Announcement

Collapse
No announcement yet.

Pure skill

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Pure skill

    I have a simple sort of jig that I made for turning the end of all thread rod so that it is held in the 4 jaw exactly concentric to the threads. When I have time I will post some pics, it's dead simple.

    That isn't the main point of this post however. I was using the jig to turn the end of some grade 8 1/2 x 13 UNC all thread to accept a pair of bearings on the end. I first needed to turn it to .392". I was turning down a 2" long area on the end of the all thread with only the .5" furthest from the end needed at .392 to suit the ID of the bearing. I was trying the bearing for fit and was looking for a very light press fit. The next bearing on the bitter end of the rod has an ID of .375. In order to test the fit of the larger bearing I cranked in the cross feed and took a cut to reduce the diameter to make testing the fit of the .392 bearing easier. Perfect fit! Then I realized that I hadn't measured or taken any notice of how much I had cranked in the cross slide. The remainder of the shaft had to be .375" OD to fit the smaller bearing. Gack. I grabbed the calipers and measured. 0.3755".

    Pure skill.

    Free software for calculating bolt circles and similar: Click Here

  • #2
    Its gotta be the southbend 9c.
    Hehe, no really, mine has 60+ years of wear on it, it always cuts a little less than indicated, saved me once already.

    Comment


    • #3
      Evan -

      This sounds a bit like Fermat's last theorem. Make sure you follow up or you may have the world guessing for centuries!

      ------------------

      Comment


      • #4
        I'll take some pics tonight.
        Free software for calculating bolt circles and similar: Click Here

        Comment


        • #5
          Whenever I do that it comes out 0.3745". Sure is hard to put those little chips back on....................................

          ------------------
          Barry Milton

          [This message has been edited by precisionworks (edited 04-11-2005).]
          Barry Milton

          Comment


          • #6
            <font face="Verdana, Arial" size="2">Originally posted by precisionworks:
            Whenever I do that it comes out 0.3745". Sure is hard to put those little chips back on....................................

            </font>
            yeah, same here! ;-(

            Comment


            • #7
              There are three kinds of machinists.

              Those who make things happen.

              Those who watch things happen.

              Those who wonder what happened.

              I usually fall into the last one.

              Comment


              • #8
                Yeah, the rule is to first sketch the part, then build the part, then measure the part, then design the part, then tolerance the part. Of course, one must never make two of the same parts.

                It's amazing how accurate one can make something if they ONLY would follow that simple rule!

                Sheesh..

                Comment


                • #9
                  Good eye Evan. It's amazing how close you can come with just the eyeball. If you do a lot of machining, seems like the eye gets trained to sizes. Done it a few times myself.

                  Cutting down shafts, I usually get within .030-.050 then start watching the dial after measuring. A few times I've hit within .005 and a few times I've hit -.005

                  Comment


                  • #10
                    I eyeballed a boring cutter in the mill to the center of a hole yesterday, and I can't measure any offset from where it is supposed to be. Must be some of that pure skill going around. Then I carefully measured, centerpunched, and drilled a hole- precisely in the wrong spot--- IFLAI.

                    (I feel like an idiot)

                    Must be some dumb going around too.
                    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                    Comment


                    • #11
                      Yea that's what I say. There's no problem drilling precision holes. Anyone can do that. It's getting them in the right spot that cost money. That's what I tell customers.

                      Comment


                      • #12
                        And when it all comes together magnificently....there is no one about to witness the event

                        cheers, Ken
                        Ken.

                        Comment


                        • #13
                          I didn't takes pics of the setup for machining all thread rod but it is easy enough to describe. Just buy a couple of connector nuts used to tie two pieces of all thread together. The ones for 1/2 x 13 are about 1 3/4" long. Chuck one up in the three jaw and turn about two thirds of the flats off to round. Chuck up the other and do the same. In my case the spindle through hole is just over 3/4" ID so I turned the second nut down just enough to fit. A 3/4" washer is placed on the second nut.

                          To hold the rod for machining chuck up the first nut on the round OD in the four jaw. Put the rod through the spindle and thread it through the nut until maybe an inch sticks out. Thread on the other nut with the washer so that it locates and supports the rod in the back end of the spindle. Adjust the nut in the chuck until the threads are running true and tighten down the back nut with a wrench. Start machining, facing and center drill to start. Then adjust the rod to whatever you need and continue.
                          Free software for calculating bolt circles and similar: Click Here

                          Comment


                          • #14
                            I was told the difference between an accident and a plan is the ability to do it three times in a row.The guy was in the ER with four finishing nails in the same hand
                            I just need one more tool,just one!

                            Comment

                            Working...
                            X