Flattening a bench stone

[Elden]

Quote from Ken S:
"I almost ruined a two hundred dollar diamond flattening plate flattening my grandfather's old oilstone. I won't kill off the diamond plate or my hands with carborundum powder trying to rescue a twenty nine dollar stone grader. Like grinding wheels, it is a consumable.. The smooth side is also cupped. It has served honorably and has been retired."


   What is the best way to flatten a bench stone? That is a complex question which possibly can not be answered before some other questions are answered. One of those might be, what material  is the stone made of? Another might be, how much money do I want to spend to accomplish the goal?

   From an auction (the same one the drill bits came from), I acquired a badly dished bench stone. I think it is an aluminum oxide stone. It has a coarse and a finer side. The coarse side was much more dished than the fine side. The stone was included with something else that I wanted to purchase. I do NOT recommend buying a bench stone in that condition, it is repairable, however.

   With Ken's comments about his experience with such in mind, I tried a concrete block. It will work if you have a lot of time to spend and have several concrete blocks. The bench stone does an excellent job of smoothing the concrete block! There had to be a better way.

   Having a Makita 4 1/2 angle grinder and a masonry grinding wheel, I decided to give it a try on the stone. It worked much better and much more quickly. The masonry grinding wheels are relatively inexpensive and are readily available. Maintaining flatness of the bench stone can be a slight issue. Once the dishing of the bench stone is almost removed,  several swipes on the concrete block will reveal where the high spots are located on the stone. Lightly grind those spots. Alternate the use of grinder and of the concrete block until the stone is fully flattened. Finish by using the concrete block. I have done the coarse side and have started on the fine side.

   Will it work for the stone grader? I believe so, although I have not tried it. I think it should open up a fresh cutting surface as well as flattening the surface of the grader.

   Disclaimer: There might be some bench stones that may not respond as desired to the masonry grinding wheel. Is the stone grader one that will not?
   

[Ken S]

Elden,

I have not previously posted what I did with that oilstone before using the diamond flattening plate. Both the coarse and fine sides were cupped. I was at a sharpening class, and spent about an hour and a half rubbing it against carborundum powder imbedded in mylar on glass. When I got home, I spent perhaps three of four hours over time rubbing it against wet or dry abrasive on glass. By then the fine side was flat and the coarse side was near flat. It was hard work and hard on my hands.I put a lot of time and expense into an old stone which I could have replaced for $20 to $35. And, I have not used the stone since flattening it. It was a waste of time.

If you enjoy fooling around with such things, more power to you. However, I do not believe it is any better use of your time and expense than mine was.

In the same spirit, I do not feel it is worthwhile to spend much time or money trying to rejuvenate my stone grader. That may sound wasteful, but I value my time and see no use to subject my hands to so much pain for so little gain.  Donate your stone to Goodwill. Someone will think he got a deal.

Ken

[Elden]

   Agreed, Ken. I am doing this one so as to see if it can be accomplished with less pain and much less expense than you encountered. It can be, but you are correct, it is not worth it.

[Ken S]

That's fine, Elden. You are going into this with no unrealistic expectations. I think your efforts might be more productively focused elsewhere, but that's just my opinion. Follow your own course.

Ken

[SharpenADullWitt]

That was one reason I choose waterstones over oilstones.  They are just softer enough that flattening is less work and I don't let them get to the point of bad.  (probably the bigger part of it)
Still use them for light touch ups as they are in a different area of the house then the Tormek.  My view is keep some of that stuff with other stuff.  We do the same with steels and our kitchen blocks don't we?

[grepper]

I've heard that a belt sander works to quickly flatten a stone.  The issue being that, depending on the stone, it chews through belts pretty quickly and considering the cost of a new stone it might not be worth it.