Announcement

Collapse
No announcement yet.

Burned out on Run out

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

  • Burned out on Run out

    Drilling undersize thru holes in small parts on a lathe. Flipped part around, then open one end, using a shorten reamer in the tailstock .
    The hole is out by +.005". And can see only one side of the reamer cutting.
    A good piece of drill rod, chucked, shows .0025" runout. Cant get any closer.
    Bored the aluminum Monster jaws using a machined washer, cut from another lathe.

    I thought the chuck runout was the problem.
    But the drill hole itself is only off by less than a .001" from the drill bit itself.
    When I chuck the reamer, I get the same runout, .0025". So I assume its not the reamer.
    Ckd the tailstock alignment also.

    Im outta solutions.

  • #2
    It sounds like your tailstock is not aligned with the spindle axis-
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

    Comment


    • #3
      Could be low as oposed to sideways, mine was!
      Mark

      Comment


      • #4
        So whats the best way to ck this, even with chuck runout ?

        I used a 4MT in the chuck, spunit to see if straight, then a 3Mt in tailstock.
        Eyeballed the 2 pts together, from above and sideways.

        Comment


        • #5
          Originally posted by kNucKlbustr View Post
          So whats the best way to ck this, even with chuck runout ?

          I used a 4MT in the chuck, spunit to see if straight, then a 3Mt in tailstock.
          Eyeballed the 2 pts together, from above and sideways.
          When you bring the two points together, hold a piece of onion skin paper between them You will be able to see any offset much more easily by examining the resulting dimples under a glass.

          Pops

          Comment


          • #6
            Chuck runout can be eliminated by chucking up some scrap and turning a point on it. Then the tail stock with a center mounted in it is brought up to that point. The errors in alignment may be seen visually, or you lightly pinch a smooth flat disc, or piece of sheet something between the points. The way the piece tilts shows you which way the alignment is out. This works if the tail stock is high or low, forward or rearward, but it has to be parallel to the spindle axis first. There's more than a full can of worms here as there are lots of areas where error can be, and correcting them in the proper sequence is important.

            One method I've read about seems to be a decent one. Because the tail stock usually rides on its own ways, they are far less likely to be worn beyond a reasonable accuracy. You can mount some scrap, then turn a morse taper on it that matches the tail stock. You then loosen up the assembly of the tail stock and mount it on that tapered stub. This will get the tail stock aligned to the spindle axis. You then play with shimming and adjusting to get the tail stock mount solidly under the upper part, without pulling it out of alignment as you tighten it down. Once that's done, you should have a good alignment. It should allow you to run the tail stock ram in and out without it losing concentricity with the spindle axis, and it should be good anywhere along the ways.

            You will have to be able to turn a proper taper with the correct angle before you can use this method. Bear in mind that with the weight of the tail stock hanging on the taper, there's going to be some sag. When you're shimming, you would try to compensate for this.

            Some have suggested that the alignment of the tail stock is not all that critical. If it's close, then tooling such as a reamer can still self-center to a great enough degree that the problem you are having would not be there. Of course all this is assuming that this area of possible mis-alignment is what's causing your problem. It seems to me that it is, but there could be other factors.
            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

            Comment


            • #7
              Originally posted by darryl View Post
              It sounds like your tailstock is not aligned with the spindle axis-
              This cannot cause or have to do with runout when he is drilling holes.... that's the chuck, AND only when not finishing the part in one chucking.

              It MAY be a problem when the reamer is cutting on one side of ITSELF, but not if only one side of the hole is getting touched

              The hole might run out if the drill doesn't drill straight in, if it flexes or wanders off center.
              1601

              Keep eye on ball.
              Hashim Khan

              Comment


              • #8
                Chuck can run out a full inch, but when you drill a hole or machine a surface, that feature is true
                to the spindle axis. If your reamer is cutting only on one side, look at the tailstock.
                Swipe the quill with an indicator in a few places and map it. It might need even shimming,
                asymmetrical shimming, or set over adjustment.

                --Doozer
                DZER

                Comment


                • #9
                  Originally posted by kNucKlbustr View Post
                  When I chuck the reamer, I get the same runout, .0025". So I assume its not the reamer.
                  Ckd the tailstock alignment also.

                  Im outta solutions.
                  Between the reamer being less than straight and the tail stock being more than .0002" out of alignment it's not going to be easy.

                  A floating reamer holder will solve the reamer issue and the TS alignment issue to a degree.
                  I just need one more tool,just one!

                  Comment


                  • #10
                    Originally posted by wierdscience View Post
                    Between the reamer being less than straight and the tail stock being more than .0002" out of alignment it's not going to be easy.

                    A floating reamer holder will solve the reamer issue and the TS alignment issue to a degree.
                    Whats a floating reamer holder ?

                    Anything like when tapping holes, letting the drill chuck loose in tailstock and letting it power in itself ?
                    btw- the material used is soft

                    Comment


                    • #11
                      Agree that if the drilled hole is off center, the reamer won't make it centered. It would tend to cut one side of the hole, but also follow the hole. The result would be a larger than expected hole, probably slightly tapered. Good point.

                      That's another issue, that of getting a drill started well centered. Only by boring can you centralize an off-center hole- a reamer is unlikely to do it. But if the reamer could hold position like a boring bar, then the hole is going to be cut on one side only and will end up larger than the reamer. The reamer is acting like a boring bar in that case.

                      Anytime a reamer enters a hole which is not centered, the hole will be screwed.
                      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                      Comment


                      • #12
                        One thing that has changed in the last month is the chuck.
                        Was using a 3jaw 4" chuck w/ standard steel jaws.
                        This one is a 6" w/ those massive reversible Monster jaws and new back plate.
                        Before that, I cant recall this prob.

                        Ive tried reaming at the same end that was drilled also. Same prob.
                        Did alot of things before I came here.

                        Anyways, will go back re-ck everything again. Have to. It ships Mon.

                        Comment

                        Working...
                        X