No announcement yet.

Help! Taper Troubles

  • Filter
  • Time
  • Show
Clear All
new posts

  • Help! Taper Troubles

    I recently decided to replace the worn out chuck on my 12" bench drill press with a new, keyless model. The new chuck, however, constantly gets loose and drops down (especially with "larger" drills including a 3/8" drill bit I was trying to use on a piece of mild steel plate this morning.)

    Taper on both is a J33. I examined (under a magnifying glass) both the spindle taper and the taper on the new chuck. Both are unmarred, smooth and when pressed together have no play. I've tried tapping (hard) the chuck unto the spindle with a rubber mallet and using the feed lever to press on the chuck held against a wooden block. (Although I'm told this is not good for the spindle or its bearings.) Neither fix worked.

    Is there some way to keep the new chuck from getting loose?

    Thanks to all for any help.

  • #2
    The taper may be be un marred on both the spindle and the chuck but for some reason there is not enough contact area between them to hold them tightly together.Are you sure one is not worn,or both.
    Being smooth does not mean they are compatibale and unworn.
    Are they both correctly compatibale tapers. I once heard about a guy who wrapped his chuck spindle with a fine piece of paper first but I am not sure if this will take up the slack .Sorry sounds like wear to me. Alistair
    Please excuse my typing as I have a form of parkinsons disease


    • #3
      if all else fails,freeze your chuck and lightly heat the spindle taper, then slam together


      • #4
        Check to see if the seating depth of the drill press taper is too long for the chuck.

        Clean both the tapers and the with a solvent such as alcohol, acetone, etc. to remove any oils or grease. Then give the chuck a good solid push into the drill press.

        [This message has been edited by fixxit (edited 12-06-2004).]


        • #5
          Er....Isn't that heat the chuck and freeze the spindle? Or is is feed a fever and starve a cold?

          I never could keep them straight.
          Jim H.


          • #6
            Forget freezing the spindle, just heat the chuck until it's almost too hot to handle by hand. Give it time for the inside of it to come to that temperature, then quickly spin it up onto the spindle and press down on the wood block. It would be best to chuck a short piece of rod first, or close the jaws all the way, so you're pressing the chuck straight onto the spindle. You don't want to be forcing it sideways as it goes on. As stated earlier, clean both mating surfaces well beforehand, and don't touch them after that.
            That has worked for me, and it has withstood the bit of milling I sometimes do on the drill press. Not in metals, of course, but wood and plastics.
            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


            • #7
              Many thanks to those who have responded.

              Here's some info tha my help clarify the problem.
              --I carefully cleaned both chuck and spindle each time I tried to mate them (with no change resulting.)
              --The drill press is less than two years old and has only had moderate use. It has had only one (the original keyed chucked) on it.
              --The keyless chuck is brand new and has no wear on it
              Bottom line: I doubt wear is a factor.
              --I checked both spindle and chuck to make sure there was enough room (lenghwise)for a tight fit.
              However, even though they seem to fit together tight, I wonder (after reading the comments) if the match is not even throughout the length of the taper? I will try wrapping the spindle in paper tomorrow and see what happens.

              The heat-the-chuck-solution sounds like it might work if it can be heated enough.

              Thanks again. Would welcome any other views or solutions.



              • #8
                On my benchtop drill press
                the instruc. said to open up the chuck jaws completely, then tap the chick assembly onto the shaft.


                • #9
                  Clean both surfaces and rub magic marker over the male taper. A quick twist should tell you if the tapers are in the ballpark of each other. You can use loctite if the tapers are close, but not perfect.

                  Or you can just heat the chuck and see if you have any more trouble.
                  Location: North Central Texas


                  • #10
                    it may be tough to twist the taper if it has a tang on the end. if it doesnt have a tang blackboard chalk is a much better indicator of taper contact. mark at 3 eqidistant places around the shank then insert and giveer a twist..jim


                    • #11
                      This is the approved procedure taught by the Jacobs rep at a class I took in 1978.

                      First ensure the spindle taper and the chuck socket fits properly and they are both smooth, clean, and dry. Next heat the chuck in a toaster oven to 350 F degrees (it will smell a little but this limited heat will not hurt the chuck or the temper of its materials. When the chuck is hot grip it in an oven mitt and hurry it to the drill press. Shove it tight on the taper and hold it for 20 seconds with a block of wood.

                      The chuck will shrink on the 33JT spindle taper with about 0.0012" interferance fit resulting in about 58,000 PSI hoop tension on the taper. No Lok-Tite required.


                      • #12
                        Thanks again to all for your help
                        Forest A: Much appreciate your detailed info on the procedure to heat and mount the chuck. (I'll see if I can find an oven mitt my wife won't miss.)



                        • #13
                          Had an eary(70's?) Japanese drill press in need of a better chuck, years ago. Looked like a J33 but not quite. Removed the spindle and turned the taper to J33. I used a MT2 to J33 adapter set up between centers, DI on center height to adjust compound to match. I don't know if there were any other machines like that out there but I would definately check taper fit first; as stated by others.


                          • #14
                            Use valve grinding compound on each part, work back & fourth like lapping a valve, until both peices show the light scratches where the compound & tapers are touching. Clean real good & try, we use this method for seating flywheel tapers on small engine used for racing & turning in excess of 9,000 RPM's with out a key, to alter the timing. This method works for us !!!