Is it true that ....? (some questions on machining wisdoms)

[graham-xrf]

I have some questions. Please forgive if they seem a bit silly. They are also a bit random. I consider myself able to think through most things, and usually, where there exists reason that makes some logical sense, or sufficient gathered wisdom from the very experienced, or accumulated knowledge that transcends transient fad opinion, I can usually see it, and go with it.

There are some nagging ones that have not yet been resolved. I would appreciate answers to these. If it results in some myth-busting, so much the better.

1. Old files etched
Is it true that one can "rejuvenate" an old file by cleanng it up with wire brush. or a piece of old copper pipe (ex-YouTube!), and then dunking it in sulphuric acid for a while?
Then naturally, it follows to ask - will the acid from a dead old battery do?
Will the file keep corroding after unless one substitutes sodium carbonate in an electrolysis method? Would sodium bicarbonate (baking soda) do for the electrolysis instead?
Is a whole 12V from a battery charger, and 6A necessary?
Can the process be undertaken more than once? Obviously there is a limit as the teeth are eaten away entirely? Has anybody in the forum actually tried to rejuvenate an old file this way? If so - do tell.

2. Re: Moore pattern, "frosting", oil retention, "flaking", "decorative".
All being terms related to surface scraping. Is it true that ..
Lathes ways might be ground or scraped, or a bit of both, but should not be given the 0.001" deep half-moon scrapings supposedly to retain oil. Instead, it is the mating surfaces on the saddle that should get the treatment. Can this be true?

3. Non-detergent oils, and oiling in general
We get it that oils without detergent, and with a additive to make them "sticky" is the logic that drives specifications for way oil. We bow to the general wisdom that Mobil Velocite 10 is the absolute best for a South Bend 9 spindles, and Mobil Vactra 2 is OK for the ways. Even so, I read from the man who used Mobil 1 0W-20 for 20 years as spindle oil, without problems.

We have the explanation that non-detergent allows the contaminants to "fill the pores in the metal" instead of being carried away to a non-existent filter. Is this right? Even with total loss oiling, so long as oil keeps coming, we should be OK - right? Can we get some weight and either real data or trusted experience on this?

I will admit to having a can of Mobil 1 0W-20 stood right next to the Velocite 10.
As for the ways, I also have a whole 4 litres of very sticky chainsaw oil that looks as if it will do the job just fine. Am I wrong?

Moving on to the the less mentioned oiling - the gears. Except it does not smell so fine, the (Extreme Pressure?) EP-80W90 types seem ideal for quiet running. Good enough for the gears in the car, why not the lathe? Except for where there is maybe the possibility of corrosion of brass or bronze bushings from sulphur-phosphorous additives (that be sulfur in USA), I don't see a problem, and I am sure all sorts of oils have been used on lathes if they happen to be handy. Am I wrong?

4. Measuring wear with a level
That you can check out the wear along a lathe bed by using a sensitive level between successive measure points. The level has to be a 4 or 5 arc-second type, like 0.02mm/m or near equivalent in inches, like 0.0003"/ft, and one has to be careful about cumulative errors. This whole scenario seems a bit marginal to me - but do tell..

There are a whole lot more that buzz through the head, but these will do for now. Thanks if you can explain. It is perfectly OK to have contrary opinions, or differing experiences. I already know there is unlikely to be one "right answer" to most of these.

 

[benmychree]

#1 it was done in the past, but is it worth the effort? There would be no need for electrolisis, just neutralize the acid with either bicarb or soda ash.

#2 Lathe beds should not be flaked, it just allows dirt and fine chips to get under the carriage, this style of flaking is a favorite of used machinery dealers; the only flaking should be under the carriage where it can't be seen.

#3 Yes, non detergent oils are the best for machine tools Vactra #2 is good for most anything, I'd stay away from chain/bar oil, it is not so pure, I've heard. EP oils are not for ordinary gearing, they are only for spiral bevel or hypoid gears, they stink, and are bad for brass/bronze parts, the additive corrodes the metal, and that is worn off by the moving parts (continously). Back to Vactra #2, I used some on the feed clutch on my 9" Monarch lathe, a cone clutch, metal to metal, after I used it it has trouble keeping engagement; its good for ways, but not so good for things that need friction.

#4 Yes, a level and suitable fixtureing, like the Kingway alignment device can tell some things about geometry and wear on a lathe bed, but scraped straightedges and color media transfer also tell the story and need for correction by scraping or grinding.

 

[T Bredehoft]

Thank you,. Ben, for reminding all of us what we should already know.

 

[graham-xrf]

#1 it was done in the past, but is it worth the effort? There would be no need for electrolysis, just neutralize the acid with either bicarb or soda ash.

Thanks for the reply.
You are right that fussing with chemicals is not really worth it to rescue a file that could be replaced at less cost. I get that. I sometimes wonder if one could use the old file metal for anything. Even those who make knives would likely start with some new (other) steel. I was intrigued with the claim the file gets re-sharpened. I did not know, and I just wondered if it was true.

The chemical route I know is also used for de-rusting, and here is where I understand any use of acid, be it vinegar, whatever, leaves the pores of the clean metal in a very rust-prone state, and hard to seal up again. Also, the metal fundamentally gets "eaten up". The dimensions (in theory) change, and rust-style pitting is actively happening. One needs hot alkali, or various surface after treatments to kill it. Using electrolysis with a carbonate salt with the other electrode being also iron apparently guarantees by the chemistry you only attack the rust, and end up rust free, with no pitting or etching, and with the current finally only decomposing the electrolyte. Acid rust converters using phosphoric acid apparently convert the rust into something else that protects the spongy surface.

#2 Lathe beds should not be flaked, it just allows dirt and fine chips to get under the carriage, this style of flaking is a favorite of used machinery dealers; the only flaking should be under the carriage where it can't be seen.

Thanks much. This is what I wanted confirmed. I see many great posts about scraping ways. What I had not understood was the scraped surface was not the same as the "finish flaked" surface. So I take it that the (deeper) half-moon style cuts are for oil retention, appropriate for under the saddle, and if seen on ways, it was purely for decoration, or an attempt to mislead.

Re. #3. OK on everything you said about oils.

#4 Yes, a level and suitable fixtureing, like the Kingway alignment device can tell some things about geometry and wear on a lathe bed, but scraped straightedges and color media transfer also tell the story and need for correction by scraping or grinding.

I saw posts about the Kingway device. I wish I had one. It measures while referencing from unworn surfaces. Maybe to be taken with a pinch of salt, but I was meaning the notion that you can "walk" a level along a worn surface in a series of steps, and track the ups and downs. I guess the level would need to stand on small blocks, and the whole scene only OK for horizontal surfaces. I don't really believe it, which is why I thought it "marginal"

 

[tech610]

I buy old files on a local fleamarket. I find the sizes that I can't buy at reasonable prices. I pick decent ones with most of their teeth still there, then I put them in the vinegar for a few days and after that they are perfectly usable. The handles come from a Dollar Store screwdrivers.

 

[RJSakowski]

I resharpen files with muriatic acid. It doesn't return them to "like new" but it does restore service to an otherwise dead file. The acid fairly uniformly removes material from the surface creating a sharp edge that was blunted before.