wood guy trying to do a grind---how smooth??

[Bsheffer]

My goal is to apply an epoxy coating when ready. I am also coming at this from a standpoint of doing fine woodworking/finishing for 25 years.

So A buddy of mine loaned me a brand new high end planetary grinder made by cimex. Amazing piece of equipment. He uses it in high-end floor maintenance in grade "A" office buildings. I am simply trying to grind my 20 year old concrete garage floor that is in excellent condition to prepare it for epoxy.
He had a box of grinding discs that he uses and the lowest grinding disc has a grit of 50. I ground a small spot using these discs and it appears to have worked real well but I was very surprised at the resultant surface in that it is very smooth. How smooth??? I got a piece of 220 grit sandpaper I use for woodworking and the ground surface is noticably smoother than the sand paper. The catch 22 is that to get any lower grit grinding discs is cost prohibitive for me. SO, I have a $100K car that I cannot afford to put presumably the correct tires on as apparently I should be using 25 grit grinding discs.

The question is...

1) Is my woodworking correlation a fair comparison?
2) When you ground your concrete, how smooth was it before you appied the epoxy

 

[03roadking]

@Bsheffer I am a woodworker also and after I used the clarke floor maintainer with the daimabrush attachment on my garage floor I was surprised at just how smooth it was also. After the daimabrush and a powerwashing I would call it closer to 320 grit or higher as a comparison to sandpaper. all of the diamond "blades didnt appear to be worn down much at all when I got it from home depot also. I am thinking it will leave it a little smoother than some people think. Is that bad or ok? I dont know.

 

[Armorpoxy]

If you are putting down an epoxy coating, a #50 is fine to grind with. It has enough grit left for a good bit, and any minor swirl marks should be hidden.

 

[Garage Flooring]

What type of epoxy coating are you using?

 

[Bsheffer]

I am using the Legecy epoxy products.

The below is the grinding disc set I am using. Part of that system is a 50 grit disc.


http://www.stadeatools.com/wet-diamond-polishing-pads-discs/series-ult-a/


One of these "polishing discs" is a 50 grit disc. In woodworking, 50 grit is 50 grit so one of the thoughts I had was that all 50 grit discs may not deliver the same amount of abrasion in general in the concrete world

 

[Armorpoxy]

Hi
These pads are what we call 'resin' pads and are used for polishing concrete, marble,etc. Normally they are not used on concrete until successive sets of metal-bond diamonds have been used up to #200, but it appears these pads can be used wet and there is a #50. Resin pads won't grind much in our opinion, but they are good for polishing which is not what you want to do here, you need more of a 'grind'.

 

[Bsheffer]

Armorpoxy, for my simple mind....are we saying a 50 grit resin pad will not cut like a 50 grit metal-bond diamond product??? As I said, I am coming at this from a woodworking perspective and as far as I can tell, all 50 grit wood product will leave essential the same "scratch pattern", I think???

 

[Armorpoxy]

Hi we own a surface prep company and have a fleet of diamond grinders and hundreds of assorted diamond pads and polisher pads and have never seen nor can we understand how size 50 diamonds could be held in a flexible resin pad so we really don't know the answer. That type of aggressive grinding we thing would tear it up.

All standard diamond floor grinders use the same numbers and metal bond pads go up to about 120 and then the resins take over since the resins can hold small diamonds but not larger ones. Your supplier though may have some new technology that we are not aware of so best to contact them and ask how these work and if the numbers equate to standard numbers you are familiar with so you get the profile you want.

The popular Diamabrush offers #25 and #100 on a metal holder but nothing on a resin either in these low numbers.

Let us know what they say!


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[Bsheffer]

Thank you....This completely makes sense....On a related analogy, it seems like these products are like "ski slopes". No matter what ski hill you go to, you will always find a black diamond run which indicates the most aggressive runs on the hill. Conversely, there will always be green runs which indicate the least aggressive. When comparing the typical east coast slope to the typical west coast slope, a black diamond slope in many of the east coast hills equals a blue(moderate) slope in the west...and so forth.

Conversely, a 50 grit in the eyes of the resin manufacturer might simply be designed to indicate their most aggressive. I have read in multiple places where there is little uniformity across most of the abrasive manufacturer product lines industry wide which might also explain the variances.

 

[Armorpoxy]

Great analogy! Let us know what you find out.


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