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Drill size calculator for tapping holes

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  • Drill size calculator for tapping holes

    This is a small program I wrote for calculating what size drill to use for tapping a hole. The program defaults to National
    threads which most online charts seem to be based on. It can also calculate Unified threads as well as the hole size for
    Forming taps. The program will prompt for Major Diameter, TPI, and Depth Of Thread (DOT). It will output the calculated
    hole size and nearest drill size along with actual DOT. It also prints a chart of standard sizes to either side of that size
    along with their calculated DOTs. Here is a screenshot of what 1/4-20 at 75% DOT looks like:


    This is what the help screen looks like:

    The suggested DOTs on the help screen were posted by mklotz in several threads on this forum.

    The .zip file linked to here:

    contains 3 files.
    TapDrill.exe runs in a Windows command window.
    TapDrill runs in a Linux terminal.
    TapDrill.txt contains this brief description:
    Code:
    There are 2 executables in this archive. TapDrill.exe is a Windows
    executable that runs in a command window. It will not run under DOS.
    TapDrill with no extension is a Linux executable.
    
    The program will prompt for Major Diameter, TPI, and Depth Of
    Thread. It calculates hole size and closest standard size drill
    bit. It also prints the standard sizes to either side of that
    drill along with the percent Depth Of Thread they would produce.
    
    The program does Imperial and Metric. It also can do National,
    Unified, and Form threads.
    
    This is what the screen for 1/4-20, 75% DOT, National thread looks like:
    
    ------------------------------------------------------------------------
                        #12    0.1890"    4.8006MM  93.9%
                     4.8 MM    0.1890"    4.8000MM  93.9%
                        #11    0.1910"    4.8514MM  90.8%
                     4.9 MM    0.1929"    4.9000MM  87.9%
                        #10    0.1935"    4.9149MM  87.0%
                         #9    0.1960"    4.9784MM  83.1%
                       5 MM    0.1969"    5.0000MM  81.8%
                         #8    0.1990"    5.0546MM  78.5%
                     5.1 MM    0.2008"    5.1000MM  75.7%
                         #7    0.2010"    5.1054MM  75.4%
                   13/64 in    0.2031"    5.1594MM  72.2%
                         #6    0.2040"    5.1816MM  70.8%
                     5.2 MM    0.2047"    5.2000MM  69.7%
                         #5    0.2055"    5.2197MM  68.5%
                     5.3 MM    0.2087"    5.3000MM  63.6%
                         #4    0.2090"    5.3086MM  63.1%
                     5.4 MM    0.2126"    5.4000MM  57.6%
                         #3    0.2130"    5.4102MM  57.0%
                     5.5 MM    0.2165"    5.5000MM  51.6%
                    7/32 in    0.2188"    5.5563MM  48.0%
    
    Nearest size=        #7    0.2010"    5.1054MM  75.4%  Thread=National
    Diameter=0.2500"  TPI=20.0000   Thread Depth=75.0%  Hole Size=0.2013"
    New Major Diameter, enter to skip, h for help
    ------------------------------------------------------------------------
    
    This is what the help screen looks like:
    
    ------------------------------------------------------------------------
    Examples of properly formatted input: "#0000" "#8" "1.1" ".182" "5/16" "1 1/2"
    Leave out the quotes. Inputs with extra characters will not be accepted.
    Suggested DOTs:
    60-65 MILD AND UNTREATED STEELS
       50 HIGH CARBON STEEL, STAINLESS STEEL
       55 HIGH SPEED STEEL
       60 FREE CUTTING STAINLESS STEEL
    70-75 CAST IRON
       65 WROUGHT ALUMINUM
       75 CAST ALUMINUM
       60 WROUGHT COPPER
       70 FREE CUTTING YELLOW BRASS
       65 DRAWN BRASS
       55 MANGANESE BRONZE
    55-60 MONEL METAL
    50-60 NICKEL SILVER (GERMAN SILVER)
    
    Use "m" to toggle between Imperial and Metric and "q" to quit.
    "n" for National, "u" for Unified, or "f" for Form threads.
    The program defaults to Imperial and National threads.
    To start in Metric and Form threads, run "./TapDrill mf"
    
    New Major Diameter, enter to skip, h for help
    ------------------------------------------------------------------------
    Location: Long Island, N.Y.

  • #2
    Or just subtract the pitch from the nominal diameter.
    Works inch or metric.

    -D
    DZER

    Comment


    • #3
      Cool, but I have a scan of the table of threads, drills and thread % in the Tool Engineer's Handbook pinned up over my drill press where it's handy.
      Location: Jersey City NJ USA

      Comment


      • #4
        Thanks. I grabbed the Linux version.

        Dan
        At the end of the project, there is a profound difference between spare parts and left over parts.

        Location: SF East Bay.

        Comment


        • #5
          I am unable to run the Linux version from the command line (terminal) in Ubuntu. I used "chmod +ax TapDrill" to set execute permission for all users as well as owner, but when I type "TapDrill" it replies with "Command not found".

          I also tried to run from the GUI Files listing, but it does nothing. The GUI application I created in Lazarus does run from the GUI, but gives the same "Command not found" error message from the command line.

          If you can send me the source files, I might be able to create a Linux GUI application, as well as perhaps a Windows version, and even maybe an HTML version with JavaScript so it can be run from a browser, which could even be on a smart phone or tablet.
          http://pauleschoen.com/pix/PM08_P76_P54.png
          Paul , P S Technology, Inc. and MrTibbs
          USA Maryland 21030

          Comment


          • #6
            Originally posted by Doozer View Post
            Or just subtract the pitch from the nominal diameter.
            Works inch or metric.

            -D
            Thats what I use. For normal metric sizes I remember the drill sizes anyways...
            But I can also imagine someone using this program when you need to find acceptable substitute and have to decide between A, E, 6.1mm and #1
            Location: Helsinki, Finland, Europe

            Comment


            • #7
              Originally posted by gellfex View Post
              Cool, but I have a scan of the table of threads, drills and thread % in the Tool Engineer's Handbook pinned up over my drill press where it's handy.
              Yeah, I don't know why the "digital" guys have to make it so complicated. I have a couple of those printed charts of 75/50% threads hanging by each machine capable of drilling. I don't drill and tap every day. I'm not going to run a program when I can simply look on the wall for the size drill I need.

              Comment


              • #8
                Originally posted by PStechPaul View Post
                I am unable to run the Linux version from the command line (terminal) in Ubuntu. I used "chmod +ax TapDrill" to set execute permission for all users as well as owner, but when I type "TapDrill" it replies with "Command not found". ...
                Try it like this:
                Code:
                ./TapDrill
                Location: Long Island, N.Y.

                Comment


                • #9
                  So, you need to run another program for the speed?

                  Comment


                  • #10
                    I tried that as well. I discovered that TapDrill is a 32 bit application and I had to install support for that architecture on my machine.

                    The file properties are displayed by using "file TapDrill"

                    Then I had to follow the steps in this web page:


                    Code:
                    sudo dpkg --add-architecture i386
                    sudo apt-get update
                    sudo apt-get install libc6:i386 libncurses5:i386 libstdc++6:i386
                    
                    sudo apt-get install multiarch-support (might not be necessary)
                    I doubt that I'll ever use this in its present form, in Ubuntu or Windows. But if I can convert it to use on my Android tablet or as an HTML/JavaScript web app, it might be worthwhile.

                    Thanks.
                    http://pauleschoen.com/pix/PM08_P76_P54.png
                    Paul , P S Technology, Inc. and MrTibbs
                    USA Maryland 21030

                    Comment


                    • #11
                      Originally posted by MattiJ View Post
                      ... But I can also imagine someone using this program when you need to find acceptable substitute and have to decide between A, E, 6.1mm and #1
                      That's the reason the extra drill sizes and their DOTs are printed out. What if you have an imperial tap and metric drills, or vice versa. What if you don't
                      have letter size drills (like me). Do you have a substitute that will provide a DOT you find acceptable?

                      If charts work for you, that's fine. Nothing wrong with that. If tapping everything at 75% DOT is your preference, then subtract pitch from diameter.
                      More than one way to skin a cat.
                      Location: Long Island, N.Y.

                      Comment


                      • #12
                        What about STI drill sizes? I have lots of STI taps for Helicoils and I have no idea what drill sizes are used for them.. Get to work

                        Comment


                        • #13
                          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.
                          http://pauleschoen.com/pix/PM08_P76_P54.png
                          Paul , P S Technology, Inc. and MrTibbs
                          USA Maryland 21030

                          Comment


                          • #14
                            Originally posted by RichR View Post
                            If tapping everything at 75% DOT is your preference...
                            NOOOO!! I remember getting my mind blown many years ago finding out that my "cheat" of using a size or 2 larger drill for steel was not only OK, it was recommended!

                            FWIW, here's a shot of my table, it has all the various possible drill sizing. I'd happily post the whole thing but wouldn't that be a copyright infringement and get the site in trouble?

                            Location: Jersey City NJ USA

                            Comment


                            • #15
                              Originally posted by gellfex View Post
                              Originally posted by RichR View Post
                              If tapping everything at 75% DOT is your preference...
                              NOOOO!! I remember getting my mind blown many years ago finding out that my "cheat" of using a size or 2 larger drill for steel was not only OK, it was recommended! ...
                              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.
                              Location: Long Island, N.Y.

                              Comment

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