Farm Boy dimensions

[Speedy Builder5Participant @speedybuilder5]

I have just received the drawings for Farm Boy Ic engine.  There are many strange dimensions which approximate to a fractional 1/32″ or 1/64″ equivalents.

Was Farm Boy ever a full sized engine and scaled dimensions resulted in the use of 1/32 and 1/64″ fractions ?

Bob

 

[JasonBModerator @jasonb]

It is a freelance engine.

The strange dims may be due to the CAD rounding up/down, number of decimal places or dividing a larger size by 2

[DalboyParticipant @dalboy]

I think that they approximate those measurements to make things easier for the builder to find drill bit and the like. Remember that this was drawn in America where they tend to use imperial rather than metric.

The only fractions I can see written on there are for the 1/32″ cotter pins or as we prefer split pins

 

[JasonBModerator @jasonb]

That’s the other one, number drills given as decimals. Looking at some of Jerry’s other drawings he seems to do that eg a hole given as 0.070″ which is infact a No50 drill. Probably many are common clearance sizes fot UN threads and an American builder would not think twice much like we know what to drill as clearamnce and tapping for common BA sizes off the top of our heads.

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