Flattening the flattener

[David Romano]

I purchased a set of Norton waterstones a while back and am very satisfied with them. I'm having problems with keeping them flat though. Their flattening stone is great at dressing the stones but is useless if it is not flat. I tried to flatten it with 60 grit glued to a granite surface plate. The sandpaper doesn't last worth a darn though. Does this scenario sound familar?

I'm considering a DMT extra large coarse diamond stone, hoping it will stand up toe the extremely tough material that the flattening stone is made of. Any suggestions?

thanks in advance
David

[Todd Burch]

I've never done this, but I suspect stone-on-stone would work well - they would both flatten each other.

[glenn bradley]

Todd??? Two uneven surfaces will even each other out just by being rubbed together???

[Todd Burch]

Why wouldn't they? Back and forth, round and round, side to side... What else would they do?

[Dan Forman]

I use "GatorGrit" 100 grit black zirconium sandpaper on glass to flatten the flattening stone. You will probably find more info in the Neander forum than up here RE: waterstones and their maintenance.

Dan

[george wilson]

I always flattened even Arkansas stones by laying an old fashioned sandstone,which we had several of in a museum,and rubbing the whetstone on it with water. I learned this trick from an old timer. It worked perfectly,and very quickly,too.

I was in the Gunsmith Shop once. One of the guyd had some 600 grit wet or dry wrapped around a file,and was trying to flatten a BLACK arkansas stone with it. That's the hardest of those stones. I pulled their sandstone wheel out of the trough,and had the black stone flat in about 5 minutes. If I hadn't shown him that trick,I think he would be there to this day,except he died young. That was the most inefficient attempt to flatten a stone I ever saw.

[Cliff Rohrabacher]

Todd??? Two uneven surfaces will even each other out just by being rubbed together???

If it's done correctly. You need random application of energy speed and weight. Trying for a consistent stroke will produce a mess.

I worked in a shop where there was a large hand lapping operation requiring millionths of an inch in flatness measured using light bands.
The Janitor was way far better than the machinists 'cause he had no ingrained need to be consistent.

[Wes Grass]

"Two uneven surfaces will even each other out just by being rubbed together?"

Nope.

"Why wouldn't they? Back and forth, round and round, side to side... What else would they do?"

It'll make one of them concave, and the other convex. And create a perfect (if you do it right) spherical form in the process. This is the process used to make telescope mirrors, and lenses for hundreds of years.

You need 3 to create a flat surface. There was a good post on this a couple weeks ago, regarding generating straight edges.

The flattening stone works by being much more wear resistant than the water stone, but it too will eventually wear out of flat. You can even this out to some extent by alternating which one is on the top or bottom as you flatten your stone.

The one on top becomes concave IIRC. But it may be more dependent on which is larger. Long time since I ground a mirror.

[Thomas Williams]

I use 100 grit drywall screen on granite to flatten my water stones and my Norton flattening stone. Works well and does not cost much.

[John Coloccia]

"It'll make one of them concave, and the other convex. And create a perfect (if you do it right) spherical form in the process. This is the process used to make telescope mirrors, and lenses for hundreds of years.

You need 3 to create a flat surface. There was a good post on this a couple weeks ago, regarding generating straight edges.


+100

And the reason why is actually pretty complex, but he's absolutely correct.

Personally, I use 60 or 80 grit on a granite block. I don't find it to be a difficult task. Then again, I flatten after every use. It takes me 1 minute to flatten if I do it every time. If I waited until it was really cupped, it'd take be all day!

[Russ Ambrose]

i also use a granite block with wet/dry sandpaper. works great and the granite block was relatively inexpensive (~$25).

[David Romano]

I looked up the gator grit paper but am unsure if the material is harder than the green SiC of the flattening stone. I read some older posts and one popular method is to use the diamond stone directly on the waterstone, not to flatten the flattener. To me getting out the granite plate is such a PITA, that I don't do it, and I have no other solution. It is undoubtedly the flattest surface in the shop though, so anything else is a compromise. I do use the granite plates for shapening jointer knives, but that is only occasionally.

I read that the diamond stones are flat to +/- 2 mils. That's an awful lot I think. I wonder if this is true?

[george wilson]

Diamond stones may not be exceedingly flat,but they should be flat enough to flatten your stone o.k.. I use my diamond stones to pre flatten ceramic stones,and to clean them of little steel particles that do stick to them,and must be gotten rid of. If you have a diamond,try it. Do it over a plastic basin of water,with frequent dunking. I would not recommend doing it in your sink,as you may gradually clog the pipes with stone sediment if you do enough of the flattening. I'd pour the water outside.

[Michael Faurot]

Why wouldn't they? Back and forth, round and round, side to side... What else would they do?

Whichever of the stones is more coarse, is going to transfer its (mis)shape to the lesser stone.

[Myk Rian]

I've used my belt sander to flatten stones.
Don't overheat it.

[Joe O'Leary]

Get the DMT. I think mine was on sale for about $60.

Joe;)

[Mike Henderson]

It'll make one of them concave, and the other convex. And create a perfect (if you do it right) spherical form in the process. This is the process used to make telescope mirrors, and lenses for hundreds of years.

You need 3 to create a flat surface.
+ another 100. If you rub two surfaces together, you'll get two conforming surfaces, generally a concave one and a convex one.

Those flattening stones are worthless. Throw your's away and get a DMT diamond plate.

Mike

[Todd Burch]

Whichever of the stones is more coarse, is going to transfer its (mis)shape to the lesser stone.

I would agree. But it just seems that two stones of equal material would flatten each other. One day, I'll have to do this.

[harry strasil]

I used to buy old antique stones for almost nothing that were really concave, I just used a concret block or a sidewalk surface to flatten them, then used some wet dry sandpaper on an old cast iron surface plate to finish them off.

I don't use any kind of jig to sharpen with, just my fingers and instead of a back and forth motion, I use a circular motion using the whole stone, so I don't cut teeth in the surface and end up with an edge like a toothing plane.