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Long story short,not a rant but, RATS-ele-motors

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  • Long story short,not a rant but, RATS-ele-motors

    Purchased online a capacitor start 3 hp induction motor.
    Ordered: 220v
    2 pole
    cap start
    cw rotation
    18 amp-3600 rpm
    Purchased price $675
    This is for a brick chop saw. Installed to machine and attached the 2 driven sheaves to shaft. Here's the "rats part" they sent me a ccw motor.
    Called the supplier- no return on what they called used motors. They would not restock due to the impressions left by the sheaves set screws and that the motor was purchased 3 months prior to date.

    Ok, now to get inside the motor and do a bit of restructuring.
    The only external wiring is the 2 leads for L1 and L2. Everything else is hard
    wired internally.

    My past experience, 40 years ago, studied the Devry method of electronics,
    DC and AC. Time takes its toll but I recall to reverse direction I must flip
    start windings,cap and centi-switch.

    Anyone have any tips, advice, what to watch for, what type of solder and
    such?


    -------------------------

    Part 2:

    I also need to reverse the direction of 2 universal motors such as those used in a circular saw and that of a 9" disc grinder.
    Typical types include, Dewalt, Skill, Makita.

    Any advice would be appreaciated as the above? What would be the best
    manuf. type to use? Any comments or snags and what to watch fors.

    Purpose for for reversals are for specific types of slitting operations.

    Anyone done anything similiar?
    Thanks,
    Patch
    Last edited by Patch; 04-24-2012, 02:12 PM.

  • #2
    On the induction motor, follow L1 and L2 into the motor. At some point each will Y into the start and run windings. That point might or might not be visible. Either winding needs to reversed to change motor rotation. An ohm meter will tell you which wires are common to a given winding( short the cap. terminals temporarily) once the splice point is opened up and the wires isolated. Simply reverse one winding and you should be go to go. Make sure the fan is bidirectional.

    Swap the brush wires to reverse the universal motors. The fan will reverse and this may not cool the motor sufficiently. Also the brush position is designed for best running in the original direction. Reversing will likely cause a lot of brush sparking and commutator burning. Power will be down a bit as well.

    RWO

    Comment


    • #3
      On reversing the universal motors- check to see whether the brush angle is straight-on to the commutator. They usually are, but if they aren't you will never get them to work right.

      If they are, then when you reverse the rotation the brushes will have to seat to the comm again. I would help them to begin with by sanding the profile. You would take a strip of fine paper, say 400 grit or so, wrap it around the comm where is passes under the brushes, then pull it through in the direction in which you want the motor to turn. The grit side is out so that the brush will get contoured- keep the sandpaper tight to the comm where is passes under the brush so the correct contour gets impressed into the brush. You will likely have to do each one separately so things don't get mucked up.

      This prepares the brushes to ride on the comm in the preferred direction. They will still have to seat in with some running time. I find it best to run the motor at slower speeds, unloaded, and at a few different speeds during this time. The comm will get carboned up as well, and I like to sand it clean at least once as a part of this run-in procedure. Use the same fine grip paper, wrapped around the comm as a belt, and turn the armature by hand. Don't use too much pressure as you don't want to distort the (hopefully) perfectly round and concentric shape of the comm.

      I like to 'wear out' a strip of sandpaper before I even touch the comm with it. I usually just clamp a bit of pipe or some scrap in the vise, then pull the paper across it in both directions to knock off all the high spots and remove particles that might be ready to fall off already. This is an important step as you don't want any abrasive particles to lodge in the copper segments, nor between the segments. After you have cleaned between the segments, spin the armature around in both directions with the band of sandpaper around it to knock off any burring which you might have raised when dragging a tool between the segments.

      This will go a long way towards enhancing the seating of the brushes, and the lifetime of them.
      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

      Comment


      • #4
        If you can make the shaft stick out of the other end of the stator by trading end bells you will have reversed the rotation.

        Dave

        Comment


        • #5
          Originally posted by Patch
          Purchased online a capacitor start 3 hp induction motor.
          Ordered: 220v
          2 pole
          cap start
          cw rotation
          18 amp-3600 rpm
          Purchased price $675

          Patch
          Jesus H Christ was it gold plated ?
          .

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



          Comment


          • #6
            I just reversed a "non-reversible" induction motor last week. (Compressor project). As stated, simply reversing either the start or run windings should do the trick.

            One confusing issue I ran into was that there were what appeared to be not an even number of leads (2 for each winding) but an odd number. I had to carefully free up and pull out enough of the leads to discover that there was a jumper between a pair of (parallel connected) windings. This gave the appearance of an extra connection point that was really just a duplicate as far as the circuit was concerned.

            When I've done this before I've often found it convenient to re-fastened the windings with zap-ties, rather than fiddling with anything like the original binding twine.
            "A machinist's (WHAP!) best friend (WHAP! WHAP!) is his hammer. (WHAP!)" - Fred Tanner, foreman, Lunenburg Foundry and Engineering machine shop, circa 1979

            Comment


            • #7
              Originally posted by RWO
              On the induction motor, follow L1 and L2 into the motor. At some point each will Y into the start and run windings. That point might or might not be visible. Either winding needs to reversed to change motor rotation. An ohm meter will tell you which wires are common to a given winding( short the cap. terminals temporarily) once the splice point is opened up and the wires isolated. Simply reverse one winding and you should be go to go. Make sure the fan is bidirectional.

              Thanks RWO,
              I thought I was thinking right to that respect


              Swap the brush wires to reverse the universal motors. The fan will reverse and this may not cool the motor sufficiently. Also the brush position is designed for best running in the original direction. Reversing will likely cause a lot of brush sparking and commutator burning. Power will be down a bit as well.

              Well, I had a chance to open up one of the saws. There is enough room to invert the fan, also, the brush locations are perpendic
              to the comm.
              Looking at it, it appears to be a reasonably easy swap of the brush wires given a little length to the wiring.
              Thanks for your help.

              RWO

              Originally posted by darryl
              On reversing the universal motors- check to see whether the brush angle is straight-on to the commutator. They usually are, but if they aren't you will never get them to work right.

              yae, they are at 180 deg. and perpendic to comm

              If they are, then when you reverse the rotation the brushes will have to seat to the comm again. I would help them to begin with by sanding the profile. You would take a strip of fine paper, say 400 grit or so, wrap it around the comm where is passes under the brushes, then pull it through in the direction in which you want the motor to turn. The grit side is out so that the brush will get contoured- keep the sandpaper tight to the comm where is passes under the brush so the correct contour gets impressed into the brush. You will likely have to do each one separately so things don't get mucked up.

              This prepares the brushes to ride on the comm in the preferred direction. They will still have to seat in with some running time. I find it best to run the motor at slower speeds, unloaded, and at a few different speeds during this time. The comm will get carboned up as well, and I like to sand it clean at least once as a part of this run-in procedure. Use the same fine grip paper, wrapped around the comm as a belt, and turn the armature by hand. Don't use too much pressure as you don't want to distort the (hopefully) perfectly round and concentric shape of the comm.

              I like to 'wear out' a strip of sandpaper before I even touch the comm with it. I usually just clamp a bit of pipe or some scrap in the vise, then pull the paper across it in both directions to knock off all the high spots and remove particles that might be ready to fall off already. This is an important step as you don't want any abrasive particles to lodge in the copper segments, nor between the segments. After you have cleaned between the segments, spin the armature around in both directions with the band of sandpaper around it to knock off any burring which you might have raised when dragging a tool between the segments.

              Very good advice darryl. The comm. is somewhat charred now; cleaning it up with the sandpaper should do a good job of it.
              Thanks,



              This will go a long way towards enhancing the seating of the brushes, and the lifetime of them.

              Originally posted by becksmachine
              If you can make the shaft stick out of the other end of the stator by trading end bells you will have reversed the rotation.

              Dave, I wish it were as simple as that. There is no stub shaft protruding from the other side. I did for a bit think about adding additional length to the shaft tho. I think my best shot at this is going to be with the internal wiring. Good idea to keep in mind for the next big project.
              Originally posted by John Stevenson
              Jesus H Christ was it gold plated ?

              You would think so. This is 2012, not 1950. With the crap economy we've been in lately everything has gone nuts pricewise.
              What was a good price in the past is now I better think about it twice.

              Anyway, in todays market I think I did pretty good paying what I did for the
              new motor.

              I added a few links to show what others are charging for the exact same motor.
              http://www.grainger.com/Grainger/DAY...of-Motor-4K814

              http://www.drillspot.com/products/13...ripproof_Motor

              http://www.bargainmarge.com/servlet/...t-motor/Detail

              My next post will entail a bit more re: the resaons for the saw/universal motor reversal.

              Thanks guys,

              Patch

              Comment


              • #8
                Originally posted by John Stevenson
                Jesus H Christ was it gold plated ?
                No kidding......

                But, motors seem to be attracted to me...... I have to turn them down..... I have too many right now, single and three phase, from a 5 HP single phase on down to a couple 1/25 HP PSC. If I have $100 in the lot of them, I'd be shocked.

                Grainger is high...... you are paying for them having it in stock when you just gotta have it now to fix the essential machine that is "down" and losing you money.
                Last edited by J Tiers; 04-25-2012, 01:06 AM.
                1601

                Keep eye on ball.
                Hashim Khan

                Comment


                • #9
                  Over the years this is the cutter I purchase for the guys.

                  http://www.southstarsupply.com/catal...roducts_id=674

                  We use them in the final floor finishing of the homes we build. They make quick and straight cuts in heavy carpet and vinyl. Sometimes, (often) several
                  layers at once. What is nice too is they relieve a lot of hand stress, recuts and fatigue.

                  What prompts the investigation of the circular saw and disc grinder is this.
                  Over the last several years we've had three of the cutters grow legs never to be seen again from the job sites.
                  We've hashed several ideas, one being retrofitting a circular saw and grinder.

                  In the shop I have two full size pallet crates filled with dozens of damaged
                  circular saws, sawzalls,grinders,nailguns, anchor guns, decking screw guns,
                  chainsaws, drill motors, staple guns,and the list goes on.
                  Each has been damaged due to age, dropping and breaking a handle, sole plates bent, line cords cut or pulled from the unit, too many reasons to give.

                  The plan is to see if some of the saws can be refitted with a new shoe similiar to Wolf. We think it can be done with little effort.

                  Problems with the wolf. They are great to use, you just need to hold your tongue the right way. What I mean is this. The only problem they have is with the shoe. Without a problem cutting fabrics and such but, when cutting
                  on an irregular floor surface, power trowled certainly, and wood subfloors, is hitting a bump in the road or a wood floor jointing seam. The front of the cutter shoe needs to be raised to override the obstacle. Another problem
                  is, especially on concrete, the excessive shoe wear.

                  Our thoughts are to include a leading roller made of delrin to the new shoe.

                  The reversal of the motor direction is criticle to the full operation of using a
                  circular saw or grinder for this retrofit.


                  So, there you have it. Any ideas pop into your minds that may help now that you know its intended purpose?

                  Thanks much for all the help.

                  Patch

                  Comment


                  • #10
                    Update:

                    Success to both endevours.

                    mickeyf:
                    Thanks for the tip, I did use a few of the ties.



                    Good help guys,
                    Patch

                    Comment

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