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Thread: First day of practice threading with lessons learned

  1. #1
    Join Date
    Dec 2017
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    First day of practice threading with lessons learned

    I woke up bright and early and decided to thread and cut the bolt nose on some blanks. First two turned out much better than expected. The third I took some measurements. I trued the face then cut the shank 1.000 long and turned it to 1.062. Then cut a small relief cut .295 from the shoulder. Seemed to be going well. I threw on my threading tool at 90 rpm after using my fishtail and did a handful of passes, .005 at a time till the outside threads looked sharp. Turned up the speed and lightly sanded. I measured and they had shrunk to 1.057. Then went on to cut the bolt face. Used a 11/16 cutter just to see how it would do, then finished with a short boring bar. My goal was .150 deep and .705 wide. It ended up .143 deep and .702 wide. I didnít clean off the face good enough when I measuring the depth and must have got a chip on the mouth cause I was sure it was right at .150 in the shop before I cleaned it up.
    Lessons learned:
    The compound moves when Iím turning the shank down if it is at 29deg.
    The chuck t handle at 505rpm goes across the shop
    The bolt nose cutter needs a pilot
    I should true the shoulder on the shank then clean off the barrel face. I didnít true the shoulder.

    Any advice welcome guys!!
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  2. #2
    Join Date
    Feb 2003
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    south beloit,il.
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    251

    Threading

    Good work.......... your on your way..........
    IMHO:
    you may see improvement if you.....
    use HS threading tool......... less tool pressure..... better finish.....
    use boring bar for bolt nose clearence....... less tool pressure and better concentricity.......
    OMHO.... but that`s the way I do it....
    bill larson

  3. #3
    Join Date
    Feb 2003
    Location
    Mt Pleasant Michigan
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    Turn yourself a plug gauge that is .7050" in diameter.
    You can use it to check the fit of the bolt nose counter bore and it's good practice to turn to an exact size.
    Keep trying different methods for threading. If you haven't tried feeding with the compound, try that way. Then thread another piece using just the cross slide and see if there is any difference in the two.
    You should also get a set of thread wires to measure with.
    There is a LOT to learn.
    My project today is trying to cut a metric thread.

    Joe Hynes

  4. #4
    Join Date
    Jul 2016
    Location
    Albany, OR
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    I think you've diagnosed most of the issues - you definitely want to true up the shoulder before doing anything else - it's the critical surface from whence all your other measurements are made (directly or indirectly).

    If your compound moves when set over, see if the gib is loose. If it seems to have little to no affect, take the compound apart and troubleshoot it. Also make sure you're allowing for backlash by always feeding into the cut. (i.e. when adjusting don't feed in too far, then back up to the correct mark - the last motion should always be feeding in.) Or is the compound rotating out of position? Something is wrong here and you should fix it. In either case it is probably affecting your other turning too, and you may just not have noticed it yet. I leave my compound set at 29.5* unless I need to adjust it for clearance issues.

    Try to develop the habit of never taking your hand off the chuck key when it is in the chuck.

    Your results are much better than my first day!

    GsT

  5. #5
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    Jan 2015
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    Greenwood, Ca
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    152
    Lathes can kill you. A chuck key is no joke. I think you've learned a lesson, but a chuck key should NEVER be left in the chuck.

  6. #6
    Join Date
    Dec 2017
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    Idaho
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    Thanks for the pointers guys. T-handle snafu is fixed. Just realized my ďthreadingĒ tool was actually a cutter. Iscar stuff on order so that will be remedied. The advice is really helping. Running into piece will help. Cross slide creep is fixed.

  7. #7
    Join Date
    May 2010
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    Colorado
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    Angry

    Quote Originally Posted by Rubicon Prec. View Post
    Lathes can kill you. A chuck key is no joke. I think you've learned a lesson, but a chuck key should NEVER be left in the chuck.
    Got sent home from lathe class during last years spring semester for leaving the chuck key in the chuck. Third time was the charm!

  8. #8
    Join Date
    Oct 2007
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    Northwest Ohio
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    Mram, if you haven't checked them out before there are some great videos on YouTube about threading, and general machining. Best I have found are tubalcain (Mr pete 222), the viper (Bob pastor), and Toms techniques. Not sure if you discussed it earlier , but the threads appear to have two crowns on them which may be a misinterpretation on my part, though. Good luck with your endeavors, and keep sharing!
    Mike

  9. #9
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    I have watched those guys. Going to watch viper again tomorrow. Long vids but worth it. Wish he had one on threading because he doesnít spend much time on the threading aspect

  10. #10
    Join Date
    Jul 2016
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    Quote Originally Posted by Mram10 View Post
    I have watched those guys. Going to watch viper again tomorrow. Long vids but worth it. Wish he had one on threading because he doesnít spend much time on the threading aspect
    Here's a set of instructions I did some time back. http://firearmsdesigner.com/?p=52 .

    Good luck!

    GsT

  11. #11
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    Great read G! Thanks. Got a lot out of it. Iíll post pics of the next piece.
    Last edited by Mram10; 12-25-2017 at 06:12 AM.

  12. #12
    Join Date
    Feb 2003
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    Tennessee
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    Quote Originally Posted by Mram10 View Post
    I woke up bright and early
    .
    Lessons learned:
    The compound moves when Iím turning the shank down if it is at 29deg.
    The chuck t handle at 505rpm goes across the shop
    The bolt nose cutter needs a pilot
    I should true the shoulder on the shank then clean off the barrel face. I didnít true the shoulder.

    Any advice welcome guys!!
    Not to hurt your feelings but PLEASE, PLEASE, get some professional training before you seriously get hurt. That little lathe can cut your arm off!! I witnessed it happening once by a guy running a Monarch 10EE.

    Look up a local technical college that teaches machine shop courses. You don't have to take the residual courses for a AS degree, just the basics of machining. The US Dept of Labor machinist training takes 4 years to get a machinist 3rd class certificate...for a reason. Much to learn.. Good luck.


    .

  13. #13
    Join Date
    Feb 2003
    Posts
    1,468
    Safety should always be your number one concern. Listen to the experts and take their advice. Treat the lathe with utmost respect. It CAN hurt you. Eye protection must always be used, NO EXCEPTIONS. Never use gloves or rags around a lathe. They can get wrapped up in the work and jerk you into harms way in a flash!

    Machining can be so much fun and very rewarding. I hope you enjoy it as much as I have. Have fun, be safe and keep in touch with us.

    Gene Beggs
    Odessa, TX

  14. #14
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    Idaho
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    Did this today. Shank diameter was about .007 small. Other measurements were +/- .001 of target. Critiques please.
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  15. #15
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    Quote Originally Posted by Mram10 View Post
    Did this today. Shank diameter was about .007 small. Other measurements were +/- .001 of target. Critiques please.
    Are those all the same piece? The first pic looks pretty good, the last looks like there's some gumminess. Are you using cutting oil? To refine things:

    1. Minimize the amount the tool is hanging out from the toolholder.
    2. Minimize the amount the work is sticking out of the chuck.
    <now check all your clearances so you don't hit the compound with a chuck jaw as you get close to the end of the thread>
    3. reduce the cut depth on your last few passes.
    4. Oh yeah, verify that your cutter is at the center of your workpiece height.

    All told, definitely an improvement - this'll be old-hat in no time!

    GsT

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