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Super basic question regarding hand files

NC Rick

Aluminum
Joined
Oct 7, 2007
Location
Asheville, NC
Hi folks, I have been thinking strange random thoughts about the most basic of machinists tools, the hand file. I have been brought up to use them in a particular way. Cleaning with a file card, stroking in one direction, draw filling etc. I have come to believe that it is nearly a crime to put oil on one, let alone using one with oil. Chalk is the only compound to be added but I seldom do since the kids long ago used it on the driveway.

My question is: why no oil? I can’t think of a reason. I’m scared to try it!

I will appreciate input from the practical and knowledgeable folks so well represented here.

Thanks in advance!
 
I don't think you're going to do any damage experimenting with oil. I don't think you'll damage the file and in fact, I suspect a light coating of oil would help with long-term storage.

That said, I don't recommend it. There's no heat generated in filing, so you don't need oil to draw off unwanted temperature. It will make the teeth slide more easily, but I don't think that will help in cutting. I actually think you want to generate a decent amount of cutting pressure in order to get the teeth to bite, and oil might actually interfere just a little by reducing friction. But probably not enough to notice. Lastly, I typically clean a file with my hand (run it up the teeth towards the tip to clean out chips) in between application of the file card. The oil would tend to make the chips stick to the file and your hand and in general be gross. But you could use a shop-rag or paper towel.

There are no file police, however, so YMMV
 
Typically it's just to prevent small filings from sticking in the file teeth. Chalk helps them easily fall away as it's dry and slippery. Oil is slippery but as it's a liquid it will hold the tinier filings in the teeth. Other than that there's no issue. Oil won't hurt the file but may make it more of a pain in the butt to use due to needing to clean it out (card it) more often. A lot of guys just slide a piece of wood parallel to the file teeth to clean them out also.
 
Those points make perfect sense. Particularly fine files would be a gooby mess oiled. My reason for thinking of it was reaching for a 12” rat tail file from my board yesterday, I don’t think it’s been used in 25 years. I noticed some corrosion. Oil would maybe help preserve them(or not?)and washing them off with mineral spirits before use would be fine. Really, they seem to take a lot to make rust anyhow. The old file cut beautifully fitting a notch in 4130 tubing.
 
I have use oil to keep filings from building up in the file teeth, I honestly didn't know I wasn't supposed to. I had always heard to use chalk but I never have any so I went with oil. It does make a pretty good mess though.

On a side note I used the edge of a round piece of brass run parallel to the teeth to remove jammed filings that a file card wouldn't touch in some files I "inherited" at a new job.
 
Yea, one row at a time with a dental pick or something. Wood on the file card works sometimes but I clog them, normally by using a handy file for something it isn’t supposed to do. I’m not changing now! :-)
 
With a somewhat coarse file a file card works ok, but often you'll get some pinning that requires picking out with brass. On finer files brass is really the best, it's tedious running it down all the gullets but worth it. I have 4 cut and 6 cut files that are 20 years old and still cut really well.

Oil is messy but won't hurt the file. Chalk is messy and doesn't seem to make much difference really. If you want more file mystique, I was taught to use new files for brass and graduate them to steel after some time. The thinking is steel might chip the new sharp teeth, where brass with wear them slightly and then they're less prone to chipping.
 
I use a 1/2 x 1/2 x 4 piece of aluminum
use the edge,like at 45 degrees running parrell
when all 8 edges get rounded,put in mill and cut a little off and your good again
 
I use oil all the time...especially when filing aluminum.

Cleaning? I usually use compressed air. Fast and thorough. An oily file evacuates well when you hit it with 150PSI.

My biggest problem with files is when they break in half when I try to use them as a screwdriver, when I'm using a screwdriver instead of a prybar, to pry something apart. No idea why those bastards can't make a decently strong file...
 
I have use oil to keep filings from building up in the file teeth, I honestly didn't know I wasn't supposed to. I had always heard to use chalk but I never have any so I went with oil. It does make a pretty good mess though.

On a side note I used the edge of a round piece of brass run parallel to the teeth to remove jammed filings that a file card wouldn't touch in some files I "inherited" at a new job.
I borrowed some from my friend's kid. ha
 
I use way oil on smooth fine cutting files when deburring thin sheet aluminum pieces (1-2mm thick), oil helped to reduce chatter when rounding over an edge to prevent secondary burr, it also makes cleaning the file super easy - just wipe off with a rag, basically zero buildup in the file teeth

I've been told that wax is used for this application, I didn't have any, so I used thickest oil I had, and it worked perfectly, didn't use much, just couple drops
 
I use way oil on smooth fine cutting files when deburring thin sheet aluminum pieces (1-2mm thick), oil helped to reduce chatter when rounding over an edge to prevent secondary burr, it also makes cleaning the file super easy - just wipe off with a rag, basically zero buildup in the file teeth

I've been told that wax is used for this application, I didn't have any, so I used thickest oil I had, and it worked perfectly, didn't use much, just couple drops

Somthing I’ve been using is dry ptfe spray, seems to work good on Ali copper and lead, early days yet but the teeth haven’t dropped off the file and pinning is virtually eliminated
Mark
 
I’m going to try oil. My question didn’t come from wa ting to, I just was thinking about it. For soft metal with big area I have what we used to call “Vixen” files with widely spaced curved edges. Those were just the thing for dressing aircraft propellers. I recently purchased a similar but much finer tooth thing called a Lathe File, thinking it would be good for doing a quick and dirty chamfer on aluminum parts, which it will if it doesn’t suck your hand into the Chuck first ;-)
 
Files will rust. I OCCASIONALLY use a bit of oil on them after cleaning and before storing them. I do not use it while using the files to file. Please notice my emphasis on the word "OCCASIONALLY". That probably amounts to once a year or less. And they are probably going to pick up some oil in use anyway. It is the seldom used files that get that bit of oil, usually when rust starts to show.

I find a fine brass brush does a better and faster job of cleaning them than a file card. Anyway, that's my observation.
 
Hard to describe my method of depinning a file, but here goes;
If you have a cast iron 90 degree sharp edge, a milled edge, set your file against it at an angle so that pushing down pushes the edge into the teeth in the direction of the angle of the teeth (Mill bastard teeth) and slide the file down so the whole length is so cleaned. It takes a second if your slow, but the down side is that eventually the sharp 90 degree edge rounds over. Done right it doesn't dull the file.
My first real job was as a saw filer, many hundreds of thousands of file strokes in it, most boring job I ever had.
 
Never use oil on a file to file something. Applying oil as a preservative to prevent rust is not a bad thing, but always wash the oil off before use. The reason is simple. The biggest problem n cutting anything with anything (including files) is swarf removal. The chips must be removed or double cutting occurs as well as the swarf inadvertently cutting and ruining the finish of the work. I also never use a file card because the hard steel bristles will dull the file. I use a stiff brush, compressed air and occasionally a pick when required. The use of chalk is a release agent in the same way Tricloroethylene does. Dull files can also be sharpened with the use of pickling acid (sulferic or nitric) at least once.
 
This is getting fun! I’m about to learn more stuff. Have been actually! The double cutting from trapped swarf makes tons of sense and is something I experience.

I am skeptical of the file card dulling files appreciatively. My file cards have a brush and wire side.

I’m going to continue to disbelieve acid can sharpen a file anymore than it would sharpen a lathe tool or an end mill. I’m open minded and will listen to reason but it’s going to take some very well explained principles which I do not understand at present to change my mind on that one. The sharp points are what acid will attack best in my opinion.
 
This is getting fun! I’m about to learn more stuff. Have been actually! The double cutting from trapped swarm makes tons of sense and is something I experience.

I am skeptical of the file card dulling files appreciatively. My file cards have a brush and wire side.

I’m going to continue to disbelieve acid can sharpen a file anymore than it would sharpen a lathe tool or an end mill. I’m open minded and will listen to reason but it’s going to take some very well explained principles which I do not understand at present to change my mind on that one. The sharp points are what acid will attack best in my opinion.

Yup, acid will sharpen a file, by eating away at the flanks of the teeth. If you have ever seen a really rusty nail, it still comes to a point. That is actually one reason NOT to oil a file, so it can be “ready” for the acid treatment.. it will make it rougher so it can’t work more that a few times, and for certain cuts and uses it may not work well at all ( single cut used for fine drawfiling).
 
I know it's been mentioned any number of times before, but you can get files resharpened, using 100+ year old process of steam/abrasive blasting. Any type or size.

I just box up my old files and send them along with a note indicating how many are in the box, and a while later they come back all clean and sharp, along with a modest bill. Each one gets tested after sharpening and those that don't make the grade are returned at no charge, but still better than they left:

Boggs Tool & File Sharpening Company
 








 
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