Author Topic: Please advice on floor grinder vs. Rotex for terazzo flooring? Or both?  (Read 583 times)

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Offline puggie

  • Posts: 1
I am planning to cast terazzo-cement floor in my bathroom.

Which tools do I need to finish the floor. I was planning on buying a Rotex sander 125 or 150 and diamond pads. Are diamond pads effective enough for working on terazzo floors? Howabout the Sapphire from Festool are they effective?

Initially after the casting step I would need to do some rough grinding would this be possible with the Rotex or do I need a dedicate floor grinder like the RG130 or an angle grinder...? Would prefer to purchase the Rotex only as I am going to use that for other things as well.

The bathroom is only 3 square meters (guest's basement bathroom)

I am looking forward to hear your replies. Thank you.

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Offline Peter_C

  • Posts: 1123
Welcome to the FOG :)

Having just ground my concrete garage floor, I see no use for an RO sander. I rented a dual head floor grinder, and for the outside edges I used a grinder with a cup wheel, all with dust collection.

Seems like a small bathroom to be grinding in and an upright machine will probably barely turn around. If you decide to do it rent the dust collector they offer. I used my own CT36 AC, but it doesn't have the pull of the larger rental dust collector. Put plastic walls up to keep the rest of the house clean too.

If it were me I would tile the bathroom, but I like the look of tile.

Biggest recommendation would be for you to watch a bunch of youtube vids and see if it is a project you want to tackle.

Offline Frank-Jan

  • Posts: 1195
  • Dutch Canadian living in Belgium
I didn't know there were diamant pads available for the rotex. But I doubt the rotex would be of any use in your project.

Ironically, I bought my rotex 150mm years ago for a similar job, I needed to grind down a bit on a cement floor, (not terazzo or concrete) which I had seen someone do with a beltsander once before, and people said the rotex had the power of a belt sander with dustcollection. That statement was BS, and even with saphire 35 it didn't do much. (ended up with a cupwheel on an angle grinder)(This was years ago, and nowadays I have a dedicated angle grinder with dustcollection for those kind of jobs.

The only experience with terazzo flooring I have was on a job 15 years ago, where the clients hired someone to renovate the terazzo floor in the hallway at the frontdoor, and do a new matching terazzo floor in the small hallway at the rear door. I didn't stay long when that guy was working, but I remember he had a fairly big watercooled walk behind diamant grinder with a smallish head, but for the finishing he used a small angle grinder with sanding discs, and no dustcollection (allthough that was already mandatory then from a work-safety perspective. I had planned to work on some pocketdoors that day, but due to all the dust I decided to go elsewhere, when I returned the floors he did looked nice.
« Last Edit: February 08, 2021, 06:08 PM by Frank-Jan »

Offline afish

  • Posts: 585
While I have not polished terrazzo I have done some small decorative concrete polishing and can agree no sander has any business trying to do the job.  Depending on how well the the finish ends up I would be starting with diamond cup wheel to get everything smooth and flat then switch to the diamond pads like the countertop guys use on a angle grinder.  The one I have has a hose attachment so it sprays water thorough the center.  I would use water too and a shop vac to keep excess water picked up.  Its going to be messy.  You dont need a lot of water but without it the amount of dust generated is amazing and really only suitable for outside.  If you are dead set on dry you will need a good extractor and dust shroud for the grinder.

Offline Peter_C

  • Posts: 1123
A handheld grinder and the word "flat" do not go together, not even with a 7" cup wheel. Plus you kinda want a slower speed than a standard grinder and few have adjustable speed. A large upright grinder is what is required, and they are not cheap to rent, plus you will typically have to buy the diamond inserts for grinding.

Stepping back again to tiles. Before you could finish pouring your flooring, I could have it tiled. Same look, already polished and 1/6 the amount of work. Click on this google link for ""Terrazzo tile"" and see if you like the idea.