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  • Stuff Happens :(

    Just when you do not need it, it happens.

    Doing some drilling on the milling machine Monday night when the motor shaft sheared off about 0.250" above the casing. Along with it came the three step pulley. The machine is a Grizzly G1008 knee mill. After my heart settled down to a normal rate I started to inspect the damage. The shear was clean except for the center. The shaft that sheared off is also clean, except for the center. When I examined it closer I found that the shaft that sheared off was 0.7475" in diameter. The actual motor shaft is 0.9760" in diameter. The only explanation I have is that the motor shaft and pulley shaft were center drilled and an oversized pin inserted to join the two.

    Figuring there was nothing I could do with the stub coming out of the motor, I contacted Grizzly and talked at length with a technician. The bottom line is I ordered a new motor made by Emerson. One problem is that 56 frame motors all come with 5/8" output shafts. It came today and guess what? The one thing I did not check or ask about was the length of the output shaft. It is to short. The new shaft is 1.750" long and I need 3" to even get to the set screw on the pulley.

    I need HELP, either with the old motor or the new one.

    Fred

  • #2
    Fred,
    I do a *lot* motor repairs for a living.
    Just got to pop out at the moment, give me a while and I'll get back to you.
    This one shouldn't be a problem.

    John S.
    .

    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



    Comment


    • #3
      Among the many ideas I have in reserve for the proper time is: Someday, When a shaft is damaged beyond use, Press the old shaft out of the armature and press another in. Never tried it so There may be reasons I am never going to do it. Might not work, but nothing to lose.

      Once had a armature on a 1 HP motor slip and spin on the shaft. Men pressed the lamination off the shaft, put some Knurling and punch marks and "super glue" on the shaft. Corrected the problem- motor was still in use years later (replacement was on hand should it ever fail).
      At the time, I was working for Govt- supply man said I had to get rid of the motor because it had been on the shelf too long. They put it in writing so I replied in writing. Asked if I should spend money replacing the old (known defective motor) with the new motor (and hope to get past "infant mortality" of the new motor. Or should I continue to run the old and send the brand new motor to salvage? I enclosed copies of the work order from years earlier saying how vital it was to get the machine up and running, It was only machine capable of doing the job . Told them that until i got advice in writing from their "cost center manager" (MY peer) I was holding all action in abeyance. I guess I could have taken the motor with me when I quit working.

      Maybe you could try pressing off, and let me know how it comes out? cheaper than a new motor.
      Steve

      Comment


      • #4
        I would take the shaft out of the original motor and carefully remove the centrifugal switch,then press the shaft out and make a new one.

        Don't feel like the lone ranger on this one,I have seen the same thing on three different motors,last one was a Baldor,it was a defect in mfg,the bearing shoulder did not have a radius,it failed at that point leaving the shaft sticking through the bearing and end bell.
        I just need one more tool,just one!

        Comment


        • #5
          Why not just use/make a motor arbor. Don't you have to link the 5/8" shaft to the 3/4" pully anyway?

          Comment


          • #6
            Fred,
            Two ways to do this.
            One is to press the shaft out and make a new shaft or stub it.
            If you are pressing you will need a decent press, probaby about 15 tons to get it moving and less to push it out.
            Measure the shaft both sides of the rotor as some have slight tapers on hem. if ou lok carefully you can see by distorsion marks on the rotor laminations which way it was pressed in and you need to go the opposite way.
            It goes without saying you need a good sketch of the relative positions of bearing diameters from rotor face etc.
            The new shaft is obviously copy of the old one. They usualy have a straight knurl to grip the rotor. Cold rolled is fine for material.

            If you are stubbing you need to hold the rotor in the lathe and a steady on the bearing diameter and drill and bore to accept the stub.
            Make the stub a nice slide in fit right up the the shoulder and then riase the surface of the shaft about 8 to 10 thou with straight knurl in two or three bands.
            Use hight strengh loctite retainer and press the new shaft in.

            Here's some photo's of a 4 HP DC fork truck motor being done.

            http://homepage.ntlworld.com/stevens...0armature1.jpg

            http://homepage.ntlworld.com/stevens...0armature2.jpg

            http://homepage.ntlworld.com/stevens...0armature3.jpg

            http://homepage.ntlworld.com/stevens...0armature4.jpg

            http://homepage.ntlworld.com/stevens...0armature5.jpg

            Let us al know how you get on.

            John S.
            .

            Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



            Comment


            • #7
              Nice work, John.
              What make/model lift truck did that motor come out of?
              Is it a - traction motor/hydraulic pump motor/ steering motor?

              How in the world would the operator manage to break one of those? (one of the few things I actually haven't seen broken by lift truck drivers)

              Comment


              • #8
                Holy Smokes John, when did you clean the bench?
                Jim
                Jim

                Comment


                • #9
                  Are the Loctite and the knurl all that hold the new shaft in place? I see the milled recess in the original shaft, but it doesn't look like it gets used.

                  Roger
                  Any products mentioned in my posts have been endorsed by their manufacturer.

                  Comment


                  • #10
                    Jaymo,
                    I have no idea on make of truck or it's type.
                    I'm guessing it's a traction motor by the type of shaft.
                    Hydraulic drive motors tend to have either a slot in the end for a coupling or internal splined like:-

                    http://homepage.ntlworld.com/stevens...es/spline1.jpg

                    http://homepage.ntlworld.com/stevens...es/spline5.jpg

                    I only do the repair work for some rewind companies and it's rare for me to get the whole motor, I usually only get the parts that need reworking.

                    Shaque,
                    Naw, I just slid everything to the side

                    Winchman,
                    Yes thats all that holds it. I've been doing these now for more years than I care to remember and never had one come loose.
                    The keyway you see is for the alloy cooling fan to fit.
                    In fact one job I do are some motors that go into plating plants. The stuff they pump, something thats like ammonia, is that corrosive the only things it won't eat is some plastic and titanium.
                    The pump is all ABS plastic and the shaft is stubbed with a titanium shaft.
                    Motor is a standard 3 phase motor about 3HP. This lasts about 9 months to a year and then the fumes eat the case away and rust the bearings up.
                    They keep spare motors and can swap rotors and fit new bearings but every so often due to the motor suppliers changing design the rotors can't swap over so we take the titanium shaft from the old one and fit it to the new one.
                    Some of these shafts have had possibly 8 or 10 'owners'

                    The shaft in a normal motor is only press fitted or shrunk on in manufacture or has a straight knurl.
                    It's only when you get up to the 15 HP mark they sometimes start fitting keys.
                    Here's a 35 HP rotor shaft that has two semi circular grooves to take two round keys but it's still a press fit.
                    http://homepage.ntlworld.com/stevens...g%20shaft2.jpg

                    John S.

                    [This message has been edited by John Stevenson (edited 05-13-2004).]
                    .

                    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                    Comment


                    • #11
                      What do you use to make those internal splines?
                      David from jax
                      A serious accident is one that money can't fix.

                      Comment


                      • #12
                        <font face="Verdana, Arial" size="2">Originally posted by sandman2234:
                        What do you use to make those internal splines?
                        David from jax
                        </font>
                        Shaper or broach.

                        Comment


                        • #13
                          Fred,

                          I would call Grizzly back and see if they can help you with a motor that will be a direct replacement. I know that you're anxious to get the milling machine working again but sometimes it's better to wait and get the proper part than to improvise a solution. Also if you modify the motor, you'll forfeit the warranty from Emerson.

                          Comment


                          • #14
                            David,
                            I use a vertical slotting machine AKA "the nodding donkey"

                            http://homepage.ntlworld.com/stevens...es/spline3.jpg

                            I have used a shaper but the problem with a shaper is you are always working blind, especially if it's a closed hole.

                            John S.

                            [This message has been edited by John Stevenson (edited 05-13-2004).]
                            .

                            Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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