Announcement

Collapse
No announcement yet.

Drill size calculator for tapping holes

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Originally posted by RichR View Post
    I was responding to Doozers comment, not making a recommendation. In fact, the programs help screen lists suggested Depth Of Threads
    for a small variety of materials.
    Not knocking you, the program's cool. Just commenting about the horror of being badly taught a little and self taught the rest.
    Location: Jersey City NJ USA

    Comment


    • #17
      Fair enough.
      Location: Long Island, N.Y.

      Comment


      • #18
        Originally posted by PStechPaul View Post
        Also remember that drills have a certain diameter tolerance, and typically may drill 0.001" undersize to 0.005" oversize, especially if not perfectly sharpened, and depending on how long it dwells in the hole, and other factors.
        Totally meaningless. If you feel like that than why don't you ream all your tap holes?

        Comment


        • #19
          Originally posted by Doozer View Post
          Or just subtract the pitch from the nominal diameter.
          Works inch or metric.

          -D
          Absolutely right for most threads. The rest is BS. For % of thread like 50% for stainless - that is a different story.
          Last edited by Juergenwt; 01-23-2019, 01:13 AM.

          Comment


          • #20
            The recommended drill size is just a guideline. If excessive torque is needed (assuming the tap is good), then just open the hole to the next closest size up. Or perhaps use a pin gauge to determine the actual size of the drilled hole, if you need to tap to a very close tolerance of fit.
            http://pauleschoen.com/pix/PM08_P76_P54.png
            Paul , P S Technology, Inc. and MrTibbs
            USA Maryland 21030

            Comment


            • #21
              Major Diameter - Pitch = ~75% tap drill
              Major Diameter - (Pitch x .66) = ~50% tap drill
              For inch threads Pitch = 1/TPI

              As Doozer said, it works for both inch and metric threads.
              Stuart de Haro

              Comment


              • #22
                Originally posted by hornluv View Post
                Major Diameter - Pitch = ~75% tap drill
                Major Diameter - (Pitch x .66) = ~50% tap drill
                For inch threads Pitch = 1/TPI

                As Doozer said, it works for both inch and metric threads.
                Why not complete the generalization...

                Major Diameter - (Pitch x DOT/75) = DOT% tap drill

                where DOT = desired depth of thread expressed as percentage
                Regards, Marv

                Home Shop Freeware - Tools for People Who Build Things
                http://www.myvirtualnetwork.com/mklotz

                Location: LA, CA, USA

                Comment


                • #23
                  All I ever did was use the single page pocket chart from Cleveland and my now almost wore out Tapping handbook from Dormer, also pocket size.
                  If you are doing it a lot you start remembering most..

                  Comment

                  Working...
                  X