THE SCUTTLEBUTT
The Scuttlebutt is the official newsletter of the Rocky
Mountain Shipwrights – Its objective is to promote, develop and further scale model shipbuilding and the study of maritime subjects, art, history and traditions. VOLUME 12,NUMBER 3
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MARCH
MEETING
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SHOP
NOTES
By Richard Painter OBJECTIVE: to cut an octagonal cross- section piece from one with square cross-section:
Step 1: Mark each longitudinal face (all 4 of them) of the piece with two parallel line drawn as follows:
Where 3/10 W just means 3/10ths of the dimension of the square cross-section. So the marked piece looks like
Step 2: Then trim off using the guide lines on adjacent faces.
To give a specific example, the stock piece supplied for the bowsprit had a 3/8" square cross section. My little calculator gives (.3)(3/8)=.1125. This is a smidge less than .125=1/8, so I marked each face as
Footnote: How close to true regular octagon is the cross-section obtained in this manner? The answer is REAL CLOSE. Specifically, the marked lines should not be marked 3/10 but rather (2-V2/2=.292893…. which is real close to 3/10. If the piece were 1" square, the error in the face width would be less than .02" and on my bowsprit mentioned above the face width error is less than .006". That is non-detectable even with our modelers' magnifiers. Anyone interested in the geometric foundation for this method may contact me at my email address: painter@math.colostate.edu NAME BADGES Name badges can be purchased through Sun Signs, Inc at 4420 Tennyson St, Denver Co. 80212. You can visit the shop or call 303-477-1594 and have the badge mailed to you. ANNUAL
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