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| Overview | The image (below) shows how I set my dividers accurately. Set the caliper jaws at the dimension 0.177" and lock the jaws. Close your divider points onto the I.D. blades of your caliper until you feel a light touch of the divider points on the caliper jaws. Once established scribe two arcs across the long centerline- see image below. Lightly center pop them. Scratch Building Tip. Don't use a conventional center punch, I use a sharpened piece of hardened silver steel 1/8" diameter. First grind a shallow, long point on one end using a grinding wheel. Next heat the end for approx 1 inch until it is yellow hot, that means until the colour of the end becomes yellow from your flame, when it does immediately quench in cold water. Clean the end with emery cloth so it shows silver color again. To temper the ground point hold your flame 1 inch away from the tip of your scriber cum center punch (press) and watch the colours creep toward the point. The first colour you will observe will be 'spotted red brown' 265 C. Next 'brown-purple' 271 C. Then 'light purple' 2276 C. And the colour we wan to reach and then immediately quench is 'full purple' 282 C. You can clean the tip up to make the whole piece silver/metal and the tip will be nicely tempered and remain sharp for a good number of years. You can make harder cutting and scribing tools if you wish. Check if your steel merchant (or online steel merchant) carries stellite, its the material I use. Available in 1/8 dia rods X 12 inches long. A superb alternative is using small allen keys. Grind off the small cranked end until you are left with the long length of hexagonal steel. Grind a point to the shape you prefer, et voila, a center punch and/or, with a longer point, a nice scriber. Don't even need to do the flame thing. Next Tip. Don't use cheapo allen keys for this. Purchase either 'Unbrako' allen keys or the original 'Allen Key' allen key. Top dollar but they don't chip when you hit them with a hammer and you will still keep your eyes intact
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[Page1][Page 5][Page 10][Page 15][Page 20] Last updated : November 18, 2007 13:01
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