I have a Craftsman 137.248760 table saw that has recently started giving me problems. When I run the saw, the blade appears to loosen and continues to spin freely on the arbor after I turn the saw off. I've tried tightening the nut back down and replacing the blade but it immediately loosens. It hasn't completely come off the arbor yet but I'm afraid it will.

Any ideas how I can make this stop happening?


If the blade is spinning, but the nut remains secure add a washer between the blade and nut. If the nut is loosening look at it's threads for evidence of cross-threading; it may be stripped. If so apply a thread-locking fluid and snug it tight. Check that the blade opening is the correct size for the arbor (I'm sure it is but...) and that the blade doesn't have a knock-out bushing that has come detached.

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  • The nut is loosening at the same time so I'll try the thread-locking fluid. I don't have the wrench I need to hold the arbor in place while I tighten down the nut so I've just been bracing a block of wood against the blade. Maybe it's not tightening down as much as it needs to. – Evan Aug 26 '15 at 12:13
  • There isn't a knock-out bushing that I can see and I don't see anything about it in the manual. Should there be one or is that just something that saws occasionally have? – Evan Aug 26 '15 at 13:16
  • some blades (the sizes under 10 inches) have a diamond shaped knock-out. Table saws not usually. – ojait Aug 26 '15 at 15:04
  • If the problem started after you installed a new blade make sure the blade isn't thinner than usual. If it is than maybe the nut isn't snugging up to the blade. If ,for some reason, the rotation of the motor was reversed (not likely) it would loosen the nut. – ojait Aug 26 '15 at 15:09
  • Try installing a garden hose washer (or an "O"-ring) in between the arbor nut and the blade. Most arbors are 5/8 inches. The rubber compressed against the nut face will add surface friction to oppose the nut trying to spin loose. – ojait Aug 26 '15 at 15:13

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