Rust removal on precision parts collets, sleeves, etc.

I have an old tool and cutter grinder that I am cleaning up.
Several collets and other bits and pieces have some mild rust on them. With reference to 'mild rust', say rust equivalent to the photo on the first page in the below link.

Obviously, the collets are hardened and tempered. Many processes therefore can cause hydrogen embrittlement.

I have read a few posts on derusting but am still undecided as to which are the best methods.

The best post I could see was: https://www.practicalmachinist.com/vb/general/rust-removal-335522/?highlight=cleaning+rusted+parts


Please let me know if this is covered somewhere else.

I am inclined to use one of the these options: Wire wheel (steel wire), Evaporust or Grandma's Molasses.



Any input on the following questions would be greatly appreciated.

Will the wire wheel cause the precision ground parts to become out of tolerance/ dimension?
If so, are there alternatives to a wire wheel such as a nylon wheel/ scotchbrite wheel, etc.?
I was planning on using steel wool to clean the inside of some of the parts (such as sleeves) whilst spinning them up on the work head.

Does Evaporust or Grandma's Molasses cause hydrogen embrittlement?
Is one more likely to maintain original tolerances using the chemical methods?

I’ll talk to my chemist friend about the embrittlement.
Chelation like evaporust etc...I like the “rust911” concentrate myself.
Eventually they will erodethesteel to the tune of a few millionths over the entire part.
The black dust is some of the iron.
If you don’t rinse the part it will act as a barrier to future rust from atmospheric moisture.

Wire wheels just beat the shit out of things.

Wire wheel is way worse.... marks up the part and probably removes 4x the amount of material, including good material.

There is a question how much hydrogen embrittlement can happen when the thing is in the cold solution for maybe 15 min. Plus you can bake it out at a reasonably low temp is you are worried. I use phosphoric acid, cold, and have never observed any problem.

As for material removal, phosphoric and maybe some other choices will fo for the corrosion first. You have to admit to yourself that the "precision" went away with the rust in general, so you are not within the original specs anymore just on account of rust.

That all said, I often prefer to use a wet-or-dry sandpaper, 400 or 600 grit, with a light oil. Works fast, no worries of any hydrogen embrittlement. You also remove nearly zero material.

I know folks tend to think the sandpaper will "destroy any remaining precision".... But if you think about it, leaving aside the issue of "rusty precision", it's really hard to take off even a tenth with fine sandpaper. I used abrasive paper to lap in some parts a while back. I needed a couple tenths off over a small areal, maybe 5.16" square (no SG where I was) It took a LONG time to do it.

That cured me of the idea that a person could seriously change even a fairly small surface with the sandpaper and oil.

A bonus of the sandpaper and oil process is that it simehow seems to give a very good oil coating, that is good at preventing further rust. Maybe the oil is forced into the minute scratches, I don't know, but it works.

Abom79 posted this on youtube.

YouTube

Is molasses OK to use or would most recommend Evapo-Rust (not the cheapest but if it is far better then there's not much point squabbling about the price)? Chemical reaction time is of no concern for me...

I also need to remove the rust from inside of the work head (on the tapers) so I will try some fine sandpaper and oil as JST recommended. Unless there is a better chemical way to do it without pulling the head apart (e.g. a gel)?

Red scotch brite pads and WD40, plus a little elbow grease goes a long way...

I tried Evaporust for the first time a while back on some BD drill grinder collets and was very happy with the results.

Another vote for Evaporust. Tractor Supply sells it by the gallon.

I use Kroil, I buy it by the gallon, have a few spray cans too. They do have a rust remover, I have a pint can of it but can't say I like it. I did try it on something but been a while, haven't used it since and if my memory is correct I didn't think it worked that good. I might not be thinking what others say is rust on a precision collet or other surfaces. I'm thinking a surface rust that's not pitting the surface. I don't use WD 40 for rust or rust protection. On a rather humid month the table on my mills would turn brown over night, WD made it look good after spraying it, wiping it down and before leaving give the table a spray. Next day it was light brown again! TAL worked better but the Walmart equivalent was cheaper and worked about as good! I also concocted a fluid that works great for storage even it means a week or two. I mixed outboard motor oil with coolant. It don't mix easy but shaking the hell of of a spray bottle with the stuff in it will eventually get it mixed. I spray it on, when I need the machine it wipes off easily. At one time I used coolant direct but after a while it gets kinda sticky and not easy to clean off. On the other hand if I get a machine in that was in the rain while on the truck I quickly spray everything with coolant direct, unmixed.

My solution of EDTA in water seems to be almost as good as evporust and much cheaper. I do not think it has any embrittlement problems if done at room temperature.
I have wondered what it would do as coolant.
Bill D.

EDTA, Evaporust and molasses all work by chelation. If molasses is cheap and readily available, the use it, just don't feed it to the cattle afterwards. I've used it as well as electrolysis and phosphoric acid. The chelants and electrolysis won't remove non corroded metal. Acids will.

Why not feed it to cattle? wouldn't it just be iron rich?
Bill D.

I have found nothing better than "The Must For Rust". I shudder at the thought of using wire wheels.

Bill D said:

Why not feed it to cattle? wouldn't it just be iron rich?
Bill D.

Click to expand...

If you want rust tinged milk....

Seriously, it (the molasses) just won't taste all that good.

Ive had a play with rust removal. Citric acid works much much faster than molasses and you avoid the stink and mold, 25kg of granules is cheap as chips. The acid is less hassle to setup than electrolysis but you have to degrease the parts first, a rinse in baking soda helps with flash rust.
I had a tank setup for some lorry wheels, did seem that it took a little good metal with it if you left it in, not 100% sure on this as others have said it doesnt. Be nice to see a side by side test.

I like electrolytic in bakeing soda works well and zero risk.

Hydrogen embitterment is only a issue on high strength hardened goods, collets would fall into that category, http://www.heat-treat-doctor.com/documents/hydrogen embrittlement.pdf is my kinda go to referance text, a post bake is a lot easier and won't harm anything, as the temps are well bellow temper temperatures used for most steels. Collets snap there only fit for the bin, hence a few hours in a toaster oven at least to me seams a simple case of a ounce of prevention betters a pound of treatment.

That said, depending on the exact steel in the parts and what type of bath and electrolytic power levels you run at greatly effects the risk but it realy is just as simple as a few hours at circa 180C and theres no longer a question about it. In my case i use the heat from the oven immidiatly to dry the parts off all in one hit as it were, then out of the oven and a dunk in some light hydrulic oil and you have clean good rust free parts.

adama said:

I like electrolytic in bakeing soda works well and zero risk.

That said, depending on the exact steel in the parts and what type of bath and electrolytic power levels you run at greatly effects the risk but it realy is just as simple as a few hours at circa 180C and theres no longer a question about it. In my case i use the heat from the oven immidiatly to dry the parts off all in one hit as it were, then out of the oven and a dunk in some light hydrulic oil and you have clean good rust free parts.

Click to expand...

I heat about 1/2 inch of baking soda at about 300F for 1 hour. Stir a few times. Then it goes into the tank.

Instead of drying in a oven, I use compressed air. Takes a few seconds. Then apply light oil or The Must For Rust.