One other thing I have done in in the past was to take the next size up bolt and turn it on the lathe to make it into a shoulder bolt with a custom OD. That takes some tricky work with the single-point thread cutting tool, but I bet a decent machinist could do that for a lot less than the $580 ea quoted for the oversize bolt. I wouldn't use a cut thread like that for an application that loads the bolt in bending or tension, but I think it would be fine for a shear application, especially a double-shear application like this one.
 
Bob Kuykendall said:
One other thing I have done in in the past was to take the next size up bolt and turn it on the lathe to make it into a shoulder bolt with a custom OD. That takes some tricky work with the single-point thread cutting tool, but I bet a decent machinist could do that for a lot less than the $580 ea quoted for the oversize bolt. I wouldn't use a cut thread like that for an application that loads the bolt in bending or tension, but I think it would be fine for a shear application, especially a double-shear application like this one.
Click to expand...

Something similar is done to the bolts that hold on (in shear) the outer wing panels for Fletcher and Cresco aircraft (certified Ag type aircraft used in Australia and NZ). These aircraft have the same derivation as the Thorpe T-18 with the "bent wing". See http://www.aerospace.co.nz/aircraft/cresco/description. A few years ago I was talking to a certified machinist who makes these bolts and if I recall correctly I think he starts with a 1/2" AN bolt and turns it down to the required size and then cuts a new thread. He also said he would not do this to a close tolerance bolt as they are harder steel and I think he said they may be susceptible to hairline cracks if machined.

Fin
9A
 
Isn't that essentially...

Finley Atherton said:
Something similar is done to the bolts that hold on (in shear) the outer wing panels for Fletcher and Cresco aircraft (certified Ag type aircraft used in Australia and NZ). These aircraft have the same derivation as the Thorpe T-18 with the "bent wing". See http://www.aerospace.co.nz/aircraft/cresco/description. A few years ago I was talking to a certified machinist who makes these bolts and if I recall correctly I think he starts with a 1/2" AN bolt and turns it down to the required size and then cuts a new thread. He also said he would not do this to a close tolerance bolt as they are harder steel and I think he said they may be susceptible to hairline cracks if machined.

Fin
9A
Click to expand...

...my proposed solution from post #30 and subsequent?

A smaller bolt with a shrunk on, or force fit, steel sleeve is equivalent to a machined shoulder bolt....:) But easier to make.
 
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