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Thread: 3520b switch

  1. #1
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    3520b switch

    The switch on my 3520b takes a solid tug to turn on the lathe and pretty good whack to turn off the lathe. Is this the nature of the switch or is mine just a hard one to use ? What switch can I replace mine with and still have the mushroom head ?

  2. #2
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    How old is your lathe? If it has been used quite a bit, then there is a good chance that it is full of dust. Blowing it out with compressed air may solve your problem. If the switch is hard to use but still works, then you can always make your own remote on/off switch and use that in series with the original. I made one for my Jet 1642 using a regular cheap light switch. That was ten years ago and it is still working!
    Steve

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  3. #3
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    Quote Originally Posted by Robert Hayward View Post
    The switch on my 3520b takes a solid tug to turn on the lathe and pretty good whack to turn off the lathe. Is this the nature of the switch or is mine just a hard one to use ? What switch can I replace mine with and still have the mushroom head ?
    There is no AC power on the on/off switch. You can replace it with almost any switch you can find - it only needs to switch 10 volt DC control line. Doc Green has some articles about the PM including info about replacing the switch. http://www.docgreenwoodturner.com/ar...tml#Powermatic

    That said, you can also remove and disassemble the switch. I did that with a Jet 1642 switch that appears to be identical to the PM switch. In my case the switch was full of fine sawdust. I cleaned, lubricated, reassembled, and sealed the outside of the switch from future sawdust intrusion. No more problems. It is still easier to turn on and off than my PM 3520b switch which I haven't messed with yet.

    If I remember correctly, the mechanical part of the switch provides the resistance to pulling and pushing by means of a tiny steel ball pressed into a detent with a spring. If so, you could cut off some of the spring to weaken it and/or maybe smooth the edge of the detent hole so the ball rides easier.

    While you're messing with the switch, you can add a remote on/off switch. Mine has one wired in series (I think) with the primary switch with a big bright yellow plastic actuator to make it quick to hit. It has magnets on the back so I put it on the front of the lathe out of the line of fire so I can turn it off with my leg if needed.

    JKJ
    Last edited by John K Jordan; 09-03-2017 at 9:18 AM.

  4. #4
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    I have the switch disassembled and it is the mushroom actuator that is the trouble. The actual switch is smooth and easy to move. A new actuator looks to be in the $40 ~ $50 range shipped.

    Have not figured out how to get inside the actuator without breaking any thing. Looks like the metal disk on the bottom of the actuator is the "keeper". One way security type head. How do I get that off ?

    Mushroom button 1a.jpg

    Steve, the lathe is about five years old, maybe four. I have cleaned and dry lubed the actuator with no difference. If I can get it apart I will relieve some of the tension on the spring. If that fails I found a replacement switch with similar specs for about $26.00 shipped from Zoro.
    Last edited by Robert Hayward; 09-03-2017 at 11:00 AM. Reason: Added comment

  5. #5
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    Robert - PM sent about the remote switch. Easy way to solve the issue.
    Steve

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    Please don’t let that happen!
    Become a financial Contributor today!

  6. #6
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    Problem fixed. I was able to grab the very tip of the edge of the metal disk with a pair of needle nose pliers with newish serrations. The good bite gave a solid grip. Then just twisted the mushroom and the metal disk is actually a course threaded plug which twisted right off. Then I was able to pull the innards out the other end.

    No ball bearing, gone. Twenty minutes of quality time on my knees with a serious bright LED light crawling around the garage floor with the dog wanting to lick my face. No luck. A close examination using a magnifier lamp showed no signs of wear from a bearing nor a detent for the bearing to snap into or out of. More examining and I think my actuator does not use a bearing. It does not. The plastic spring loaded plunger snaps back and forth over a ridge inside the housing. The entire mechanism is limited in movement by the metal plug in the pull direction and the mushroom cap in the push direction.

    With that knowledge it was an easy matter of snipping a portion of the plunger spring coils until I got the feel I was comfortable with. The switch now operates smooth and easy.

    Mushroom button 2a.jpg

  7. #7
    My 3520 switch is the same way. You have to smack it to shut it off. I think I'll be taking mine apart this afternoon.

  8. #8
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    Quote Originally Posted by Robert Hayward View Post
    More examining and I think my actuator does not use a bearing. It does not. ...
    With that knowledge it was an easy matter of snipping a portion of the plunger spring coils until I got the feel I was comfortable with. The switch now operates smooth and easy.
    Mushroom button 2a.jpg
    Yes, that's an entirely different design! Thanks for figuring it out - it is nice to know how they differ, maybe the Jet uses that design now too. I may take the one on my PM apart and do what you did and make it smoother. So glad you got it working!!

    PS, when I took the Jet switch apart I also spent some time on the floor looking for the ball which I saw fly out and land in shavings. Duh! I found it with a magnet.

    JKJ

  9. #9
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    If you break something working on it here are the Schneider part numbers.

    Actuator ZB5AT84
    Switch ZBE102
    Mount ZB5AZ009

    The link John provided above has some really useful information about this switch.

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