I have never done this so I am just guessing here, but doesn't the time it takes to grind the floor dependent on how bad the floor is to start with? What I mean by that is, some concrete is pitted and some is stained and some may not be very level in spots. Stuff like that. I am assuming you want the floor to be level and as flat as possible before you apply the epoxy. That's why I am thinking the time it takes to get the job done varies with the condition of the floor before you grind it.
The grinding time will be dependent on the current state of the floor, up to a point. The diamabrush machine isnt going to level out a floor. It will ride on top of the floor contours. If there are some really low spots, those might have to be done by hand. The diamabrush will sit there all day and not level out the floor. There isnt enough weight to the machine - even if you add a bucket of sand to it.
Thanks for your comments. If the finish has a reasonably acceptable appearance, I will use a clear penetrating sealer. I would consider adding a tint if that would tend to hide blemishes. If the ground finish is not acceptable, I will have to consider an opaque covering.
Regarding wet or dry grinding, I had no plans to rent a grinder plus dust catching equipment. I can rent the floor maintainer and diamond tool from Home Depot for about $130 for a day. From what I have read, it seems to be the prudent grinding method for a novice. See this link.
http://allgaragefloors.com/how-to-grind-garage-floor/
If other non-professionals have ground their floor and preferred the dry method, please let me know why you did it that way.
Adding a tint to your sealer isnt going to conceal anything other than blotchy concrete. Think of it like automotive paint. If the car body isnt perfect, it shows through the basecoat, and clearcoat. Tinted or not. The only way to conceal some imperfections would be to use a decorative flake.
As for grinding wet or dry. Wet just makes more of a mess, and you'll need to powerwash your floor afterwards. Then wait for it to dry out ( a few days)
Dry is the way to go, and consider dust collection too. For the few bucks more, its money well spent. Concrete dust is really bad for you, and there will be lots of it.
As for a time to grind. Plan for a day. Things that will determine how long a process are: Concrete Density. Hand troweled vs Power trowel. Sealer currently on floor. Bond of diamonds on machine. RPM of machine. Machine weight /quality.
If you rush the process you'll be re-doing it in a few years. Spend the time and do it proper! An extra day for $100 is better spent now, then having a half assed floor.
