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internal wrenching bolt



 
 
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  #21  
Old August 23rd 19, 08:41 PM posted to rec.bicycles.tech
JBeattie
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Posts: 5,870
Default internal wrenching bolt

On Friday, August 23, 2019 at 7:59:41 AM UTC-7, Tom Kunich wrote:
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.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


That tapered head was made to cover the majority of the washer. Cap head bolts support less of the washer.


Wouldn't that depend on the size of the washer? https://images.amain.com/images/larg....jpg?width=475 Note that stem bolts also come in a conical configuration, too.
https://tinyurl.com/yxo9pvyb

-- Jay Beattie



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  #22  
Old August 23rd 19, 09:18 PM posted to rec.bicycles.tech
Chalo
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Posts: 5,093
Default internal wrenching bolt

jbeattie wrote:

Note that stem bolts also come in a conical configuration, too.
https://tinyurl.com/yxo9pvyb


To Tom, that makes them "internal wrenching bolts", despite the fact that they aren't.
  #23  
Old August 24th 19, 12:19 AM posted to rec.bicycles.tech
jOHN b.
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Posts: 2,421
Default internal wrenching bolt

On Fri, 23 Aug 2019 05:09:24 -0700 (PDT), wrote:

On Thursday, August 22, 2019 at 8:21:45 PM UTC-4, AMuzi wrote:

But for every web search 'internal wrenching bolt' I get Mil
Spec fasteners priced $15 t $30 each which are a magnitude
or more expensive than a cap screw, even a German cap screw.
The term seems to have special meaning.


The special meaning is that the manufacturer can bill the US DoD $30 for a bolt, when a $0.30 316SS hex cap screw will work just fine.


You are buying, or hope that you are buying, a bolt made to rather
exact specifications both in size and strength. And you are paying for
the company to stamp the "standards" specification number on the bolt.

The specification of the MS20004-20 bolt include:

MS20004-20 Features and Spec.
Thread Class:
3a
Thread Direction:
Right-hand
Thread Length:
0.475 inches minimum and 0.525 inches maximum
Fastener Length:
1.735 inches minimum and 1.765 inches maximum
Head Style:
Bevel-conical
Head Diameter:
0.428 inches minimum and 0.438 inches maximum
Head Height:
0.250 inches nominal
Internal Drive Style:
Hexagon
Thread Diameter:
0.250 inches
Width Across Flats:
0.188 inches minimum and 0.190 inches maximum
Thread Qty Per Inch (tpi):
28
Min. Tensile Strength (psi):
160000 pounds per square inch
Hardness Rating:
34.0 rockwell c minimum overall and 40.0 rockwell c maximum overall
Material:
Steel comp 4140 overall or steel comp e4340 overall or steel comp 6150
overall or steel comp 8735 overall or steel comp 8740 overall
Material Specification:
Mil-s-5626 mil spec 1st material response overall or mil-s-5000 mil
spec 2nd material response overall or mil-s-8503 mil spec 3rd material
response overall or mil-s-6098 mil spec 4th material response overall
or mil-s-6049 mil spec 5th material response overall
Surface Treatment:
Cadmium overall and chromate overall
Surface Treatment Specification:
Qq-p-416 type 2 class 3 fed spec all treatment responses overall
Thread Series Designator:
Unf


Now, the question is: If you are using one bolt to hold the wing on
your home built aircraft would you prefer the above bolt? Or your
$0.30 cap screw?
--
cheers,

John B.

  #24  
Old August 24th 19, 03:23 PM posted to rec.bicycles.tech
Tom Kunich[_5_]
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Posts: 1,231
Default internal wrenching bolt

On Friday, August 23, 2019 at 1:18:29 PM UTC-7, Chalo wrote:
jbeattie wrote:

Note that stem bolts also come in a conical configuration, too.
https://tinyurl.com/yxo9pvyb


To Tom, that makes them "internal wrenching bolts", despite the fact that they aren't.


You and Frank should get together - he thinks that he is a mechanical engineer as well.
 




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