Flattening waterstones

[cputnam]

Atoma 400 grit for me. It's reserved for stone flattening.

[GeorgeV]

I use an ATOMA 400 to flatten my Sigma Power ceramic 1000-6000-13000 stones.

http://www.toolsfromjapan.com/store/inde...ts_id=1667

[EricU]

I'd like to see a study showing what really happens when you rub 2 similarly sized stones together. Pretty sure you won't be left with 2 flat surfaces or 2 mating surfaces.  Pretty sure this is a woodworking myth started by sellers of Japanese water stones.

I worked for someone who did a study on this and it does work fine.  People worry about forming a convex stone and a concave stone, but that doesn't happen in practice.

[Derek Cohen]

I have used waterstones for 20-odd years ... ahh the days of King stones which were so soft, and I found impossible to keep them flat. I used sandpaper at first, then drywall mesh and, when I switched to Shaptons, began using a DMT extra coarse diamond stone. This did such a good job that Toshio Odate and Garrett Hack copied me. I receive a card every Christmas from them saying how I changed their lives.


Well, the last part is partially true, both use diamond stones to (regularly) flatten their waterstones.

Regards from Perth

Derek

[C. in Indy]

This one is now active on "the auction site"...
I wonder at what point (if ever) they stopped using it?

   

[titanxt]

Not sure where the notion comes from that you cannot use two stones to create a flat. From my machinist time, google lapping granite surface plates. These plates have to hold extremely flat tolerances over their entire face and are lapped with either another stone or a large piece of cast iron and abrasives. When done well, the surface will be within .0005 or less over the entire face, which can be a rather large surface.

[hbmcc]

Not sure where the notion comes from that you cannot use two stones to create a flat. From my machinist time, google lapping granite surface plates. These plates have to hold extremely flat tolerances over their entire face and are lapped with either another stone or a large piece of cast iron and abrasives. When done well, the surface will be within .0005 or less over the entire face, which can be a rather large surface.

The largest granite surface plate I saw was during one of my lunchtime visits to Boeing Surplus in Kent, WA. It had to be about 20 feet long and 4-feet square. (My brain wants to say it was 30-feet, but you know how memories are....) 

I remember a fellow jr. or sr. high student grinding two glass discs together to make a telescope lens the same way.

[Timberwolf]

The largest granite surface plate I saw was during one of my lunchtime visits to Boeing Surplus in Kent, WA. It had to be about 20 feet long and 4-feet square. (My brain wants to say it was 30-feet, but you know how memories are....) 

I remember a fellow jr. or sr. high student grinding two glass discs together to make a telescope lens the same way.

................
IMO, "flat" is a state of mind...."almost" flat..is good enough..

[EricU]

................
IMO, "flat" is a state of mind...."almost" flat..is good enough..
 

I have done some work in precision engineering where flat is never considered flat enough. Pretty much no such thing as flat.  I enjoyed the relentless pursuit of doing things better. But woodworkers are definitely going further than they need to with hand plane soles, for example.  

We used some granite tables at that job.  Some of them came from IBM back when they made hard drives.  Those were 6' by 4' by 2' or thereabouts mounted on air isolation legs. I wish I had one of those, but moving it would cost too much, and then I would have a 2000 pound table. There were two larger tables.