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  1. #1
    Join Date
    Apr 2005
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    Brisbane
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    350

    Default Lathe gears problem...

    I have restored an old inherited lathe, and got it working again, and I have done a bit of turning to test it all out, and it's been really good, but just today, something has loosened. It's almost like oil has finally got into a significant part of the gears and loosened up a part. Anyway, now when I turn it on, it just spins the wheels, but not the chuck, which is super, but also bad. How do I get it back again?

    I will explain in detail, referencing the picture below...

    On the main shaft at the bottom, are 4 components - a small gear at the left, 3 belt wheels in the centre, and a large gear on the right, and of course the chuck on the right. On the second shaft at the back are two extra gear wheels which can mesh with the two on the main shaft, or can be disengaged by the lever on the very left of the photo.

    Until today, all three components on the main shaft acted as a single unit. The pulley belt was used to select the speed via one of the 3 flat belt wheels, and this drove the chuck directly. The gears at the back were simply used as a locking mechanism, which was a handy way to lock the main shaft and remove threaded chucks. I thought it was a strange locking mechanism, but I have heard of geared brakes that are designed like this, so I just accepted it.

    Now today, it is behaving differently. On the main shaft, the small gear wheel on the left and the belt drive wheels are disengaged from the main shaft, and spin freely on it, while still locked to each other. The large gear wheel on the right is still firmly attached to the main shaft. When I turn on the lathe with the rear shaft disengaged, the chuck will turn, but any pressure causes the chuck to stop while the belt and wheels keep spinning. In fact, it's quite easy to stop the chuck by hand with the lathe turned on, and it runs quite smoothly like this. Now the interesting part is that the rear shaft has now changed function. With the rear shaft engaged, the belt drives the wheels and the smaller wheel attached to it, which then drives the large wheel on the rear shaft, which drives through to the small wheel on the rear shaft. This then drives the large wheel on the front shaft, thus driving the chuck, VERY SLOWLY!

    So, this is a nice feature, particularly if I want to do some metal turning. I no longer have to exchange pulley wheels at the back of the lathe - I could just engage this 2nd shaft in this manner. It was also very handy today as I am doing a danish oil finish on my first piece, so it was nice to run it slowly to wipe off the oil.

    BUT, I don't know how to re-engage the belt to drive the chuck directly, which I need to do for normal wood turning. I have looked it over, and I can't see anything obvious to re-engage it. There is a bolt on the side of the large gear wheel, but that wasn't loose, and doesn't seem to lock it to the belt wheels. I don't want to pull the whole shaft apart to figure out what's going on there.

    This is a converted Barnes #5 metal lathe from the 1890s, so there is no manual! Hopefully it is a similar setup to something that someone has seen before.

    Does anyone know the trick?
    Attached Images Attached Images
    Good things come to those who wait, and sail right past those who don't reach out and grab them.

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  3. #2
    Join Date
    Feb 2012
    Location
    Nowra, NSW, Australia
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    65
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    Default

    Is it possible that a key locking the gears to the shaft has sheared? Just a thought.
    ... Steve

    -- Monkey see, monkey do --

  4. #3
    Join Date
    Mar 2012
    Location
    sydney
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    Default

    ON the side of the big gearwheel on the main spindle there should be a locking tab that should be pushed into it locks on to the pulley. The normal way to lock that is with a locking pin. That pin can have falling out, I got a Hercus lathe that works that way, but nearly all lathe have this setup works the same. So look for a locking device between belt pulley and front gear wheelattachmenmodt.jpg

  5. #4
    Join Date
    May 1999
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    Tooradin,Victoria,Australia
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    Default

    I would say that you have put it into neutral through the back gears.

    What is this handle?shaft.JPG

  6. #5
    Join Date
    Apr 2008
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    Melbourne Australia
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    Default

    Brings back memories

  7. #6
    Join Date
    Apr 2005
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    Brisbane
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    Default

    Quote Originally Posted by View Post
    I would say that you have put it into neutral through the back gears.

    What is this handle?shaft.JPG
    That handle was I think originally intended to put the lathe into neutral, but as a converted wood lathe, the whole front shaft has been locked, so engaging the back shaft with this handle has been functioning as a lock for the main shaft.
    Good things come to those who wait, and sail right past those who don't reach out and grab them.

  8. #7
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    Apr 2005
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    Default

    Quote Originally Posted by tore View Post
    ON the side of the big gearwheel on the main spindle there should be a locking tab that should be pushed into it locks on to the pulley. The normal way to lock that is with a locking pin. That pin can have falling out, I got a Hercus lathe that works that way, but nearly all lathe have this setup works the same. So look for a locking device between belt pulley and front gear wheelattachmenmodt.jpg
    Yes, that was it! The little bolt that I mentioned was exactly where you indicated. It wasn't really loose, but must have moved just enough to lose purchase. I had looked at this, but couldn't find any way to lock it. However, on further inspection, at a particular alignment with the pulley wheels, there is a slot where the bolt can be pushed right to the outside of the wheel, and it locks in to the next one. All happy now.

    Thanks!
    Good things come to those who wait, and sail right past those who don't reach out and grab them.

  9. #8
    Join Date
    Sep 2008
    Location
    North Carolina, USA
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    2,327

    Default

    Surfdabbler,

    You might find some information about your lathe here:

    https://www.google.com/#q=barnes+mod...C+instructions
    So much timber, so little time.

    Paul

  10. #9
    Join Date
    Sep 2008
    Location
    North Carolina, USA
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    2,327

    Default

    Surfdabbler,

    Metal lathes have the back gear for very slow turning. They are arranged so that by putting the pin to lock the cone pulley and the big gear on the spindle and back gear disengaged, you have direct drive. If you put it into the back gear with the pin in, it locks the spindle. Forcing - trying to knock off a stuck chuck - may break the pin or break a tooth off a gear.

    Pulling the pin out and engaging the back gear will give you a very slow speed with lots of torque. Nice for rounding up out of balance odd shaped bowl blanks or drilling out vases or lamps. Tree stumps with the roots cut off in my case.

    With the pin out and back gear disengaged everything is free turning, nice to see if lubrication is getting to where it needs to.
    So much timber, so little time.

    Paul

  11. #10
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    Apr 2005
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    Default

    Hi Paul,

    Yes, this is a nice feature now that I know it is there. I will use it for sure!

    Cheers,

    Dave
    Good things come to those who wait, and sail right past those who don't reach out and grab them.

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