Thomas Prufer <prufer.public@mnet-online.de.invalid> wrote:
> On Mon, 18 Mar 2024 16:57:31 +0000, Chris Green <cl@isbd.net> wrote:
>
> >So what anti-seize should one use on steel/aluminium threads?
>
> I'm finding stuff called "marine-grade anti-seize"... one has zinc in it and
> says "for threaded steel parts assembled in aluminum or zinc castings" (LOCTITE®
> LB 8044, zinc dust plus petrolatum.)
>
I can only find that from US suppliers, I've not spent a long time
searching yet though so I may eventually find a UK/EU supplier.

> I'd add a wrap of PTFE tape, and maybe use hex grub screws?
>
I already have hex drive grub screws to replace the stupid slotted
ones that were originally used.

--
Chris Green
·

On 18/03/2024 16:52, Chris Green wrote:
> The Natural Philosopher <tnp@invalid.invalid> wrote:
>> On 18/03/2024 11:40, Clive Arthur wrote:
>>> On 18/03/2024 10:16, Tim Lamb wrote:
>>>> In message <1tblck-m0o91.ln1@esprimo.zbmc.eu>, Chris Green
>>>> <cl@isbd.net> writes
>>>>> I have some (boat) windows that I'm refurbishing.  They are secured to
>>>>> the boat superstructure with little aluminium wedges with grub screws
>>>>> through them.  Absolutely ridiculaous steel (not even stainless) grub
>>>>> screws in aluminium but I have to deal with what's there.
>>
>>> Connect a car battery, one lead to the aluminium frame and the other
>>> lead to your screwdriver/allen key - probably limit the current via a
>>> headlight bulb in series at least to start (well, you wanted a bright
>>> idea).  Wear goggles and keep a swear box handy.
>>>
>> There are simpler ways
>> https://www.machinemart.co.uk/p/clarke-it1500-1500w-induction-heating-kit/
>> Sadly these are not things that are falling off the shelves for £20 in
>> LIDL...
>>
>> In your case reverse drills and a reverse thread stud extractor, or
>> drill the whole lot out and re tap is probably best cost-benefit approach.
>>
> This is essentially what I did with the first few, I was just looking
> for a better/easier way! :-)
>
>> https://www.amazon.co.uk/left-handed-drill-bits/s?k=left+handed+drill+bits
>>
>> https://www.amazon.co.uk/CYH-T-Handle-Ratchet-Adjustable-Threading/dp/B09CG65SBZ/
>>
>> Mild steel screws in aluminium threads are a disaster waiting to happen
>> in a marine environment.
>>
> Absolutely! I fail to understand why a 'professional' business making
> windows for boats would do such a thing, but there you are. They've
> been in business since at least 1976 (when my boat was built)!
>
>
>> If these wedges can come out and onto the bench, then it will be easier
>> to totally refurbish the whole shebang properly.
>>
> As I said, using brute force (a hammer) I can get them out without
> serious damage to anything, just a few minor deformations of the
> aluminium.
>
>
>> Or you can make new ones. I am not clear (picture would help) onm
>> exactly how this all hangs together
>>
> Here's a picture, end on, of a clean, new one:-
>
> https://gvps.uk/pics/wedge.jpg
>
> ...and this is a rather poor picture of them in my boat:-
>
> https://gvps.uk/pics/p1040188.jpg
>
> I think you can probably make out how they work.
>

The photos make things much clearer.

This is very much a drastic solution. If you can get an angle grinder
cutting blade underneath the wedge, cut through the screw.

This should allow the wedge to fall out.

Then put the wedge in some hot oil and leave to soak. With a bit of luck
the screw should then be removable.

David <david@nospam.com> wrote:
> >> Or you can make new ones. I am not clear (picture would help) onm
> >> exactly how this all hangs together
> >>
> > Here's a picture, end on, of a clean, new one:-
> >
> > https://gvps.uk/pics/wedge.jpg
> >
> > ...and this is a rather poor picture of them in my boat:-
> >
> > https://gvps.uk/pics/p1040188.jpg
> >
> > I think you can probably make out how they work.
> >
>
> The photos make things much clearer.
>
> This is very much a drastic solution. If you can get an angle grinder
> cutting blade underneath the wedge, cut through the screw.
>
This is what I did on the first few, however some can't be reached
with an angle grinder. Knocking them out with a hammer has worked
pretty well on the less accessible ones. Thus removing them isn't
really the issue.

> This should allow the wedge to fall out.
>
It does! :-)

> Then put the wedge in some hot oil and leave to soak. With a bit of luck
> the screw should then be removable.
>
Any old oil? I can certainly try this when I get home. I was just
hoping there might be some specific sort of hot liquid that would work
well.

--
Chris Green
·

On 18/03/2024 21:26, Joe wrote:
> On Mon, 18 Mar 2024 13:21:11 +0000
> The Natural Philosopher <tnp@invalid.invalid> wrote:
>
>
>>
>> Mild steel screws in aluminium threads are a disaster waiting to
>> happen in a marine environment.
>>
>>
>
> Marine? Have you tried removing alloy wheels from steel hubs after a
> few years in fairly mild inland weather? Yes, I dropped the car (gently
> and with precautions) onto the wheel after removing the bolts. Not a
> sign of movement.
>
> I followed the advice of the Internet, and used progressively larger
> chunks of timber to bash the wheel on alternate sides, and eventually
> it came loose.
>
> Not a trace of salt...
>
No, by that time the salt was in fact gone. The corrosion in the alloys
is Aluminium oxide .

Normally that protects the aluminium from chemical attack, BUT it seems
that any conductive water in combination with two different metals will
produce an electrochemical reaction that strips the oxygen out of the
water lets the hydrogen go free and oxidises the two metals.

So it's not the salt per se that does the damage, its *any* conductive
ions in the water.

https://en.wikipedia.org/wiki/Galvanic_corrosion

....makes a fascinating read, if you are interested.,

--
“I know that most men, including those at ease with problems of the
greatest complexity, can seldom accept even the simplest and most
obvious truth if it be such as would oblige them to admit the falsity of
conclusions which they have delighted in explaining to colleagues, which
they have proudly taught to others, and which they have woven, thread by
thread, into the fabric of their lives.”

― Leo Tolstoy

On 19/03/2024 08:29, Thomas Prufer wrote:
> On Mon, 18 Mar 2024 16:57:31 +0000, Chris Green <cl@isbd.net> wrote:
>
>> So what anti-seize should one use on steel/aluminium threads?
>
> I'm finding stuff called "marine-grade anti-seize"... one has zinc in it and
> says "for threaded steel parts assembled in aluminum or zinc castings" (LOCTITE®
> LB 8044, zinc dust plus petrolatum.)
>
> I'd add a wrap of PTFE tape, and maybe use hex grub screws?
>
The zinc is there to 'take the heat' in the same way it does in a
galvanised steel situation
It meeds to be in contact to work, so the PTFE is an alternative, not a
supplement

>
> Thomas Prufer

--
Climate is what you expect but weather is what you get.
Mark Twain

On 19/03/2024 09:30, Chris Green wrote:
> David <david@nospam.com> wrote:
>>>> Or you can make new ones. I am not clear (picture would help) onm
>>>> exactly how this all hangs together
>>>>
>>> Here's a picture, end on, of a clean, new one:-
>>>
>>> https://gvps.uk/pics/wedge.jpg
>>>
>>> ...and this is a rather poor picture of them in my boat:-
>>>
>>> https://gvps.uk/pics/p1040188.jpg
>>>
>>> I think you can probably make out how they work.
>>>
>>
>> The photos make things much clearer.
>>
>> This is very much a drastic solution. If you can get an angle grinder
>> cutting blade underneath the wedge, cut through the screw.
>>
> This is what I did on the first few, however some can't be reached
> with an angle grinder. Knocking them out with a hammer has worked
> pretty well on the less accessible ones. Thus removing them isn't
> really the issue.
>
>> This should allow the wedge to fall out.
>>
> It does! :-)
>
>
>> Then put the wedge in some hot oil and leave to soak. With a bit of luck
>> the screw should then be removable.
>>
> Any old oil? I can certainly try this when I get home. I was just
> hoping there might be some specific sort of hot liquid that would work
> well.
>

Any mineral oil would do. You don't need the latest (and expensive)
synthetic oil. At a pinch, you could even try cooking oil.

Also after soaking the wedge in the hot oil, try removing the old screw
while hot - the aluminium should have expanded more than the steel screw
which should make removal easier.

On Tue, 19 Mar 2024 08:51:41 +0000, Chris Green <cl@isbd.net> wrote:

>Thomas Prufer <prufer.public@mnet-online.de.invalid> wrote:
>> On Mon, 18 Mar 2024 16:57:31 +0000, Chris Green <cl@isbd.net> wrote:
>>
>> >So what anti-seize should one use on steel/aluminium threads?
>>
>> I'm finding stuff called "marine-grade anti-seize"... one has zinc in it and
>> says "for threaded steel parts assembled in aluminum or zinc castings" (LOCTITE®
>> LB 8044, zinc dust plus petrolatum.)
>>
>I can only find that from US suppliers, I've not spent a long time
>searching yet though so I may eventually find a UK/EU supplier.

I'd use any "anti-seize". I got a tube of some mix of grease, copper, graphite,
and magic stuff (ceramic? MoS?). A very little goes a long way, and it stains.

>> I'd add a wrap of PTFE tape, and maybe use hex grub screws?
>>
>I already have hex drive grub screws to replace the stupid slotted
>ones that were originally used.

Come to think of it: would a hex head bolt work, with the head towards the
bulkhead? More head to get purchase on, when it comes to removing it? (ugly,
though).

Thomas Prufer

Thanks for all the ideas folks.

I can report *some* success, I realised that in many cases the grub
screws projected enough to get a half nut and then a full nut onto
them. By locking the nuts very tightly together I have managed to
remove four (out of seven I've taken from the current window) of the
grub screws.

The grub screws are surprisingly clean (the ones I've removed anyway).
I think maybe the corrosion was more from where they bear on the steel
superstructure than due to nearby aluminium.

Of the remaining three still stuck grub screws only one has any usable
thread, the other two really have corroded away to a craggy stump.

The grub screws are steel, or they're magnetic anyway and not
stainless because they drilled our fairly easily.

So I think my main search now is for suitable anti-seize compound.

--
Chris Green
·

On Tue, 19 Mar 2024 09:29:12 +0100, Thomas Prufer wrote:

> On Mon, 18 Mar 2024 16:57:31 +0000, Chris Green <cl@isbd.net> wrote:
>
>>So what anti-seize should one use on steel/aluminium threads?
>
> I'm finding stuff called "marine-grade anti-seize"... one has zinc in it
> and says "for threaded steel parts assembled in aluminum or zinc
> castings" (LOCTITE®
> LB 8044, zinc dust plus petrolatum.)
>
> I'd add a wrap of PTFE tape, and maybe use hex grub screws?
>
>
> Thomas Prufer

I like the idea of PTFE tape.

On 18/03/2024 08:51, Chris Green wrote:

> Any bright ideas anyone? Or should I simply give up and drill them
> all?
>

If you need to apply heat consider

https://www.ebay.co.uk/itm/293699782302

https://www.youtube.com/watch?v=H3iNqSnfbYs

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

Thomas Prufer <prufer.public@mnet-online.de.invalid> wrote:
> On Tue, 19 Mar 2024 08:51:41 +0000, Chris Green <cl@isbd.net> wrote:
>
> >Thomas Prufer <prufer.public@mnet-online.de.invalid> wrote:
> >> On Mon, 18 Mar 2024 16:57:31 +0000, Chris Green <cl@isbd.net> wrote:
> >>
> >> >So what anti-seize should one use on steel/aluminium threads?
> >>
> >> I'm finding stuff called "marine-grade anti-seize"... one has zinc in it and
> >> says "for threaded steel parts assembled in aluminum or zinc castings" (LOCTITE®
> >> LB 8044, zinc dust plus petrolatum.)
> >>
> >I can only find that from US suppliers, I've not spent a long time
> >searching yet though so I may eventually find a UK/EU supplier.
>
> I'd use any "anti-seize". I got a tube of some mix of grease, copper, graphite,
> and magic stuff (ceramic? MoS?). A very little goes a long way, and it stains.
>
> >> I'd add a wrap of PTFE tape, and maybe use hex grub screws?
> >>
> >I already have hex drive grub screws to replace the stupid slotted
> >ones that were originally used.
>
> Come to think of it: would a hex head bolt work, with the head towards the
> bulkhead? More head to get purchase on, when it comes to removing it? (ugly,
> though).
>
Thomas, that is brilliant! There's enough (but not a lot to spare)
clearance for the head to rotate and it makes for a much larger
bearing surface apart from anything else. Appearance doesn't matter,
the whole thing is pretty ugly and will be hidden by insulation/lining
anyway.

Thank you, lateral thinking rules OK! :-)

--
Chris Green
·

On Tue, 19 Mar 2024 09:34:08 +0000
The Natural Philosopher <tnp@invalid.invalid> wrote:

> On 18/03/2024 21:26, Joe wrote:
> > On Mon, 18 Mar 2024 13:21:11 +0000
> > The Natural Philosopher <tnp@invalid.invalid> wrote:
> >
> >
> >>
> >> Mild steel screws in aluminium threads are a disaster waiting to
> >> happen in a marine environment.
> >>
> >>
> >
> > Marine? Have you tried removing alloy wheels from steel hubs after a
> > few years in fairly mild inland weather? Yes, I dropped the car
> > (gently and with precautions) onto the wheel after removing the
> > bolts. Not a sign of movement.
> >
> > I followed the advice of the Internet, and used progressively larger
> > chunks of timber to bash the wheel on alternate sides, and
> > eventually it came loose.
> >
> > Not a trace of salt...
> >
> No, by that time the salt was in fact gone. The corrosion in the
> alloys is Aluminium oxide .
>
> Normally that protects the aluminium from chemical attack, BUT it
> seems that any conductive water in combination with two different
> metals will produce an electrochemical reaction that strips the
> oxygen out of the water lets the hydrogen go free and oxidises the
> two metals.
>
> So it's not the salt per se that does the damage, its *any*
> conductive ions in the water.
>
> https://en.wikipedia.org/wiki/Galvanic_corrosion
>
> ...makes a fascinating read, if you are interested.,
>

I understand the chemistry, I was pointing out that the extremely high
conductivity of salt water was not necessary for some very good
corrosion, the very weak acidity of rainwater was quite sufficient.

--
Joe

Chris Green wrote:

> The Natural Philosopher wrote:
>
>> Mild steel screws in aluminium threads are a disaster waiting to happen
>> in a marine environment.
>
> Absolutely! I fail to understand why a 'professional' business making
> windows for boats would do such a thing, but there you are.

Nylon or some other plastic set-screws as replacements?

Joe wrote:

> Have you tried removing alloy wheels from steel hubs after a
> few years in fairly mild inland weather? Yes, I dropped the car (gently
> and with precautions) onto the wheel after removing the bolts. Not a
> sign of movement.
>
> I followed the advice of the Internet, and used progressively larger
> chunks of timber to bash the wheel on alternate sides, and eventually
> it came loose.

Last time I was in that predicament, I did have a bug lump of wood in
the car, and a club hammer, no joy, ended-up reinstalling the bolts, but
not very tight, driving round a supermarket car park doing heavy
braking, eventually freed the wheel from the hub.

Andy Burns <usenet@andyburns.uk> wrote:
> Chris Green wrote:
>
> > The Natural Philosopher wrote:
> >
> >> Mild steel screws in aluminium threads are a disaster waiting to happen
> >> in a marine environment.
> >
> > Absolutely! I fail to understand why a 'professional' business making
> > windows for boats would do such a thing, but there you are.
>
> Nylon or some other plastic set-screws as replacements?
>
I've wondered about this but I'm not sure that nylon would be strong
enough, the windows have to be pulled pretty tight against the seals
to make them watertight.

--
Chris Green
·