Concrete sanders

[1967marti]

So, I just got done checking with both brands of big box stores and they both want 250 a day for the floor sander (not the buffer type) with the attached big vacuum. This model looks like a buffer with a little more meat on it, but still with a single exposed sanding/grinding disk. The buffer type is about 40 a day.
That’s kinda on the high-side for just sanding my floor. The guy in the rental room was saying that it will leave swirl marks on the floor (I expected that) but how bad are they going to be? I was planning on laying down some densifier and be done with it but I’d rather not do that if the floor is going to be like sandpaper after I grind it. I’m looking for a smooth-ish surface, something that sweeps well at least.
Has anyone on here used a big-box floor sander? Any pictures or reviews of the result?

Thanks!

 

[LegacyIndustrial]

1967Marti:
If you want to make the floor smooth, you are talking diamond grinder or diamond brush (Diamabrush). A sander will make a mess and waste your money.

Why don't you post a few pics and we can see whats going on with your floor.

 

[Jkaz]

It sounds like you are talking about grinding your floor when all you may be looking to do is scrub and polish? Agreed with Legacy, we need more info!

 

[widesheds]

Absolutely, a couple of pics will be good to have a better insight and look about what could be done for a smooth finish. I too think that scrubbing and polishing will indeed provide the smooth finish.

 

[Spahrman5]

I have the exact same question as the OP. Since it seems he has forgotten about this thread, I'll take it!

The previous owner painted the floor with some sort of epoxy. Since I reconfigured some walls to redo the garage, the concrete is bare in some areas. I want to remove the coating and go back to smooth concrete for the entire area. Probably add something over to seal the dust (densifier?).

Here are some pics.

Superstrip from Sherwin-Williams takes it down to bare concrete, but at $24/gal it will be quite expensive to go this route (550 sqft). What is the simplest way to restore my floor?

Thanks

 

[admranger]

Definitely wanting to see replies to this as I'm in the same boat. I need to take the epoxy off and get back to concrete.

Subscribed.

 

[LegacyIndustrial]

Guys:
The best way to prepare a garage floor for coatings is a diamond grind.
You need to get the old stuff off and open the floor up for good adhesion.

The best coatings still need a good "lock" into the concrete for longevity.
Visit your local rental houses or seek a pro's help at least for the prep.

 

[Spahrman5]

Guys:
The best way to prepare a garage floor for coatings is a diamond grind.
You need to get the old stuff off and open the floor up for good adhesion.

The best coatings still need a good "lock" into the concrete for longevity.
Visit your local rental houses or seek a pro's help at least for the prep.

Legacy,

I don't want to prep the concrete for anything. Just want to remove the old coating and have smooth concrete. Will the diamond grinder leave a smooth surface?

 

[LegacyIndustrial]

Diamond grinders can be used to polish floors. However, the type of diamonds you will find at a rental house will be for removing and rough grinding. It takes a skilled hand and an ascending level of metal bonded diamonds and then polymer bonded diamonds to achieve a polished surface. 50, 100, 200, etc... all the way to 1500 and 3000 grit.

If your space is small you could do it with a hand grinder (designed for this with a water feed) and use the velcro backed pads. I wouldn't do this for a space over 300 sq ft.

Lastly, polished floors are not stain resistant and need touch-ups from time to time, traffic dependent.

You may want to look at removing the coating you have and applying a clear sealer, satin finish. This may be more to your liking.

 

[Baada]

Those rental rates seem a bit high. I had to remove an old epoxy coating also. I rented a walk behind grinder with 10" diamond cup, a 7" hand held grinder with a diamond cup and the big vacuum for less than $175/24 hours. It took me two 24 hour rentals to do 850sqft but I had to leave the stuff in my basement and move it from one side to the other and then back otherwise I'd probably have been able to get it done in one session.

The finish I got on my floor was pretty darn smooth. There wasn't any grooves left or anything like that, it was close to 120-150 grit sandpaper. I am going to epoxy mine but it is definitely smooth enough to leave alone if I wanted to.

Keep in mind though...with the pits in yours it's going to take some significant material removal if you want to get them out and the type of grinding medium that will leave a smooth finish would take forever to grind the pits out.

 

[1967marti]

Sorry for the long reply, work and the long weekend got the better of me 
Update: I rented a diamabrush attachment for a “floor maintainer” and rented both from home depot.
I only rented it for 4 hours thinking it wouldn’t take that long to do one half, move everything to the other side and then do the last half… Wrong… it took about 7-8 hours to get everything all of the old epoxy off the floor. I still have to use a diamond wheel on a 4.5 grinder to get around the walls and corners.
The tool rental guy said to use the diamabrush dry but I think I remembered legacy industrial mentioning to use water with it. So I gave it a quick 10 second run “dry” (just for kicks) and it was quite aggressive and took quite a bit off, but the dust was crazy.
I figured water would keep the metal pads cool and help with keeping the pads clean. So I soaked my floor with water and let her rip. Besides having to stop every 20 min or so and sweep the “slury” out and replace with clean water it went pretty smooth.
The floor is now smooth to the touch, but is in no way “flat” nor do I care to grind it to that point. The flexible nature of the diamabrush “fingers” let it get inside of shallow grooves and ripples and smooth everything out. Only think that ***** is not I have epoxy in all of the small holes and divots in the floor. But not they are easy to see, so I’m going to chisel them out and fill with some cement mix to level out the floor as much as possible.
I’ll get some pictures up ASAP. But I am quite happy with the results.

So here are the quick facts:
Cost: 110 for 24 hours from HD for the diamabrush and floor maintainer.
Time : 7-8 hours
Very messy. Expect a few hours of clean up after.
Way better than acid etching. I clean all the old oil drips with industrial purple before but the machine sanded off any stains off the floor.
I used the stripping diamabrush (the one with less “brushes” but the finish was still quite smooth, yes you can see a slight swirl pattern but only if you look closely, and I can’t feel the marks if I rub the floor with my hand.
You will need a small grinder for the strips along the walls and corners as the machine’s disk is about 18” wide.

 

[Spahrman5]

Sorry for the long reply, work and the long weekend got the better of me 
Update: I rented a diamabrush attachment for a “floor maintainer” and rented both from home depot.
I only rented it for 4 hours thinking it wouldn’t take that long to do one half, move everything to the other side and then do the last half… Wrong… it took about 7-8 hours to get everything all of the old epoxy off the floor. I still have to use a diamond wheel on a 4.5 grinder to get around the walls and corners.
The tool rental guy said to use the diamabrush dry but I think I remembered legacy industrial mentioning to use water with it. So I gave it a quick 10 second run “dry” (just for kicks) and it was quite aggressive and took quite a bit off, but the dust was crazy.
I figured water would keep the metal pads cool and help with keeping the pads clean. So I soaked my floor with water and let her rip. Besides having to stop every 20 min or so and sweep the “slury” out and replace with clean water it went pretty smooth.
The floor is now smooth to the touch, but is in no way “flat” nor do I care to grind it to that point. The flexible nature of the diamabrush “fingers” let it get inside of shallow grooves and ripples and smooth everything out. Only think that ***** is not I have epoxy in all of the small holes and divots in the floor. But not they are easy to see, so I’m going to chisel them out and fill with some cement mix to level out the floor as much as possible.
I’ll get some pictures up ASAP. But I am quite happy with the results.

So here are the quick facts:
Cost: 110 for 24 hours from HD for the diamabrush and floor maintainer.
Time : 7-8 hours
Very messy. Expect a few hours of clean up after.
Way better than acid etching. I clean all the old oil drips with industrial purple before but the machine sanded off any stains off the floor.
I used the stripping diamabrush (the one with less “brushes” but the finish was still quite smooth, yes you can see a slight swirl pattern but only if you look closely, and I can’t feel the marks if I rub the floor with my hand.
You will need a small grinder for the strips along the walls and corners as the machine’s disk is about 18” wide.

1967marti, do you have any pictures of the process or the final product?

Edit: nevermind, you said the pics are coming. Take your time!

 

[Edger]

1967marti, that sounds like a great result, however it is difficult to dig out and fill and smooth those holes that still have epoxy in them. If it looks OK now I reckon you should leave it that way. Congrats on the great job and write up.

 

[admranger]

1967 Marti, by "floor maintainer" do you mean the floor polishers with the motor mounted directly over the pad and then a long "T" handle? I have never gotten the hang of those. When I've tried them in my misguided youth I resembled a cartoon character spinning around uncontrollably...

Also, did you only do one pass or multiple passes? All the youtube videos I've seen seem to indicate that multiple (6-8?) passes are necessary on each level of pad.

 

[STIBuilder]

I called every Home Depot in my area and none of them carry anything other then the hand grinders.

 

[1967marti]

At my local home depot they have two machines for floors... One is a "maintainer" that has the "t" handle and a motor mounted above the connecting hub and the other machine is a "floor sander" that has a Velcro wheel mounted under the motor. The sander works lust like a small hand-held version but is way bigger (think of round sanding pads that are 15 inch in diameter).
I did a few passes on the floor. Mostly i did a wide sweeping motion to help flush off the diamabrushes.

 

[1967marti]

here are the pics of the "after" I didn't think/have time to take progress or before pics