Thread: derusting a shaft in a hole

Hi Ken,
Can you fit it in your electrolysis tank? That would be the most sure fire way I could think of.

Ew

Strong acid dissolves rust. A quick bath treatment might do it, but will also attack the steel.
An electroplater showed me showed me this trick, OK for surface rust.
It might not work in your case, if it's inside mating parts.

Jordan

Originally Posted by Ueee

Hi Ken,
Can you fit it in your electrolysis tank? That would be the most sure fire way I could think of.
Ew

To get the best action in an electrolysis tank the other electrode (anode) should be down the middle of the shaft

Phosphoric acid shouldn't attack iron too quickly, if you want to go with an acid based attack.
Other than that, there's a DIY recipe of 50% automatic transmission fluid and acetone.
However, I'd splash out for five litres of Evaporust - http://www.evapo-rust.com.au/

there has been a lot of chat here about transmission oil and acetone mixed 50/50.
is a great rust loosener. if loosener is a word.
can you hit the shaft with a hammer. Id heat spray heat spray and bash with a hammer
aaron

The part I spoke of holds up one end of my roller door, and therefore cannot be removed.

Sounds like Evaporust might be the only solution.

Ken

I suspect that the butane torch has not got the parts hot enough.

I don't know how it works but I find that heating to red hot with an oxy works just about every time for me. There is the obvious expansion that occurs in the steel of course, but the heat also seems to 'dry out' the rust, the rust in the rusted joint crumbles to a powder. The chemists here will be able to explain it.



EDIT Roller door, house? Maybe red hot is not a good idea.

Originally Posted by bob ward

I suspect that the butane torch has not got the parts hot enough.

I don't know how it works but I find that heating to red hot with an oxy works just about every time for me. There is the obvious expansion that occurs in the steel of course, but the heat also seems to 'dry out' the rust, the rust in the rusted joint crumbles to a powder. The chemists here will be able to explain it.



EDIT Roller door, house? Maybe red hot is not a good idea.

Dead on, butane has nowhere near the thermal output to heat the parts either hot enough or quick enough.
Ideally, you want to heat the outer as hot and as fast as you can, while keeping the inner as cool as you can. Got a friend with oxy acetylene or oxy lpg?
I can possibly add a little to the rust drying out and crumbling question. Iron oxide (rust), has a different expansion rate to steel and therefore it is sort of cracked off and pulverised by the differential in their expansion rate.

Well there you go, a little googling and it appears that heat does change the composition of rust, it literally dries out.

From yahoo answers

Rust, in its usual hydrated form is FeO(OH).

Rust occurs when iron reacts with oxygen in the presence of water:
4Fe + 3O2 + 6H2O --> 4Fe(OH)3

It "dries" to form the common hydrated form:
Fe(OH)3 --> FeO(OH) + H2O

Water vapor from the air usually is enough to keep most rust as FeO(OH).

When fully dehydrated, rust is Fe2O3
2FeO(OH) --> Fe2O3 + H2O

Hi Ken.
I have used methyl salicitate,the good old Oil of Wintergreen liniment ,to good effect.
It crops up in searches for penetrant with some quoting use in US Navy equipment.Its relatively cheap $8 a bottle obtainable at pharmacies


My application was only a small 6mm bolt frozen in its thread. You may have to make a dam of plasticine or blue tack to allow it to wick in.

I know evaporust works very well on surface rust but I understand it must be immersed.

Hope this helps

Grahame