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  1. #1
    Join Date
    May 2010
    Location
    Lower Lakes SA
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    58
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    2,607

    Default Switching 2 speed motor for drill press

    I would like to adapt this washing machine motor for a drill press, mainly for the 2 speed feature. I've done a lash-up for testing and I'm satisfied with its performance. Couple of questions if I may.

    What would be the proper way to set up the switching? I'm hoping I can use simple switches instead of contactors. Bad idea? What sort of start current would I need to rate for? I imagined an on/off and a hi/lo. But what about a DPDT with centre off? With the active flipping for speed selection and the neutral jumped for on/off/on?

    In case it's relevant to current, the motor has a capacitor as well as a centrifugal switch, which has me confused. I thought there should be one or the other.
    Am I looking stupid yet?

  2. #2
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
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    72
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    3,102

    Default

    Bryan,
    my old drill press runs one of these motors since about 1975....
    I have a simple 10A 250V DPDT centre off switch on it. Your set-up for switching is fine.
    By the way, it won;t have 1/2HP in low speed - mine is actually plated 1/4HP for the low speed and 1/2HP for the high speed. It draws less current (3.2A form memory) than yours in low speed though, so yours may be 1/3HP in low speed.

    The capacitor is a starting capacitor which is switched off by the centrifugal switch once it runs and is used to start the motor in both speeds.
    Starting capacitor and centrifugal switch was the norm a couple of decades ago. These days they have electronics switching the capacitor (and run winding) off.
    There are 'split phase' motors which will start without a capacitor - they are usually smaller sizes (up to 1/2HP) but draw a high starting current.
    There are also motors with just a run capacitor (e.g. in my lathe, ex industrial sewing machine) with so little starting torque that is is fitted with a clutch. It takes about 15 seconds to run up to speed and any load will stop it unless it's at speed - when it has 1/2HP. That particular setup also has a brake, which is nice on the lathe. I've got it set up with a pedal - when you press it the cluch engages, when you let go the brake goes on.
    Lastly, there are single phase motors which have both start AND run capacitors (e.g. on my bench saw and compressor), in which the starting capacitor and start winding is switched off by centrifugal switch. They have good starting torque with acceptable start current. I'm estimating they take a second or two to get up to 'run' speed.

    Hope that helps.
    Joe

  3. #3
    Join Date
    May 2010
    Location
    Lower Lakes SA
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    58
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    2,607

    Default

    Joe, that does help, many thanks. Something like the switch pictured be ok? I guess by rights I should include an e-stop. Mutter mumble.

    I know the 2 speed thing is a compromise, but it seems like an easier solution than fitting a jack shaft like you did, mainly because of the enclosed belt guard on the Tough. Plus we don't all have tame foundries handy! But if this is too pathetic I'll have to find a way to make that option work.

    My old speeds were approx 500, 1000, 2000, 4000.
    Now I have 330, 495, 635, 960, 1185, 1785, 2375, 3575. Much better.

  4. #4
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
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    3,102

    Default

    Even better than my old switch, Bryan. Should be OK.
    An e-stop could be fitted in addition - e.g. where you can hit it with your knee or with your head. Just put it in series with the active and only use it as an e-stop (so as not to wear out the usually only 8A contacts).
    Joe

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