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Thread: maybe bad MT

  1. #1
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    maybe bad MT

    Pictured below is the mandrel I use for pens on those rare occasions when I use a mandrel. It is one of the 'professional' adjustable styles. Lately, when using it, I cannot remove by tapping from behind. In fact, some hard whacking won't budge it. I have to lock the indexer and turn the MT with a wrench to bust loose. Not a happy thing to do to my lathe.
    I acquired this thing used and suspect it got spun at some point, or two, or twenty.
    Wadda y'all think, should I try to just clean it up with sandpaper or something, or is it toast? I'm leaning towards toast.
    Attached Thumbnails Attached Thumbnails mandrel.jpg  

  2. #2
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    Frank, cleaning it would be my first thought. Also cleaning the spindle interior as well. Sometimes gunk can seize things...
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  3. #3
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    Frank,

    I think taking some coarse emery cloth strips to the mandrel first to clean it up and then going finer and finer to polish it up. Cheaper than replacing it right away.

    My greater concern would be with the lathe collet, the interior surface might have been marred by the mandrel. Take a close look with a flashlight or, if you have one, a pistol/rifle bore light. It might need to be lightly reamed if the surface has been damaged.

    Cheers.
    Dan Gonzales
    Whittier, CA, USA
    Dona nobis pacem

  4. #4
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    i say yu need to go to flat work and drop this spinny stuff, and this is just the first hint frank i would also sand it morse tapers are made to fit all the way around and once yu clean it some it should regroup itself and fit nice agian..
    If in Doubt, Build it Stout!
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  5. #5
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    Quote Originally Posted by Jeff Bower View Post
    Frank, cleaning it would be my first thought. Also cleaning the spindle interior as well. Sometimes gunk can seize things...
    Did that to both. What you are seeing IS the cleaned MT.

  6. #6
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    Quote Originally Posted by larry merlau View Post
    i say yu need to go to flat work and drop this spinny stuff, and this is just the first hint frank i would also sand it morse tapers are made to fit all the way around and once yu clean it some it should regroup itself and fit nice agian..
    Will try. thanks.

  7. #7
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    Not what you want to hear, but it sure looks galled to me, and you say you had to use a wrench to break it loose only confirms my suspicions. Morris tapers work by friction and rely on a perfect fit to the taper. there's no way you'll fix it with sanding, you just can't hold a perfect angle on both pieces which you'd need to fix it right.

    Bite the bullet and pick up a new mandrel and MT2 finish reamer. It's much easier to fix the damage now with a finish reamer before it gets too severe.

    Mike

  8. #8
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    Mike, the inside of the MT on my lathe is OK. I checked with my pinky last night. But, I agree, the galling is bad news for the lathe if I keep using it. My first instincts are probably safest way to go. Bad toast. Will get tossed and I'll buy another.
    BTW, since I acquired this used, fergit where, probably a trade with someone here, I don't know the make. But, I'm sure the steel is softer than what my lathe spindle is made of and that is what prevented damage.

  9. #9
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    Quote Originally Posted by Frank Fusco View Post
    Mike, the inside of the MT on my lathe is OK. I checked with my pinky last night. But, I agree, the galling is bad news for the lathe if I keep using it. My first instincts are probably safest way to go. Bad toast. Will get tossed and I'll buy another.
    BTW, since I acquired this used, fergit where, probably a trade with someone here, I don't know the make. But, I'm sure the steel is softer than what my lathe spindle is made of and that is what prevented damage.
    Frank, I have successfully dressed the morse Taper on spindles before with the following procedure:

    Chuck the spindle in something, (lathe or DP)
    make a sanding block by wrapping (or gluing) a piece of Good quality emery cloth tight around a short flat block of wood, then with the spindle turning, press the sanding block "FLAT" against the taper and slide it back & forth about a 1/4" along the taper to keep from getting any grooves as it turns. Graduate to finer grits until you get the degree of polish you want.

    I have also fitted and glued a fine grit emery cloth around a spindle to clean the taper inside a collet as it turned.

    The secret on the spindle is keeping even pressure on the sanding block so it remains FLAT against the full length of the taper, which isn't hard to do.

    I would give it a try if I were you.

  10. #10
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    Quote Originally Posted by Norman Hitt View Post
    Frank, I have successfully dressed the morse Taper on spindles before with the following procedure:

    Chuck the spindle in something, (lathe or DP)
    make a sanding block by wrapping (or gluing) a piece of Good quality emery cloth tight around a short flat block of wood, then with the spindle turning, press the sanding block "FLAT" against the taper and slide it back & forth about a 1/4" along the taper to keep from getting any grooves as it turns. Graduate to finer grits until you get the degree of polish you want.

    I have also fitted and glued a fine grit emery cloth around a spindle to clean the taper inside a collet as it turned.

    The secret on the spindle is keeping even pressure on the sanding block so it remains FLAT against the full length of the taper, which isn't hard to do.

    I would give it a try if I were you.

    Thanks. Really nothing to lose. Will try.

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