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Thread: AC Switch bypass

  1. #11
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    Nov 2008
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    Vancouver Island
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    It sounds like you were right, dehrlich's switch had also failed.

    I wonder if it was from opening the cover to interrupt the machine. It seems to me that this is how the switch gets damaged. It is not protected from the back emf surge from the motor. Sparks jump in the switch when the motor current is interrupted.

  2. Default

    Quote Originally Posted by dehrlich View Post
    I replaced the switch with one from my parts machine. All is well now, thanks for all the input!
    Glad you got it up and running!

  3. Default

    I always made a conscious effort to always push the stop button before opening cover and mine went out at about 150 hours.

  4. #14
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    Nov 2008
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    Vancouver Island
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    It would be interesting to take these switches apart and see why they failed. Was it fatigue or was it fused contacts or was it just dust?

  5. #15

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    Quote Originally Posted by bergerud View Post
    I wonder if it was from opening the cover to interrupt the machine. It seems to me that this is how the switch gets damaged. It is not protected from the back emf surge from the motor. Sparks jump in the switch when the motor current is interrupted.
    I don't think that this is the case. A properly-designed switch should be able to actually switch current and not just allow it to pass with no damage. Switches are rated for the number of contact closures at current:
    "The contact rating is the voltage/current that the switch can repeatedly connect and interrupt without degrading it's design life-cycle operation count."
    I think dust more likely. My "close cover" switch failed within a couple of weeks, as did the warranty replacement. I substituted a proper sealed switch and have had no issues since - is it 6 or 7 years now?.

  6. #16
    Join Date
    Aug 2008
    Location
    Bangor, ME
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    614

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    The switches do come apart if you're careful. My control side switch appeared to have failed twice from sawdust. Appeared meaning I took it apart, there was dust in there, I blew it out and it worked afterward. I also had issues with the connectors losing contact from vibration while it was running so it could have been that. Problem is, once the switch sets a fault you pretty much have to scrap your project and take the machine apart to fix it. That's why I bypassed mine. I considered adding in manual bypass switches, but that's just asking for more failed connections IMO.

    I also think the control side switch is too low of quality for the vibrations and dust it experiences.

  7. #17
    Join Date
    Dec 2014
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    Kaukauna, Wisconsin
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    767

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    I am kind of wondering, why LHR does not use better switches for the purpose they are intended. The environment that these switches live is harsh as far as dust goes. Even with a dc there is still dust to contend with just a lot less. The cover switches are a safety concern and the rollers switches are the same type, not a safety concern , but still a cause of many issues I see on the forum. I would think that looking into sealed switches may be a way to go here. Micro switches are out there in many types, direct replacement sealed switches should be out there. I do not believe the cost would be that different, could be I would have to look into it, but thinking not.

  8. #18

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    Quote Originally Posted by Mugsowner View Post
    Micro switches are out there in many types, direct replacement sealed switches should be out there.
    There are replacement switches available. I replaced the "close cover" switch on my machine years ago: http://forum.carvewright.com/showthr...125#post119125 I have not had an issue with the cut motor switch.

  9. #19
    Join Date
    Dec 2006
    Location
    Brunswick, GA
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    8,123

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    Quote Originally Posted by Mugsowner View Post
    I am kind of wondering, why LHR does not use better switches for the purpose they are intended. The environment that these switches live is harsh as far as dust goes. Even with a dc there is still dust to contend with just a lot less. The cover switches are a safety concern and the rollers switches are the same type, not a safety concern , but still a cause of many issues I see on the forum. I would think that looking into sealed switches may be a way to go here. Micro switches are out there in many types, direct replacement sealed switches should be out there. I do not believe the cost would be that different, could be I would have to look into it, but thinking not.
    Ha! If you had been to one of the CW Conferences a few years ago, you would know why they use the switches that they use! You can blame Underwriters Laboratories for that one. One of the CarveWright engineers told the attendees just some of his frustrations with UL...

    The original CW design and sample submitted to UL was equipped with heavier duty, sealed cover switches. UL decided this was a particular model switch they weren't familiar with and put the nix on a UL approval unless they were changed to the ones you see on the machines today. Thank you UL!

    Now, I must tell you, I have never had a cover switch failure on either of my machines over ten years of use. Have they gotten dust in them? Yes! Was it easy to clean out? Yes! WD-40 or contact cleaner and compressed air usually does the trick. Also, the switch can be pushed back a little so it doesn't engage properly when the cover is closed. Just loosen the screws and pull it towards you and tighten the screws.

    I once had a "stubborn" switch that seemed it had permanently failed after trying cleaning for a half hour or so. I gave up and ordered a new one. Almost immediately after placing my order, I went out to the shop and tried some more WD-40, clicking the switch furiously in/out, puffing some air in it, etc. and lo! It worked! I still have that brand new switch in my spare parts drawer, and I'm thinking I'll probably never have to use it.
    Michael T
    Happy Carving!


    ═══ Links to Patterns & Resources for CompuCarve™ & CarveWright™ ═══

  10. #20
    Join Date
    Jan 2007
    Location
    NE PA USA
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    As for opening the cover to stop the machine... I have been doing it since 2007 and knock on wood I have not had a cut motor switch failure yet... I have never been a "Stop Switch guy"... Lazy... The sparking and EMF theory DO have merit in my opinion.

    LHR #1 has commented on the Switches years ago when asked why a sealed magnetic switch was not used... ???? His reply was that it was all about the UL Certification and the rules required a mechanical switch as did it require a 2 wire power cord with NO Ground 3 wire plug.... UL rules...

    Glad you got the bad switch replaced.

    AL

    EDIT.... OK... MT Types FASTER then ME... Didn't see his answer when I started...
    Last edited by Digitalwoodshop; 04-08-2017 at 02:36 PM.
    Favorite Saying.... "It's ALL About the Brass Roller"..... And "Use MASKING TAPE" for board skipping in the X or breaking bits.

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