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BT3 HELI-COIL Horror

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  • BT3 HELI-COIL Horror

    After experiencing the blade height stripped thread failure, I went thru the lengthy (& stressful) procedure of installing a heli-coil. I
    thought
    I had everything aligned in the drill press to drill & tap for the coil. Alas, when I installed the threaded shaft it did not "quite" line up with the hole in the bottom bracket. Off about 1/2 of the hole. I considered hogging out the bracket hole, but realized this would only misalign the shaft & motor assembly and jam up.
    Is my best solution to buy a NEW motor assembly?

    P.S Thanks to JohnG for his detailed description of the rebuild process.

  • #2
    The drill must not of stayed centered in the hole and cut out one side. The only thing I could think to do to salvage the motor would be to dig the helicoil out and make a new solid insert to fit in its place, install the insert, then drill and thread the new insert the proper thread. Iíd make the new insert out of a piece of fine thread bolt the appropriate size for the new hole.
    i much prefer to use a threaded insert which is a threaded solid piece of steel vrs a spring shaped insert like the helicoil. Threaded inserts use a standard size drill/tap vrs the weird sizes for a helicoil.

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    • #3
      Thanks capncarl. My hindsight gets better every year.
      What I ended up doing was leave the motor assembly in the saw, drilling out the coil (which was ugly), then re-drilling and tapping for a new coil. Probably not enough thread left to hold the coil for long but seems to work for now. When that fails, I'll try the threaded insert route.
      Thanks again for your input.

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      • #4
        Originally posted by Phil View Post
        What I ended up doing was leave the motor assembly in the saw, drilling out the coil (which was ugly), then re-drilling and tapping for a new coil. Probably not enough thread left to hold the coil for long but seems to work for now. When that fails, I'll try the threaded insert route.
        Your experience is fairly common for Heli-coils, one reason they are not considered a "permanent" repair. A solid insert like a Time-Sert works much better and is a permanent repair. Unfortunately the cost is higher.

        Watch for people parting out BT3's, you may be able to get a good used one for a reasonable price. Just make sure you get the right one, there were some variations in the part.

        --------------------------------------------------
        Electrical Engineer by day, Woodworker by night

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        • #5
          Yeah, I guess "permanent" always depends on how much stress is on it, and other factors like oxidation. I completely agree on his recommendation for Time-Sert kits. Just something to have around the shop if you work on metal stuff all the time, from motorcycles to tools to Jeeps. Something is going to break where it can help.

          That said, I've had Heli-coils stay in place "forever" in light-duty applications.

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          • #6
            Our local ďnut and boltĒ company, ( thatís about all they sold, along with some Makita tools) carried a good line of threaded inserts that didnít require special taps and drilling fixtures. That way you didnít have to buy a $70 kit to fix one messed up hole. Iíve lost touch with them, I think they have changed management, but suspect you could buy simular inserts at Fastenal or maybe Napa. I keep harping on the simular inserts because I used a wide variety of threads a nd the thought of having to buy the kit to get one hole repaired ran against my grain.

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            • #7
              Thanks for the input guys. When my coil fails, I'll go the threaded insert way.

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              • #8
                For what it's worth, I just found and ordered a new motor bracket and shaft from ereplacementparts.com. $9 for the shaft and $29 for the motor bracket. I'll post and let everyone know how they work when they get here and I get them installed. Motor Bracket Part Number: 4800031

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                • #9
                  IS the replacement motor bracket made of aluminum, I think the original is?
                  That's one reason the insert is better solution, A steel thread to work with vs a threaded aluminum hole; the steel thread has the possibility of lasting much longer.
                  remember the elevating rod is steel.
                  Loring in Katy, TX USA
                  If your only tool is a hammer, you tend to treat all problems as if they were nails.
                  BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

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                  • baumer64
                    baumer64 commented
                    Editing a comment
                    The posting just says made of metal. I'm sure it's the same as the original. I just figured the original lasted me for years so a replacement of the same should last me as well.

                • #10
                  Well the motor bracket showed up today and it was the wrong one. Maybe it was for the 13 amp? Anyway, I guess I'll be looking for a threaded insert now..

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