stunthanger.com
Building Tips and technical articles. => 1/2 A building. => Topic started by: sleepy gomez on April 10, 2013, 08:35:39 PM
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Is a 5-40 or 5-48 the right crank shaft thread for the prop?
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Cox 049 is 5-40.
#5 fine thread is 5-44; 5-48 doesn't exist in nature.
The thread on my PeeWee reed-valve 020 is 3-48 (well, at least it's .098" diameter, coarser than 2-56 and finer than 4-40 -- I'll take that to be 3-48).
What was LeRoy Cox thinking when he used those odd threads?
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3-48 and 5-40 were very common at the time those engines were designed. I believe that a rationalization of screw sizes has virtually eliminated those sizes. 3-48 screws are perfect for mounting cox 1/2 A engines. 5-40 screws are great for .29- .35 size engine mounting.
Pat
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3-48 are also the screw size for the Fox 049/07/10/15 engines also Gilbert and Wen Mac and most of the other early small engines. Perfect products sold 3-48 mounting sets for years as I remember.
Dennis
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I still see them (5-40 and 3-48) as standards, in better hardware and fasteners' outlets.
What was supposed to have replaced them, please? Metrics?
No sarcasm intended here, I'm just alarmed. (stack this info on top of sequester, guns & roses, er, Magazines! et al.)
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I still see them (5-40 and 3-48) as standards, in better hardware and fasteners' outlets.
What was supposed to have replaced them, please? Metrics?
No sarcasm intended here, I'm just alarmed. (stack this info on top of sequester, guns & roses, er, Magazines! et al.)
AFAIK they're just less popular than the even-numbered screws.