A-B threading selector jammed
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  1. #1
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    Default A-B threading selector jammed

    This machine sat for a couple decades so some things work pretty reasonably and some things are quite stuck.
    This control is stuck in the B position. After some effort and gentle persuasion I was able to pull the knob out, but I'm not able to turn it by hand. Is there anything I should move that might free it up? Otherwise, how much do I need to tear into the gearbox to get that part off? Can I just slide it out from between the headstock and the lower gearbox or do I have to take more apart?


    OOPS, sorry, posted too soon! If you just remove the grubscrew from above the shaft, the selector and shaft all just come out the front of the box. I apologize for the bandwidth, I'm just trying hard to not make anything worse in the process of getting things moving again.

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  3. #2
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    I'm pretty sure that you can see where that shaft goes in the gearbox if you remove the 1/4 round plate above it. It might be easiest to remove the lh/thread/rh selector housing above it first.

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    Maybe not relevant, but upon inspection of mine during exploratory surgery, I found that years of coolant use had seeped past the non existent seals on the output shafts causing a toxic solidified goo to seize those knobs.

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    Very very basic question: did you try rotating the spindle as you were turning the selector knob? Often when the knobs don’t move completely it is because there is a tooth in the way and rocking the spindle solves the problem. Also, is the gearbox in mesh, or is it released?

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    I did try rotating the spindle while engaged, I tried released, I tried in CDE settings on the next gear. It wasn't just that it didn't shift fully, it was that it didn't budge even the slightest. The gearbox had sat dry for decades and I suspect strongly the oil film went away on some sliding part but left a hardened gummy residue. I pulled out the shaft and shaft bush and that was all fine so squirted some light oil on stuff through the hole and tried a bit more forcefully.
    Now it moves but is still a lot stiffer than my normal 10EE experience, I've filled the gearbox with thinner than usual oil and plan to just let it soak like that and run it without a load for a bit then drain and refill so see if that won't clear things out.

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    Quote Originally Posted by teletech View Post
    I did try rotating the spindle while engaged, I tried released, I tried in CDE settings on the next gear. It wasn't just that it didn't shift fully, it was that it didn't budge even the slightest. The gearbox had sat dry for decades and I suspect strongly the oil film went away on some sliding part but left a hardened gummy residue. I pulled out the shaft and shaft bush and that was all fine so squirted some light oil on stuff through the hole and tried a bit more forcefully.
    Now it moves but is still a lot stiffer than my normal 10EE experience, I've filled the gearbox with thinner than usual oil and plan to just let it soak like that and run it without a load for a bit then drain and refill so see if that won't clear things out.
    I just reassembled this part of my 1957 square dial. The A-B selector knob turns a gear that engages a rack that rides on a square slide (that eventually makes a gear engage with one part of the train or another). Sounds like the square slider may be galled or gummed up.

    It is not that difficult to remove just the top of that gearbox and address it. You remove the tumbler lever and slide out that shaft (sounds like you may have already done that), remove a couple bolts on the side by that lever and tow cap screws in the top and the cover slides right off. Be careful of the gasket on the right side; it is easy to crush when reassembling.

    If it would be helpful I’ll post a photo when I get to my desk.

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    If the gears are not stuck, put the box in the highest feed possible, and run the machine in forward and reverse. Getting the gears spinning fast causes the oil to splash up to the upper part of the box.
    I have an old manufacturing model I use all the time, the thread cutting machine, I just don't use much, and I have to run it awhile in a coarse feed setting to get it to shift when I need to use it.

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    Quote Originally Posted by jim314159 View Post
    I just reassembled this part of my 1957 square dial. The A-B selector knob turns a gear that engages a rack that rides on a square slide (that eventually makes a gear engage with one part of the train or another). Sounds like the square slider may be galled or gummed up.

    It is not that difficult to remove just the top of that gearbox and address it. You remove the tumbler lever and slide out that shaft (sounds like you may have already done that), remove a couple bolts on the side by that lever and tow cap screws in the top and the cover slides right off. Be careful of the gasket on the right side; it is easy to crush when reassembling.

    If it would be helpful I’ll post a photo when I get to my desk.
    I did get as far as pulling the tumbler and shaft. Knowing the cover comes off like that is a big help and thanks for the gasket tip!
    After having squirted some oil onto that square slide or at least it's environs and working the lever a bit and also running the lathe a bit, it's gradually improving. Something about having sat untouched for nearly forty years... :-)

    Now if I could just figure out why I can't get my spindle speed over 1200RPM or so. :-(

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    [QUOTE=teletech;3543919Now if I could just figure out why I can't get my spindle speed over 1200RPM or so. :-([/QUOTE]

    Check the voltage on the field, bet you that it doesn't ever drop. That's how the motor gets above base speed. Lots of possible reasons, many depending on the drive type. Also have to ask: is the drive system original, replaced or modified?

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    Quote Originally Posted by rke[pler View Post
    Check the voltage on the field, bet you that it doesn't ever drop. That's how the motor gets above base speed. Lots of possible reasons, many depending on the drive type. Also have to ask: is the drive system original, replaced or modified?
    thread on the drive system is here:
    New to me 10EE ser39962, with drive issues (of course)
    but it has a lot of false leads and random dead-ends.

    In brief.
    Original drive system.
    Armature goes from 0-225V
    Field is 85V to 750RPM then drops as spindle speed rises at 1300RPM it's 35v, today the lathe went all the way up to 1900RPM at which point the field was 20V but at that point the FA relay started pulsing. If I hold the FA relay open I notice more arcing at the top brush than the others and increasing speed while holding FA open the arcing gets bad enough it jumped the gap and the drive shut down. So I guess adjusting brushes is the next thing on my list. I just have to find the instructions for that.


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