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Stopping threaded telescope parts sticking together?

hughgilhespie

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hughgilhespie

hughgilhespie

Posted
Posted

Hi,

Looking for advice about how to stop screwed bits sticking together. More specifically, the threaded aluminium bits used in telescopes and cameras. 

When I was much younger, the advice was to run the threaded bits through your hair but these days hair is in rather short supply, so what to do now?

Regards, Hugh

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JOC

JOC

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I've never seen boot polish used in this way, but I get that it could work well.  Maybe a clear or neutral coloured polish would leave less visible marks or clothes or other gear if it migrated or accidentally wiped against something though?  How about a hard wax like a rub with beeswax?  Or des it need to be softer than that - I must admit I would tend toward silicone based or even candle wax unless there was a good reason not to do so - would anyone like to tell me that there is just so that I am enlightened?

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Star101

Star101

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Wish I had known about this a few weeks ago. I have a spacer stuck in my OAG. Fortunately, the OAG came with two size openings (M42 and M48), so I removed the 4 screws holding the fist opening (M42)stuck spacer and fitted the spare opening(M48) and the spare spacer instead. A bit of faffing that could have been avoided had I known about boot polish ?

And yes, still stuck :(

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Ben the Ignorant

Ben the Ignorant

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I had this problem a few times, it seemed some hard residue from machining and/or anodizing polluted the threads. Before rubbing them with silicon or organic grease I cleaned them, but you must use a rag fine enough to enter the grooves in the thread, and remove all the dirt. I was surprised by how little dust is enough to make the rotation rough, or make it seize.

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JamesF

JamesF

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7 minutes ago, Star101 said:

Wish I had known about this a few weeks ago. I have a spacer stuck in my OAG. Fortunately, the OAG came with two size openings (M42 and M48), so I removed the 4 screws holding the fist opening (M42)stuck spacer and fitted the spare opening(M48) and the spare spacer instead. A bit of faffing that could have been avoided had I known about boot polish ?

And yes, still stuck :(

Could be worth either cooling the stuck parts or warming them to see if either helps to release them?

James

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vlaiv

vlaiv

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I use fairly simple technique to unscrew stuck extension rings / adapters, without any polish or grease or whatever.

It happens regularly that some piece of equipment simply can't be unscrewed when disassembling things. This happens because of difference of "loads" on items that have threads on both ends. If you can't unscrew an adapter / extension, just simply take another piece with a same thread as "free" side of stuck item, and (this will sound crazy but it works) - screw it in, pretty tight, on free side. Then unscrew both items together - one that was stuck together with one that you just added. It will unscrew normally. After that just unscrew those too parts - this will usually work ok, but if they are stuck again (happens sometimes) - use the same approach.

This diagram explains a bit what happens:

image.png.93f8b6d927589567c482d36a0b7953ba.png

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michaelmorris

michaelmorris

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In terms of prevention, boot polish and the use of the deldrin spacers sold by FLO are pretty effective.

https://www.firstlightoptics.com/adapters/baader-t2-delrin-spacer-ring-set.html

For removal of stuck items, #Uranium235 showed me the trick of applying a downward twisting pressure on the stuck components using a rubber-faced glove.  Works really well in many circumstances.

 

 

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Stub Mandrel

Stub Mandrel

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I separated two camera adaptor rings that had been 'fused' for years with a spray that combines a lubricant with a freezer 'shock unlock', sprayed on the inner part.

Kiwi bootblack is an interesting idea, I was going to suggest a light dab of vaseline as unlikely to migrate or cause harm.

 

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Stub Mandrel

Stub Mandrel

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29 minutes ago, skybadger said:

don't join similar threaded metals. Ally onto ally is particularly bad.

You don't get a lost of choice in that with astro/photography kit. ?

Anodising helps as it stops cold welding and galling which both need metal to metal contact, but it isn't a guaranteed cure.

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Alien 13

Alien 13

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I want to clarify regarding the use of boot polish, you apply a tiny amount with a matchstick then rub it into the treads with a cloth or better still your finger, wait a few mins then wipe it all off with a cloth (some will remain so dont worry) the result is no more sticky parts. 

The subject of cold welding is one that I personally dont believe exists, spent a lot of time using high energy vibration machines for environmental testing with slip tables that had stainless steel inserts and stainless bolts, never an issue.

As to undoing a stuck adapter I have yet to find on that I cant undo with just the palms of my hands, a useful tool is a pair of table tennis bats if you want to cheat.

Alan 

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skybadger

skybadger

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1 hour ago, Alien 13 said:

personally dont believe exists, spent a lot of time using high energy vibration machines for environmental testing with slip tables that had stainless steel inserts and stainless bolts, never an issue.

Funny that, so did I. They didn't cold weld either. Broke a few satellites though. 

However metal into metal threads of similar hardness will gall and distort easily if pushed, making them very to separate. Anodising will help by hardening and smoothing but a touch of noise grease will always so the trick if applied before hand. 

 

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saac

saac

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8 hours ago, hughgilhespie said:

A goldmine of information!

Looks like I will need to ask the butler where the boot polish is kept.

Thanks, Hugh

If he can't find it Hugh then I'll have my batman parcel up a few tins. :) 

Jim 

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