seized bottle screw - any suggestions

Burnham Bob

Burnham Bob

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a bit of PLusgas, a bit of effort and all my bottle screws and lock nuts are running freely. except one. it's seized where the fork that attaches to the stay goes in. so i've soaked it in Plusgas and i'm going back tomorrow (whatever did i do before i retired!).

any other suggestions? and by the way what do forumites use to adjust bottle screws? 'a suitable bar' is recommended. apart from hacksawing off the bit end of an old screwdriver so it goes through the holes in the screw i don't have anything really beefy. the small phillips screwdriver that worked on the others just isn't man enough for the job on the seized one.
 
Burnham Bob said:
a bit of PLusgas, a bit of effort and all my bottle screws and lock nuts are running freely. except one. it's seized where the fork that attaches to the stay goes in. so i've soaked it in Plusgas and i'm going back tomorrow (whatever did i do before i retired!).

any other suggestions? and by the way what do forumites use to adjust bottle screws? 'a suitable bar' is recommended. apart from hacksawing off the bit end of an old screwdriver so it goes through the holes in the screw i don't have anything really beefy. the small phillips screwdriver that worked on the others just isn't man enough for the job on the seized one.
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try heat, be very careful you dont "gaul" the thread.
use copper grease on reassembly
 
If its stainless steel it may have galled. I had one that did this and nothing would shift it. Held it in a vice and heated it but it did not work. I think I probably destroyed the thread trying to force it. I ended up replacing it. I wouldn't have trusted it anyway.
 
sailorman said:
try heat, be very careful you dont "gaul" the thread. . . . . .
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It can only be "Gauled" if you give it to a Frenchman. :p

If it is standing rigging, lay a 5lb club hammer against one side of the bottle screw and with a small light (1 ounce) hammer lightly tap, tap, tap on the opposing side many times. Like a woodpecker. In this way you will shock the thread which is causing you the problem. Repeat from the other side. Soak in 'Plus-Gas' and repeat. It can take a couple of hours or more before you start to see movement but it will come free using this method.

As has been suggested above applied heat, from a propane torch will help to free it off but you must not overheat or apply too much as the heat can travel down the stay by conduction and do damage to GRP or timberwork below (and above)! :rolleyes:

ps: Galling is usually associated with soft metals like aluminum and copper. ;)


.
 
Molybdenum based Never-seeze is the only thing that I've found that helps prevent galling in stainless and then it's not perfect.
 
If it's galled you can give up on it but try a bit of heat first and it may free up.As said use a good grease on it next time.
It will only gall when being turned under load so it may just be a bit dirty.
 
As I understand "galling" it is cold welding due to a combination of pressure and heat during assembly. That doesn't seem likely for a bottle screw because the load is spread over a large area of thread. I'd think it more likely due to the fact that the mated thread on a bottle screw is unusually long, so any dirt or corrosion has that much more effect and any release oil takes so much longer to get through. I'd give it a good few days soaking.
PS. Don't try to hacksaw through a screwdriver, use an angle grinder!
 
I don't know if 'galling' is the correct term, but un-oiled stainless, particularly with fine threads can seize very firmly, I think it's related to crevice corrosion.
If you cannot undo it with moderate heat and reasonable size tools, you may have weakened it, maybe it's time for a new one.
I have found that 'never seize' stuff which is like copper grease with silver coloured metal in it, to be very effective.
If you can slacken all the others, you should be able to unload it without doing anything horrible to the mast.
 
CreakyDecks said:
As I understand "galling" it is cold welding due to a combination of pressure and heat during assembly. That doesn't seem likely for a bottle screw because the load is spread over a large area of thread.
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Ooh...galling certainly can occur in such fittings. Been there. Of course that's not to say that the OP's problem necessarily is galling.

If it's any consolation, titanium-on-titanium is even worse.
 
Stainless steel threaded components are renowned for galling, which is a form of adhesive wear. Although the general temperature of the components is at ambient temperature, on a micro scale peaks of adjacent parts weld together. Where there is relative movement, for example cams and tappets, the result is a severe roughening of the two surfaces. Where there is no movement the components can weld together.

A colleague of mine conducted research into the topic and sat on an International forum investigating it. The best palliative found was molybdenum disulphide, although that is not perfect.
 
macd said:
Ooh...galling certainly can occur in such fittings. Been there. Of course that's not to say that the OP's problem necessarily is galling.

If it's any consolation, titanium-on-titanium is even worse.
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It happened on a rigging screw on my boat.The thing became unmovable.I had to throw it away and replace it.Now I have bronze ones.
 
boaterbaz said:
If it is stainless then it could well be gauled. If that is the case renewal is the only answer. Never use copper grease on stainless. It actually increases the chance of gaulling. Clean threads and a little light oil. paraffin for choice.
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I'm surprised to hear that "Coppaslip" or similar is bad for galling with stainless. I use it without any problem.........so far.
 
NormanS said:
I'm surprised to hear that "Coppaslip" or similar is bad for galling with stainless. I use it without any problem.........so far.
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Then you would have had had no problems without it! That's the random nature of galling!

Whilst light oils and even talc can help with assembly, especially in 'clean' environments like food processing, it's only molybdenum disulphide based never-seezes that have been demonstrated to be both helpful and durable enough in the joint to help with disassembly as well. But then only to a degree. Bronze bodies and turnbuckles with stainless screws are the only real solution to rigging galling problems.

There's lots of research on this as it's a very common and expensive problem.
 
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