Fire up the parts cannon, we're grubbing for a root! The slow death of this harbor freight impact wrench is a novel one. Looks like the heat cycling during use causes the armature to slowly fail. High resistance brush/commutator connection speeds up the process.

By AvvE

17 thoughts on “Mystery solved! why impacts get weaker”
  1. Avataaar/Circle Created with python_avatars Charles Hultquist says:

    the guts of the motor also contained a bearing….could that have at least been partly to blame?

  2. Avataaar/Circle Created with python_avatars Sejdini Service Ripair Electric Tools says:

    😬

  3. Avataaar/Circle Created with python_avatars Chuck James says:

    Maybe that's why they use a different manufacturer now.

  4. Avataaar/Circle Created with python_avatars S Bayko says:

    On a 2 brush setup this motor wont even turn unless you jumpstart it.
    Because its a 4 brush setup, it start but at least 2 winding dont participate.

    I have had couple of hitachi die from that the windings internally short out.

  5. Avataaar/Circle Created with python_avatars tomdickharryjane says:

    "Mystery Solved! | Why Impacts get weaker"
    And if it's not broke, I can fix that.
    And it is not the rotor that gets weak. Technically it is the armature. Rotor=AC, armature=DC.
    And as others have said, what is the winding to winding resistance? Higher? Lower? Compare next time please. Inquiring minds and all that.

  6. Avataaar/Circle Created with python_avatars John Galt says:

    Dude thanks for keeping it real and not selling yourself and content to these fucking corporate leeches. Love it man

  7. Avataaar/Circle Created with python_avatars MadelnOahu says:

    Something to admire is that this guy goes through the trouble of actually changing one part at time to have proof of whats the failure

  8. Avataaar/Circle Created with python_avatars Auto Hut says:

    You can shim the back of the brush to get enough pressure on so you don’t have to buy new ones.

  9. Avataaar/Circle Created with python_avatars Joel Garcia says:

    Thanks for doing a follow up to the original video

  10. Avataaar/Circle Created with python_avatars Big John says:

    Gotta like this kind of dedication.

  11. Avataaar/Circle Created with python_avatars Justin H says:

    It could be the bearings as well as armature resistance. Idk they put never sneeze in it so they could be gummed up.

  12. Avataaar/Circle Created with python_avatars Jeep Guy says:

    So can anyone weigh in on the overall chooch of this gun? I've had one for about five years and only use it for swapping snow tires on and off three vehicles. The speed is fine, and batter life is good (only 24 tires a year), but the torque is underwhelming on snug lugs. I usually break the nuts with a bar first, then use the gun. I don't see the tire shop guys having to do this with airguns. Is this normal for battery powered nut smackers, or is mine maybe weakling? I don't feel any wrist straining torque under load either. But I've only ever used this particular nut smacker.

  13. Avataaar/Circle Created with python_avatars Hrvoje Leko says:

    Bearings?

  14. Avataaar/Circle Created with python_avatars Bannik254 says:

    I don't see any winding damage, wire insulation looks intact on the outside.

    I'd be curious to know what the megohmmeter reads, test the winding insulation. Do a 500vdc test, clamp one lead to the shaft and touch the other lead on the comm, see if there's any grounding.
    When you have a loss of torque, that means one or more of the magnetic fields is weakening. Insulation is a prime suspect.
    Another thing to troubleshoot, Armature windings(lamination stack) need to be lined up with the stator(field) coils(magnets), if they are misaligned you will lose torque, a lot of torque.

    A lot of power tool companies won't DPI, Epoxy or Varnish dip their windings due to manufacturing costs, it would save their motors from vibration-induced damage. They also tend to use as small of a gauge of copper wire as they can get away with, which means very little tolerance for electrical surges and overheating, which will break down insulation over time and cause grounding/shorts.

    There are a great many things that go wrong on small cheap motors, junk is never worth repairing. Cheaper to simply replace than rewinding something so cheap.

    “Industrial motor mechanic and rewinder“

  15. Avataaar/Circle Created with python_avatars Archy Banks says:

    Love the commentary and you save me a bundle on my car insurance.

  16. Avataaar/Circle Created with python_avatars TehKaiser says:

    Every battery-powered tool is at risk for this type of failure. The car starter is just super-guzzling electric motor and they often fail this way. Lower voltage can cause an increase in amperage and thus could result in gradual heat damage.

  17. Avataaar/Circle Created with python_avatars Aleksandar Krstić says:

    You rewind the damn thinglidadli

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