I need to undo 4 x CSK stainless steel screws 3/8x24 UNF
These are screwed into 6061 anodized billet aluminium.

Fixed by a Loctite (or similair) thread lock

The heads are imperial allen socket.

From past experience I know that even non-Loctite ones can be difficult
to remove, the screws being stainless are relatively soft and they will
round out easily.

Any thoughts over best approach .... I could leave a soak in Plus-gas
penetrating oil, but unsure if that will help .... or I could apply heat.

If the latter then how much to help break loctite, without damaging
anodized finish or softening screw. .... I have a micro propane torch so
could apply localised heat ...

I also have a pneumatic impact wrench .. I could also use that rather
than just allen socket in ratchet handle

On 06/12/2016 15:18, rick wrote:
I need to undo 4 x CSK stainless steel screws 3/8x24 UNF
These are screwed into 6061 anodized billet aluminium.

Fixed by a Loctite (or similair) thread lock

The heads are imperial allen socket.

From past experience I know that even non-Loctite ones can be difficult
to remove, the screws being stainless are relatively soft and they will
round out easily.

Any thoughts over best approach .... I could leave a soak in Plus-gas
penetrating oil, but unsure if that will help .... or I could apply heat.

If the latter then how much to help break loctite, without damaging
anodized finish or softening screw. .... I have a micro propane torch so
could apply localised heat ...

I also have a pneumatic impact wrench .. I could also use that rather
than just allen socket in ratchet handle

I would expect them to snap if you try impact. Heat will break up
loctite, but it will be hard to get significant heat to the right point.
A T bar driver would be favourite, trying forward and back till they
come free. Otherwise drill the heads, remove the fitting and get mole
grips on the remains.

On 12/6/2016 3:18 PM, rick wrote:
I need to undo 4 x CSK stainless steel screws 3/8x24 UNF
These are screwed into 6061 anodized billet aluminium.

Fixed by a Loctite (or similair) thread lock

The heads are imperial allen socket.

From past experience I know that even non-Loctite ones can be difficult
to remove, the screws being stainless are relatively soft and they will
round out easily.

Any thoughts over best approach .... I could leave a soak in Plus-gas
penetrating oil, but unsure if that will help .... or I could apply heat.

If the latter then how much to help break loctite, without damaging
anodized finish or softening screw. .... I have a micro propane torch so
could apply localised heat ...

I also have a pneumatic impact wrench .. I could also use that rather
than just allen socket in ratchet handle


IIRC it should soften at something like 150 C, and certainly by 200.
Also at temperature, differential thermal expansion will be working your
way. These temperatures won't soften the screw and should not affect the
anodising. I wouldn't try to heat locally, I would cook the whole thing
in an oven (assuming it will fit).

"rick" wrote in message news

I need to undo 4 x CSK stainless steel screws 3/8x24 UNF
These are screwed into 6061 anodized billet aluminium.

Fixed by a Loctite (or similair) thread lock

The heads are imperial allen socket.

From past experience I know that even non-Loctite ones can be difficult to
remove, the screws being stainless are relatively soft and they will round
out easily.

Any thoughts over best approach .... I could leave a soak in Plus-gas
penetrating oil, but unsure if that will help .... or I could apply heat.

If the latter then how much to help break loctite, without damaging
anodized finish or softening screw. .... I have a micro propane torch so
could apply localised heat ...

I also have a pneumatic impact wrench .. I could also use that rather than
just allen socket in ratchet handle

Red hot poker (or preferably a copper bar) applied to the screw head. Once
the Loctite is close to 100 deg C it will let go and can be undone.

Andrew

On 06/12/2016 15:45, MrCheerful wrote:


I also have a pneumatic impact wrench .. I could also use that rather
than just allen socket in ratchet handle

I would expect them to snap if you try impact. Heat will break up
loctite, but it will be hard to get significant heat to the right point.
A T bar driver would be favourite, trying forward and back till they
come free. Otherwise drill the heads, remove the fitting and get mole
grips on the remains.


Drilling not an option ... this is an assembled part - been replaced
under warranty - have to send old one back - they have agreed to split
it to make package much smaller ... but can't damage anything.

I have a T-bar so will use that .. I can apply heat direct to screw head
but concerned aluminium will draw away the heat

On 06/12/2016 16:22, newshound wrote:
On 12/6/2016 3:18 PM, rick wrote:
I need to undo 4 x CSK stainless steel screws 3/8x24 UNF
These are screwed into 6061 anodized billet aluminium.

Fixed by a Loctite (or similair) thread lock

The heads are imperial allen socket.

From past experience I know that even non-Loctite ones can be difficult
to remove, the screws being stainless are relatively soft and they will
round out easily.

Any thoughts over best approach .... I could leave a soak in Plus-gas
penetrating oil, but unsure if that will help .... or I could apply heat.

If the latter then how much to help break loctite, without damaging
anodized finish or softening screw. .... I have a micro propane torch so
could apply localised heat ...

I also have a pneumatic impact wrench .. I could also use that rather
than just allen socket in ratchet handle


IIRC it should soften at something like 150 C, and certainly by 200.
Also at temperature, differential thermal expansion will be working your
way. These temperatures won't soften the screw and should not affect the
anodising. I wouldn't try to heat locally, I would cook the whole thing
in an oven (assuming it will fit).


No this is effectively T shaped .... 48" long bar into a 18" long strut
..... mortice & tennon style fits with 4 cross screws. 2 from each side.

On 06/12/2016 16:28, Andrew Mawson wrote:


Red hot poker (or preferably a copper bar) applied to the screw head.
Once the Loctite is close to 100 deg C it will let go and can be undone.

Andrew


You think that would be better than a micro flame direct onto screw head
(I can do either)
Didn't think it would release at 100 thought it would be up around
3-400 at least. So maybe successful then.

I could also apply a heat gun to surrounding aluminium ... or do you
think best apply heat only to screw head

On Tue, 6 Dec 2016 15:18:56 +0000, rick
wrote:

I need to undo 4 x CSK stainless steel screws 3/8x24 UNF
These are screwed into 6061 anodized billet aluminium.

Fixed by a Loctite (or similair) thread lock

The heads are imperial allen socket.

From past experience I know that even non-Loctite ones can be difficult
to remove, the screws being stainless are relatively soft and they will
round out easily.

Any thoughts over best approach .... I could leave a soak in Plus-gas
penetrating oil, but unsure if that will help .... or I could apply heat.

If the latter then how much to help break loctite, without damaging
anodized finish or softening screw. .... I have a micro propane torch so
could apply localised heat ...

I also have a pneumatic impact wrench .. I could also use that rather
than just allen socket in ratchet handle

http://henkeladhesivesna.com/blog/ho...-threadlocker/

Heat works on all thread lockers. At 200 - 250 deg C the thread
locker should be soft enough to allow removal of the bolt.

On 06/12/2016 17:20, Peter Parry wrote:
On Tue, 6 Dec 2016 15:18:56 +0000, rick
wrote:



http://henkeladhesivesna.com/blog/ho...-threadlocker/

Heat works on all thread lockers. At 200 - 250 deg C the thread
locker should be soft enough to allow removal of the bolt.



Peter - do you know will it soften the ss screw or harm the anodizing
that temp ?

From that link ... applying heat direct to screw face with my micro
burner ...should be enough ... judging 200C may be more interesting ....
time to dig out thermocouple & MM I think

On 06/12/2016 15:18, rick wrote:
I need to undo 4 x CSK stainless steel screws 3/8x24 UNF
These are screwed into 6061 anodized billet aluminium.

Fixed by a Loctite (or similair) thread lock

The heads are imperial allen socket.

From past experience I know that even non-Loctite ones can be difficult
to remove, the screws being stainless are relatively soft and they will
round out easily.

Any thoughts over best approach .... I could leave a soak in Plus-gas
penetrating oil, but unsure if that will help .... or I could apply heat.

If the latter then how much to help break loctite, without damaging
anodized finish or softening screw. .... I have a micro propane torch so
could apply localised heat ...

I also have a pneumatic impact wrench .. I could also use that rather
than just allen socket in ratchet handle

There are several grades of thread locker. Colours are for Loctite,if
blue the screws should just unscrew with no heat, purple is the lightest
grip of the lot only the red stuff should require heat .

Heat gun on the entire area plus your micro torch on the head should
allow removal of red whilst the blue stuff should only need more torque
(BUT DO NOT USE THE IMPACT GUN) whilst the purple will require more
torque but not as much as the blue.

On Tue, 6 Dec 2016 17:34:50 +0000, rick
wrote:

On 06/12/2016 17:20, Peter Parry wrote:
On Tue, 6 Dec 2016 15:18:56 +0000, rick
wrote:



http://henkeladhesivesna.com/blog/ho...-threadlocker/

Heat works on all thread lockers. At 200 - 250 deg C the thread
locker should be soft enough to allow removal of the bolt.



Peter - do you know will it soften the ss screw or harm the anodizing
that temp ?

Neither should be affected by that temperature.

From that link ... applying heat direct to screw face with my micro
burner ...should be enough ... judging 200C may be more interesting ....
time to dig out thermocouple & MM I think

Some sources recommend touching a Beeswax rod to the screw head when
up to temperature. The wax melts and finds its way into the thread
making it easier to remove.

On 06/12/2016 17:34, rick wrote:
On 06/12/2016 17:20, Peter Parry wrote:
On Tue, 6 Dec 2016 15:18:56 +0000, rick
wrote:



http://henkeladhesivesna.com/blog/ho...-threadlocker/

Heat works on all thread lockers. At 200 - 250 deg C the thread
locker should be soft enough to allow removal of the bolt.



Peter - do you know will it soften the ss screw or harm the anodizing
that temp ?

From that link ... applying heat direct to screw face with my micro
burner ...should be enough ... judging 200C may be more interesting ....
time to dig out thermocouple & MM I think

Stainless is a relatively poor conductor of heat - thats why ss
teaspoons dont burn you when you stir hot liquids etc.
Might be better trying to apply heat to alloy around thread.

On 12/6/2016 5:07 PM, rick wrote:
On 06/12/2016 16:28, Andrew Mawson wrote:


Red hot poker (or preferably a copper bar) applied to the screw head.
Once the Loctite is close to 100 deg C it will let go and can be undone.

Andrew


You think that would be better than a micro flame direct onto screw head
(I can do either)
Didn't think it would release at 100 thought it would be up around
3-400 at least. So maybe successful then.

I could also apply a heat gun to surrounding aluminium ... or do you
think best apply heat only to screw head

I'd go for heat gun to surrounding metal, to get benefit from the
thermal expansion too. You don't want to over-heat the polymer to the
extent that it turns into a carbonaceous char, with some mechanical
strength.

On 12/6/2016 7:33 PM, Robert wrote:
On 06/12/2016 17:34, rick wrote:
On 06/12/2016 17:20, Peter Parry wrote:
On Tue, 6 Dec 2016 15:18:56 +0000, rick
wrote:



http://henkeladhesivesna.com/blog/ho...-threadlocker/

Heat works on all thread lockers. At 200 - 250 deg C the thread
locker should be soft enough to allow removal of the bolt.



Peter - do you know will it soften the ss screw or harm the anodizing
that temp ?

From that link ... applying heat direct to screw face with my micro
burner ...should be enough ... judging 200C may be more interesting ....
time to dig out thermocouple & MM I think

Stainless is a relatively poor conductor of heat - thats why ss
teaspoons dont burn you when you stir hot liquids etc.
Might be better trying to apply heat to alloy around thread.

Good point. Also Aluminium is a *good* conductor, so this way you will
get the temperature up all the way to the root.

Seems a bit of a daft design to use screws but then glue them in, they
either want them to be removable or they don't. Loctite used to do a loctite
neutraliser product but how you are supposed to get it into a screw thread
has always eluded me. Best results I've had was with impact driver though. A
straight wrench normally ruins the heads or sheers the bolt off. I used to
have to try to get these sort of screws out of small modular boxes with
rubber sealed lids and cable entries used in some radar installations nd to
be honest I think the makers were all sadists.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"rick" wrote in message
news
I need to undo 4 x CSK stainless steel screws 3/8x24 UNF
These are screwed into 6061 anodized billet aluminium.

Fixed by a Loctite (or similair) thread lock

The heads are imperial allen socket.

From past experience I know that even non-Loctite ones can be difficult to
remove, the screws being stainless are relatively soft and they will round
out easily.

Any thoughts over best approach .... I could leave a soak in Plus-gas
penetrating oil, but unsure if that will help .... or I could apply heat.

If the latter then how much to help break loctite, without damaging
anodized finish or softening screw. .... I have a micro propane torch so
could apply localised heat ...

I also have a pneumatic impact wrench .. I could also use that rather than
just allen socket in ratchet handle

On 06/12/2016 21:47, newshound wrote:


Good point. Also Aluminium is a *good* conductor, so this way you will
get the temperature up all the way to the root.


I had thought that screws are surrounded by huge chunk of aluminium
....it might soak away heat ... but will heat up both.

On 06/12/2016 17:58, soup wrote:


There are several grades of thread locker. Colours are for Loctite,if
blue the screws should just unscrew with no heat, purple is the lightest
grip of the lot only the red stuff should require heat .

Heat gun on the entire area plus your micro torch on the head should
allow removal of red whilst the blue stuff should only need more torque
(BUT DO NOT USE THE IMPACT GUN) whilst the purple will require more
torque but not as much as the blue.



Unfortunately until I get first one out - don't know what they used ...
hoping it's not red.
I only normally put blue on screws I need to remove in future.

On 07/12/2016 08:19, Brian Gaff wrote:
Seems a bit of a daft design to use screws but then glue them in, they
either want them to be removable or they don't. Loctite used to do a loctite
neutraliser product but how you are supposed to get it into a screw thread
has always eluded me. Best results I've had was with impact driver though. A
straight wrench normally ruins the heads or sheers the bolt off. I used to
have to try to get these sort of screws out of small modular boxes with
rubber sealed lids and cable entries used in some radar installations nd to
be honest I think the makers were all sadists.
Brian



The screws are in an item that takes a lot of vibration & jarring forces
....... they have a habit of coming loose, and then the holes/threads
become worn hence they are loctited in now during manufacture.

I want to remove as sending it back to US assembled require3s a 50" x
36" box ...... if I split it .. can roll it up in cardboard and be only
48" x 4"



I did make error in original description ... aluminium is 7000 series,
not 6061 (that was older item)