Adapting a dial thread gauge Metric Vs imperial

Discussion in 'QUESTIONS & ANSWERS (Get Help Fast Here!)' started by piscov, Dec 4, 2012.

  1. piscov

    piscov Active Members Active Member

    Likes Received:
    0
    Trophy Points:
    0
    City:
    Odivelas
    State:
    Outside US / Canada
    Hello all,

    I have a Optimum 180X300 lathe with metric set up but that can also do some thread sizes in Inches .

    My problem is that this a a very basic lathe and does not have the dial thread gauge to help me threading. I am doing the threads by "eye" and some times I make mistakes.

    My question are:
    1) Can I adapt a dial thread gauge on my lathe? I think that yes,I can, and this lead me to the next question:

    2) Will it work when I am doing an Imperial thread for instance 36TPI, or its going to work only when I am doing metric threads?? ( I am assuming i can only install a metric dial gauge as my lead screw is metric.

    3) is this easy to install?

    Best regards

    Vasco
     
  2. 12bolts

    12bolts Global Moderator Staff Member Supporter

    Likes Received:
    3
    Trophy Points:
    38
    City:
    Hinchinbrook
    Vasco
    A thread dial allows you to pick up the leadscrew in the same place each time you engage the half nuts. Depending on the thread pitch you can engage it at different segments of the dial indicator.
    If you are making/adapting a thread dial for your lathe then the number of teeth on the dial gear will affect how/where you can engage it on your lathe. However if you only re-engage the half nuts on the same mark on the dial each time then you should be good to go. It may be a little slower waiting for the mark to come around, but it will be faster than reversing back to the start each time.

    Cheers Phil
     
  3. JT.

    JT. Active Members Active Member

    Likes Received:
    0
    Trophy Points:
    16
    Location:
    europe
    City:
    home
    State:
    Outside US / Canada
    from what i now you can not use the metric thread dial for imperial threads
    ore visa versa the problem is not the dail but the leadscrew it never returns to the exact place
    so the treads will change every cut
    so you need to keep the halfnut ingaged al the time and reverse the motor to go back
    if you got no ververse direction on the lathe you need to do it by hand ore change the feed direction
    please correct me if I am rong
     
  4. Tony Wells

    Tony Wells Administrator Staff Member Administrator

    Likes Received:
    17,593
    Trophy Points:
    113
    Location:
    Tyler, Texas
    City:
    Tyler
    State:
    Texas
    That is how you must do it to cut Metric on most Imperial lathes, so it seems reasonable that it would work the same the other way around.
     
  5. 12bolts

    12bolts Global Moderator Staff Member Supporter

    Likes Received:
    3
    Trophy Points:
    38
    City:
    Hinchinbrook
    As I understand it, if you try to use the segments on the dial you wont pick up the same spot on the leadscrew but if you only use the one same mark on the dial each time then it should be ok to use.
    But I stand to be corrected:whiteflag:
    I will have to try this on my lathe and see what happens :bitingnails:

    Cheers Phil
     
  6. GK1918

    GK1918 Active Members Active Member

    Likes Received:
    17
    Trophy Points:
    38
    City:
    No. Dighton
    State:
    Massachusetts
    Phils right, although I am not into metrics but I think the lathe doesnt care what threads are being cut.
    Its just a matter of timimg. The feed screw, the half nuts do not change, rather its the when and where
    to engauge half nuts. Dials are like a vehicle speedometer a driver (feed screw) driven the dial. One
    of my SBends never had one (dial) way over priced so I put an Atlas dial (dime a dozen ebay). Problem
    is Atlas dial gear is a lot smaller and less teeth than the correct one, so what happens is lines and
    number will not work. But it does work only on ONE mark. What I do is turn chuck by hand and when
    the half nut slides in, I will engauge the mesh on the dial on say No.2. And No 2 will be the number
    through out the operation. I write this if you wish to make your own. I use to run a speedometer
    cable off the leed screw to a cardboard dial with a pointer it did work, didnt look good, then the old
    timers use to paint gear teeth at engaugement points. Also I was never a beleiver in reversing the
    machine that only puts more wear Now, on both sides of the half nuts. samuel
     
  7. piscov

    piscov Active Members Active Member

    Likes Received:
    0
    Trophy Points:
    0
    City:
    Odivelas
    State:
    Outside US / Canada

    Hi Phill,
    If you could try it would be great. Please let me know.

    I will only buy the dial thread if I'm certain it will do the trick. The threads I need to do have 3-5 mm long and no more than 1 mm deep. Maybe I will be ok doing JT says. I will not even use the motor, I will rotate by hand. This threads are made on plastics.

    Cheers

    Vasco
     
  8. JT.

    JT. Active Members Active Member

    Likes Received:
    0
    Trophy Points:
    16
    Location:
    europe
    City:
    home
    State:
    Outside US / Canada
    i wonder how mutch wear will occure on the half nut after backing up the cutter en reversing the machine
    i tought it was that way most modern machines are used to cut threads
    another thing he will not need the dail
     
  9. Tony Wells

    Tony Wells Administrator Staff Member Administrator

    Likes Received:
    17,593
    Trophy Points:
    113
    Location:
    Tyler, Texas
    City:
    Tyler
    State:
    Texas
    Normally, the half nut is disengaged at the end of the thread, and the carriage is run back to take another pass, with the thread chasing dial used to synch the half nut to the previous pass.

    For such a shallow cut in plastic, I'd be tempted to do it all in one pass, once I have proven what the DoC should be. Not necessary to hand feed it, unless you are very close to a shoulder and don't feel comfortable under power. If done in a single pass, no thread chasing dial needed at all.
     
  10. lotechman

    lotechman Active Members Active Member

    Likes Received:
    1
    Trophy Points:
    0
    City:
    Abbotsford
    State:
    British Columbia
    Something that helps clarify the concept of a thread dial is to set a ruler on the ways and with the power off and thread dial engaged move the carriage noting the inches of travel and what numbers are indicated on the thread dial. Conventionally one number on the dial represents one inch of travel..... but not always if the lead screw has an unusual pitch. When operating that dial is simply an imaginary ruler travelling down your threaded piece.
    Logically if you are cutting threads per inch you can pickup on every inch. You cannot pickup on a half inch mark on the thread dial if you are cutting 11 threads per inch because you would be five and a half threads along your work. Having a imperial thread pitch on your lead screw prevents you from picking up on a metric thread. If you had a 3 mm pitch lead screw you could easily pickup on threads that were a multiple of 3mm such as 6mm but you would have difficulty picking up on a thread pitch of say 2 mm.
     
    Last edited: Dec 7, 2012
  11. piscov

    piscov Active Members Active Member

    Likes Received:
    0
    Trophy Points:
    0
    City:
    Odivelas
    State:
    Outside US / Canada
    Thank you all! You have been very helpful.
     
  12. 12bolts

    12bolts Global Moderator Staff Member Supporter

    Likes Received:
    3
    Trophy Points:
    38
    City:
    Hinchinbrook
    Hi ya Vasco,
    Sorry I was a bit slow getting to this.
    The thread chasing dial will work on any thread, provided you only use the one same mark on each engagement of the 1/2 nuts. The leadscrew/carriage relationship does not care whether you are machining a 3TPI acme, 14TPI whitworth, or 1.0 mm, (which in effect is just a 25.4TPI) anyway.
    --->JT The point of the exercise is to avoid having to wait for the carriage to travel back to the starting point to recommence the next pass, not to reduce nut wear. Also something that is a pain to do if you dont have reverse on your lathe. Cranking the drive pulley backwards gets real old real fast.

    Cheers Phil
     
  13. Tony Wells

    Tony Wells Administrator Staff Member Administrator

    Likes Received:
    17,593
    Trophy Points:
    113
    Location:
    Tyler, Texas
    City:
    Tyler
    State:
    Texas
    Phil, just out of curiosity, did you do this experiment on your lathe? If so, please remind me of what kind of lathe you ran it on. I've not done the Imperial on a Metric lathe thing before, but on an Imperial setup Mazak, even using the same number on the chasing dial, it never tracked the Metric thread the same way twice.
     
  14. 12bolts

    12bolts Global Moderator Staff Member Supporter

    Likes Received:
    3
    Trophy Points:
    38
    City:
    Hinchinbrook
    Tony,
    I have a change gear Hercus 9". It is an imperial lathe, and has had some mods done to it over the years, (some by me, others not by me). My chasing dial is not original (I dont think). Yes I did run it on my lathe. Although I only scored the thread on some ally rod, disengaged, wound back, re-engaged, and followed the previous score exactly. No compound movement. I didnt complete the full thread. Now you got me thinking maybe I was just lucky :thinking:

    Cheers Phil
     
  15. Tony Wells

    Tony Wells Administrator Staff Member Administrator

    Likes Received:
    17,593
    Trophy Points:
    113
    Location:
    Tyler, Texas
    City:
    Tyler
    State:
    Texas
    No Phil, I doubt it. I was just working over in my mind how the Mazak could have been geared differently. Of course, Yamazaki lathes are Japanese built, so I would presume they are natively Metric, and those sent to Imperial-land are geared to cut Imperial threads. But then, it's been quite a while since I scrapped....I mean re-worked those parts for Bell Helicopter. I took 2 or 3 passes before I saw it was not re-tracing the thread. Ended up doing the forward and reserve thing to cut the parts.

    There was probably more to making that lathe properly cut Metric than I knew at the time.
     
  16. 12bolts

    12bolts Global Moderator Staff Member Supporter

    Likes Received:
    3
    Trophy Points:
    38
    City:
    Hinchinbrook
    Nontheless Tony I think I will go back and redo that test, but actually cut a full thread......Dont want to be putting wrong info out there....

    cheers Phil
     

Share This Page