Grinding Disc- Concrete?

[karoc]

I have one of those M18 4 1/2 disc grinders. I finish little concrete work around my shower drain. I have couple ridges and little high spot that I like to smooth out little and grind those ridges down flush with slab. I was wondering what grinding disc for concrete to buy? Looking for recommendations that fit my Milwaukee 4.5 grinder. Thanks again

 

[eviltwin]

I used this for smoothing out some high spots for framing when I poured a shed foundation. Worked great and super cheap for a one time use tool purchase. Used on my 4.5” DEWALT grinder.

https://www.amazon.com/dp/B07ZGC3VP5?tag=atomicindus08-20

 

[Firebrick43]

I use a dished diamond wheel similar to what @eviltwin linked. Its fast and leveled a lot of places where clearance pipes came up thru my Composite steel suspended slab after the concrete was poured and the finishers didn't get right up to the pipes after the pour.

I would suggest buying a crappy corded HF grinder so you are not upset when the concrete dust ruins it. Wear a respirator as its pretty nasty

 

[larry4406]

I use a dished diamond wheel similar to what @eviltwin linked. Its fast and leveled a lot of places where clearance pipes came up thru my Composite steel suspended slab after the concrete was poured and the finishers didn't get right up to the pipes after the pour.

I would suggest buying a crappy corded HF grinder so you are not upset when the concrete dust ruins it. Wear a respirator as its pretty nasty

Harbor Freight does sell concrete polishing/grinding discs and vacuum attachments for their grinders. I’ve not tried them.

For a one and done project, I would grab a grinding disc, shop vac, water spray bottle, dust mask, and have a go at it. If grinder dies, oh well.

 

[kyrbz]

IMO those diamond cup wheels for angle grinders are way too aggressive for what you need to do. On fresh concrete, I would try a rubbing brick first. It will make quick work of removing high spots and leveling and make way less of a mess than an angle grinder.



Another more expensive option is the diamond flap wheel sold by Crowne tool. I really like using them for smoothing and shaping concrete even though they're marketing them for tile work. The diamond flap wheel is easier to control and gives a much better finish than the diamond cup wheels the others have mentioned. I only use diamond cup wheels when I need to do serious removal of lots of material.




Another less expensive option from Crowne tool are their diamond polishing pad. The 60 grit gives a pretty nice finish and removes minor ridges in fresh concrete. It doesn't remove a lot of material and would mostly be good for concrete that's already pretty smooth and just needs a slight clean up. You'd also need their backer pad for attaching it to your angle grinder.

 

[Mr Ratchet]

I you do end up using a diamond cup wheel, grind it wet. If you do it dry, you won't see your hand if front of your face in 10 seconds or so.

 

[karoc]

I never gave dust thought, thanks for heads-up

 

[Firebrick43]

IMO those diamond cup wheels for angle grinders are way too aggressive for what you need to do. On fresh concrete, I would try a rubbing brick first. It will make quick work of removing high spots and leveling and make way less of a mess than an angle grinder.



Another more expensive option is the diamond flap wheel sold by Crowne tool. I really like using them for smoothing and shaping concrete even though they're marketing them for tile work. The diamond flap wheel is easier to control and gives a much better finish than the diamond cup wheels the others have mentioned. I only use diamond cup wheels when I need to do serious removal of lots of material.




Another less expensive option from Crowne tool are their diamond polishing pad. The 60 grit gives a pretty nice finish and removes minor ridges in fresh concrete. It doesn't remove a lot of material and would mostly be good for concrete that's already pretty smooth and just needs a slight clean up. You'd also need their backer pad for attaching it to your angle grinder.

With a dished diamond wheel its fast and aggressive if you angle it and put pressure but if you lay it flat on its face and put no pressure it does a beautiful job and is smooth. The concrete that I ground was just as smooth as the power troweled areas around it.

 

[larry4406]

I’ve used a piece of a CMU as a grinding block to knock concrete ridges down similar to the grinding block posted above.

You don’t need perfect. Your tile guy can accommodate a multitude of concrete sins if he’s good.

 

[kyrbz]

I’ve used a piece of a CMU as a grinding block to knock concrete ridges down similar to the grinding block posted above.

You don’t need perfect. Your tile guy can accommodate a multitude of concrete sins if he’s good.

Years ago I had a mason working for me who couldn’t stop making fun of me having a fancy store bought rubbing block instead of just using a broken piece of CMU

 

[kyrbz]

With a dished diamond wheel its fast and aggressive if you angle it and put pressure but if you lay it flat on its face and put no pressure it does a beautiful job and is smooth. The concrete that I ground was just as smooth as the power troweled areas around it.

I would agree with you, but someone who is inexperienced using one or just doesn’t have the finesse required can mess something up really fast.

 

[larry4406]

Years ago I had a mason working for me who couldn’t stop making fun of me having a fancy store bought rubbing block instead of just using a broken piece of CMU

If you can get one that has a piece of the interior web still attached to the faces, it makes for a nice handle.

 

[kyrbz]

Looking again at the OP, I realize my diamond flap disk and diamond polishing pads are probably not an appropriate recommendations. I use them for detailing and contouring finished concrete work that is exposed and needs to be nice. The diamond flap wheels and polishing pads are really good to have in the arsenal for those applications. Given the Op’s situation, I think a little rubbing block action is all that’s required.

 

[tarbellb]

I can vouch for the the dust issue

Surprisingly good- HF dust hood for angle grinders. Hercules I think? Hooks up to a vac.

 

[RTM]

Years ago I had a mason working for me who couldn’t stop making fun of me having a fancy store bought rubbing block instead of just using a broken piece of CMU

They’d be laughing at me too. I’d have to
1. buy a cinder block and
2. break it, and then
3. store all the extra bits for next time.

On relatively fresh concrete, the rubbing block is much faster than cleaning up the mess from the power tool. I save that for well hardened stuff.

 

[kyrbz]

This thread inspired me to do a toilet flange in a bathroom I'm working on for one of todays projects. The toilet will eventually sit directly on a concrete floor. When they poured the floor, the concrete ramps up around pvc drain pipe so I knew I was going to have to do a little grinding to get the flange to sit flat. Rather than an angle grinder, I used a rubbing block and my Festool Rotex sander with a very aggressive sanding disc to flatten and smooth the area around the drain pipe. Very little dust doing it this way. Even after flattening the area around the drain pipe, the flange sat a little high due to the radius on its underside. I used a round over bit in a router to radius the inside of the drain pipe which allowed the flange to drop all the way flat against the floor. Didn't have the right tapcon to screw it down, so I'll do that another day. I like the concept of the Sioux Chief PushTite flange. It's not glued and would be super easy to change if the flange were to break. From the reviews I read, the Sioux Chief is rated better than other brands of this style flange.

 

[karoc]

Well heck, I had google CMU. Lucky me I have couple those that use as prop for my trailer. Going give that try first, if that don’t work go plan B. Thanks for all suggestions