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  1. #1
    Join Date
    Nov 2012

    Default Hafco AL-336 Imperial Thread

    I am hoping someone can help - we have recently bought a Hafco AL-336 Lathe and want to be able to cut imperial threads. On the gear cover, there is a reference to a "Z" gear (see photo) but we have nothing marked as this and there is no reference in the manual to a Z gear in the change gear list. Can anyone shed any light?
    thanks in advance

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  3. #2
    Join Date
    Jun 2007


    I take you are new to using these machines.
    The Z gear you refer to is shown on your threading chart.
    Look at the line with the Z and go across,these other numbers are the change gear that needs to be fitted to the gear train to achieve the desired TPI.

  4. #3
    Join Date
    Aug 2010


    Heh - that one had me going when I first got my AL335 too. Just to add to what Pipeclay said, if you note on the left hand side of your threading chart there is a little diagram showing the gear locations.

    For a practical example or two, if it helps (it took me a little bit to get my head around it for a start), take the first column in your imperial threading chart (ignore the bottom 3 rows for the moment). It shows in the diagram on the left to put the 48 tooth gear at the spindle, driving the 127 tooth gear, which in turn drives the 'Z' gear. Now, the first column shows 'Z' as a 24 tooth gear, and if you install a 24 tooth gear in position 'Z', you will be able to cut 4 TPI by setting (in the cluster of 4 knobs on the gearbox) the bottom left knob to 'A', the top left knob to '2', the top right knob to 'M', and the bottom right knob to 'II'. If you then change the bottom right knob to 'I' (leave the rest the same), you can cut 8 TPI.

    The second column across shows that 4.5TPI and 9TPI are available with the same gear at 'Z', but the top left knob must be set to '3'. When you get to the third column, you have 9.5TPI and 19TPI available (providing you set the letter and number knobs according to the table), but the row marked 'Z' shows that you must have a 38 tooth gear installed in position 'Z'.

    And finally, the bottom three rows on the table have another gear position diagram next to them, which indicates that a 24 tooth gear must be installed at the spindle, driving the 127 tooth gear which then drives the 'Z' gear. This makes available the 48 tooth gear that was previously installed at the spindle, and allows for much finer TPI counts, as can be seen as you move across the columns.

    Probably worth stating more clearly that the imperial threading chart is actually two completely separate threading charts, they are just arranged one atop the other so that the manufacturer didn't need to print a second set of the headings 'A2', 'A3' etc...

    Hope that helped to clarify things if you were still a bit unsure!

  5. #4
    Dave J Guest


    If it's like mine you when going from metric to imperial you will need to place the spacer on the Z gear shaft to the other side of the gear so it lines up with the 127 tooth gear for imperial. There is also a key that will need reversing.

    With the Z gear it's just a position for the gears, so it really should say the Z position in the manual.

    If you look at the chart and pick 11 threads per inch, you will need it in the M1 position with the 22 gear in the Z position and the levers in the C3 position.

    Hope this helps.


  6. #5
    Dave J Guest


    You posted while I was typing.


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