First, I want to say that Wilbur's Bench Rest Central Web site may have the largest collective group of shooting/machinist intellectuals. We all enjoy shooting and sharing our ideas for the rest of the web site community. We all may not agree on the methods but we all agree on the results.
Yesterday evening, I had a call from a shooter/gunsmith who frequents this forum. He asked me about the bolt nose cone angle of a particular manufacture. The action manufacture has been in business for a number of years and has changed their bolts a couple of times. I did not have any notes nor could I find any on the internet.
I recommended that he use a machinist protractor to set the compound on his lathe. He is an experienced gunsmith machinist and asked why not just use the indicated marks on his cross feed and compound. I explained that his indicated marks on his lathe should be verified with a protractor before using them. I told him over the years I had seen a number of lathes that were not indicated/marked accurately. He did not have functional machinist protractor and was going to get one the following day.
I explained that he could use the protractor to determine the bolt nose cone angle and to set his compound. I told him the protractor is made square a little larger than a business card. The protractor has a long arm that has a indicator mark on the short end that correlates with the protractor scale. The top and bottom sides are parallel and the sides of the arm are parallel to the indicator mark.
I explained to my friend by placing the protractor bottom on the face of the bolt and sticking the arm out at the indicated angle would give him a reference to guide the compound. By setting the flat side of tool holder on the back side compound. and adjusting the angle of the compound to run parallel to the angle of the protractor arm one can lock down the compound on the correct cutting angle. I use a small boring bar to cut the
correct cone angle in the tenon.
This explanation went off like a light bulb in my friends head. Maybe it will help someone else.
Nat Lambeth
Yesterday evening, I had a call from a shooter/gunsmith who frequents this forum. He asked me about the bolt nose cone angle of a particular manufacture. The action manufacture has been in business for a number of years and has changed their bolts a couple of times. I did not have any notes nor could I find any on the internet.
I recommended that he use a machinist protractor to set the compound on his lathe. He is an experienced gunsmith machinist and asked why not just use the indicated marks on his cross feed and compound. I explained that his indicated marks on his lathe should be verified with a protractor before using them. I told him over the years I had seen a number of lathes that were not indicated/marked accurately. He did not have functional machinist protractor and was going to get one the following day.
I explained that he could use the protractor to determine the bolt nose cone angle and to set his compound. I told him the protractor is made square a little larger than a business card. The protractor has a long arm that has a indicator mark on the short end that correlates with the protractor scale. The top and bottom sides are parallel and the sides of the arm are parallel to the indicator mark.
I explained to my friend by placing the protractor bottom on the face of the bolt and sticking the arm out at the indicated angle would give him a reference to guide the compound. By setting the flat side of tool holder on the back side compound. and adjusting the angle of the compound to run parallel to the angle of the protractor arm one can lock down the compound on the correct cutting angle. I use a small boring bar to cut the
correct cone angle in the tenon.
This explanation went off like a light bulb in my friends head. Maybe it will help someone else.
Nat Lambeth