Machine screw: 14 -20 or 1/4"-20?

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Old 01-08-07, 07:44 PM
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Machine screw: 14 -20 or 1/4"-20?

I have a machine screw (bolt) that came out of a piece of structure and now I have to replace this machine screw with a longer one of the same thread size. It is 20 threads per inch and when I measure across the threads with the calipers the diameter is .240 inches.
According to my thread dimensions chart this is the thread diameter of a number 14 machine screw or, it is the thread diameter of a worn 1/4"-20 machine screw. (Visually, I suspect it's the latter). So, how can I tell the difference? Are these two machine screw sizes interchangeable?
regards,
Joe
 
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Old 01-09-07, 04:03 AM
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A machine screw ceased to be a screw, technically, when you reach the 1/4" size. It will be considered a bolt. If your inside thread measurements is approximately .240, then it is a 1/4" bolt with a machine thread. Most of the home centers have a bolt size/thread test plate in the bolt area. Take your bolt there and try it in the appropriate holes to make double sure you have the right one.
 
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Old 01-09-07, 06:40 PM
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Thanks very much for the clarification.
Regards, Joe
 
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