Talk:Fastener

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[edit] Why is the standard for the head on a countersunk fastener 82 1/2 degrees.

This is my very first attempt to make a contribution so I hope this is the appropriate place to do so. If it is not I hope someone will assist in the process. I am going to cut and paste a document I created some time ago. I have a long carrier as a maxhinist and manufacturing & engineering instructor. The information I am submitting was interesting to me and my fellow instructors, I love to know the reasons behind "why things are the way they are". This is an attemt to share my findings on this topic. Any help in posting this would be greatly apprecited since I have very little time to do it myself much less figure out how. Here goes.

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In 1990 during a class on blueprint reading a question was posed to the students by instructor Gary Zolkoske.. The following summary is the result of many hours of research.

Question: “Why is the head on a countersunk or flat head screw 82 (82 1/2)?”

After nearly 9 years of trying to track down a definitive answer by researching various texts on engineering, strength of materials, manufacturing processes and fastener industry literature and after asking the same question of every person with even the slightest bit of knowledge on the subject, I believe that I have found the answer. The answer was always there, the challenge was to find the one source of information that had enough background on the subject to be sure the answer was correct and not just conjecture. The expanding universe of the Internet finally came to my rescue on the last week of September 1999 when I made contact with Mr. Frank Akstens, Senior Staff Engineer for the Industrial Fastener Institute. Mr. Akstens directed me to Mr. Ed Tauscher who according to Mr. Akstens, “Has years of exposure to the B18 Sub 6 Committee that has responsibility for these matters.” I was given the telephone number of Anchor Screw and Bolt Co. ( 708-681-2100 ) and told that I should call and talk with Mr. Tauscher. I did this on the morning of September 27, 1999 and found Mr. Tauscher to only be available on Friday mornings so I finally made contact in person with him on the morning of October 1, 1999 and my findings follow.

I asked Mr. Tauscher the question and after a brief chuckle he said that he did have the answer. He stated that he had been in the fastener business for over 50 years. He had retired some years ago and now acted as a consultant to industry. HALLELUJAH! I had at least found someone that would say they had the answer. Mr. Tauscher stated the European standard for these types of screws (countersunk and flat head) was the 90head used for wood fasteners. This head angle gave good holding strength in woods and provided good slot depth for the screwdriver to function without damage to the fastener. The 90head was easy to manufacture at the time since bar stock was used and this angle lent itself to easy manufacture under the techniques of the day. However, when this design was applied to use in metals there were problems. The angle of the head put pressures on the slot that would cause it to collapse into itself and then the head of the fastener would fail either by loosening in the countersink or breaking off all together. Manufacturers in the United States then sought a stronger fastener design. Testing of different head angles and slot depths and widths showed that using an 82 angle (actually 82 ½ for a slight interference at the top) and decreasing the slot depth provided the best trade off to obtain structural integrity of the both the head and the slot. Remember this was all taking place before the introduction of the Phillips head or any subsequent driver styles in use today. In addition, Mr. Tauscher stated, “Americans always like to be different and the change in head style gave the United States a marketing advantage.” I asked if there was any written history on this and other facts about fastener development and Mr. Tauscher said none that would address this specific question but his long background in the industry provided him with the answer.

So perseverance pays off and until someone can come up with a more authoritative source of information this answer should hold up to scrutiny. In any case it’s good enough for me to feel that my quest has ended.

(If I knew more about what I was doing I would insert an example of a countersunk screw here) I have one but can not get it into this document, help again would be appreciated.

--BigBadWolff100 18:51, 10 December 2006 (UTC)