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Old August 23rd 19, 12:41 AM posted to rec.bicycles.tech
JBeattie
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Posts: 5,870
Default internal wrenching bolt

On Thursday, August 22, 2019 at 3:22:26 PM UTC-7, AMuzi wrote:
On 8/22/2019 4:46 PM, Tom Kunich wrote:
On Thursday, August 22, 2019 at 10:21:26 AM UTC-7, Chalo wrote:
AMuzi wrote:

Tom has a point in that most linear ("V") brake anchors do
not
have cylindrical heads and actually do look more like an
'internal
wrenching bolt':

Tom misses the substantially more important point that you won't find an "internal wrenching bolt" with metric threading, and that functionally the thing that fixes a V-brake's cable is a metric socket head cap screw. Just as a brake pivot bolt is usually a button head socket cap screw whether its head is domed or conical.


Not to be too critical - but it is the HEAD shape that is critical. As all of the illustrations that Jeff published shows - they are available in any threads. Can you explain to me exactly why you believe that the THREAD is what makes an internal wrenching head?

You're sounding more and more like Frank every day. He doesn't even understand that the difference between a taper head screw and a cap screw is. You're joining his club I see.


I have to admit I had never heard the term 'internal
wrenching bolt' until you wrote that.

Given the high profile disasters from counterfeit fasteners
sold to the Air Force and the required specification for
same (material, fit/finish tolerances, plating, hardness
etc) I could well imagine that USAF simply made up a
distinctive head shape to keep stray hardware out of their
system, keep engine mounting bolts separate from brake
system bolts and so on. I don't know that, but it's not
unreasonable.


Logically, an internal wrenching bolt is every bolt that is not an external wrenching bolt. It's like a giant venn diagram that would have socket head cap screws in the middle.

Here, study this: http://navybmr.com/study%20material/...14014A_ch6.pdf Note:

"View C shows an internal-wrenching bolt. Both the countersunk-head bolt and the internal-wrenching bolt have hexagonal recesses (six-sided holes) in their heads. They are tightened and loosened by use of appropriately sized Allen wrenches."

"Socket-Head — Socket-head machine screws are designed to be screwed into tapped holes by internal wrenching. They are used in applications that require high-strength precision products, compactness of the assembled parts, or sinking of the head into holes."

Please have a full report on my desk by 0400!

-- Jay Beattie.
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