Using wires and balls to measure pitch diameter
It is customary to use wires and balls to measure pitch diameter of gages, not product threads.
However, in this software, wire and ball specifications are displayed on the product dimension screen.
They are calculated for the basic pitch diameter sizes, as applicable.
Normally, the best size wire or ball for symmetric threads (in this software, 60° and Acme threads) is the one that
would contact the flanks at the pitch diameter if there were no lead angle. Buttress threads use different rules.
For symmetric threads, this software provides two best size wires : one as just specified, the other one using
the Vogel method. There are three ways to determine a wire "constant" :
- The "zero lead angle" method, in which the effect of the lead angle is ignored;
- Using a formula that takes the lead angle into account, for small enough angles;
- The constant calculated by the Vogel method, not applicable to internal or buttress threads.
Tips on using this software : wires and balls
- For all thread profiles, you can choose to "Use" or "Ignore" (default) the lead angle. This makes a small difference in the
way the "constant" is calculated. The "best" size wire (or ball) is the same in both cases, as specified by the relevant standard.
- For symmetric threads, you have the additional choice of "Vogel", which uses the Vogel method to determine both the best size
wire and constant.
- If you enter an actual size for wire or ball, then the constant and MOW or MUB reflect that size.
- When you print the specification report, the wire/ball size printed is the best size, unless you enter an actual size.
- At present, this software does not provide specifications for wires used with tapered threads (e.g. NPT,NPTF,ANPT).
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