4-40 or 6-32 control arms?

[Rcmaster199 at aol.com]

Rick, exactly right.  They will shear off at the base where the load  is 
maximized. It's less of an issue with the case hardened bolts since there is  
substantial margin for error, but if that was to break, that's where it  would 
appen.
 
By usingthe partially threaded bolts, the moment arm is reduced and the  load 
at the base of the thread decreased. If it ever broke, (doubtful) it would  
break at the base of the thread, most likely. The core diameter is smaller 
there  than the shank diameter. 
 
Epoxying the shank of the bolt into the hard point works great. 
 
I prefer the softer bolts because I can bend these easily with the  technique 
I have outlined before, to bring the actuation point on the hinge  line.
 
MatK
 
In a message dated 2/15/2005 2:57:25 PM Eastern Standard Time,  
knowhow3 at bellsouth.net writes:

Is the failure point on these bolts always at the base where it  goes into 
the control surface? Never having had a failure of one, I  don't know, but 
physics kind of dictates that it would be.
If so, why wouldn't a socket head or other type bolt that is only  partially 
threaded work better, since it would remove the stress  risers (threads) at 
the base area, where the force is concentrated.  Lop off the bolt head and glue 
it in. The smooth portion of the bolt  could easily be roughed up with a 
Dremel sanding drum or cutoff  wheel for CA or epoxy to grip it going into the 
control  surface.
 
Am I missing something obvious here with this idea?
 
Rick



 
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