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Quality Taps with drill size on them?

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  • #31
    Originally posted by Alan Smith View Post
    I'm tending only to buy spiral flute taps now. They just work so well.
    My preferred choice is always spiral POINT tap unless I need bottoming thread. Spiral flutes are more picky about correct tap and material combination to extract the chips and sometimes the tap breaks on exit when chip gets stuck between the tap and the hole.
    Location: Helsinki, Finland, Europe

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    • #32
      Originally posted by BCRider View Post
      Looking around the web even a little turns up some very good charts that can be printed out and either kept handy in some smaller size version or printed out more largely, glued to a backing and mounted on a wall or side of a cabinet or to the inside of the tool chest lid alongside the decimal size drill chart.

      If ANY of us are relying on either the web or a Machinist's Handbook to look up this data each and every time we need it then that's pretty poor advance planning. We should no more be doing that than we should be locating our drill index on the side of the shop furthest from the drill press or lathe.

      Plus I've always found that the better the taps the "thinner" the printing or stamping is on the shanks. In a few cases I've had to engrave the size onto the shank with a little diamond wheel. And for others to whip out the big magnifying glass. So in that case I'd rather just look at a chart anyway.
      UK members will be familiar with the Zeus Book. This lists thread pitches, diameters etc and recommended tapping drill sizes for the more common threads (Metric coarse and fine, UNC, UNF, BSF, BSW, BA). It's small enough to fit in a pocket and the pages are coolant proof.
      Last edited by Mark Rand; 03-25-2018, 05:00 PM.
      Location- Rugby, Warwickshire. UK

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      • #33
        Just how is that so? I have seen both high and low quality taps with and without tap drill sizes on them. I have even seen taps of the same size with two different drill sizes on them.

        I fail to see any relationship between the two things. And I use my own table or for critical jobs I have a calculator that not only finds an exact drill size for any percentage with any thread, but it also picks the closest standard drill size from a table and then displays the thread percentage for that drill. And you can enter different drill sizes to see what thread percentage they will result in.

        Very few of the generally stated drill sizes actually produce a 75% thread with inch threads. Metric threads usually work out better in this respect. I have been using taps for a long, long time. I have found that brand name is a much, much better indicator of the quality level than the presence or lack of a drill size marked on the shank. Also a ground tap is usually better than one that is not ground. That is also a better indicator of the quality level. Oh, and price. The list of better indicators goes on and on.

        I still say that equating a drill size marking on the tap with the quality level is very poor logic.



        Originally posted by cameron View Post
        An overly critical person might remark that those two sentences suggest that you may have failed the ones you took.
        Paul A.
        SE Texas

        And if you look REAL close at an analog signal,
        You will find that it has discrete steps.

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        • #34
          Originally posted by Paul Alciatore View Post
          Just how is that so? I have seen both high and low quality taps with and without tap drill sizes on them. I have even seen taps of the same size with two different drill sizes on them.

          I fail to see any relationship between the two things. And I use my own table or for critical jobs I have a calculator that not only finds an exact drill size for any percentage with any thread, but it also picks the closest standard drill size from a table and then displays the thread percentage for that drill. And you can enter different drill sizes to see what thread percentage they will result in.

          Very few of the generally stated drill sizes actually produce a 75% thread with inch threads. Metric threads usually work out better in this respect. I have been using taps for a long, long time. I have found that brand name is a much, much better indicator of the quality level than the presence or lack of a drill size marked on the shank. Also a ground tap is usually better than one that is not ground. That is also a better indicator of the quality level. Oh, and price. The list of better indicators goes on and on.

          I still say that equating a drill size marking on the tap with the quality level is very poor logic.
          Poor logic or not I had never seen good quality taps with drill sizes on them.With my limited machining knowledge I have only used Sowa,YG,Presto,Doall and Haycock taps all a pleasure to use after using hand taps.I was glad to see all the positive feed back from the members with more knowledge and mileage than I will ever have.I play around with this stuff for farm repairs and improving my shop equipment.I been in this Farming business for a long time and not all logical choices are the correct ones lol!
          Dale

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          • #35
            Originally posted by Tundra Twin Track View Post
            I picked up some taps at a garage sale and was surprised to see the drill size on some of them,it was mentioned on here a while back if drill size was on tap they would low quality.I was very shocked when I tryed these they went thru 1/2 MS like butter,I even tapped a 5/8" NF with drill press holding it in the drill Chuck.I also tapped thru 3/4" sockets with 1/4" NF gold coloured ones in left side of pic,name could not read on them.

            In bottom pic is what my collection is mostly,why would I bother with having these styles when the long spiral flute would do both semi bottoming and thru tapping.
            Spiral point cut easier. I guess your mileage may vary. I won't say that having the drill size listed on the tap means they are low quality, but I do know I've taken to looking up the tap drill reference table I've saved and selecting my drill by percentage of drill form. 75% most times for aluminum. 50-75% for steel depending on strength requirement, hardness of steel, ease of proper setup, etc.
            *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

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