Noisy solenoid

Discussion in 'Other metal working projects' started by Petee716, Dec 22, 2021.

  1. Smoking Shoe

    Smoking Shoe Silver

    Could.
    I also hadn't considered that if he is using it to control a solenoid then he is dealing with an inductive load. That has it's own set of problems compared to a simple resistive load. If the SSR turns out to be the source of the problem then this might help?
     

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  2. rocco

    rocco Silver

    Quick question to those of you familiar with the finer points of SSR usage, what type of SSR is most appropriate for powering a solenoid, zero-crossing or random turn on? The one used here is a random turn on type, any chance that could be contributing to the problem?
     
  3. Smoking Shoe

    Smoking Shoe Silver

  4. rocco

    rocco Silver

    THAT is precisely why we're all here!
     
  5. Petee716

    Petee716 Gold Banner Member

    I’ve concluded that it’s probably not the SSR. A little more background. The basic operation of the parent machine is shown here

    The focus of the discussion is on the knife carrier (the two longer levers used to actually cut the paper, not the forward clamping levers).
    The modification is shown here

    The modification assembly is mounted to the machine frame around the back, on the operator’s right, chest level, to align with the knife carrier at its top holding position.
    There are 2 independent switching systems for the solenoid involved.
    One is a rocker switch that is activated when the left hand cutting lever is pulled. It sends power straight to the solenoid. It does not go through the SSR.
    The other switch is a proximity sensor. That one sends a signal to the SSR which then sends power to the solenoid as soon as the knife carrier begins to move downward and remains closed until the knife carrier returns to its upper position. I think I was advised to do that switching through the SSR to protect the proximity sensor.
    So the order of switching is:
    Pull levers, left side first, and the solenoid retracts just prior to knife beginning to move. That’s when the buzzing starts.
    Proximity sensor activates in response to the movement so both signals are sent concurrently until the levers are released.
    Proximity sensor continues to send the signal until knife carrier reaches its top holding position and the solenoid releases the pin.
    Clear as mud?
    Well, the buzzing starts when pulling the lever only, before the knife carrier even starts moving and thus before the SSR-involved circuit even activates.
    On cycling the machine, once the levers are released the buzzing stops and the proximity sensor circuit silently remains closed until the knife bar returns and the solenoid releases the pin. So the issue must be in the lever switch circuit. I’ll replace the switch first and see if it resolves the buzzing and I’ll double check my connections as well.
    Sorry to have led ya’ll down a bit of a rabbit hole here. I’d built this unit based on advise and “common sense” as opposed to a thorough understanding of the processes involved so it took me awhile to figure out what I’d actually done.

    Pete
     
    Melterskelter likes this.
  6. rocco

    rocco Silver

    Hey Pete, the rest of us aren't able to see that second video, it says. "This video is unavailable".
    BTW, I'm familiar with machines like that, I used to work at a place that had a similar but much larger machine. It always scared me a bit, it could slice through a 1000 sheets of 20lb bond or 4" stack of card stock like it wasn't even there.
     
  7. Smoking Shoe

    Smoking Shoe Silver

    But there just seems to be no end to that project.................:)
     
  8. rocco

    rocco Silver

    Exactly right, that's the whole point, never stop learning!
     
    Smoking Shoe likes this.
  9. Petee716

    Petee716 Gold Banner Member

    Try that Rocco. I believe I’ve corrected the video situation. I hope it’s not too much of a letdown! Lol.
    Yes indeed those cutters get big. My actual Challenge cutter is the same size as the one in the video: 26.5” wide with a max backgauge depth of 26.5”. That will cut about 2.5” of paper. My larger cutter is a 36” and will cut a 4” stack like it wasn’t even there. It is also programmable and has a power backguage so it runs repetitive cutting sequences accurately and very productively. BTW they get much larger than that as well.
    This 265 is super handy for certain applications.

    Pete
     
  10. Melterskelter

    Melterskelter Gold Banner Member

    I wanted to have the unit in hand before answering. It is 120V. So, I will use a step-down transformer power the fan. The fan is very quiet---it can barely be heard.

    Denis
     
  11. Petee716

    Petee716 Gold Banner Member

    I had some time to dig back into this today. I mentioned above that the first signal being sent to the solenoid was from the lever switch. There was no SSR involved in that circuit. It just sent 110v straight to the solenoid. That's the one that was causing the buzzing in the solenoid. I moved the terminal wire to the switching input of the SSR so now that signal to the solenoid comes through the SSR. The buzzing has stopped. But something weird is going on with the solenoid.
    I close the lever switch with the machine lever and the solenoid activates, the knife carrier starts to move which closes the proximity sensor circuit which then sends a concurrent signal to the SSR, so that when the lever switch opens there is a continuity of voltage to the SSR from the proximity switch and thus to the solenoid. And that is what happens...mostly. When the lever switch opens the solenoid briefly loses power, probably on the order of milliseconds, then re-energizes for the rest of the cycle until the knife carrier returns to its top resting position and the proximity sensor circuit opens. I can see and hear the solenoid pin release and retract at the exact moment the lever switch opens.
    So it would seem that I'm creating a fluctuation in the switching current when I open the lever circuit triggering the SSR to briefly open?
    I'm okay with it. It's not creating any problems with the cutter, and the buzzing has stopped. It's just a little unexpected.

    On another note, after cycling the machine about 25 times in a row there is no detectable heat being generated by the SSR (at least nothing I could feel).

    Pete
     

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