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  1. #1
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    I have a 1946 EE with M/G set-up and square dial. Feeds,speeds,accuracy all perform superbly but I cannot get the threading leadscrew to turn when set up for LH or RH threading.It does turn in Feed mode on the gearbox selector(but not Thread mode) and does
    reverse as the spindle reverses.When in that set up the leadscrew turns LH with the spindle running RH and RH when spindle is running LH.
    With everything set for correct threading,and
    spindle turning,if I push the leadscrew towards the headstock,it tries to turn but only about 1/4 turn-this happens either LH or
    RH.I don't have a good manual.Can anyone steer me in the right direction-what isn't happening, and why?
    Thanks-Great Forum!

  2. #2
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    Hi Tractorman:
    There are lots of things that it could be.
    The first place to look in my opinion, is the shearpin that locks the leadscrew to the output shaft of the gearbox.
    It's at the headstock end of the leadscrew.
    If your upper gearbox output shaft turns when the leadscrew doesn't..that's your trouble.
    The next place to look is the detents on the gearbox levers.
    I checked out a Monarch once that had the same symptoms as yours, and it turned out that one of the levers had a chunk of scrap steel jammed into the detent, and blocked the lever from going into the correct position to engage.
    The same machine had a totally worn out detent notch on another of the levers, and would't stay in gear.
    The way to check this, is to slip the levers into what you think is the correct position, and then try to bump them back out of engagement with the heel of your hand, but without depressing the ball handle.
    Another symptom...if the levers hop around when you turn on the lathe, this may well be it.
    Try turning the spindle by hand, and rocking the feed/thread selector knob too.
    It may be sticking and tricky to fully engage. When it's all the way in, you'll feel the pull of the geartrain when you turn the spindle.
    The third easy one, is if the quadrant has dropped out of position
    If it's none of these, then you may well have stripped gears in the gearbox or on the headstock.
    Finding these is going to take some sleuthing, and maybe some disassembly.
    Hope this helps.
    Cheers

    Marcus

  3. #3
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    Hello Marcus,
    Thanks for the input.I have determined that the problem is not the first two possibilities you mentioned.What do you mean when you say that the quadrant may have dropped out of position?
    Thanks again for the direction.

  4. #4
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    Hi Tractorman:
    When you open the main belt cover on the headstock end of the machine, you will find a gearbox cover behind which is the idler gear set that connects the headstock output shaft to the gearbox input shaft.
    The cover is just to the right of the spindle and a bit below it when you're standing at the headstock end, and looking toward the tailstock.
    It's bolted in place so you'll have to undo a couple of socket head capscrews to get access.
    This set of gears is used only by the threading function; the feeds are driven into the main gearbox by the flat belt that runs off the main spindle.
    So, the gears between the output gear on the headstock, and the input gear on the gearbox are attached to a quadrant plate that allows you to set the backlash or put a metric set in etc etc.
    The quadrant plate can be unbolted and swung around.
    If it comes adrift, the threading function will become inoperative, while the feed function is preserved.
    That would be the next place I'd look.
    While you're in there, try shifting the thread/feed selector knob from RH to Feed to LH and see if the headstock output shaft turns(while turning the spindle over by hand of course) when you're in RH or LH.
    If she won't turn reliably, your problem is in the headstock gears, if she does, your problem is in the main gearbox.
    Good luck with it.
    Cheers

    Marcus

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    Thank You Marcus.
    I will check that out promptly.Your input
    is greatly appreciated.
    Thanks again.

  6. #6
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    Hello Marcus,
    I wanted to thank you again for your guidance
    and for being a part of this great forum.I couldn't
    take a look at the lathe until this morning,but
    you were exactly right,the quadrant was kicked out of place.The gears,bearings etc. inside look like new,why that was totally out of synch.is a mystery.I set the backlash on the gears and have chased several different threads to test and it is threading quietly and accurately.These machines are so nice to use,again thank you for your input!

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    Hi Tractorman:
    I'm very pleased that it turned out to be something so simple and CHEAP to fix.
    If you've ever seen the price of genuine Monarch anything, you'll know exactly what I mean.
    I'd hate to even guess what stripped gears would have cost you...probably as much as the purchase price of the machine!!!
    Enjoy the lathe...you are the fortunate owner of a truly magnificent machine tool.
    Cheers

    Marcus


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