Jim's Mirror Making Page 3
Stage 1 - Rough Grinding
- Apply 60/120 silicon carbide to the surface of the tool with a brush.
- Apply the stroke shown while walking around the post.
- when grinding action stops clean off the carbo and reapply fresh carbo. (wet)
- measure the depth of the mirror using a straight edge
- and a feeler gauge set to the value 'e' (from the theory page)
- when the gauge fits under the straight edge, rough grinding is almost completed.
The End of Stage 1 - Rough Grinding
Centre over centre stroke
the tool and mirror positions can be changed to clean up the curve.
At the end of the first stage, the tool and the mirror are not true to each other. clean up the curve with centre over centre strokes.
Stages 2 & 3
- Clear away and clean all surfaces before starting stage 2.
- Apply 320 carborundum to mirror as to remove the pits left by stage one.(may take 20 wets)
- Use centre over centre or use W strokes
- Check all pits from the previous grade have gone using a strong lamp
- Repeat procedure for stage three using the 303 grade carborundum.
- When all of the pits have gone you are ready for polishing
Checking for pits
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