue 12-Segment Turbo Cup Grinding Wheel-HD-TAW7012L1 - The Home Depot

[Drisump]

How important is it to control the point of contact? If somewhat important, the smaller cup grinder is probably your best choice. You describe a very small area that won't take long whatever you use. When grinding dry, be prepared for an unbelievable dust cloud... needless to say masks and glasses need to be used. Cheers

[wdfifteen]

Great info!
I've been looking at replacing the whole slabs or grinding down the edge of a couple of sidewalk sections that have heaved up. I wasn't sure how I was going to grind them down. Having the slabs replaced is going to cost $300. If this 4" cup wheel will work on my Ridgid 4" angle grinder that would save mucho $$$. I assume this cup wheel is made for the angle grinder I have. I didn't know that cup wheel existed.

[NY65912]

I had 1 slab heave, and thankfully dropped about 90%, so I was thinking of doing the same. Luckly I do have the Hilti tool at my disposal, which has a vac attached.

While driving home the other day I saw a great cloud of smoke and cars swerving up ahead.

There were two Indian dudes trying to grind the sidewalk witha 7" grinder with regular carborundum discs, they weren't getting too far. Later on that evening I saw the guy chipping the concrete witha flooring chisel trying to smooth put the damage.

We have a ton of Indian and Pakistani "masonary contractors" in Brooklyn. 90% work like back home, no tools, no safety, and always a big mess. Every once in a while you'll see a good contractor, but he gets more $ for his work.

[flipper35]

Dad used the 4" on his entrance to his garage to fix some settling and let the garage door fit snug all the way across. Came out very smooth.

[Tim Hancock]

I just bought this 5" diamond turbo blade at Harbor Freight to use on my little Metabo angle grinder. I used it to cut some block and a bit of concrete on a small home project. It is not really designed to grind surfaces but rather to make cuts. It worked very nicely to cut thru block and I also used it to remove some high spots on blocks and motor joints. Never had used one before, but it easily chews thru concrete blocks. Very impressed.

[look 171]

Originally Posted by wdfifteen

Great info!
I've been looking at replacing the whole slabs or grinding down the edge of a couple of sidewalk sections that have heaved up. I wasn't sure how I was going to grind them down. Having the slabs replaced is going to cost $300. If this 4" cup wheel will work on my Ridgid 4" angle grinder that would save mucho $$$. I assume this cup wheel is made for the angle grinder I have. I didn't know that cup wheel existed.

I will bring popcorn, a chair and a 6 pack for ya. Sure it will works but it will take you a long time and lots of cussing,not to mention 4" grinder maybe spinning way too fast for that wheel. If appearance is not important, try a diamond cutting wheel and ease the edge to eliminate tripping hazard. For 300 bucks, its a no brainer to hire out and remove the slab.

We rent the grinding tool if and when we need to grind down a floor. They have a water hose hook up to knock down dust. My flooring guy has a 7" angle grinder made specifically for this propose. Its not an angle grinder but a specific tool for grinding concrete. Cuts dust free too. They use it to remove dips and high spots on a concrete floor before hardwood install.

[David]

Rent a scarifier

[A930Rocket]

^^^ We’ve used a three diamond wheel grinder to cut down concrete before. You can rent them at rental places.

It might be overkill, but you can do the work in a matter of hours, instead of weekends.

[dad911]

Originally Posted by richardgravner

..........

Hmmm.... Every one of your posts has a hidden link to another website.. so I won't quote.

Spammer in hiding??

Edit: richardgravner is definitely a spammer. Don't quote his posts.........

[gregpark]

A horrible, filthy, unhealthy job. I've done my share over the years, now I sub it out

[KevinTodd]

I just had a commercial building that I own done, and it came out absolutely fantastic.

2500 sf that had the original LVT from 1946. The black mastic underneath was on thick--so thick that it had to be broken and scraped up with hammer-drills.

Then the wet diamond-grinding--4 passes with a progressively finer grit. Alot of slurry to deal with--but not hazardous so no real issue. The machine was massive. It had to be hardwired into my panel with a 60A pigtail, and when they started it the lights dimmed....lol.

Final result exposed a beautifully finished pad with tons of great color---blues, grays, oranges. There are several spots that still have the "grain" of the 2X4 the original masons used to level it out when it was poured.

No real fissures anywhere and each of the segments in the space are basically slightly different; the result I suppose of the concrete mix being slightly different for each one.

$11k.

Worth every penny.

[Bill Douglas]

Richard there are grinding disks for large size angle grinders. Designed for what you have in mind.

Edit: Looks like this.