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Speed,Combat,Scale,Racing => Speed Talk => Topic started by: Lane Puckett on March 18, 2018, 09:43:01 PM
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The AMA speed rules reference the general section for line button dimensions. But in the general section Fig. 1 I'm not sure how to interpret the information.
https://www.modelaircraft.org/files/ControlLineGeneral2017-2018.pdf
What are the monoline button internal ID and external OD for above 0.015 and below?
It is also silent on material (steel/brass).
Am I just not seeing the information?
My guess is the ID inside is the 0.125 and material can be brass or steel. I don't see where you can come up with the right OD though.
Thank you,
Lane Puckett
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For 0.015 and under the minimum button I.D. is 8 x wire dia. There is no spec for O.D., Groove Width, or material. At a minimum the O.D. has to trap the wire. The wire needs to securely stay in place with out line tension. It can't be too large or the flying wire may become distorted during hook-up. On units and bellcranks I'm familiar with the buttons have been at least 0.250 O.D. There are also differences when using a button on a bellcrank or on a mono-line unit, where the torque wires have to be accommodated. Brass or steel are the materials of choice.
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thank you both this gets me all the detail I was looking for. Making up some twist units and couldn't figure out the minimum rules. Everything you have described has solved the puzzle.