Countersink dim
Countersink dim
(OP)
The question is Countersink dim. for a 4-40, 100 deg. c'sink
Helical sharp dim. for this screw is .225
print size callout is .231 + - .005 = .226 to .236
is this a aerospace standed
the low end seams to close to helical Max dim. of .225
or a case of lazy engineering, just use = + - .005





RE: Countersink dim
What's the assembly condition, fixed or floating?
What's the primary design consideration, flush head?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Countersink dim
+ - .005
What's the assembly condition, fixed or floating?
Fixed
What's the primary design consideration, flush head?
Flush
RE: Countersink dim
If .005 this corresponds to pos tol dia .014 (give or take a tenth of a thou)
So, to guarantee flush you need the minimum counter sink size to be the 'max sharp diameter' of the screw head, + pos tol of csk hole + post tol of threaded hole.
So if your numbers and my assumptions are correct that'd be:
.225+.014+.014 = .253 minimum.
My guess, it's a case of lazy/uneducated engineer.
Note - that while this guarantees flush, it does not optimize stress under the head or anything else, just guarantees the head should always be flush or below flush.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Countersink dim
You put in black and white the hole picture as I also see it
Dockken
RE: Countersink dim
Are you in a position to go back to the person that came up with the .231+-.005 and question/educate them?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Countersink dim
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: Countersink dim
If I get an opportunity will try, but they are reluctant to change
RE: Countersink dim
Plus the head of the screw and/or the material it's going into probably deform a bit.
Plus, unless they're really looking for it they may not notice heads just a few thousandths above flush.
However, there are situations where not being truly flush, or generating more stress under the screw heads can be a real problem.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Countersink dim
Generly around 1/8 covers, done manualy
no fun
using
Micro-Stop Countersink Units
http://www
Dockken
RE: Countersink dim
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Countersink dim
dockken