Differences

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--- techtalk:ref:tools120 [2019/01/09 00:34]
ixl2relax ↷ Links adapted because of a move operation
+++ techtalk:ref:tools120 [2019/03/14 00:58]
hippysmack
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 {{:techtalk:ref:tools:types_of_taps_by_dr_dick.jpg?direct&300|}} ((photo by Dr Dick, annotated by Hippysmack of the XLFORUM http://xlforum.net/forums/showthread.php?t=1717904))
-===== Thread Tap and Drill sizes =====
-==== NPT ====
-    * Pipe threads come either straight (nps) or tapered (npt).  ((DR DICK of the XLFORUM  http://xlforum.net/forums/showthread.php?t=1810036&highlight=tap+die&page=2))
-    * Both are based on the pipe outside diameter as follows:
-    * 1/8 pipe = .405 pipe dia.  ((DR DICK of the XLFORUM  http://xlforum.net/forums/showthread.php?t=1810036&highlight=tap+die&page=2))
-    * 1/4 pipe = .540 dia.  ((DR DICK of the XLFORUM  http://xlforum.net/forums/showthread.php?t=1810036&highlight=tap+die&page=2))
-    * 3/8 pipe = .675 dia.  ((DR DICK of the XLFORUM  http://xlforum.net/forums/showthread.php?t=1810036&highlight=tap+die&page=2))
-    * The above sizes are the major dia of the male straight thread (as the pipe od is the major) and major dia. of tapered male thread at its big end (if fitting is made to the americian standard). ((DR DICK of the XLFORUM  http://xlforum.net/forums/showthread.php?t=1810036&highlight=tap+die&page=2))
-    * The tapered thread has diameter reduced on a taper of .0625 per inch of thread length. Almost all hardware store fittings will be tapered thread.((DR DICK of the XLFORUM  http://xlforum.net/forums/showthread.php?t=1810036&highlight=tap+die&page=2))
-    * Little known fact: All iron heads pipe threads used in cases, rocker boxes, and oil pumps are straight female thread, fitted with tapered thread male fittings.((DR DICK of the XLFORUM  http://xlforum.net/forums/showthread.php?t=1810036&highlight=tap+die&page=2))
-==== NPSC Tap Drill Sizes ====
-^Tap / Thread Size  ^Drill Size ((Starrett tap drill sizes chart)) |
-|1/8-27  |11/32  |
-|1/4-18  |7/16  |
-|3/8-18  |37/64  |
-|1/2-14  |23/32  |
-|3/4-14  |59/64  |
-\\
-==== SAE and Metric Tap Drill Sizes ====
-Below are standard pre-drill sizes for size taps used. These are common drill sizes and they are sufficient for most applications on a Sportster. ((Starrett tap drill sizes chart unless otherwise noted))
-^  SAE Tap  ^  Drill Size  ^  Drill Bit  | ^  Metric Tap  ^  Drill Bit  |
-^  Thread size   ^  #/Letter  ^  Diameter- in  | ^  Thread Size  ^  Diameter- mm / in  |
-|6-32  |  36  |0.1065 in ^ |M3 x 0.5 |2.50 mm / 0.0984 in   |
-|6-40  |  33  |0.1130 in  ^ |M3.5 x 0.6 |2.90 mm / 0.1142 in   |
-|8-32 / 8-36  |  29  |0.1360 in  ^ |M4 x 0.7 |3.30 mm / 0.1299 in  |
-|10-24  |  25  |0.1495 in   ^ |M4.5 x 0.75 |3.70 mm / 0.1457 in   |
-|10-32  |  21  |0.1590 in   ^ |M5 x 0.8 |4.20 mm / 0.1654 in   |
-|12-24  |  16  |0.1770 in   ^ |M6 x 1 |5.00 mm / 0.1968 in  |
-|12-28  |  14  |0.1820 in   ^ |M7 x 1 |6.00 mm / 0.2362 in  |
-|1/4-20  |  7  |0.2010 in  ^ |M8 x 1.25 |6.70 mm / 0.2638 in  |
-|1/4-28  |  3  |0.2130 in   ^ |M8 x 1 |7.00 mm / 0.2756 in  |
-|5/16-18  |  F  |0.2570 in  ^ |M10 x 1.5 |8.50 mm / 0.3346 in  |
-|5/16-24  |  I  |0.2720 in  ^ |M10 x 1.25 |8.70 mm / 0.3425 in  |
-|3/8-16  |  5/16  |0.3125 in  ^ |M12 x 1.75 |10.20 mm / 0.4016 in  |
-|3/8-24  |  Q  |0.3320 in  ^ |M12 x 1.25 |10.80 mm / 0.4252 in  |
-|7/16-14  |  U  |0.3680 in  ^ |M14 x 2 |12.00 mm / 0.4724 in  |
-|7/16-20 |  25/64  |0.3906 in  ^ |M14 x 1.5 |12.50 mm / 0.4921 in  |
-|1/2-13  |  27/64  |0.4219 in  ^ |M16 x 2 |14.00 mm / 0.5512 in  |
-|1/2-20  |  29/64  |0.4531 in  ^ |M16 x 1.5 |14.50 mm / 0.5709 in  |
-|9/16-12  |  31/64  |0.4844 in  ^ |M18 x 2.5 |15.50 mm / 0.6102 in  |
-|9/16-18  |  33/64  |0.5156 in  ^ |M18 x 1.5 |16.50 mm / 0.6496 in  |
-|5/8-11  |  17/32  |0..5312 in  ^ |M20 x 2.5 |17.50 mm / 0.6890 in  |
-|5/8-18  |  37/64  |0.5781 in  ^ |M20 x 1.5 |18.50 mm / 0.7283 in  |
-==== Thread Tolerance ====
-Threads can be cut to a tighter or looser fit depending on the needs or sometimes availability of drill bit sizes. For instance, drill bits are available in a wide variety of sets or kits. The most common sizes are usually the ones that are provided. However, many suppliers carry a drill index kit which comes with a huge amount of drill bits in step sizes. Some are in 1/32 steps and some are in one thousandths increments. So, if you want a close tolerance fit on a 3/8"x16 threaded connection, you could use a 0.2969" pre-drill or for a looser fit you could use a 0.3230" pre-drill. Even with a standard 0.3125" drill bit, a hand drill is not going to produce a straight hole every time. If you have to over compensate with it and wallow out the hole just a bit to get it straight, you may be producing a looser threaded connection without realizing it. Care should be taken on tighter pre-drilled holes since it creates more friction and heat when tapping than a standard or slightly larger hole and it can lead to breaking taps off in the hole or cracking the piece you're working on. ((hippysmack from the XLFORUM))
-\\
-----
-====== Removing a Broken Tap ======
-  * The best way to remove a broken carbon steel tap is to use a small hole punch to the center of the broken tap and smack it with a hammer while exploding the hardened tap. You don't stand a chance at drilling it out without damaging the hole/ threads and chances are since pressure was enough to break the tap, it'll take more pressure than that to remove the broken lil stubby that's left. ((hippysmack)) ((Article by Oldrump1 [[http://xlforum.net/forums/showthread.php?t=1959533]]))
 ====== Tap Wrenches ======

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