Author Topic: Aluminum on Aluminum Threads Freeze  (Read 2072 times)

jeffweiss9

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Aluminum on Aluminum Threads Freeze
« on: April 25, 2016, 09:08:21 PM »
Anyone have experience freeing up aluminum on aluminum threads (both anodized) that are now frozen?
I have a focal reducer / field flattener (Riccardi 0.75x) that has had a 92m x1 to 82m x1 adapter on it for 3 years which is now completely frozen to the 82m x1 threads of the Riccardi.  I now need to remove that adapter and mount it permanently on the 3.5" Feathertouch Focuser with 92m x1 threaded endcap in order to accommodate the old focal reducer as well as a new Riccardi 1.0x field flattener I have ordered to flatten my f/6 images over my new larger chip (ML16200).
Seeking advice.
Thanks,
CS/Jeff

John Pierce

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Re: Aluminum on Aluminum Threads Freeze
« Reply #1 on: April 25, 2016, 09:46:10 PM »
if it wasn't optics, I'd suggest dribbling a very small amount of Kroil on the threads, and letting it wick in, but I wouldn't let that stuff get within a mile of optics.

I think I'd try gentle cold + heat...  idea is to get the inside piece as cold as you can, (maybe put the whole piece in a baggy in the fridge or freezer?) then warm the outer piece with a hair dryer, or dew heater wires, or something so it expands.


jeffweiss9

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Re: Aluminum on Aluminum Threads Freeze
« Reply #2 on: April 26, 2016, 07:21:13 AM »
Hi, John-
The cold/hot with the fridge and then a dew heater on the adapter flange is a good idea.  I had tried the hair dryer (low temp) but the hot air is too dispersed to target just the flange.  I will probably try that before I get desparate with WD-40.  I did read of a frozen aluminum thread case on the web (adapter on a $3K telephoto lens) where WD-40 did nothing up to 24hrs after applied, but the guy tried again at 40 hours and the thing unscrewed as if there had never been a problem.  I think I can keep it away from the optics (the big risk obviously) but, once the parts separate, I can clean it off the threads.   I first plan to bring it in to a shop this morning to see what they think (although I probably won't let them touch it if it involves anything remotely risking the lens)
Thanks,
Jeff

John Pierce

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Re: Aluminum on Aluminum Threads Freeze
« Reply #3 on: April 26, 2016, 10:25:21 AM »
WD40 is a water dispersant, its a lousy penetrant and worse lubricant.

Kroil (in aerosol cans, tis called AeroKroil) is the best penetrant out there, PB Blaster is the 2nd best, you can find these at better auto parts stores (Winchester Autoparts has AeroKroil), Liquid Wrench is the weak 3rd place.

jeffweiss9

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Re: Aluminum on Aluminum Threads Freeze
« Reply #4 on: April 26, 2016, 11:39:20 AM »
John-
Thanks.  I got an old can of Kroil from a friend but am reluctant to use it. The shop manager at work proposed to cut two square notches, 180 degrees apart, in the flange of the adapter and construct a spanner/wrench that would grab those two notches to then be able to work the two pieces apart.  They do a lot of optical work and was confident that would work.  He also commented that in pieces like that adapter, they usually include notches such as those he proposes to cut with a matching wrench exactly for this purpose.  But I am going to try the fridge/dew heater strap technique first tonight. If it doesn't work, then it goes in for the notches and wrench removal tomorrow.
Or, since I still need this adapter in the future reconfiguration, maybe having those notches cut would be a good improvement for the future...
-Jeff

John Pierce

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Re: Aluminum on Aluminum Threads Freeze
« Reply #5 on: April 26, 2016, 11:52:59 AM »
I'm remembering now having a camera filter get stuck onto a camera lens umpteen years ago.   I put it in the freezer (in a baggie) and was going to do the heat thing, but when it was ice cold, it just unscrewed.


jeffweiss9

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Re: Aluminum on Aluminum Threads Freeze
« Reply #6 on: April 26, 2016, 07:42:00 PM »
Yes, that's what Markus (APM Telescopes) told me when I told him what I planned to do.  "Just the cool down works many times."
It's in  the fridge now.
Cheers,
-Jeff

jeffweiss9

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Re: Aluminum on Aluminum Threads Freeze
« Reply #7 on: April 28, 2016, 01:12:13 PM »
End of story:  The cool down didn't work (but the fridge was only 49 deg).  The shop cut the notches in the adapter flange and they were freed.
-Jeff

DDK

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Re: Aluminum on Aluminum Threads Freeze
« Reply #8 on: April 28, 2016, 04:18:24 PM »
Phew. The fanboys were on hooks, Jeff.
TAC - astro anarchy at work <*>

jeffweiss9

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Re: Aluminum on Aluminum Threads Freeze
« Reply #9 on: April 28, 2016, 08:58:55 PM »
I was trying to build up the suspense :>)
Cheers,
-Jeff