[Carl Boyd]

wrote in message
...
whats better for strength? i have four fasteners to choose from:

8-32

10-24

10-32

1/4"-20

If diameter is fixed, whats stronger, more or less threads?

The load will be shear, i.e., it will try to shear the bolts off,
putting stress on them in that direction.

The material is aluminum.

The screws are stainless steel.

The load will be subject to intense vibration (its an intercooler
mounted on the front of a car) and weighs about 30lbs.


Use Helicoils of similar threded inserts.

Carl Boyd

[[email protected]]

On Feb 3, 8:16*pm, "Carl Boyd" wrote:
wrote in message

...





whats better for strength? i have four fasteners to choose from:

8-32

10-24

10-32

1/4"-20

If diameter is fixed, whats stronger, more or less threads?

The load will be shear, i.e., it will try to shear the bolts off,
putting stress on them in that direction.

The material is aluminum.

The screws are stainless steel.

The load will be subject to intense vibration (its an intercooler
mounted on the front of a car) and weighs about 30lbs.

Use Helicoils of similar threded inserts.

Carl Boyd- Hide quoted text -

- Show quoted text -

let me clarify:

the fastener will go through a 1/8" thick steel bracket (unthreaded,
just a hole), and then will enter the threaded aluminum intercooler
wall, which is 3/16" thick.

the intercooler weighs 30 lbs, which makes all of this somewhat
critical i think, especially if the mounting fails, the intercooler
hits the freeway at 80mph pulling the rest of the engine with it...

is the 3/16" thickness of the aluminum too thin to do this?

i dont want to weld to the aluminum because thats just a little too
permanent, i may need to remove the bracket

what about rivets? stainless rivets can handle 1000 lbs shear...the
would be semi-permanent but could probably be drilled out if needed

[ff[_2_]]

wrote in message
...
On Feb 3, 8:16 pm, "Carl Boyd" wrote:
wrote in message

...





whats better for strength? i have four fasteners to choose from:

8-32

10-24

10-32

1/4"-20

If diameter is fixed, whats stronger, more or less threads?

The load will be shear, i.e., it will try to shear the bolts off,
putting stress on them in that direction.

The material is aluminum.

The screws are stainless steel.

The load will be subject to intense vibration (its an intercooler
mounted on the front of a car) and weighs about 30lbs.

Use Helicoils of similar threded inserts.

Carl Boyd- Hide quoted text -

- Show quoted text -

let me clarify:

the fastener will go through a 1/8" thick steel bracket (unthreaded,
just a hole), and then will enter the threaded aluminum intercooler
wall, which is 3/16" thick.

the intercooler weighs 30 lbs, which makes all of this somewhat
critical i think, especially if the mounting fails, the intercooler
hits the freeway at 80mph pulling the rest of the engine with it...

is the 3/16" thickness of the aluminum too thin to do this?

i dont want to weld to the aluminum because thats just a little too
permanent, i may need to remove the bracket

what about rivets? stainless rivets can handle 1000 lbs shear...the
would be semi-permanent but could probably be drilled out if needed



Just curious, are there four fasteners to choose from because there are
pre-existing tapped holes in the intercooler of those four sizes?

Fred

[Gunner Asch[_2_]]

On Sun, 3 Feb 2008 22:15:02 -0800 (PST), "
wrote:

The screws are stainless steel.

The load will be subject to intense vibration (its an intercooler
mounted on the front of a car) and weighs about 30lbs.

Use Helicoils of similar threded inserts.

Carl Boyd- Hide quoted text -

- Show quoted text -

let me clarify:

the fastener will go through a 1/8" thick steel bracket (unthreaded,
just a hole), and then will enter the threaded aluminum intercooler
wall, which is 3/16" thick.

the intercooler weighs 30 lbs, which makes all of this somewhat
critical i think, especially if the mounting fails, the intercooler
hits the freeway at 80mph pulling the rest of the engine with it...

is the 3/16" thickness of the aluminum too thin to do this?

How many of these bolts are you using?

Id say yes, its too thin by a considerable margin for a dynamic load
of 30lbs when vibration and G loading is included. The more bolts the
better.

weld on thickeners, at least 3/8"..many of them.

Gunner



"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

[T.Alan Kraus]

Lets see: a 1/4-20 stainless bolt has a max of 1300 lb/f of clamping
force. Shear is about 60% of that, and you plan on using 4 bolts. So
four bolts will resist a maximum shear of 3120 lb/f if torqued to about
65 inch/lb (note inch not foot). The intercooler produces a shear force
of 30 lbs at 1 G, at 10 Gs its 300, at 100 Gs its 3000. The question is
whether it will ever experience 100 Gs.

cheers
T.Alan