|Forum topic by SirTonka||posted 10-20-2013 04:51 AM||2260 views||0 times favorited||12 replies|
10-20-2013 04:51 AM
In a previous post here I asked y’all for help finding the grit of a few mystery stones. Last week I ordered an EE coarse DMT plate (the 8” version of DMT’s lapping plate) and started to test the stones. My goal was to find out what grit order each stone fell into and to record the process. Before I jumped into sharpening everything in sight I wanted to get my mind around what was going on. So I started out with what gave me the best testing surface available, by purposefully lapping through the various stones with the sole of a small bullnose plane.
First things first, the EE coarse is simply, hot damn! Was impressed after the testing and decided to compare the abrasive power versus a cinder block, even with the longer stroke of the block, the EE cuts true, and fast!
The stones and plates tested:
Starting out with a fresh EE made for quick initial lapping, the story changed when moving up to a used coarse.
The planned method of testing was to lap the bullnose sole using a known surface and test against the mystery surface to pin down a best estimate for the grit ranges. Having issues with the jump in DMTs I went to the dark brown stone, the likely candidate for coarser mystery stone. This left a scratch pattern finer than the EE and seemingly finer that the coarse, and I noticed a haze develop over the entire sole. The EE had full coverage, the DMT coarse was hitting only the highs, and the dark drown was doing a great job on everything but the deepest of EE grooves.
Everything was moving along and I started lapping with the king 1000 and then the 1200.
DMTs scratch patterns are easily seen and progressing to the next plate leaves a contrasting boundary area highlighting the change. With the stones, all I could see was a finer matrix of RGB clusters. And when moving from a fine stone to a fine DMT, I find the flatness of a diamond plate persistent indeed.!
I know DMTs are as near a perfect plane my shop will ever need, and the surface of the sole ended up looking like a metal worker went to town hand scraping true flat. But I do enjoy the kaleidoscopic properties left by the stones!
Hope to add something to the knowledge base
Not the final word, now my plan is to buy a microscope and see just what is going on with that metal.