Protecting & Maintaining Machined Surfaces

[ericc]

It is remarkable how little rust it takes to ruin a precision flat surface. Best not to let it take hold. Used or handled tools do not rust as quickly. I have a forged keychain which will never rust. It will wear away first.

 

[John Hasler]

John,

Thanks,

Rod

I usually dilute the stuff I buy locally (different brand) about 4:1 and leave the part in overnight. Heating the solution to near boiling reportedly reduces the time to about 15 minutes and produces a better finish but I haven't tried that yet. I then rinse the part carefully so as to not disturb the phosphate coating, let it air dry, apply a thin coat of linseed oil, and then hang the part in the sun for the linseed oil to set up.

It is remarkable how little rust it takes to ruin a precision flat surface. Best not to let it take hold. Used or handled tools do not rust as quickly. I have a forged keychain which will never rust. It will wear away first.

I wouldn't use phosphoric acid on a precision flat surface unless it was just to strip off heavy rust before refinishing.

 

[uncle harry]

I usually dilute the stuff I buy locally (different brand) about 4:1 and leave the part in overnight. Heating the solution to near boiling reportedly reduces the time to about 15 minutes and produces a better finish but I haven't tried that yet. I then rinse the part carefully so as to not disturb the phosphate coating, let it air dry, apply a thin coat of linseed oil, and then hang the part in the sun for the linseed oil to set up.

I wouldn't use phosphoric acid on a precision flat surface unless it was just to strip off heavy rust before refinishing.

That's where Evapo Rust is champion.

 

[louosten]

EvapoRust is great for many applications, especially for small, uniform parts that fit in a bucket. It is relatively expensive in comparison with other methods, especially for non-uniform and large parts. I use Naval Jelly frequently because it is inexpensive and lends itself to mostly any size and shape that requires cleaning. Due to its jelly-like, brush on nature, you don't necessarily have to coat the entire part in question to restore an accurately machined surface.

When I acquired this drill press, it was pretty rusty:



The column was obviously a precision surface that needed to be cleaned and restored; I considered an EvapoRust bath, but couldn't locate a long, slender tub for my purposes, so I fashioned the following (cheap) set-up:



Two 5 gallon buckets, an old shop broom, and Wifey's discarded liberal newspaper to catch the drippings! After 10 cycles of soapy wash, wire brush, and Naval Jelly, I had a pretty clean column:



This obviously facilitated a smoothly operating machine:



I chose not to repaint everything just yet, but to restore the drill press to full functionality. So far, the 'Old Iron' has lived up to its deserved reputation!