Rough Grinding – Fine Grinding

I built a “grinding board.” It raises the grinding level seven inches above the table top for the sake of my back. I made it out of particle board scrap. I found a 17″ round of pine at Home Depot for $4. The disk sits on three furniture slides hammered into the particle board box. The pine disk is kept in place by four rests of particle board. Raising the grinding surface 7″ does wonders for my lower back!

 

2014.03.14. Pi Day. Some distressing excitement today as I continued fine grinding with 5 micron: first, I slightly chipped the mirror at the beveled edge.

And then in the first round of grinding after cleaning up the chip, beveling and washing off the bevel-grinding dust, I heard a slight scrap. In fact at the next inspection, I noticed two scratches. One is about 3/16 inches long and right at the edge, the other is an inch in from the edge, and an inch long. the resident experts indicated that they were both rather shallow and could likely be ground out. I spent an extra hour grinding at 5 micron to get rid of them. there was some effect, but not their elimination. I need still to decide next time whethere to keep trying with 5 micron or to give up an move to 3 micron.

Here is a table of the time I spent with each grit during the rough and fine grinding phase: 20.5 hours.

Grit size Hours Grinding
60 grit 4.5
80 .66
120 1.66
220 1.66
320 3
500 1.66
20 micron 2
12.5 2
5 1.33
3 2

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