A little while back I bought two of these.
They are the Asian knock-off of the Norton bench stones. Reviews say they are quite soft - I would agree with that.
Are they flat? Well, when rubbing them together, they seem not too bad. Each one had some high spots and the reverse side had some lows.
So I decided to copy Robin Renzetti and surface grind them (my little grinder and my skill level are far from Robin’s, so my result will not match his).
I ground them dry with a Norton diamond wheel on my INGAR RT-618-2A. I used the shop vac for dust control.
Here are some pictures of the process.
The high area is clearly visible on this side of the one stone. It took about 15 thousands to get this side flat.
Here is the second stone with a dished area. I used three folded up pieces of paper (one is just visible) between the stone and the mag chuck to stop it from rocking - 3 points of contact (as the bottom side was not yet ground, but was flatter than the top).
The first picture is 6 thou after touch-off on the highest point. The next two are 2 thou DoC passes.
Almost got it… just the tiniest area left
1/2 thou DoC for the last cutting pass. Then four ”spark-out“ passes (no more down feed) with ever smaller step-overs per pass to finish off the side.
So were they flat? Not really. Now they are orders of magnitude better than before... I call that a win.
Probably will get a pair of Norton stones in the near future and grind them as well now that I know I can do it with the tools I have. Nortons are quite a bit more $$s than these cheap Harbor Freight ones. Did not want to practice on the dear stuff…
They are the Asian knock-off of the Norton bench stones. Reviews say they are quite soft - I would agree with that.
Are they flat? Well, when rubbing them together, they seem not too bad. Each one had some high spots and the reverse side had some lows.
So I decided to copy Robin Renzetti and surface grind them (my little grinder and my skill level are far from Robin’s, so my result will not match his).
I ground them dry with a Norton diamond wheel on my INGAR RT-618-2A. I used the shop vac for dust control.
Here are some pictures of the process.
The high area is clearly visible on this side of the one stone. It took about 15 thousands to get this side flat.
Here is the second stone with a dished area. I used three folded up pieces of paper (one is just visible) between the stone and the mag chuck to stop it from rocking - 3 points of contact (as the bottom side was not yet ground, but was flatter than the top).
The first picture is 6 thou after touch-off on the highest point. The next two are 2 thou DoC passes.
Almost got it… just the tiniest area left
1/2 thou DoC for the last cutting pass. Then four ”spark-out“ passes (no more down feed) with ever smaller step-overs per pass to finish off the side.
So were they flat? Not really. Now they are orders of magnitude better than before... I call that a win.
Probably will get a pair of Norton stones in the near future and grind them as well now that I know I can do it with the tools I have. Nortons are quite a bit more $$s than these cheap Harbor Freight ones. Did not want to practice on the dear stuff…
