Stuck thread/fed knob
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  1. #1
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    Default Stuck thread/fed knob

    Got my new-to-me HLV-H up and running on three phase and am starting to learn the machine. I've determined that the thread/feed knob on the headstock is stuck. I've tried penetrating oil for several days, I've tried slowly turning the spindle by hand while trying to get the know to disengage. Nothing seems to work. I can see the parts through the inspection plate and nothing appears to be broken. Any ideas?

  2. #2
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    Prybar...put some muscle behind it.

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    Is it stuck in a operating position? Or in the middle.
    If it was in a running position I would see if running the machine up to temp might work.

    Sometimes I use a 3/8 square stick to jam in the thread gear assembly to keep it from moving when I need to loosen the screw on a gear.
    Open the gear box and see if everything turns.

    Last time I had the collet closure and black hand wheel removed I could see the engagement of that knob inside the head.
    I removed the hand wheel with thin wooden wedges and light taps.

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    First determine whether it is the knob shaft or the gear/rack that is stuck.

    Does the knob have any small free movement? If so then the gear is stiff on the shaft.

    If the the knob is solid (which from my experience is more likely) then remove the plastic knob , open the panel at the back of the headstock so you can get at the back of the knob shaft .

    Then tap the shaft in and , from the back, out until it frees up.

  5. #5
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    Thanks guys. It is stuck in the "thread" position and the knob has a very slight amount of play.

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    With the knob removed, I can push the shaft in until its gear clears the threads. It will then turn freely but when I push the shaft back into position and re-attach the knob, I'm back to square one.

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    My knob has a pin and a spring on the back side. The pin is located in a small depth hole at either the thread or feed positions.
    Might be something going on with that.

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    If the knob shaft is free then the gear must be stuck to the shaft.

    The gear shaft is removable from behind the spindle handwheel .

    Remove the handwheel by removing the coiled circlip -ithe hand wheel should just pull off but be careful how you lever it, if it doesn't . Don't lose the key or washer.

    There is a bearing, below the spindle , locked in with circlip. The shaft has a threaded hole (1/4 unf,?) for a puller - it'll be stuck with dried oil in your case so make sure you thread the screw in a good few turns.

    The gear will drop so grab it through the hatch before you completely remove the shaft.

    The circular rack on the gear has a line around the middle tooth and there is a line between two teeth on the knob shaft , both need to be aligned when replaced.

    Bill

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    Very helpful, thanks Bill.

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    Got it working without having to remove the shaft, again I appreciate the help.

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