Removing rusty screw from mainplate

[YuriyV]

Very often one or more screws are rusty to impossible safely remove them from the place. Usually apply to bridge and dial screws.
What are recommended measures to remove them without damaging other parts? 
I'd narrow down my question to three typical scenarios:

1. Many parts remain on place including the dial. And other parts, hidden under it;

2. Dial and other parts removed. But MS barrel and/or gears are still under blocked bridge(s );

3. Everything is removed, including all bridges, but some non removable steel parts (like springs) are still on place; 

Thanks!

[jdm]

2 minutes ago, YuriyV said:

What are recommended measures to remove them without damaging other parts? 

Alum in warm water or a screw extractor, you can use the search box top right to find related discussions . However I would first apply some penetrating oil and try to unscrew first, even if that shears the head, because there will be less material to dissolve, and you can remove the other parts.

[YuriyV]

Thanks! Will try it.

[measuretwice]

As a sidebar, alum in boiler water is an old trick to remove a broken tap if its broken in AL or a copper alloy (non ferrous).  After a few hours it turns the tap into sludge. 

Boiling and hours is a lot harsher treatment than JDM recommends, so a shorter soak might be just the thing to eat up enough of the expanded iron oxide to free things up. 

The point though is alum can dissolves steel quite effectively so try to keep other bits of ferrous out of the mix and if they have to be there, don't leave it on the stove overnight with other bit of ferrous metal still attached  

Edited December 20, 2017 by measuretwice

[YuriyV]

Cool! Thanks.

I ordered 100g of aluminum powder out of eBay.
What are the proportions to apply? Just put some amount of powder in water and keep certain temperature?

[vinn3]

Quote

 

alum or aluminum .  VIN

[jdm]

17 minutes ago, vinn3 said:

alum or aluminum .  VIN

Aluminum potassium sulfate is very different from aluminium.

[vinn3]

thanks

[YuriyV]

After googling I understand I need ALUMINIUM POTASSIUM SULFATE KAl(SO₄)₂•12H₂O

Thanks

[measuretwice]

no need to order, you can get it at the grocery store.....just tell them there's a rusty screw in your watch.

 

 

(first part is true at least, its used in pickling)

[YuriyV]

Thanks!

[rodabod]

Personally, I just use rust remover from Cousins now. Much faster at dissolving iron.