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  1. #1
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    Default Micro switch for inside DSG headstock

    Slowly working through the electricals on my DSG lathe, and found the clutch microswitch is faulty. Itís got a nice clear actuation click but the switching is intermittent.
    Looks like itís possibly not the original and Iím guessing itís full of oil.








    I checked the spec and itís IP00 which is basically ďnot protected from anythingĒ

    Is there a particular rating or type of switch that will cope with splash oil inside a headstock?

    Steve

  2. #2
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    Werribee, Melbourne
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    Steve, if nothing else pops up I've got a couple of old undercarriage microswitches (Boeing but I can't remember if they were 727, 737 or 767) that you are welcome to try - they are built like brick dunnies and I imagine are waterproof/oilproof.
    From memory they would have been 28volt operation but I have no idea of their actual rating - marked as 'Micro USA - 1HS66' date code 7803.

    IMG_1508.jpg

    Ray

  3. #3
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  4. #4
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    I'd take the Boeing ones Steve. They'll most likely outlive the lathe.
    Chris

  5. #5
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    Thanks guys.

    Ray - really appreciate the offer, but given that this one is switching 110v I'd prefer to know that what I fit is rated for that. Likely the Boeing one would be fine, but 110vac is over my "whats the worst that could happen" threshold

    China, that Altronics one looks pretty close to being a drop-in physical replacement and its 250vac rated. IP65 so will hopefully last a bit better than this one. Just ordered one...

    Steve

  6. #6
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    Quote Originally Posted by jack620 View Post
    I'd take the Boeing ones Steve. They'll most likely outlive the lathe.
    But if they are out of a 737max, it will make the lathe more likely to crash.
    (sorry for the OT comment couldn't resist.)

  7. #7
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    Good Evening Steve,

    From your photograph I can see ratings of 480 VAC (Volts A.C.), 250VDC (Volts DC) and 125 VAC (Volts AC) written on the micro-switch, but I can't read the Current Rating (amps) - as it has worn off.

    Why do you think it has a 110V control voltage? Would that be AC or DC?

    Either way..... of several, a micro-switch will be capable of quite high voltages, but at different current levels. The Altronics micro-switch S-2722 is good for 10 Amps at 250VAC. Being conservative, it will cope with 10 Amps at 110VAC, but DC won't be so good!

    DC current - for switches - is more onerous than AC.

    The micro-switch, being part of a "control circuit" - which fires into a contactor will have quite low current levels, and not be used very often, which is important for the life of the switch. If it was operating say... every second, it would certainly "warm up!"

    It would seem to my old electrician's mind that the most important specification is the IP rating, as the micro-switch has failed due to it not being able to resist the environment it is working in.

    Hope that helps,
    Alan.

  8. #8
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    Thanks Alan.
    I looked up the spec on the existing Omron switch and its 15A rated: https://www.ia.omron.com/product/item/9669/

    Control circuit is 110vac from a separate transformer in the electrical panel, and from memory the original fuse was either 4A or 6A - so the 10A Altronics switch should be fine. The 110v only supplies the main motor contactor, the brake contactor, and a couple of indicator/warning lights.
    There's more of a back story and a photo of the circuit diagram in the project thread for the lathe >> here <<

    The switch actuates each time you engage/disengage the main clutch lever - up engages the drive clutch, down disengages drive clutch and energises the brake. As you say - the IP rating is going to be more relevant to its longevity than the cycles.

    Steve

  9. #9
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    Have to say Iím blown away with the quick delivery from Altronics.

    Ordered Monday - arrived just now. Less than 48hrs!!



    Steve

  10. #10
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    The new switch consumed quite a bit more vertical space, and I had to install it without the plastic cover over the terminals due to clearance issues.
    Itís only a physical barrier to prevent touching the terminals so no issue in this application.



    Works perfectly - thanks all.

    Steve

  11. #11
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    Hi Steve,

    The button seal at the top along with the plastic terminal cover is part of the IP65 specification ! I would paint a seal of Evostick rubber solution or something similar along the edges of the holes that the terminals come through, just to prevent any oil migration into the switch via that path.
    Best Regards:
    Baron J.

  12. #12
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    They are good. I ordered some mini relays from them and had them in Qld. in less that 24 Hrs.

    Quote Originally Posted by OxxAndBert View Post
    Have to say Iím blown away with the quick delivery from Altronics.

    Ordered Monday - arrived just now. Less than 48hrs!

    Steve
    Nev.

  13. #13
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    Quote Originally Posted by BaronJ View Post
    Hi Steve,

    The button seal at the top along with the plastic terminal cover is part of the IP65 specification ! I would paint a seal of Evostick rubber solution or something similar along the edges of the holes that the terminals come through, just to prevent any oil migration into the switch via that path.
    Thanks John - that would probably have been a good idea, but a) I don't have anything suitable and we're currently locked down so can't even get out to buy some, and b) its all back together now

    The terminals were molded into the switch body, so I don't expect its going to be an issue - but I guess time will tell.
    The plastic cover wasn't sealed in any way either, it just clipped on, hence my comment thinking it was just there for physical protection from the exposed terminals.

    Steve

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