Reply To: Hardness of steel rod…

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david pierce
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Let me start by stating that a steel nail is definately NOT going to produce an arbor that you would be happy with. There are a lot of types of steels that are cataloged in various ways. The steels that would be more suitable for watch arbors would be in the catagory of tool steels. The most suitable of these would be drill rod which is generally classified acording to the method of heat treatment. The three major categories of drill rod are called WATER HARDENING, OIL HARDENING, and AIR HARDINING. Which one is suitable for watch arbors? The answer is ALL OF THEM. They are all good quality tool steels. The traditional material for watch staffs was purchased from watch supply houses and would come in a pack of short lengths about 1/12 inches long. The steel had the letter “W” in the classification code which ment that it was water hardening tool steel. As most watch repair people bought their staff material from watch supply centers and not industrial supply houses, most watch staffs were made from water hardening tool steel. Water hardening steel also happens to be the least expensive of the three. Oil hardening steel costs a little more than water hardening steel and is hardened by quenching the red hot part into oil instead of water (usually mixed with salt). Air hardening is the most expensive and is hardened by heating to a red hot temperature and blowing air on it. The good news is a 3 foot length of air hardening drill rod in a small diameter suitable for watch staffs is only about $10.00. Three feet of this stuff will probably be enough to last several years. Check with MSC or other industrial supply houses that carry drill rod and order some. This stuff will work much better than a nail.