Diamond Grinding Questions before Epoxy-Coat

[AMarkham]

Hey guys. I've been doing a lot of research before I make the plunge into coating my garage floor. I have a two car 440 sq foot garage that is a year and a half old. It houses 2 daily driven vehicles. The concrete has a smooth finish but no sealers as far as I know. I'm leaning toward Epoxy-Coat and after doing some reading I think I would rather diamond grind my floor instead of using the acid etch method. I have never used nor seen a diamond grinder before. I saw where a rental company has several different types I can use for a very reasonable price. They have electric and gas powered models. Seem to be Edco brand. Here is a link:

http://www.sunbeltrentals.com/equipment/category.aspx?id=s340

I just need some advice on how these work. Is it pretty straight forward? I don't want to take off to much nor do I want to make my floor uneven. Would you guys recommend renting a vacuum to go along with it to help with the dust? Also, how loud are they? Sorry for all the questions, I just don't want to get in over my head.

 

[GarageEnvy]

I used an Edco dual head grinder for about 7 hours before returning it for a Core-Cut propane powered model. The Edco was highly recommended by people on this board but I thought it was poorly constructed. I had several problems with my rental unit. First, and I can't stress this one enough, make sure you have the dymaserts and that they are in good condition. The sunbelt tried to rent me a set with less than a 1/16" of diamond left for 1800 sf. I went elsewhere but even then the unit has these wood wedges to hold the inserts in. I had a problem with the wedges coming out and I couldn't pound them in hard enough to keep them from coming back out. The core-cut unit was a much more powerful unit and weighed over 500 pounds. However, it was ridiculously loud. Even with ear protection it was noisy. Both units gave a new meaning to the word dusty. Despite the fact that they don't really remove that much material, the dust was everywhere! I don't know if dragging a vacuum around would have been more or less convenient. I did have some areas where it left swirls. The were worse if I went across the slope or where I went across an expansion joint. Epoxy-Coat will not hide them either.

Here's a link to my floor project
http://garagejournal.com/forum/showthread.php?t=83035

 

[-JP]

I chose to use the diamond grinder versus the acid etch. I worked an area little over 1000 square feet and it took two days to get it done. The dust generated is amazing to say the least. I don't think dragging around a vacuum would help much at all. I rented the Edco electric model and made sure the diamond wheels were in good shape with low use. The wooden wedges were a pain to get set up. Once they are in there tight they never came out on me. Noise was not a problem with the electric model. I was pretty happy with the results as the floor had a good surface to apply the finish. Not much to see but I have posted a picture of the unit in action on the thread http://www.garagejournal.com/forum/showthread.php?t=88946

JP

 

[hpw]

Any thoughts given to a shot blast machine, I remember on the show "Hometime" that they used it to prep for an epoxy floor.

http://www.sunbeltrentals.com/equipment/equipment.aspx?itemid=0320310&catid=s347

 

[PontiacFan]

AMarkham, Did you 'water-test' your floor for sealers?

 

[HEMICANE]

I used a Blastrac gas powered 10" hi speed grinder that I rented from Home Depot for four hours. It basically takes off approx 1/8" off the surface and is pretty simple to use. One operational, you just move the machine from side to side (or 9-3 using the clock as a reference). I did my 3 car garage basically twice in 3 hrs then followed up with a hand grinder for around the wall edges etc. I still used the prep solution provided in the epoxy coat kit as instructed. FYI, I saw a floor done with the dual disc edco and saw alot of grind marks in the floor, I am not sure if that was the machine or the operator but I can tell you with the more modern machine I used my grind marks were minimal. Just keep the machine moving... Good luck

 

[tom_e]

I used a rental Edco unit too. $140 for the rental in San Jose, California. I did 500sqft with the diamond pucks held in by wood wedges in a few hours time (a couple of light passes).

I used a wet slurry grinding by hooking a hose to the unit. There was an attachment for the hose. No mess, no fuss, except for a few days later when the slurry dried out in the driveway and street. Overall not too bad.

I used expoxy coat too. Only recommendation is pre-fill any cracks with some material. I thought I'd have enough expoxy-coat to fill the cracks but I was wrong. Damn. Cracks only partially filled in some areas.

First photo is pre-grinding. Last photo is pre-coating, post grinding.

 

[dcs Inc]

Guys, I do a lot of this and in my opinion edco is a **** machine. It's a cheap way for rental companies to get into the grinding business. By the way, most rental companies have no idea on how to grind concrete.

The problem with a double head edco machine is that it's a fix head machine. They don't float with the "hills and valleys" of the concrete like a planetary type of floating heads. That and the rental experts have no idea on what kind of tooling to hand out. Down pressure is everything on grinding on a slow turning machine. That and the diamond matrix matching the hardness of the concrete. Soft bond for hard concrete, hard bond for soft. Now put that with no dust collection system..... poor.

Shot blasting is the ideal surface prep for epoxy. The problem is setting the machine properly as to not leave corn rolls on the overlaps plus having the proper shot.

Most guys will apply a really thin mil coating and these lines will show. That and the cheap..... err low cost, low solids epoxy systems used. If it's a 50% solids epoxy, once dry you will have 50% less in thickness. Even if it states a higher solids content, often the solids are fillers. If it smells, it is not 100% solids.

The guys I train I suggest a 7" grinder with a dust shroud. A 12 segment diamond cup and a drywall vac. That's the starter kit. It will out grind 2 edco machines and be a whole bunch cleaner. The 6000 rpm's will profile the surface nicely. Once they start getting projects over 8-900 sq. ft. we start talking larger machines. A 600 sq. ft. clean slab can be prepped in 4 hours.

Cracks.... Treat them first. They have quick set fillers that work fine. If it's a non moving crack, use bondo.... yep bondo. That's an old installers trick. Do so before you grind so you can clean it up nicely.

Some rental companies rent a single head edco. If you can find one with a diamond cup instead of those STUPID wedges, rent it instead of the double heads. If you have any questions shoot me an email. I'll try to check in every now and then. gene

 

[NextCoatings]

If available, attach a 40lb downforce weight to the grinder. That will give you the weight you need to properly score the floor. Remember, you are only scoring the surface, not really grinding. You should be able to get a dust shroud kit from the same place you rented the machine, but if you go electric with a vac attachment, you need enough power in your garage to handle it. 400 square feet shouldn’t take much more than an hour or two.
You should be able to find a cabosil patch for any crack filling. It’s fast setting and won’t delay the rest of the project. You can find it with accelerators that will accept grinding in about an hour and won’t affect the coating.

 

[HoustonGarageFloors]

You don't have to worry about taking too much concrete off with the Edco. It's extremely slow. I rented one from Sunbelt rentals last month, and after skating around the garage for 4 hours, I took it back and got my money back! It was a joke! Let it be known, that I got the electric one, and they rent a gas one that is supposedly better... but if the electric one doesn't work, then WHY DO THEY RENT IT OUT?

 

[Small_words]

This is why I love this forum. About to epoxy the floor and was wondering the same. Thank you fellas.

 

[BabaGanoosh]

Grinding tomorrow. I rented a diamabrush and Clarke machine at HD as used by many here. The diamabrush was old and worn and did not instill confidence. We'll see how it works.

 

[jwvess00]

Hi there!

I rented the Diamabrush and machine from Home Depot for my floor. It did a fantastic job. The floor is not glossy smooth when done, but not rough like a broomed finish. It's about as rough as denim, I'd say, for lack of a better description. It was well worth the effort.

 

[mark52621]

I did 900 sqf with a 7 in angle head. The first diamond wheel I bought from menards lasted for 300 sqf. The second wheel I got from diamondbladedealer.com did 600 sqf and showed hardly any wear.

For dust control I used a garden hose. I put it on a slow trickle pushing water into my work area.

It didn't take long to do, but I wouldn't want to do a larger job.

 

[BabaGanoosh]

Hey AMarkham. So, I started with the large Diamabrush on a Floor Polisher from HD and it did not work for me. My ego hates to admit it, but I couldn't get any control with the machine. It jumped all over the place and it actually pulled out of my hands a couple times. (Check out the picture of the nasty Tornado Sketches. Ouch!) Like other's have done, I used the 7 inch Diamabrush on a Makita hand grinder. It worked great. Much more control. I did about 800 square feet and learned as I went. I am no spring chicken and it was hard on my knees and back. Using a 14 inch diamater furniture roller and a cheap bleacher chair I fashioned a crude but comfortable version of this product > > http://www.mygaragestore.com/detail.aspx?ID=1883. It was very comfortable and gave me even more control.

Here are a couple pics of the finished floor. I confirmed in another thread that the profiling was acceptable. Any additional feedback on the quality of the profiling is welcome. Good luck with yours!

 

[asianflava]

I had no idea what I rented, but according to the link provided by the OP, I used the 3rd one with what looks like a 7in Dyma Disc. Used the 7in one because I only had 110 outlets. My floor had carpet adhesive on it because the house was a model and they had an office in the garage. Took a few hours, but it went faster after I got the hang of it.

 

[jwvess00]

Hi there!

The Home Depot machine tried to kill me. There's a thread on here about it.

I finally (!) read the instructions and took advice here, and figured it out. Downward pressure on the handles makes it go left. Pulling up makes it go right. When I was first trying to use it, I had a firm grip on it, and when I turned it on it pulled so hard to the left that it tried to remove my arms.

After that, I would start the machine with a firm grip but ever-so-slightly pulling up on the handles, which turned out to be fairly neutral. I could then "balance" between pushing down and pulling up -- both pretty gentle operations -- and guide it around without any real problems or effort. There is definitely some finesse to it but it is something you can do. I recommend having some new swear words you've been itching to try out handy while you learn

 

[jwvess00]

Hi there!

I wet the floor with a hose, enough that it was completely wetted in but no standing water. That kept the dust down. I tried it on a section dry, and it was pretty dusty. When the water dried it left a concrete paste on the floor. That came up really nicely with a pressure washer.

Legacy makes a good gel crack filler, and Rustoleum makes one too. The Rustoleum one cures really hard, and reminds me at lot of JB Weld in how it mixes, applies, cures, and finishes.

 

[Trey T]

^what rustoleum did you use? Where did you get it?

 

[mwehnes]

Interesting read about your experiences with various machines. I'm also in the middle of prepping my floor for epoxy painting (Legacy's product) and having a hell of time getting the results I expected.

The local Sunbelt wanted $240 for a single head Edco with Dyma serts (3). For half the cost I ended up renting a General unit (same thing as the Edco) but with C8 grinding stones , since they didn't have Dymaserts. What a nightmare.

I had to do my entire floor, 820 sqft, twice with these stones to get a resemblance of a good surface. After the headache of transporting a 300lb unit and wasting an entire day (7 hours grinding + travel & setup time) I still didn't have a profiled floor. The next day I broke down and bought Muriatic Acid and etched the floor with a very strong mix ratio.

All in I've got at least 4 full days invested in prepping my floor between degreasing, power washing, grinding, power washing, etching, power washing, power washing again.

My advise to everyone, **** it up and rent a high quality machine with dymaserts you'll save yourself so much frustration and additional costs.

 

[LegacyIndustrial]

I like the Edco type machine.


Sent from my iPhone using Tapatalk

 

[jwvess00]

^what rustoleum did you use? Where did you get it?

Hi there!

Rustoleum makes a hard epoxy floor patch:

http://www.rustoleum.com/en/product...ete-prep-and-repair/concrete-patch-and-repair

I bought it at my local Home Depot. Amazon carries it too.

It comes in two parts, mixed 2:1. I used a kitchen scale to get the mix ratio right (probably a bit too picky but I wanted it right). I mixed about 300g total, per mix. I spread it with a kitchen tablespoon and a plastic spreader (like you'd use for auto body filler). It filled some rather deep defects as well as cracks.

I used it with the gel crack filler, as a filler for deep spots where the previous owner installed some interior walls and fastened the walls to the floor. I removed those walls, which left holes to fill.

The Rustoleum stuff really reminds me of JB Weld. It sands really nicely.

Honestly given how hard it cures and what not, it might not be a terrbile material to use for casting small parts...

 

[Trey T]

Thanks, man!

 

[Diacutex]

The outcome of the epoxy is determined by the floor prep, a poor prep may even cause a decent epoxy to fail. When we talk about the floor surface preparation, someone recommends to use water and acid to do the prep work, but this is never a good idea. A concrete floor grinder with a good dust shroud will be ideal to do prep work. Also if you choose the stand-up walk behind concrete floor grinder, it will save your back and hours of hard labor. As for the grinding wheels or grinding pad, 7” grinding cup wheels with 12 segments will be good if you use hand-held angle grinder, if you use the stand-up walk behind concrete floor grinder, metal bond diamonds and 10” grinding discs will be ok. Different hardness floor require different diamond grit level, but 30# grit is pretty typical for this type of work. Some guy recommended a single head and compact sized concrete floor grinder to me, it can be folded and put in trunk, also it can grind the floor as well as the corner. Below is the link, any comments, pls advise
http://www.diacutex.com/products/equipments-and-accessories/floor-grinder/

 

[Armorpoxy]

Hi All,
When grinding remember it's almost mandatory that an epoxy primer be used as grinding makes the floor more porous, so if not primed, you can get uneven sheen results and such.