Before making new parts I decided to take the time to zero in my machines. On the lathe the usual method is to use shims to align the bed but the is awkward. I drilled and tapped holes close to the mounting bolts to use as leveling screws. A long time ago I did the same with my 3-jaw chuck so I could center it to "0". I reset the tail stock.
I aligned the head of the mill. I found that this process is called "tramming". I had used the lugs in the bottom of the dividing head to mount it but this is not accurate. I removed the lugs and attached the dividing head to an aluminum plate I had machined. I replaced the lugs with one round lug in the front and alignment screws in the back. This makes the dividing head pivot and it is fairly easy to align parallel to the back of the bed. I used a 12" piece of ground drill rod tightened in the chuck.
I found that the chuck was not centered so I drilled and tapped four holes to use with alignment screws and set the chuck to "0".
I also found that it is necessary to set the dividing head parallel to the top of the bed at the same time as setting it parallel to the back. As a circle touches a straight line at only one point, the point of the dial indicator must touch the test bar at the same place along its entire length. This is actually easy to do by setting up two dial indicators. One mounted to the knee for the parallel of the back of the bed and one mounted to the spindle or head for the parallel to the top of the bed.
After I did this I rotated the dividing head 90degs. I attached a dial indicator to the spindle and set the dividing head to "0" by moving the spindle up and down. It is important that the spindle does not rotate. I used a vise grip to clamp the drive belt to the pulley edge to keep the spindle from moving as my lock is worn.
I use carbide insert and HHS cutting tools. I sharpened a lathe tool and turned a new blank for the bolt carrier. I mounted it in the dividing head and am ready to bore the 10 holes. After finding the center with a wiggler I used a dial indicator to measure the .775 radius.
I believe I have done each step correctly and the bolts should be in the correct position with the new bolt carrier. After this I will make a new pan. One more thing, I suggest buying American made cutting tools for accuracy, such as the .438 ream used for these holes.
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