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Broken motor shaft...Help!

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  • Broken motor shaft...Help!

    I had posted over in Yahoo Mill/dril but thought I might also ask here. I have a ZAY7045M mill/drill from Wholesale Tool. I have about 1-1/2 hrs on the spindle. Last night it malfuctioned. The while running but not cutting the spindle stopped turning but the motor continued to turn. I have some pictures if anyone is interested. When I removed the motor I found the shaft had sheared at the point where the final finish to diameter machining had ended. The surface of the shear has a fine roughness(like 400 grit paper). Other than the finish it looks like it had been parted off. Two things came to mind. The bore for the shaft is not centered with the machined mount for the motor. Measured and found about a .002" eccentricity. I dont know if that is enough to cause such a failure. Second, I wonder if the shaft was flawed.
    Any thoughts would certainly be appriciated.

  • #2
    Take a good look at the part line. If there is not a radius at that point that wiil explain a lot. Sharp corners are always a prime source point for fractures. take a look at an automotive crankshaft. You won't find a sharp corner anywhere on it. The amount of excentricity should not bee of concern if all it is. That's the big problem with these outfits. for most of them QC is something for the customer to worry about
    Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.


    • #3
      I once had a brand new Us motor do the same thing right out of the box the shaft broke off flush with the bearing. The shaft did have some radius in the corner however The sales rep said that they had a number of such failures and it was finaly attributed to poor metalurgy.They did replace the motor at no charge because the failure was with out a doubt their fault. You could also disassemble the unit weld on a new piece slightly larger than the original and remachine it for your bore size and bearing radius.

      [This message has been edited by wierdscience (edited 01-12-2003).]
      I just need one more tool,just one!


      • #4
        Call your salesman up or their service department. Tell them what went on, and ask how that they are going to fix it. If you are within a reasonable period of time, the company or it's reps will fix it for free. If you ask nicely, they may throw in some extras for your inconveience and not screaming and yelling at them.



        • #5
          Here is the latest,
          Don Garriot, Wholesale Tool's tech rep for these machines is on the Yahoo group. He jumped right on top of the issue and is working on getting me a replacement motor. The machining on the shaft looks to have left basically a square shoulder.
          More info as it comes available.
          Thanks for the help.


          • #6
            Well, Wholesale Tool is OK in my book. Don had a motor in the mail to me before lunch today. We still don't understand what happened to it.
            Thanks for everyone's help. More to follow.