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How to get the Diameter of the threads, in thousandths, Knowing only the Gauge.
Take the Gauge number on the tap or die and multiply by 13 and then add 60. This will get you the overall or "Major" diameter of the threads in thousandths of an inch ( 1/1000).
Ex: A 3-48 thread is; 3 X 13 = 39 + 60 = .099", which it IS.
OR, on a 1-72 thread is: 1 X 13 = 13 + 60 = .073", which it IS.
However, if you measure a thread at its outside diameter or "Major" diameter with your micrometers or dial calipers and it is; .114", just subtract .060" (60) leaving .054" (54) then, divide by 13 and you will get .004" or (4), which it IS. Ex: 4-40, 4-48. For the number of threads per inch you will have to get a thread gauge and compare them to, or, with it.
Charts that you may find useful
| Size Of Thread & Threads Per Inch | Major Diameter/ Body Diameter | Pitch Diameter | Minor Diameter Internal Threads | Commercial. Tap Drill for approx. 75% Thread | Decimal Equivalent of Tap Drill |
| 0 - 80 | .060" | .0519" | .0465" | 3/64", (#55) | .0469" |
| 1 - 64 | .073" | .0629" | .0561" | #53 | .0595" |
| 1 - 72 | .073" | .0640" | .0580" | #53 | .0595" |
| 2 - 56 | .086" | .0744" | .0667" | #50 | .0700" |
| 2 - 64 | .086" | .0759" | .0691" | #50 | .0700" |
| 3 - 48 | .099" | .0855" | .0764" | #47 | .0785" |
| 3 - 56 | .099" | .0874" | .0797" | #45 | .0820" |
| 4 - 40 | .112" | .0958" | .0849" | #43 | .0890" |
| 4 - 48 | .112" | .0985" | .0894" | #42 | .0935" |
| 5 - 40 | .125" | .1088" | .0979" | #38 | .1015" |
| 5 - 44 | .125" | .1102" | .1004" | #37 | .1040" |
| 6 - 32 | .138" | .1177" | .1042" | #36 | .1065" |
| 6 - 40 | .138" | .1218" | .1109" | #33 | .1130" |
| 8 - 32 | .164" | .1437" | .1302" | #29 | .1360" |
| 8 - 36 | .164" | .1460" | .1339" | #29 | .1360" |
| 10 - 24 | .190" | .1629" | .1449" | #25 | .1495" |
| 10 - 32 | .190" | .1697" | .1562" | #21 | .1590" |
| 12 - 24 | .216" | .1889" | .1709" | #16 | .1770" |
| 12 - 28 | .216" | .1928" | .1773" | #14 | .1820" |
| 1/4 - 20 | .2500" | .2175" | .1959" | #7 | .2010" |
| 1/4 - 28 | .2500" | .2268" | .2113" | #3 | .2130" |
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Notes: 1.) Believe it or not, there are also gauge sizes 7, 9, and 11. Though rarely used, their diameters are .151", .177" and .203, respectively. 2.) Using a #55 drill for the 0-80 thread gives you .005" more clearance (1-1/2 hairs) and may help prevent breaking the tap. Music Wire GaugeSizes for Norton Springs (Buescher)
#08 = .024" wire
All Norton springs are a 3 - 48 thread size.
|
| Morse #0 | .250" - .367" |
| Morse #1 | .367" - .517" |
| Morse #2 | .569" - .744" |
| Morse #3 | .744" - .988" |
Flute pad openings-
Here is a little difference of opinion on specifications, but they are all so close; the best way is to to try and see for yourself. I believe it can vary from one instrument design (brand) to the next. No magic answer.
Suggested Flute pad openings:
| Location | Ferree's | Phelan/Brody (from book) | Butkevicious |
| trill & hi C | .080" | .100" (& thumb) | .110" |
| body joint | .110" | .120"-.125" .125", G# .100" | .125" |
| foot joint | .150" | .135" D# .125", C, C#, B .135" | .135" |