Meeting with some of my engineers today left me astonished. If left to
their own devices, they will turn everything into the Space Shuttle.
Actually, I think I have some of those tendencies under control. Part of
the discussion today was whether to chamfer the countersunk holes for socket
head cap screws. My point was why are the holes being countersunk to begin
with if screw heads don't get in the way of anything? Jaws dropped! Is it
an ego thing that cosmetics have a psychological contribution to pride in a
mechanism? I have to keep the budget in consideration. I'm a
form-follows-function kind of guy, but does a few extra hours of "polishing"
contribute to the energy flow of the builders? I've made some ugly stuff in
my time that works just fine.

Buerste wrote:
Meeting with some of my engineers today left me astonished. If left to
their own devices, they will turn everything into the Space Shuttle.
Actually, I think I have some of those tendencies under control. Part of
the discussion today was whether to chamfer the countersunk holes for socket
head cap screws. My point was why are the holes being countersunk to begin
with if screw heads don't get in the way of anything? Jaws dropped! Is it
an ego thing that cosmetics have a psychological contribution to pride in a
mechanism? I have to keep the budget in consideration. I'm a
form-follows-function kind of guy, but does a few extra hours of "polishing"
contribute to the energy flow of the builders? I've made some ugly stuff in
my time that works just fine.



ICK! If you are not going to countersink, use a button head screw.

You do not want people who don't care enough to make it look
professional. Sooner or later, those people start saying, "Close
enough" too often.

Stuart Wheaton fired this volley in news:8d5db
:

ICK! If you are not going to countersink, use a button head screw.

FCS! Did he say he was going to use flat-head screws in un-countersunk
holes?

Please. ASSUME that even "shorting" the design for appearance, he'd
still use the appropriate fasteners for the job. Even the friggin'
Chinese do that, and they don't give squat for quality, safety, value,
life, honesty, integrity... aw, ****... they don't give a crap about
anything except taking your money..., and they STILL use the appropriate
screws.

Wouldn't you just automatically give an American engineer snaps for
having that same skill WITHOUT instructing him on the proper way to do
it?

LLoyd

On Oct 6, 7:43*pm, "Buerste" wrote:
Meeting with some of my engineers today left me astonished. *If left to
their own devices, they will turn everything into the Space Shuttle.
Actually, I think I have some of those tendencies under control. *Part of
the discussion today was whether to chamfer the countersunk holes for socket
head cap screws. *My point was why are the holes being countersunk to begin
with if screw heads don't get in the way of anything? *Jaws dropped! *Is it
an ego thing that cosmetics have a psychological contribution to pride in a
mechanism? *I have to keep the budget in consideration. *I'm a
form-follows-function kind of guy, but does a few extra hours of "polishing"
contribute to the energy flow of the builders? *I've made some ugly stuff in
my time that works just fine.

Shouldn't the holes be "counterbored" for socket head cap screws?

On Tue, 6 Oct 2009 19:43:25 -0400, "Buerste"
wrote:

Meeting with some of my engineers today left me astonished. If left to
their own devices, they will turn everything into the Space Shuttle.
Actually, I think I have some of those tendencies under control. Part of
the discussion today was whether to chamfer the countersunk holes for socket
head cap screws.

Hey, it only takes a click on checkbox to c'bore (you did mean
c'bore?) a hole, and one more check to put a cham on it. What's the
big deal? g

--
Ned Simmons

"Denis G." wrote in message On Oct 6, 7:43 pm,
"Buerste" wrote:
Meeting with some of my engineers today left me
astonished. If left to
their own devices, they will turn everything into the
Space Shuttle.
Actually, I think I have some of those tendencies under
control. Part of
the discussion today was whether to chamfer the
countersunk holes for socket
head cap screws. My point was why are the holes being
countersunk to begin
with if screw heads don't get in the way of anything? Jaws
dropped! Is it
an ego thing that cosmetics have a psychological
contribution to pride in a
mechanism? I have to keep the budget in consideration. I'm
a
form-follows-function kind of guy, but does a few extra
hours of "polishing"
contribute to the energy flow of the builders? I've made
some ugly stuff in
my time that works just fine.

xxx Shouldn't the holes be "counterbored" for socket head
cap screws?

Seems to me that if the SHCS are on a rotating or otherwise
moving part
it would be safest if the heads were flush. In that case a
quick swipe with
a deburring tool would take care of that sharp edge at the
top of the hole.
If the SHCS are not a safety concern and can be proud of the
surface
why sink'em?
phil

Phil Kangas wrote:
"Denis G." wrote in message On Oct 6, 7:43 pm,
"Buerste" wrote:
Meeting with some of my engineers today left me
astonished. If left to
their own devices, they will turn everything into the
Space Shuttle.
Actually, I think I have some of those tendencies under
control. Part of
the discussion today was whether to chamfer the
countersunk holes for socket
head cap screws. My point was why are the holes being
countersunk to begin
with if screw heads don't get in the way of anything? Jaws
dropped! Is it
an ego thing that cosmetics have a psychological
contribution to pride in a
mechanism? I have to keep the budget in consideration. I'm
a
form-follows-function kind of guy, but does a few extra
hours of "polishing"
contribute to the energy flow of the builders? I've made
some ugly stuff in
my time that works just fine.

xxx Shouldn't the holes be "counterbored" for socket head
cap screws?

Seems to me that if the SHCS are on a rotating or otherwise
moving part
it would be safest if the heads were flush. In that case a
quick swipe with
a deburring tool would take care of that sharp edge at the
top of the hole.
If the SHCS are not a safety concern and can be proud of the
surface
why sink'em?
phil


If flush then wire tied. Racing, baby!

"Ned Simmons" wrote in message
...
On Tue, 6 Oct 2009 19:43:25 -0400, "Buerste"
wrote:

Meeting with some of my engineers today left me astonished. If left to
their own devices, they will turn everything into the Space Shuttle.
Actually, I think I have some of those tendencies under control. Part of
the discussion today was whether to chamfer the countersunk holes for
socket
head cap screws.

Hey, it only takes a click on checkbox to c'bore (you did mean
c'bore?) a hole, and one more check to put a cham on it. What's the
big deal? g

--
Ned Simmons

Hexheads are cheaper and grade 2 is just fine for most stuff. But, I DO
know not to micromanage. It's when they hijack my designs and add foof that
I speak up. I started doing prints in PDF.

On Oct 6, 7:32*pm, "Buerste" wrote:
"Ned Simmons" wrote in message

...



On Tue, 6 Oct 2009 19:43:25 -0400, "Buerste"
wrote:

Meeting with some of my engineers today left me astonished. *If left to
their own devices, they will turn everything into the Space Shuttle.
Actually, I think I have some of those tendencies under control. *Part of
the discussion today was whether to chamfer the countersunk holes for
socket
head cap screws.

Hey, it only takes a click on checkbox to c'bore (you did mean
c'bore?) a hole, and one more check to put a cham on it. What's the
big deal? g

--
Ned Simmons

Hexheads are cheaper and grade 2 is just fine for most stuff. *But, I DO
know not to micromanage. *It's when they hijack my designs and add foof that
I speak up. *I started doing prints in PDF.

Sounds like you need to have a "meeting" with your engineering team &
their leader (if they have one).

Extra features cost money.
Maybe your design team would change their mind about adding unneeded
features & fastener choice if they had to pay the difference between
your desired design & their delivered design.

Looks can matter (who's going to buy a luxury item that looks like
crap) but function & cost are important.

Maybe your engineers need a bit more schooling or supervision.
Designing a part or assembly like it's destined for the space shuttle
when it's going on a washing machine is engineering malpractice.

There is a difference between micromanaging & spelling out your design
criteria / philosophy. Given proper guidance they should be
delivering what oyu what not what they want. Your engineers should
be working for you, not getting paid to fulfill there own desires.
Are they working or is this a hobby?

When you ask for & want a Yugo they shouldn't designing & delivering a
Cadillac.

cheers
Bob

"Buerste" wrote:

Meeting with some of my engineers today left me astonished. If left to
their own devices, they will turn everything into the Space Shuttle.
Actually, I think I have some of those tendencies under control. Part of
the discussion today was whether to chamfer the countersunk holes for socket
head cap screws. My point was why are the holes being countersunk to begin
with if screw heads don't get in the way of anything? Jaws dropped! Is it
an ego thing that cosmetics have a psychological contribution to pride in a
mechanism? I have to keep the budget in consideration. I'm a
form-follows-function kind of guy, but does a few extra hours of "polishing"
contribute to the energy flow of the builders? I've made some ugly stuff in
my time that works just fine.


I counter sunk some SHCS yesterday. Didn't need too other than the screws I had were too
short to use any other way Did look more 'pro' though (hidden under a cover )

Wes

On Oct 6, 7:43*pm, "Buerste" wrote:
Meeting with some of my engineers today left me astonished. *If left to
their own devices, they will turn everything into the Space Shuttle.
Actually, I think I have some of those tendencies under control. *Part of
the discussion today was whether to chamfer the countersunk holes for socket
head cap screws. *My point was why are the holes being countersunk to begin
with if screw heads don't get in the way of anything? *Jaws dropped! *Is it
an ego thing that cosmetics have a psychological contribution to pride in a
mechanism? *I have to keep the budget in consideration. *I'm a
form-follows-function kind of guy, but does a few extra hours of "polishing"
contribute to the energy flow of the builders? *I've made some ugly stuff in
my time that works just fine.

You sink 'em in so when the heads strip out you can't grab 'em or
grind 'em, you gotta drill 'em or weld to 'em.


Dave

Wes wrote:
I counter sunk some SHCS yesterday. ... Did look more 'pro' though ...

I think machine designers get carried away with them (SHCS). The
compound on my lathe uses them. 'Gotta blow out the chips every time,
to get the wrench in.

Bob

XR650L_Dave wrote:
You sink 'em in so when the heads strip out you can't grab 'em or
grind 'em, you gotta drill 'em or weld to 'em.

That's it! Of course - how could we have been so dense as to not see
it? [insert sarcasm emoticon here].

Bob

On Oct 7, 3:32*am, "Buerste" wrote:

Hexheads are cheaper and grade 2 is just fine for most stuff. *But, I DO
know not to micromanage. *It's when they hijack my designs and add foof that
I speak up. *I started doing prints in PDF.

I agree with your approach. But the difference in price for grade 2
and grade 5 is very small. So I would vote for grade 5 bolts. Using
grade 5 bolts you might be able to use one less bolt. And using grade
5 bolts might mean the bolt can be backed out five years later.
Instead of having the head shear off and all the extra pain that
involves.

Tell your engineers that one definition of an engineer is someone that
can do what any damn fool can do, but the engineer can do it for less
money.

Dan

wrote in message
...
On Oct 7, 3:32 am, "Buerste" wrote:

Hexheads are cheaper and grade 2 is just fine for most stuff. But, I DO
know not to micromanage. It's when they hijack my designs and add foof
that
I speak up. I started doing prints in PDF.

I agree with your approach. But the difference in price for grade 2
and grade 5 is very small. So I would vote for grade 5 bolts. Using
grade 5 bolts you might be able to use one less bolt. And using grade
5 bolts might mean the bolt can be backed out five years later.
Instead of having the head shear off and all the extra pain that
involves.

Tell your engineers that one definition of an engineer is someone that
can do what any damn fool can do, but the engineer can do it for less
money.

Dan
*****************

Good one!

"Bob Engelhardt" wrote in message
...
Wes wrote:
I counter sunk some SHCS yesterday. ... Did look more 'pro' though ...

I think machine designers get carried away with them (SHCS). The compound
on my lathe uses them. 'Gotta blow out the chips every time, to get the
wrench in.

Bob

Fill them with melted casting wax.

wrote in message
...
On Oct 7, 3:32 am, "Buerste" wrote:

Hexheads are cheaper and grade 2 is just fine for most stuff. But, I DO
know not to micromanage. It's when they hijack my designs and add foof
that
I speak up. I started doing prints in PDF.

I agree with your approach. But the difference in price for grade 2
and grade 5 is very small. So I would vote for grade 5 bolts. Using
grade 5 bolts you might be able to use one less bolt. And using grade
5 bolts might mean the bolt can be backed out five years later.
Instead of having the head shear off and all the extra pain that
involves.

Tell your engineers that one definition of an engineer is someone that
can do what any damn fool can do, but the engineer can do it for less
money.

Dan


Use the correct grade bolt. Grade 8 / 5 ain't always the best. You need a
bolt that will spring stretch in preload more than the movement of the
bolted pieces. Otherwise the bolt loosens.

"Denis G." wrote in message
...
snip--.

Shouldn't the holes be "counterbored" for socket head cap screws?

Give that man a cigar!

Yep, they sure as hell should, if anything.

Harold

On Oct 7, 11:14*pm, "CalifBill" wrote:
wrote in message

...
On Oct 7, 3:32 am, "Buerste" wrote:

Hexheads are cheaper and grade 2 is just fine for most stuff. But, I DO
know not to micromanage. It's when they hijack my designs and add foof
that
I speak up. I started doing prints in PDF.

I agree with your approach. *But the difference in price for grade 2
and grade 5 is very small. *So I would vote for grade 5 bolts. *Using
grade 5 bolts you might be able to use one less bolt. *And using grade
5 bolts might mean the bolt can be backed out five years later.
Instead of having the head shear off and all the extra pain that
involves.

Tell your engineers that one definition of an engineer is someone that
can do what any damn fool can do, but the engineer can do it for less
money.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *Dan

Use the correct grade bolt. *Grade 8 / 5 ain't always the best. *You need a
bolt that will spring stretch in preload more than the movement of the
bolted pieces. *Otherwise the bolt loosens.

Use the correct grade bolt. Grade 8 / 5 ain't always the best.

True...

but.......

You need a bolt that will spring stretch in preload more than the movement of the
bolted pieces. Otherwise the bolt loosens.

The design / assembly concept to which you refer is not accomplished
by using lower grade bolts.
Perhaps a refresher on mechanics of materials or machine design is in
order.


cheers
Bob

"fftt" wrote in message
...
On Oct 7, 11:14 pm, "CalifBill" wrote:
wrote in message

...
On Oct 7, 3:32 am, "Buerste" wrote:

Hexheads are cheaper and grade 2 is just fine for most stuff. But, I DO
know not to micromanage. It's when they hijack my designs and add foof
that
I speak up. I started doing prints in PDF.

I agree with your approach. But the difference in price for grade 2
and grade 5 is very small. So I would vote for grade 5 bolts. Using
grade 5 bolts you might be able to use one less bolt. And using grade
5 bolts might mean the bolt can be backed out five years later.
Instead of having the head shear off and all the extra pain that
involves.

Tell your engineers that one definition of an engineer is someone that
can do what any damn fool can do, but the engineer can do it for less
money.

Dan

Use the correct grade bolt. Grade 8 / 5 ain't always the best. You need a
bolt that will spring stretch in preload more than the movement of the
bolted pieces. Otherwise the bolt loosens.

Use the correct grade bolt. Grade 8 / 5 ain't always the best.

True...

but.......

You need a bolt that will spring stretch in preload more than the
movement of the
bolted pieces. Otherwise the bolt loosens.

The design / assembly concept to which you refer is not accomplished
by using lower grade bolts.
Perhaps a refresher on mechanics of materials or machine design is in
order.


cheers
Bob

Actually it does require a lower grade bolt sometimes. Years ago they used
a Grade 8 on a Hopto's arm, and was always loosening. You could not get
enough preload on the bolt to stop the loosening, and have threads still in
the arm. So a Grade 5 worked much better. You have to stretch the bolt at
least the movement length of the part and not be in the plastic range of the
bolt. Grade 8 is a stronger bolt, but it can go in to the plastic range
earlier in the tightening stage.

"Harold and Susan Vordos" wrote in message
. ..

"Denis G." wrote in message
...
snip--.

Shouldn't the holes be "counterbored" for socket head cap screws?

Give that man a cigar!

Yep, they sure as hell should, if anything.

Harold


Why not use grade 2 hex heads? And, why chamfer the c-bore other than
cosmetics?

"CalifBill" wrote in message
m...

"fftt" wrote in message
...
On Oct 7, 11:14 pm, "CalifBill" wrote:
wrote in message

...
On Oct 7, 3:32 am, "Buerste" wrote:

Hexheads are cheaper and grade 2 is just fine for most stuff. But, I DO
know not to micromanage. It's when they hijack my designs and add foof
that
I speak up. I started doing prints in PDF.

I agree with your approach. But the difference in price for grade 2
and grade 5 is very small. So I would vote for grade 5 bolts. Using
grade 5 bolts you might be able to use one less bolt. And using grade
5 bolts might mean the bolt can be backed out five years later.
Instead of having the head shear off and all the extra pain that
involves.

Tell your engineers that one definition of an engineer is someone that
can do what any damn fool can do, but the engineer can do it for less
money.

Dan

Use the correct grade bolt. Grade 8 / 5 ain't always the best. You need a
bolt that will spring stretch in preload more than the movement of the
bolted pieces. Otherwise the bolt loosens.

Use the correct grade bolt. Grade 8 / 5 ain't always the best.

True...

but.......

You need a bolt that will spring stretch in preload more than the
movement of the
bolted pieces. Otherwise the bolt loosens.

The design / assembly concept to which you refer is not accomplished
by using lower grade bolts.
Perhaps a refresher on mechanics of materials or machine design is in
order.


cheers
Bob

Actually it does require a lower grade bolt sometimes. Years ago they
used a Grade 8 on a Hopto's arm, and was always loosening. You could not
get enough preload on the bolt to stop the loosening, and have threads
still in the arm. So a Grade 5 worked much better. You have to stretch
the bolt at least the movement length of the part and not be in the
plastic range of the bolt. Grade 8 is a stronger bolt, but it can go in
to the plastic range earlier in the tightening stage.


Interesting, I can still learn!

On Oct 8, 6:35*pm, "CalifBill" wrote:
"fftt" wrote in message

...
On Oct 7, 11:14 pm, "CalifBill" wrote:



wrote in message

....
On Oct 7, 3:32 am, "Buerste" wrote:

Hexheads are cheaper and grade 2 is just fine for most stuff. But, I DO
know not to micromanage. It's when they hijack my designs and add foof
that
I speak up. I started doing prints in PDF.

I agree with your approach. But the difference in price for grade 2
and grade 5 is very small. So I would vote for grade 5 bolts. Using
grade 5 bolts you might be able to use one less bolt. And using grade
5 bolts might mean the bolt can be backed out five years later.
Instead of having the head shear off and all the extra pain that
involves.

Tell your engineers that one definition of an engineer is someone that
can do what any damn fool can do, but the engineer can do it for less
money.

Dan

Use the correct grade bolt. Grade 8 / 5 ain't always the best. You need a
bolt that will spring stretch in preload more than the movement of the
bolted pieces. Otherwise the bolt loosens.
Use the correct grade bolt. *Grade 8 / 5 ain't always the best. *

True...

but.......

You need a bolt that will spring stretch in preload more than the
movement of the

bolted pieces. *Otherwise the bolt loosens.

The design / assembly concept to which you refer is not accomplished
by using lower grade bolts.
Perhaps a refresher on mechanics of materials or machine design is in
order.

cheers
Bob

Actually it does require a lower grade bolt sometimes. *Years ago they used
a Grade 8 on a Hopto's arm, and was always loosening. *You could not get
enough preload on the bolt to stop the loosening, and have threads still in
the arm. *So a Grade 5 worked much better. *You have to stretch the bolt at
least the movement length of the part and not be in the plastic range of the
bolt. *Grade 8 is a stronger bolt, but it can go in to the plastic range
earlier in the tightening stage.


Something else going on there.....urban legend perhaps?

The "spring rate" / "axial stiff" of two geometrically identical
bolts is the same....only the yield loads are different.

The elastic moduli for alloy steels are all pretty much the same which
explains why the bolts perform the same until one yields.

Are your trying to tell me that a Grade 8 bolt will go "plastic" at a
lower load than a Grade 5 bolt?

.......I don't think so, show me the data.

better yet, here's the data

http://www.boltdepot.com/fastener-in...ade-Chart.aspx


If the bolts are short, there isn't going to be much stretching going
on.
If want to get some stretch, you have to reduce the bolt's "spring
rate" (aka "axial stiffness")

this can be done by:

going to a smaller diameter bolt,
a longer bolt,
adding some bolting compliance, like a disc spring (aka cupped washer,
Belleville washer)
using a different bolt material (copper based, Ti)

not by using a lower strength steel alloy

cheers
Bob

On Fri, 9 Oct 2009 00:33:56 -0400, "Buerste" wrote:


"Harold and Susan Vordos" wrote in message
...

"Denis G." wrote in message
...
snip--.

Shouldn't the holes be "counterbored" for socket head cap screws?

Give that man a cigar!

Yep, they sure as hell should, if anything.

Harold


Why not use grade 2 hex heads? And, why chamfer the c-bore other than
cosmetics?

Excellent question.

Gunner

GUNNER'S PRAYER:
"God grant me the serenity to accept the people
that don't need to get shot, the courage to shoot
the people that need shooting and the wisdom to know the difference.
And if need be, the skill to get it done before I have to reload."


0

"fftt" wrote in message
...
On Oct 8, 6:35 pm, "CalifBill" wrote:
"fftt" wrote in message

...
On Oct 7, 11:14 pm, "CalifBill" wrote:



wrote in message

...
On Oct 7, 3:32 am, "Buerste" wrote:

Hexheads are cheaper and grade 2 is just fine for most stuff. But, I
DO
know not to micromanage. It's when they hijack my designs and add foof
that
I speak up. I started doing prints in PDF.

I agree with your approach. But the difference in price for grade 2
and grade 5 is very small. So I would vote for grade 5 bolts. Using
grade 5 bolts you might be able to use one less bolt. And using grade
5 bolts might mean the bolt can be backed out five years later.
Instead of having the head shear off and all the extra pain that
involves.

Tell your engineers that one definition of an engineer is someone that
can do what any damn fool can do, but the engineer can do it for less
money.

Dan

Use the correct grade bolt. Grade 8 / 5 ain't always the best. You need
a
bolt that will spring stretch in preload more than the movement of the
bolted pieces. Otherwise the bolt loosens.
Use the correct grade bolt. Grade 8 / 5 ain't always the best.

True...

but.......

You need a bolt that will spring stretch in preload more than the
movement of the

bolted pieces. Otherwise the bolt loosens.

The design / assembly concept to which you refer is not accomplished
by using lower grade bolts.
Perhaps a refresher on mechanics of materials or machine design is in
order.

cheers
Bob

Actually it does require a lower grade bolt sometimes. Years ago they used
a Grade 8 on a Hopto's arm, and was always loosening. You could not get
enough preload on the bolt to stop the loosening, and have threads still
in
the arm. So a Grade 5 worked much better. You have to stretch the bolt at
least the movement length of the part and not be in the plastic range of
the
bolt. Grade 8 is a stronger bolt, but it can go in to the plastic range
earlier in the tightening stage.


Something else going on there.....urban legend perhaps?

The "spring rate" / "axial stiff" of two geometrically identical
bolts is the same....only the yield loads are different.

The elastic moduli for alloy steels are all pretty much the same which
explains why the bolts perform the same until one yields.

Are your trying to tell me that a Grade 8 bolt will go "plastic" at a
lower load than a Grade 5 bolt?

.......I don't think so, show me the data.

better yet, here's the data

http://www.boltdepot.com/fastener-in...ade-Chart.aspx


If the bolts are short, there isn't going to be much stretching going
on.
If want to get some stretch, you have to reduce the bolt's "spring
rate" (aka "axial stiffness")

this can be done by:

going to a smaller diameter bolt,
a longer bolt,
adding some bolting compliance, like a disc spring (aka cupped washer,
Belleville washer)
using a different bolt material (copper based, Ti)

not by using a lower strength steel alloy

cheers
Bob

No, I am saying the Grade 8 will not stretch as much in the elastic range
before getting into the plastic range. The Grade 8 will hold a lot more
force for the same diameter. And if you are going in to internal theads,
threads are not normally grade 8 and will pull out before you can get enough
preload on the bolt to stretch it the length needed.

On Oct 8, 11:09*pm, "CalifBill" wrote:
"fftt" wrote in message

...
On Oct 8, 6:35 pm, "CalifBill" wrote:



"fftt" wrote in message

....
On Oct 7, 11:14 pm, "CalifBill" wrote:

wrote in message

....
On Oct 7, 3:32 am, "Buerste" wrote:

Hexheads are cheaper and grade 2 is just fine for most stuff. But, I
DO
know not to micromanage. It's when they hijack my designs and add foof
that
I speak up. I started doing prints in PDF.

I agree with your approach. But the difference in price for grade 2
and grade 5 is very small. So I would vote for grade 5 bolts. Using
grade 5 bolts you might be able to use one less bolt. And using grade
5 bolts might mean the bolt can be backed out five years later.
Instead of having the head shear off and all the extra pain that
involves.

Tell your engineers that one definition of an engineer is someone that
can do what any damn fool can do, but the engineer can do it for less
money.

Dan

Use the correct grade bolt. Grade 8 / 5 ain't always the best. You need
a
bolt that will spring stretch in preload more than the movement of the
bolted pieces. Otherwise the bolt loosens.
Use the correct grade bolt. Grade 8 / 5 ain't always the best.

True...

but.......

You need a bolt that will spring stretch in preload more than the
movement of the

bolted pieces. Otherwise the bolt loosens.

The design / assembly concept to which you refer is not accomplished
by using lower grade bolts.
Perhaps a refresher on mechanics of materials or machine design is in
order.

cheers
Bob

Actually it does require a lower grade bolt sometimes. Years ago they used
a Grade 8 on a Hopto's arm, and was always loosening. You could not get
enough preload on the bolt to stop the loosening, and have threads still
in
the arm. So a Grade 5 worked much better. You have to stretch the bolt at
least the movement length of the part and not be in the plastic range of
the
bolt. Grade 8 is a stronger bolt, but it can go in to the plastic range
earlier in the tightening stage.

Something else going on there.....urban legend perhaps?

The "spring rate" */ "axial stiff" of two geometrically identical
bolts *is the same....only the yield loads are different.

The elastic moduli for alloy steels are all pretty much the same which
explains why the bolts perform the same until one yields.

Are your trying to tell me that a Grade 8 bolt will go "plastic" at a
lower load than a Grade 5 bolt?

......I don't think so, show me the data.

better yet, here's the data

http://www.boltdepot.com/fastener-in...-and-Grades/Bo...

If the bolts are short, there isn't going to be much stretching going
on.
If want to get some stretch, you have to reduce the bolt's "spring
rate" (aka "axial stiffness")

this can be done by:

going to a smaller diameter bolt,
a longer bolt,
adding some bolting compliance, like a disc spring (aka cupped washer,
Belleville washer)
using a different bolt material (copper based, Ti)

not by using a lower strength steel alloy

cheers
Bob

No, I am saying the Grade 8 will not stretch as much in the elastic range
before getting into the plastic range. *The Grade 8 will hold a lot more
force for the same diameter. *And if you are going in to internal theads,
threads are not normally grade 8 and will pull out before you can get enough
preload on the bolt to stretch it the length needed.


For identical bolt / assembly geometry, a Grade 8 & a Grade 5 bolt,
when preloaded to the same load, will stretch the same amount.

Since the yield point (either measured in load or stress) of the Grade
8 bolt is higher than that of the Grade 5 bolt....the Grade 8 bolt
will actually stretch (elastically) more before yielding than the
Grade 5 bolt. Of course, at the same load (as long as the load is
below the yield of the Grade 5), both will stretch the same amount.

for example; consider a "mystical" bolt that has a cross-sectional
area of .1 sq inch.

uisng the material properties data from the "bolt chart"

the Grade 8 bolt with yield at ~ 13,000 lbs
the Grade 5 bolt with yield at ~ 9300 lbs

so if each bolt is taken to a load just their respective yield points;
the Grade 8 bolt will actually strecth 1.4x as much as the Grade 5
bolt.
The actual bolt stretch will be driven by the active length of a
bolt.....that's why longer bolts perform better where one needs to
maintain a pre-load.

wrt base material threads not being "Grade 8", just increase the
thread engagement length. Also that's what thread inserts (aka
Helicoils) are for.

Cheers
Bob

"fftt" wrote in message
...
On Oct 8, 11:09 pm, "CalifBill" wrote:
"fftt" wrote in message

...
On Oct 8, 6:35 pm, "CalifBill" wrote:



"fftt" wrote in message

...
On Oct 7, 11:14 pm, "CalifBill" wrote:

wrote in message

...
On Oct 7, 3:32 am, "Buerste" wrote:

Hexheads are cheaper and grade 2 is just fine for most stuff. But, I
DO
know not to micromanage. It's when they hijack my designs and add
foof
that
I speak up. I started doing prints in PDF.

I agree with your approach. But the difference in price for grade 2
and grade 5 is very small. So I would vote for grade 5 bolts. Using
grade 5 bolts you might be able to use one less bolt. And using grade
5 bolts might mean the bolt can be backed out five years later.
Instead of having the head shear off and all the extra pain that
involves.

Tell your engineers that one definition of an engineer is someone that
can do what any damn fool can do, but the engineer can do it for less
money.

Dan

Use the correct grade bolt. Grade 8 / 5 ain't always the best. You
need
a
bolt that will spring stretch in preload more than the movement of the
bolted pieces. Otherwise the bolt loosens.
Use the correct grade bolt. Grade 8 / 5 ain't always the best.

True...

but.......

You need a bolt that will spring stretch in preload more than the
movement of the

bolted pieces. Otherwise the bolt loosens.

The design / assembly concept to which you refer is not accomplished
by using lower grade bolts.
Perhaps a refresher on mechanics of materials or machine design is in
order.

cheers
Bob

Actually it does require a lower grade bolt sometimes. Years ago they
used
a Grade 8 on a Hopto's arm, and was always loosening. You could not get
enough preload on the bolt to stop the loosening, and have threads still
in
the arm. So a Grade 5 worked much better. You have to stretch the bolt
at
least the movement length of the part and not be in the plastic range of
the
bolt. Grade 8 is a stronger bolt, but it can go in to the plastic range
earlier in the tightening stage.

Something else going on there.....urban legend perhaps?

The "spring rate" / "axial stiff" of two geometrically identical
bolts is the same....only the yield loads are different.

The elastic moduli for alloy steels are all pretty much the same which
explains why the bolts perform the same until one yields.

Are your trying to tell me that a Grade 8 bolt will go "plastic" at a
lower load than a Grade 5 bolt?

......I don't think so, show me the data.

better yet, here's the data

http://www.boltdepot.com/fastener-in...-and-Grades/Bo...

If the bolts are short, there isn't going to be much stretching going
on.
If want to get some stretch, you have to reduce the bolt's "spring
rate" (aka "axial stiffness")

this can be done by:

going to a smaller diameter bolt,
a longer bolt,
adding some bolting compliance, like a disc spring (aka cupped washer,
Belleville washer)
using a different bolt material (copper based, Ti)

not by using a lower strength steel alloy

cheers
Bob

No, I am saying the Grade 8 will not stretch as much in the elastic range
before getting into the plastic range. The Grade 8 will hold a lot more
force for the same diameter. And if you are going in to internal theads,
threads are not normally grade 8 and will pull out before you can get
enough
preload on the bolt to stretch it the length needed.


For identical bolt / assembly geometry, a Grade 8 & a Grade 5 bolt,
when preloaded to the same load, will stretch the same amount.

Since the yield point (either measured in load or stress) of the Grade
8 bolt is higher than that of the Grade 5 bolt....the Grade 8 bolt
will actually stretch (elastically) more before yielding than the
Grade 5 bolt. Of course, at the same load (as long as the load is
below the yield of the Grade 5), both will stretch the same amount.

for example; consider a "mystical" bolt that has a cross-sectional
area of .1 sq inch.

uisng the material properties data from the "bolt chart"

the Grade 8 bolt with yield at ~ 13,000 lbs
the Grade 5 bolt with yield at ~ 9300 lbs

so if each bolt is taken to a load just their respective yield points;
the Grade 8 bolt will actually strecth 1.4x as much as the Grade 5
bolt.
The actual bolt stretch will be driven by the active length of a
bolt.....that's why longer bolts perform better where one needs to
maintain a pre-load.

wrt base material threads not being "Grade 8", just increase the
thread engagement length. Also that's what thread inserts (aka
Helicoils) are for.

Cheers
Bob


Why would you say it stretches 40% more? Because there yield points are 40%
different. Load both bolts to 9000# and how much will it stretch? Do the
same for Grade 8. How much will it stretch? A lot less.

On Oct 10, 5:53*am, "CalifBill" wrote:
. *Load both bolts to 9000# and how much will it stretch? *Do the
same for Grade 8. *How much will it stretch? *A lot less.

Actually the all bolts , grade 2, grade 5 and grade 8 will all stretch
essentially the same as long as the bolts are not stressed above their
yield load. There are slight differences between the values of Youngs
modulus for various steels, but for engineering work one can use
30,000,000 psi for all steels.

Dan

wrote in message
...
On Oct 10, 5:53 am, "CalifBill" wrote:
. Load both bolts to 9000# and how much will it stretch? Do the
same for Grade 8. How much will it stretch? A lot less.

Actually the all bolts , grade 2, grade 5 and grade 8 will all stretch
essentially the same as long as the bolts are not stressed above their
yield load. There are slight differences between the values of Youngs
modulus for various steels, but for engineering work one can use
30,000,000 psi for all steels.

Dan

30,000,000?

I'm no mathematician, nor am I an engineer---------but 30,000 seems more
appropriate.

What am I missing?

Harold

On Oct 10, 1:23*pm, "Harold and Susan Vordos" wrote:
wrote in message

...
On Oct 10, 5:53 am, "CalifBill" wrote:

. Load both bolts to 9000# and how much will it stretch? Do the
same for Grade 8. How much will it stretch? A lot less.

Actually the all bolts , grade 2, grade 5 and grade 8 will all stretch
essentially the same as long as the bolts are not stressed above their
yield load. *There are slight differences between the values of Youngs
modulus for various steels, but for engineering work one can use
30,000,000 psi for all steels.

* * * * * * * * * * * * * * * * * * * * * * * * * * * *Dan

30,000,000?

I'm no mathematician, nor am I an engineer---------but 30,000 seems more
appropriate.

What am I missing?

Harold

The elastic modulus (Young's modulus) is (for most steels ~30,000,000
psi)

You most likely are confusing yield stress for dead soft
steel ........it is in the range of 30,000 psi

for alloy steels (depending on alloy & heat treat) yield stress can be
like 70,000 psi to 200,000+ psi

the modulus (E) relates stress to strain via Hook's law stress = E *
strain;

since strain is "dimensionless", both E & stress have the same units;
psi (for example)

btw most, if not all, mathematicians have no clue about Young's
modulus, Hook's law, stress or strain

cheers
Bob

On Wed, 07 Oct 2009 09:17:53 -0400, Bob Engelhardt
wrote:

XR650L_Dave wrote:
You sink 'em in so when the heads strip out you can't grab 'em or
grind 'em, you gotta drill 'em or weld to 'em.

That's it! Of course - how could we have been so dense as to not see
it? [insert sarcasm emoticon here].

No, they would deliberately counterbore the bolt head like that so
you can't repair it, and have to go back to the manufacturer to buy a
complete new widget. When you repair the tool or widget, they lose
money. Better yet, you have to buy two or three spare widgets, so you
don't lose productivity while the order arrives.

What the mfgrs forget to factor in is that rarely is a widget only
available from a sole source, so making a disposable device can be
more of a liability. Burn too many customers with a clever design
that is deliberately not serviceable, and they start looking around to
see where else to get the same functionality that /can/ be fixed in
the field.

Or they'll redesign it better and start building them for sale
themselves, and you just started a competitor.

-- Bruce --

Engineer is a professional . They screw up and get paid for it .


Grade II bolt is so bad , its not used in any critical stuff .
Its softer and galls . ...Zinc plating does a sim stunt on bolts .
But exclude Japaneese yellow Zinc treatment on car bolts .
Its way better .

Very hi UTS aka Tensile strength ..
makes steel competitive with other materials ,
next they want mucho Elongation to pass the stress
on to other parts of the structure .


A Square steel bar 1" by 1" elongates about .0012" for
about 30 kips , if its CRS aka Cold_Rolled_Steel.

Hot Rolled is worthless . Ornamental iron gates ...

NC bolts are better than NF . you get more thread strength .
They do not loosen easier , even with lube .

Aircraft bolts take ONLY shear loads , look at the tiny head .
The extra weight of more and bigger bolts as compensation
is only a few pounds .

But we use both . Hardened washers increase the strength
mucho .

The most accurate torque wrench is a beam type
with a H'F' dial Indicator . You can move the D'I' around
to get it to read rite .
You can make one in 15 minutes . Use a 3/8 drive
breaker bar . Add a long lever and the D'I' .
Another thing ..... A MUST have tool is Harbor Freight
$6 hand impact . hammer on one end , phillips #1 bit on other
end .

All Japaneese motorcycles needed this in the 80's ,
then they switched to hex heads .

Sears has some deals . I cant find 12 point sockets , Sears
has them , also couldnt resist some off brand socket sets at
$6 ! ..
Also the Micro-Water pump pliers / ignition pliers are
$10 .


_________________________________________


Tell your engineers that one definition of an engineer is someone that
can do what any damn fool can do, but the engineer can do it for less
money.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *Dan
*****************

Good one!

On Wed, 14 Oct 2009 18:26:59 -0800, the infamous "Paul Hovnanian P.E."
scrawled the following:

Found on the InterToobs somewhere. Author unknown.

The designer sat at his drafting board
A wealth of knowledge in his head was stored.
Like "what can be done on a radial drill
Or a turret lathe or a vertical mill?"

But above all things a knack he had
Of driving gentle machinists mad.
So he mused as he thoughtfully scratched his bean,
"Just how can I make this thing hard to machine?

"If I make this perfect body straight
The job had oughta come out first rate.
But 'twould be be so easy to turn and bore
That it would never make a machinist sore.

"So I'll put a compound taper there
And a couple of angles to make them swear,
And brass could work for this little gear
But it's too damned easy to work I fear.

"So just to make the machinist squeal
I'll make him mill it from tungsten steel.
And I'll put these holes that hold the cap
Down underneath where they can't be tapped.

"Now if they can make this it'll just be luck
'Cause it can't be held by dog or chuck
And it can't be planed and it can't be ground
So I feel my design is unusually sound."

And he shouted in glee, "Success at at last!
This goddamn thing can't even be cast!".

That's great, Paul. Thanks for sharing. I used to feel that all the
automotive design engineermuthuhs in Detroit used his exact style back
in another life, when I was wrenching for a living.

--
The blind are not good trailblazers.

-- federal judge Frank Easterbrook

On Oct 14, 8:11*pm, MansD8 wrote:
* Engineer is a professional . *They screw up and get paid for it .

* * * Grade II bolt is so bad , its not used in any critical stuff ..
*Its softer and galls . *...Zinc plating does a sim stunt on bolts .
*But exclude Japaneese yellow Zinc treatment on car bolts .
*Its way better *.

* * * *Very hi UTS aka Tensile strength ..
*makes steel competitive with other materials ,
*next they want mucho Elongation to pass the stress
*on to other parts of the structure .

* * * *A Square steel bar 1" by 1" elongates about .0012" *for
* *about 30 kips , if its CRS aka *Cold_Rolled_Steel.

* * *Hot Rolled is worthless . *Ornamental iron gates ...

* * NC bolts are better than NF . *you get more thread strength .
* * They do not loosen easier , even with lube .

* * Aircraft bolts take ONLY shear loads , look at the tiny head .
* *The extra weight of more and bigger bolts as compensation
* *is only a few pounds .

* * *But we use both . Hardened washers increase the strength
* *mucho .

* * *The most accurate torque wrench is a beam type
* *with a H'F' dial Indicator . You can move the D'I' around
* *to get it to read rite .
* * * * You can make one in 15 minutes . Use a 3/8 drive
* *breaker bar . Add a long lever and the D'I' *.
* * * Another thing ..... * A MUST have tool is *Harbor Freight
* *$6 hand impact . *hammer on one end , phillips #1 bit on other
end .

* * * * All Japaneese motorcycles needed this in the 80's ,
* * then they switched to hex heads .

* * *Sears has some deals . *I cant find 12 point sockets , Sears
* *has them , also couldnt resist some off brand socket sets at
$6 ! *..
* * * Also the *Micro-Water pump pliers / ignition pliers are
* * $10 .
* * * * * * * * * * * * * * * * * * * * * * * * * * *Dan
*****************

Good one!



Too much mis-information in this post to refute all of it in detail


Very hi UTS aka Tensile strength ..
makes steel competitive with other materials ,
next they want mucho Elongation to pass the stress
on to other parts of the structure .

huh?

A Square steel bar 1" by 1" elongates about .0012" for
about 30 kips , if its CRS aka Cold_Rolled_Steel.

if true....basically true for all steel alloys, modulus is not a
strong function of alloy


NC bolts are better than NF . you get more thread strength .

basically wrong; NC has its applications as does NF but NF is
generally stronger

Aircraft bolts take ONLY shear loads , look at the tiny head .
The extra weight of more and bigger bolts as compensation
is only a few pounds .

wrong again; designers often shoot for fasteners in shear but not
always possible, "aircraft bolts", as you call them, come in a wide
range of types and styles. Bolt heads & nuts sizes are typically
sized to fully develop bolt shank.

cheers
Bob