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Threading question

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  • Threading question

    I have been watching some threading videos on U Tube. On a 1” diameter 16 tpi steel bar similar to a rifle barrel shank They were taking heavy enough cuts to produce a continuous curling chip. Starting a thread I may take a couple of .015 cuts then reduce to .005 and on down. What DOC do you take and why?
    Byron Boucher
    Burnet, TX

  • #2
    SECO has a chart floating around that give a recommended depth for each threading pass. But I do what you do and at around 16 TPI I stop short and take .001 passes tell I get it to size. With a deep thread there is more drag on the cutter and more chance of flex.


    • #3
      I use HSS only on the smaller pitches and spend more time honing the tool so it produces a continous chip at very light cuts usually .002 or less.

      I also start rough with .006-8" passes until the last .005",then drop to .001 and finish up setting the topslide in .0005" for the last couple passes so both flanks get wiped clean.
      I just need one more tool,just one!


      • #4
        When you pay 300+ bucks for a top quality barrel, I tend to treat it carefully. It's not a production shop, or shouldn't be. Starting out with a .015" on the compound, then a few .010s, and back down to the final couple passes at .002 or .001. For a 16 TPI, somewhere around .050 to .052 advance on the compound should do it, depending on the receiver threads.