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Jet spindle question

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  • dana_hague
    This is about the 1986 vintage JMD-15 mill I just acquired... Should there be a projection inside the spindle to keep a collet from rotating as it s being
    Message 1 of 4 , Jan 30, 2013
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      This is about the 1986 vintage JMD-15 mill I just acquired... Should there be a projection inside the spindle to keep a collet from rotating as it's being tightened? Reaching my finger up inside there seems to be a bit of a bump, but unlike the locating screw on a Bridgeport, the groove on collet doesn't clearly locate into this bump. In a Bridgeport, it's a replacable set screw, but I can't see any access from the outside, nor do I see it on the exploded parts diagram. So should something be there?
    • philr_77378
      I would say it s the remains of a set screw, that in my opinion should be removed and tossed away.   If you lower the quill a bit, is there a slot?  I don t
      Message 2 of 4 , Jan 30, 2013
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        I would say it's the remains of a set screw, that in my opinion should be removed and tossed away.   If you lower the quill a bit, is there a slot?  I don't have that exact model, but I can access that screw on mine through the quill slot if I orient the spindle by hand.  There may be two stacked together to lock the position on the dog pointed one. Remove the locking one, then turn the other one until it falls out through the spindle hole.   I don't use them myself, but others may want to replace it.
        Phil R

        From: dana_hague <d-m-hague@...>
        To: mill_drill@yahoogroups.com
        Sent: Wednesday, January 30, 2013 8:33 PM
        Subject: [mill_drill] Jet spindle question

         
        This is about the 1986 vintage JMD-15 mill I just acquired... Should there be a projection inside the spindle to keep a collet from rotating as it's being tightened? Reaching my finger up inside there seems to be a bit of a bump, but unlike the locating screw on a Bridgeport, the groove on collet doesn't clearly locate into this bump. In a Bridgeport, it's a replacable set screw, but I can't see any access from the outside, nor do I see it on the exploded parts diagram. So should something be there?



      • philr_77378
        The drawbar on these Chinese machines usually has rough threads, and is often not very straight.  If you have access to a lathe, chuck it up and smooth the
        Message 3 of 4 , Jan 30, 2013
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          The drawbar on these Chinese machines usually has rough threads, and is often not very straight.  If you have access to a lathe, chuck it up and smooth the threads with a triangle file. (observe usual safety precautions ets, etc.)
          If your collets are clean, and your drawbar works silky smooth, you should be able to push your collets up against the taper and tighten up easily by hand until the axial play is gone, then finish it up with the wrench.  I have seen long arguments on the bridgeport group regarding the merits or curses related to this screw in the spindle taper.  I am of the the opinion that it's useless for 99.9% of the work that is done on these machines.  
          Phil R


          From: dana_hague <d-m-hague@...>
          To: mill_drill@yahoogroups.com
          Sent: Wednesday, January 30, 2013 8:33 PM
          Subject: [mill_drill] Jet spindle question

           
          This is about the 1986 vintage JMD-15 mill I just acquired... Should there be a projection inside the spindle to keep a collet from rotating as it's being tightened? Reaching my finger up inside there seems to be a bit of a bump, but unlike the locating screw on a Bridgeport, the groove on collet doesn't clearly locate into this bump. In a Bridgeport, it's a replacable set screw, but I can't see any access from the outside, nor do I see it on the exploded parts diagram. So should something be there?



        • Dana Hague
          ... There is a slot in the quill, but no set screw visible through it as I rotate the spindle. Not sure what the slot is for, them. Perhaps it s under the
          Message 4 of 4 , Jan 31, 2013
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            At 10:39 PM 1/30/2013, philr_77378@... wrote:
             
            I would say it's the remains of a set screw, that in my opinion should be removed and tossed away.   If you lower the quill a bit, is there a slot?  I don't have that exact model, but I can access that screw on mine through the quill slot if I orient the spindle by hand.  There may be two stacked together to lock the position on the dog pointed one. Remove the locking one, then turn the other one until it falls out through the spindle hole.   I don't use them myself, but others may want to replace it.

            There is a slot in the quill, but no set screw visible through it as I rotate the spindle.  Not sure what the slot is for, them.  Perhaps it's under the lower clamp that holds the depth stop; I'll check that next.

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