How do I create a flat surface on a small granite rock?

[gnj091405]

My daughter found a roundish granite rock she wants to keep.  I want to flatten one side so that it at least lays flat.
I tried dry grinding it with my 4 1/2" grinder and diamond blade, but now I have ground too much in the center and for the life of me can't get it flat so it doesn't wobble on whatever she sets it on.  Not to mention the dust.  What would be the best way to flatten one side without dust flying everywhere?  I was thinking a Wet Stone Grinder, but with what attachment?  Diamond Sandpaper?  Cut is approximately 5 " in diameter.
Thanks if you can help this odd question.

[Mark D.]

You can use either diamond sandpaper or a grinding cup if you want to flatten it out. The only way to avoid the dust is to use water with it. I suppose you could hook up a vacuum to catch most of the dust, but...
I just posted this in another question and it fits here too:
Try this one -A revolutionary product - diamond sandpaper!

OK, they are neither sand nor paper, but these pads have a diamond surface on a fairly flexible sheet metal backing and offer the most aggressive removal rate you can imagine - they are much faster than an impregnated grinding disc because they have 100% diamond exposure!

These Velcro backed pads can be used either wet or dry on a sander or grinder, and they operate well at any speed, plus you will be pleasantly surprised at how long they last!

Not only can you sand & finish with them, but they also work great for fabricating granite, even though they will not polish it to a high gloss.

These work on concrete, stone, tile, wood, swimming pool surfaces (the ONLY answer to quickly sanding PebbleTec), metals, even glass!

Another top quality product Diamante Italia. The 4" are sold by the grit or by the set. Here is a link for you:
http://www.defusco.com/diamond-sandpaper-discs-diamond-sandpaper-discs-c-25_30_660_664.html

You will also need a 4" backing pad. Here they are:
http://www.defusco.com/flexible-backing-pad-velcro-p-1939.html

If you want to use a grinding disc, here is one that can be run wet or dry and is flat so it is easier to make a flat plane with it:
http://www.defusco.com/fullface-brazed-grinding-disc-p-1996.html

Glad to be of service,
Mark

[Duckman]

How do you drill and tap a granite surface plate?

[Mark D.]

I don't understand...explain this to me. A surface plate? So you can put wiring through it? Drill it with a diamond drill bit. Thread it? I don't think so...

Glad to be of service,
Mark

[gnj091405]

Mark, thanks for the info, and the quick response.

What about the 4" TURBO COARSE STONE CUP - ALUM BACKER
[DSWA4CT]  how does that compare to the brazed concave cup you recommended?

Which would be better for granite?

Thanks.
greg

[Mark D.]

It works a little slower and lasts a little longer. I don't think I recommended the concave cup, I thought I recommended the flat fullface cup.
Use a flat bottom cup not a concave cup as you are trying to get a flat surface on the bottom. Any of the 15 grinding cups in our  Diamond Grinding Cups - Granite section will work, but for getting it down to a single plane I like #'s 1, 2, 6, 14 or 15. Any of these should make your work easier. If I had to pick one for the layperson to use it would definitely be #2

Glad to be of service,
Mark

[gnj091405]

Mark,
Thanks again for the reply, you are being very helpful.  Since I am a novice (layperson) I am getting a little confused.  I appreciate your assistance greatly!

I went to Diamond Grinding Cups - Granite section and looked at 1,2,6 14 and 15.  Sorry but I can't picture @2 producing a single plane because of the large NUT in the middle.  That is the problem I had with a completely flat grinding disk, I would be working on the center and due to the curvature of the blade (circumference) the middle materials was going away quickly, but the edges didn't go away as fast.  My Threaded clamp nut was in the way which didn't allow me to put the disk flat on the piece.  The only thing I can think of is that #2 is completely flat on the side that hits the rock, and that the clamp nut from my grinder won't be needed because the full faced grinding disk is "hubbed"?   I would have to secure it with a wrench between the disk and the grinder, rather than with my grinders clamp nut.?   

I thought I would need a concave cup so that the clamp nut would be out of the way.  You are right, you didn't recommend the concave one, but I guessed that it would "hide" my clamp nut.

As soon as I figure this out, I will be ordering something.  This forum is the best I have seen, and you are much more helpful than the local folks in Seattle. 

Am I on the right track with the thought on why #2 will work for me?

[Mark D.]

The nut is recessed. The picture shows the part that screws onto the grinder so you can see it. The other side is flat with 4 countersunk holes in it for the screws so when you wear one side out you can take the flange off and reverse it. In other words it is double sided so you can wear it out twice.

Since it has a screw on arbor you just screw it onto your grinder. You do not need a nut over it. If it were my choice I would use this to do flat work. I recommend it to people who are having problems with their laminations to flatten them out prior to polishing them.

This tool is a winner. Go for it!

Glad to be of service,
Mark