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DIY bearings in 5hp motor idler RPC

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  • #46
    OH ! a computer fan.
    220v single phase would be the ticket

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    • #47
      Originally posted by metalmagpie View Post


      The bearings should be a light press fit onto the shaft and a tight
      slip fit in the end caps. If you find you need a shop press to push the bearings
      on you are doing something wrong.

      I don't want to take away from MM excellent posts above, but this is not correct. The bearings are tight to the shaft, and looser in at least one of the end bells. One or more of the end bells typically have a wave washer or other for maintaining pre-loading; it is the bearing that moves in the end bell to take up the expansion and contraction of the rotor. Some motor will have a medium press fit in ONE endbell, but the end with the wave washer is a very light fit. The bearing/endbell must be greased to allow for movement. The zerk fitting on most modern motors (not all) is so the end bell can be greased, not the sealed bearing.


      More:

      Pricking the interior end bell bearing mount surface is a "quick but dirty fix" on a motor (yep, done that). The bearing has to move and if you restrict it, problems can occur,. Always best to sleeve and bore it out if possible, but registration and tolerance are way tighter than you may think. Boring for a "tolerance sleeve" is often the easier and less demanding way. See here : http://www.usatolerancerings.com/ind...re-information I've repaired several buffers with damaged end bells this way.

      If you are repairing an end bell that has been beaten up by a loose bearing, you often have to put a spacer at the very bottom to take up some of the additional space created. If you don't the wave washer may not have the range to maintain preload resulting in noisy operation and reduced bearing life. After assembly run the motor and tap firmly with a soft hammer on the ends of the shaft until it runs quietly in about the middle of a small range. This to "set" the shaft bearing in the endbell so it is preloaded with a range; don't assume the rotor will find its "sweet spot" if it is crushed to one end or the other.
      Last edited by lakeside53; 07-30-2020, 11:56 AM.

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      • #48
        Originally posted by Ringo View Post
        the bolts all pass outside the center frame, so clocking is a non issue.
        some pics of what I got, with the bearings pulled off the shaft, there is corrosion on the inner side that I could not see before.
        you can see both sides bearings are sealed, and the grease zerk on the end bell
        Did you find the wave washer(s) in the rear endbell (typical)? Don't assemble without... and make sure the end bell bearing bores are clean. RPC's are prone to vibration in the best of times, so be sure the rotor is free to expand and supported axially by the wave washer.
        Last edited by lakeside53; 07-30-2020, 11:59 AM.

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        • #49
          Data sheet for 52100 steel (ball bearing steel)
          https://www.alphaknifesupply.com/Pic...DS-Latrobe.pdf

          Notice that tempering doesn't even begin until 400F, and at that point it should be ~63 hRc. Most likely this is what the bearing manufacturer does.

          So no, I'm not real worried about boiling oil. Key thing to remember is that generally the higher the alloy, the higher the tempering temp. Some alloys temper at over 1,000 F.

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          • #50
            Originally posted by nickel-city-fab View Post
            Data sheet for 52100 steel (ball bearing steel)
            https://www.alphaknifesupply.com/Pic...DS-Latrobe.pdf

            Notice that tempering doesn't even begin until 400F, and at that point it should be ~63 hRc. Most likely this is what the bearing manufacturer does.

            So no, I'm not real worried about boiling oil. Key thing to remember is that generally the higher the alloy, the higher the tempering temp. Some alloys temper at over 1,000 F.
            tempering the bearing steel is a non-issue.
            my question was about over cooking the lube in the sealed bearing

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            • #51
              deleted...i confused posts
              Last edited by Mcgyver; 07-30-2020, 06:46 PM.
              in Toronto Ontario - where are you?

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              • #52
                Originally posted by Ringo View Post

                tempering the bearing steel is a non-issue.
                my question was about over cooking the lube in the sealed bearing
                Yeah 400 would probably over cook the lube. Of course some oil would get in to replace it. On the bearings we did at work, it didn't matter because they had full flow oil systems with pumps. But mainly I was replying to some other posters fear of changing the temper.

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                • #53
                  it's over with now, pre-heated to 225 in a toaster oven and a piece of aluminum tubing and a light hammer,
                  all done

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                  • #54
                    tell me about the wiring in the peckker head.
                    There is 9 wires from the windings, all look like 16ga.
                    the 3 inputs look like 8ga. and they are very short length to work with.
                    if I replace the 3 inputs with longer pieces, do I still need to maintain 8ga? isn't 8ga overkill?
                    I asking because the fields wires look like 16ga.

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                    • #55
                      The windings may be lighter gauge because they can be connected in series or parallel for 480/240 VAC. The input wires need to be sized for the current at 240 VAC, so will typically need to be about 3 wire sizes larger. 5 HP at 240 VAC is 27 amps so #10 AWG would be adequate, but #8 AWG would be reasonable. Wire size also depends on the insulation temperature rating as well as how tightly multiple turns are packed in a small volume. Magnet wire may be rated as high as 180o C (class H) whereas equipment wiring is often 90o or 125o.

                      https://www.coonerwire.com/amp-chart/

                      https://mwswire.com/frequently-asked-questions/

                      https://mwswire.com/insulation-characteristics/

                      http://www.pyramidwire.com/Essex%20P...te%20paper.pdf

                      https://ekeindia.com/learning-tutori...ulation-class/
                      http://pauleschoen.com/pix/PM08_P76_P54.png
                      Paul , P S Technology, Inc. and MrTibbs
                      USA Maryland 21030

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                      • #56
                        ????
                        nameplate amps is 13.6 amps
                        where did you get 5hp at 27 amps?
                        I am not a degreed electrician, but the search I got showed 5hp and 12ga input wire
                        13.6 amps vs 27 amps, one of us is missing something ??

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                        • #57
                          The lower amperage is for a 3 phase motor. 27 amps would be right for a single phase motor.
                          Peter
                          Grantham, New Hampshire

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                          • #58
                            Yes, I miscalculated, multiplied by sqrt(3) when I should have divided. So theoretical current is 3750W / ( 240V * sqrt(3) ) = 9.02A. At 80% PF, 90% efficiency, and 1.25 SF that is 12.5 rated load amps (RLA) and 15.6 full load amps (FLA).

                            https://www.electricalcalculators.or...nt-calculator/
                            http://pauleschoen.com/pix/PM08_P76_P54.png
                            Paul , P S Technology, Inc. and MrTibbs
                            USA Maryland 21030

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                            • #59
                              Don't forget all the power you are going to get can only come from the single phase supply, no matter the motor configuration.

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                              • #60
                                Originally posted by Rich Carlstedt View Post
                                Hope you scratched a mark between the center housing and the Bell Caps on each end.
                                You want to return them to the SAME exact location/orientation when rebolted

                                Rich
                                Nope Doesn't matter.Only matter with brush alinement on a DC Motor.

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