"Rick Hughes" wrote in message
news
I have an expensive item that is manufactured from Billet Aluminum.
It is assembled with 316 stainless steel csk hex head screws.

I need to disassemble and the screws are stuck fast.


The heads are 7/32" hex imperials (yep 100% sure - It's a US
manufactured product)

I have tried encouraging Allen key with mallet - no good.
Applied releasing oil - no good (happy to try a specific product if there
is a particularly good one)

So far only one of the 8 have come out !


Now one way to approach this would be to use an impact driver ... I have a
compressed air 1/2" square drive impact driver, and assorted sockets ...
but would need a 7/32" hex insert ............ anybody know where I can
get one

First off you might want to read this.

http://www.pumaracing.co.uk/ToolUse.htm

Countersunk fittings do tend to lock on very tight because of the angle and
area of the underside of the head. You need to shock these loose with
something other than an unmodified right angled allen key which can't really
be hit directly on the end very easily. A small brass or bronze drift is
ideal, especially if you can machine a pip on the end in a lathe to keep it
centred inside the allen screw so it doesn't jump about and mangle the
aluminium around it. Or just cut a bit off an old 5.5mm allen key and hammer
that. By mallet I assume you mean a wooden one. You *must* use a steel
hammer to get a proper shock loading on the drift. Hitting something with
wood will achieve three fifths of FA. If they still won't come out hit them
harder! You won't hurt anything. It's like training a dog. Once it really
knows who's boss it'll give in and stop dicking about.

To use an allen key in your impact driver simply cut a length off the long
end with an angle grinder disc and use it in a 7/32" socket.

Absolutely no point using releasing oil. The joint will be fluid tight.

You also must tighten back up each screw you loosen to take the load off the
others and when all are free remove them one at a time.

If the screws are loctited in then applying heat for a while will soften it.

Car engine oil pumps are often held together with csk allen screws and I've
had to remove god knows how many ultra tight ones over the years but nothing
has ever failed to succumb to the right technique.

I'll bet you a pound to a pint if you cut a bit off an old 5.5mm allen key,
belt that firmly with a claw hammer a few times and then just use a good
tight fitting 7/32" key they'll pop out as easy as anything.
--
Dave Baker