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Re: Drilling well centered holes

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  • anthrhodes
    D. Hair, I ve read several responses to your question and don t claim to have better information but a few points come to mind. First point, however deep you
    Message 1 of 58 , Aug 16, 2013
    D. Hair,
     
    I've read several responses to your question and don't claim to have better information but a few points come to mind.
     
    First point, however deep you wish to drill, you'll need a drill bit which sticks out of the chuck a little longer than that depth!
     
    Regarding the travel of the tailstock, if you have a QC tool post you can probably get a tool holder which mounts a Jacobs or similar chuck so the carriage traverse will provide more travel than the tailstock quill. You will have to take some care in centering the drill on the work piece, both vertically and horizontally and make certain that the chuck is in line with the spindle axis.
     
    For change gear bushings the alignment of the bore can drift a bit more than for many other kinds of work. The outer diameter of the bushing will be created by milling. The only elements which extend farther out than the outer diameter are the keys and, while you don't want to miss by much, they don't require quite the accuracy as do the basic ID and OD which do need to be concentric with each other.
     
    If your work piece extends out the back of the spindle more than a few inches make certain that you constrain it so that it can't bend out of line. If such should happen you have a flail whipping around at spindle speed.
     
    I'm attaching a photo somebody sent me when we were discussing different change gear issues and solutions. This shows his approach to milling the outside to 1/2" and leaving the 1'8" x 1/16" keys. As you will see, he was using a 1/8" end mill.
     
    Hope some of this, combined with the other responses you received, is useful to you.
     
    Anthony
    Berkeley, Calif.
    ***********************************************
    In a message dated Thu Aug 15, 2013 7:13 pm (PDT), dhlh1984 writes:
    I'm wanting to drill well centered holes in t-6061 5/8" aluminum stock 5 inches deep. What would be the best procedure and would split point drills drill a more accurate hole. I intend to use my lathe to drill and then ream to a full 3/8". This will be my first time drilling 5 inch holes and trying to keep them well centered.
  • anthrhodes
    D. Hair, You could also ask them if they can do an extrusion the full form of the section of the bushing. It s likely they can but probably not at a price
    Message 58 of 58 , Aug 18, 2013
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      D. Hair,
       
      You could also ask them if they can do an extrusion the full form of the section of the bushing. It's likely they can but probably not at a price which is acceptable to you. The question of price for the 5/8" OD x 3/8" ID section, if they don't already have the tooling, may also be a killer.
       
      (You might also consider the same methods for gear bushings for the 9", 10", and 12" lathes. I have no idea what the market is for bushings for any of the Atlas-built and similar lathes.)
       
      Anthony
      Berkeley, Calif.
      ***************************************************
      In a message dated Fri Aug 16, 2013 4:55 pm (PDT), dhlh1984 writes:
      I have a request into that company to see if they make the extrusion in an 1/8 inch larger size. That would be great and I would order 20 or so feet.
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