RUST and the other evils

[automizer]

So I have noticed on some machines I have used there is rust on some of the feet and other normally not looked after locations. As well as paint chipping on the back control doors on heavily cleaned parts of the machines. I am just wondering for other people if anyone has put a coating on things the prevent rust on exposed steal. How about the paint anyone re-paint there machines. Just after info on what others have seen or done.

[ImanCarrot]

How to kill rust while it sleeps by a chap called Frank Ford who is a blinking genius... respect and kudos to him, his site is awesome.

http://www.frets.com/FRETSPages/Mach...stremoval.html

Oh, incidentaly, my compressor resevoir outside was looking a bit rusty so I spray painted it using Hammerite (direct to rust- no sanding needed) and now it looks all shiny and new.

Also! I forgot! I got an old WWII brass portable stove, the casing was iron or something and all rusty, I used KURUST, again from Hammerite which "converts rusty metal to a clean surface in 15 mins".

I have no connection with Hammerite by the way, apart dfrom being a very satified customer

[automizer]

Thats really good info thanks.
I realy like the one he shows using the rag.
Rust and machines is in my eyes is a big issue im serprised more people havn't said anything.

[swain]

I actually repainted the front doors on a VF 3 when I redid the lexan in front.
Gave it that brand new look. Some one at haas had installed the door seeal with the split at the top...so the bottom held coolant. When I sandblasted and painted doors, put split at bottom and now coolant drain out.

Swain

[serviceman]

what about rust on the ways i see a lot of rust on the top of the rails

[Geof]

Originally Posted by serviceman what about rust on the ways i see a lot of rust on the top of the rails

If you see rust in places like this it might be an idea to check the coolant concentration. I think most coolants when they are mixed to the manufacturers specifications do not leave enough oily residue to prevent rust on bare metal when the water evaporates.

[bremenrules]

Been using Hangsterfer's S-500 soluable oil at ~8% for quite some time. Never had a big problem with rust on the surface, but there always seem to be some under the vise and whatnot when it's pulled off the table. This is after using tool oil before mounting, so I haven't been able to put my finger on the cause.

[dertsap]

exterior rust can be cleaned up fairly well with Rustmort rust converter ,i use the stuff often . http://www.azautobodysupply.com/sem69ruqusi.html

its not something to use on precision parts

[Geof]

Originally Posted by bremenrules ....but there always seem to be some under the vise and whatnot when it's pulled off the table. This is after using tool oil before mounting, so I haven't been able to put my finger on the cause.

It is galvanic corrosion. I stole this from Wikipedia:

Galvanic corrosion is an electrochemical process in which one metal corrodes preferentially when it is in contact with a different type of metal and both metals are in an electrolyte.

When two or more different sorts of metal come into contact in the presence of an electrolyte a galvanic couple is set up as different metals have different electrode potentials. The electrolyte provides a means for ion migration whereby metallic ions can move from the anode to the cathode. This leads to the anodic metal corroding more quickly than it otherwise would; the corrosion of the cathodic metal is retarded even to the point of stopping. The presence of electrolyte and a conducting path between the metals may cause corrosion where otherwise neither metal alone would have corroded.

Even a single type of metal may corrode galvanically if the electrolyte varies in composition, forming a concentration cell.

The part I made bold is the mechanism you are getting between the vise and the table of the machine.

It is practically impossible to avoid this type of corrosion. I have found the most effective approach is to smear a layer of White Petrolatum on both surfaces. This fills the space between the two metals and excludes coolant which is what provides the electrolyte that is needed for the galvanic corrosion to occur. White Petrolatum is the best to use because it is really just a very thick oil, or you could consider it a very runny wax, that has no additives. Most lubricating oils and all greases have additives for different reasons and if you use these you might stop the galvanic corrsion but then you can get chemical corrosion because some additives in oil are actually designed to react with the metal. Forming a chemical bond is how some extreme pressure additives work.

Another name for White Petrolatum is Vaseline and the funny thing is when I tell people to smear Vaseline on the bottom of their vise I normally get all kind of idiotic responses.

[ImanCarrot]

smear vaseline on the bottom of your vise

ROFL!

Seriously though, thanks for the info Geoff. Now I was thinking... on cars, they make the chassis negative earth to slow down/ prevent corrosion. Could you crocodile clip a negative battery terminal to your turret mill bare metal? Don't try this folks, it might fry some electrical stuff- just asking... if it works on cars then why not on my mill???

[Edit]Ok, you might need to have an actual current flowwing, but what about dangling christmass tree lights around the spindle head or something or! could use it as an excuse to power a radio if your boss dun allow one hehe.[/edit]

[Geof]

Originally Posted by ImanCarrot ... on cars, they make the chassis negative earth to slow down/ prevent corrosion....

Is that so? I always thought it was related to which electrode on a spark plug eroded the quickest.

I know that underground pipelines are sometimes protected by laying cables alonside and applying a potential difference. It is not a simple thing to do because if you go too far you switch from preventing galvanic corrosion to electrochemical machining and make holes in your pipe.

There is another source of corrosion which is often accompanied by a vile stench and that is bacterial action. You have probably seen pictures of the Titanic which is slowly being dissolved by iron metabolizing bacteria. When there is a source of sulfur around then it is possible to get the bugs chomping away making holes and a stink at the same time.

[ImanCarrot]

definately, that's why all the old cars are converted from positive earth to negative earth. If I recall correctly from my A-Levels (and that's going back a bit), Gain of Eletron= Reduction and Loss of Electrons= Oxidation (rust) so if you pump electrons into the metal it'll slow down the rust... the nice chaps at National Physics Lab explain it better than me here:

http://www.npl.co.uk/lmm/docs/basics...on_control.pdf

Also, I didn't know this, but if you eliminate all oxygen then no oxidation can occur, so it's time to get a scubba kit and flood the shop with inert gas... here, don't TIG and MIG welders have Argon or something? *takes aim at the welder valve with a big spanner*