Bent gun adjustment screws...
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  1. #1
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    Default Bent gib adjustment screws...

    You ever seen a mill with metric dials but all the threads on the machine is imperial? Because thatís the case with the new to me Taiwanese mill I have. I wish I can find out what brand in the US uses that model since itís just Taiwanese branding (one I have is called Da Li, another brand they have is Yung Jhing)

    Anyways I need to know where I can find a new gib adjustment screw because while I bent it back I donít want the head to break off at random times.

    Iím going to borrow a lathe from a friend and machine one myself otherwise...

    Any idea what thread it is? It looks to be about similar to M8 but does not fit M8 threads.
    Last edited by taiwanluthiers; 05-10-2019 at 07:49 AM. Reason: Stupid autocorrect

  2. #2
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    1) measure outside diameter of screw.
    2) divide mm number by 25.4
    3) measure thread pitch.
    4) divide mm number by 25.4, take inverse of result.

    Report numbers back here.

  3. #3
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    measurements:

    thread count: 21 threads per inch
    diameter (measured from the diameter of the top of the thread): .310"
    the head is about .709" in diameter, exactly 18mm.

  4. #4
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    I think it may be a fine thread M8... M8x1.25 (I don't have a nut to test it)

  5. #5
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    Quote Originally Posted by taiwanluthiers View Post
    I think it may be a fine thread M8... M8x1.25 (I don't have a nut to test it)
    I think M8 x 1.25 is coarse and M8 x 1.0 is fine. Back in the 1970's, I found that Japanese and German cars liked to use different pitches on their M8 bolts. At the time, going to an import car dealer's parts counter was the quickest way to buy a metric bolt in my city.

    Larry

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    The 21 TPI is probably too coarse a measurement. Count ten threads and give the distance for that, inches or mm.

  7. #7
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    Doesn't come out very well here, but paste it into a dumb editor like notepad (or vi ) and it should be easy to see the results.

    Thread Dia/ Dia/ Pitch/ Pitch/ Core Core Depth/ Depth/
    Name Inch mm TPI mm Dia/" Dia/mm Inch mm

    -2 THURY 0.3043 7.730 20.7 1.230
    5/16 CEI 0.3125 7.938 26.0 0.977 0.2715 6.896 0.0205 0.521
    5/16 BSF 0.3130 7.938 22.0 1.155 0.2540 6.459 0.0290 0.739
    5/16 UNC 0.3130 7.938 18.0 1.411 0.2440 6.205 0.0340 0.866
    5/16 UNF 0.3130 7.938 24.0 1.058 0.2610 6.640 0.0260 0.649
    5/16 WHIT 0.3130 7.938 18.0 1.411 0.2410 6.132 0.0360 0.904
    8 LOEW 0.3150 8.000 21.2 1.200 0.2441 6.200 0.0354 0.900
    M8 Coarse 0.3150 8.000 20.3 1.250 0.2550 6.466 0.0300 0.767
    M8 Fine 0.3150 8.000 25.4 1.000 0.2670 6.773 0.0240 0.613
    20-16 ASME 0.3200 8.128 16.0 1.588 0.2388 6.066 0.0406 1.031
    20-18 ASME 0.3200 8.128 18.0 1.411 0.2478 6.295 0.0361 0.917
    20-20 ASME 0.3200 8.128 20.0 1.270 0.2550 6.478 0.0325 0.825

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    Looks like Marks listing comes from the very comprehensive thread data in size order compilation done by Andy Pugh.

    Link here :- thread_dia_pitch

    Prettier version here :- Compilation of Thread Size Informatoin

    And an Excel format version created by Ian Wright and Micheal M Jones is on Scribd :- Thread Size | Metalworking | Joining

    Simple size order regardless of thread type is invaluable when trying to figure out what the heck something obscure is and even more valuable when trying to find something to fix / replace the obscure. Downloaded mine years ago.

    Wonderful to be able to find this stuff for free but frankly every time I use it I feel a little guilty about not having paid for it! Ton of work in there and the labourer is worthy of his hire.

    Clive

  9. #9
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    In the 1970's, I bought a Taiwan machine that had interesting fasteners. The hex bolt heads and nuts were metric, but the threads were Whitworth, and they were low strength steel. I think I replaced them with grade 5 UNC fasteners. I noted at the time that the 1/2" bolts had 12 TPI. I don't think there were any BSF fasteners in that machine, so no 5/16-22.

    Larry

  10. #10
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    img_0842.jpgimg_0841.jpgimg_0840.jpg

    This is my mill... It's a Dahlih GH-1500 (says so right on the nameplate) but without the horizontal arbor, power feed, or bells and whistles. Box ways on both the Y and Z axis and dovetail on the X (seems all Dahlih mills are built this way). It does not have a power feed on the quill, seems like it was intended that the power feed be on the knee.

    For the time being if I really have to use a boring bar I can just use a drill as "power feed"...


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