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Is my lathe possessed???

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  • Is my lathe possessed???

    OK, I've learned a little more. Thanks to Dave, I found out that the lead screw handle on the apron controls the forward/reverse of the spindle and lead screw (there is a reverse knob also that only reverses the lead screw it appears).

    If I try to start the lathe with the handle in neutral the spindle turns for about 3 seconds and shuts down. Is this normal?

    I can then lift the handle to reverse the spindle, and everything runs fine, back to neutral no problems, emergency stop but not problems shutting down.

    If I lower the handle from neutral to forward after the spindle has stopped it runs in the forward direction. If I switch to neutral it continues to run. If I hit the emergency stop button it continues to run. At first I thought the contacts were stuck on the relay. Then I realized that after a while whether it was running or unplugged that the relay would release itself. The only thing I can figure is it is somehow "bleeding" voltage back off of the start capacitor on the motor or somewhere else. It does it every time, the longer I run it in forward the longer it takes for the relay to drop out, but it does reach a maximum time. The only way to stop it is to unplug it. NOT A SAFE CONDITION!

    I need to find where the voltage is bleeding back from.

    thanks,
    Ken

  • #2
    Sounds to me like the relay is mechanically sluggish. I don't think a delay time is anything that would be built-in to an E-stop. If there's another component in the system that controls the energizing of the relay, they look there too- it could be sluggish.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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    • #3
      "If I switch to neutral it continues to run."

      this is probably to much play in the linkage. if you move the lever a bit further, it stops, right?

      Comment


      • #4
        Originally posted by darryl
        Sounds to me like the relay is mechanically sluggish. I don't think a delay time is anything that would be built-in to an E-stop. If there's another component in the system that controls the energizing of the relay, they look there too- it could be sluggish.
        Darryl:

        If I switch from neutral to forward for a few seconds, then back to neutral it continues to run for a few seconds, before stopping. If I switch back to forward for about a minute, then back to neutral it will continue to run for about a minute, before stopping. It does it everytime.

        Same thing with the E-stop, the longer it runs in forward the longer it will run after the E-stop is pushed.

        thanks,
        Ken

        Comment


        • #5
          Originally posted by dian
          "If I switch to neutral it continues to run."

          this is probably to much play in the linkage. if you move the lever a bit further, it stops, right?
          Dian:

          This wouldn't explain the E-stop button not shutting down properly.

          thanks,
          Ken

          Comment


          • #6
            You should find a schematic, or, trace out the machine and draw your own.

            It might have been "messed with".
            Last edited by lakeside53; 04-24-2012, 10:14 PM.

            Comment


            • #7
              Originally posted by customcutter
              Darryl:

              If I switch from neutral to forward for a few seconds, then back to neutral it continues to run for a few seconds, before stopping. If I switch back to forward for about a minute, then back to neutral it will continue to run for about a minute, before stopping. It does it everytime.

              Same thing with the E-stop, the longer it runs in forward the longer it will run after the E-stop is pushed.

              thanks,
              Ken
              I couldn't help myself so this AM as I was walking out the garage I played with the lathe to see what kind of curve ball it would throw at me today.

              Released the E-stop, turned on the power switch, pushed the run button. She started up and ran about 3-5 seconds, then stopped like it's been doing. Still don't know if this is normal though.

              Moved the lead screw lever down for forward, it ran in forward. After a few seconds, I switched back to neutral, it kept running for about 5 seconds and stopped.

              Moved the lead screw lever up for reverse, and it ran in reverse. Switched back to neutral and it immediately stopped.

              Moved the lead screw lever down again for forward and ran for 60 seconds. Switched back to neutral, it ran for over 5 minutes. I hit the E-stop button, after another 5 minutes I unplugged the machine.

              I think Darryl is right the relay is "sluggish" or sticking, or possibly the switch activating it from the apron is sticking. I think I'll pull the 24v power from the relay and see if it shuts down immediately or hesitates.

              thanks,
              Ken

              Comment


              • #8
                Hi customcutter,
                Your circuit is probably a 24V supply from a Transformer that feeds through the Emergency Stop Button to a Camswitch that is connected to your Forward/Reverse Lever, there would be 2 x NO Contacts on the Camswitch that feed to two Contactors/Relays that are Interlocked that feed Power to your Motor.
                Your problem could be that the Contactors/Relays are sticking due to Arcing on the Main Contacts, these may be able to be cleaned but best to replace the Contactors/Relays.
                Without having a copy of your circuit or pictures of the circuit it is only a guess at what are your problems.
                Regards,
                Keith.

                Comment


                • #9
                  I disagree....

                  with all your experts here, it's clear that your machine is in fact possessed
                  Allans Rule: Anything worth doing is going to be a pain in the butt.

                  Comment


                  • #10
                    I think I found it!!!

                    I went out and tried some things. I turned on the power, hit the start button, and it started up and ran for a few seconds, then stopped. I put the lead screw in forward and it started back up. Then I went around to the control box and pulled the power on the 24 volt output to the relays. It immediately shut down.

                    The relay is not sluggish, slow, sticking, etc. Now I know that I have a sticking switch on the forward control for the lead screw.

                    I'll try to tackle that problem tomorrow. Thanks to everyone who has been helping with this problem.

                    thanks again,
                    CC

                    Comment


                    • #11
                      Hi customcutter, glad you are making progress!

                      I wasn't very clear when I explained the "leadscrew reverse" lever.

                      The lever you are using to start and stop the spindle is just that, the spindle control lever.

                      I am guessing here not having seen your lathe, but the "leadscrew reverse" is a separate lever probably located on the headstock somewhere. It may be confusing as this "leadscrew reverse" lever is probably also the "feed reverse" lever.

                      Hope this helps, Dave

                      Comment


                      • #12
                        wrong nomenclature(sp)

                        Originally posted by becksmachine
                        Hi customcutter, glad you are making progress!

                        I wasn't very clear when I explained the "leadscrew reverse" lever.

                        The lever you are using to start and stop the spindle is just that, the spindle control lever.

                        I am guessing here not having seen your lathe, but the "leadscrew reverse" is a separate lever probably located on the headstock somewhere. It may be confusing as this "leadscrew reverse" lever is probably also the "feed reverse" lever.

                        Hope this helps, Dave
                        I guess one of the things I need to do is learn the correct names for all of the levers, knobs, dials, and switches.

                        This is a huge upgrade from my old atlas 10f-28. It had an on/off switch, power feed, and power cross feed.

                        Yes, the leadscrew reverse is a know on the headstock. What I was calling the forward/reverse on the leadscrew on the apron is actually the spindle control lever. Just looked that up in a Grizzly manual that is somewhat similar to my B'ham CT1440G (2001 model).

                        thanks,
                        Ken

                        Comment


                        • #13
                          When you push the "forward" button, it powers a coil that makes a "contactor" close. The contactor also closes a switch that bypasses the start switch, so you don't have to hold it down. That is sometimes known as the "sealing" contact, it "seals" the contactor closed.

                          When the STOP switch is pressed, it is supposed to break the control circuit that powers the contactor coil, totally independent of the start switch OR the "bypass", or "sealing" contact. Even if those are making contact, the STOP switch should open the power.

                          When it opens the power, the coil releases the main contact and the "sealing" contact, which both open, stopping the machine and preventing a restart until the "start" is pressed again.

                          So, i suspect that either that is NOT the way it is wired, OR the contactor is messing up....something sticking closed, maybe.

                          The fact that it sometimes does not stay on might be added evidence for something funky going on in contactor land.
                          1601

                          Keep eye on ball.
                          Hashim Khan

                          Comment


                          • #14
                            Originally posted by J Tiers
                            When the STOP switch is pressed, it is supposed to break the control circuit that powers the contactor coil, totally independent of the start switch OR the "bypass", or "sealing" contact. Even if those are making contact, the STOP switch should open the power.
                            Yes, that is my main concern, the E-STOP is not breaking the control circuit, that is powering the relay and therefore continues to run. I've eliminated a sticky, sluggish relay, by manually killing the 24v control power and it shuts down immediately. Now, I just have to figure out how to get the E-STOP wired properly. Also the switch on the spindle control lever is sticking in the forward position.

                            thanks,
                            Ken

                            Comment

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