View Full Version : removing aluminum from a file?

06-10-2010, 11:26 PM
How do I get galled-up Aluminum chips out of my file? :mad:
My file card just runs over the Aluminum.
Anyone have any super-secret tricks?

06-10-2010, 11:34 PM
Take a flat piece of aluminum and push it through the teeth of the file. It will remove the stuck aluminum on the file and also clean out any thing stuck in the teeth. This is a trick an old Model Shop machinist show me many years ago. after pushing the aluminum out, wipe file with a rag. It will make the file like new.

06-11-2010, 12:17 AM
Use a better "file card".

06-11-2010, 12:25 AM
Submerge it in a water and lye solution, the lye will attack the aluminum but not the steel. I removed some aluminum from a 4 flute end mill like this, I let sit over night.

06-11-2010, 01:05 AM
I use a brass cartridge case with the mouth flattened, 45-70 case works best. be sure to use an empty one :p

06-11-2010, 01:09 AM
To avoid this in the future use chalk to load the file first and avoid loading up the file with 'pinings'.

Cheapo childrens sidewalk chalk works well and is almost dirt cheap.

Forrest Addy
06-11-2010, 02:40 AM
The phenomena is called "pinning" - swarf embeds in the teeth gets friction welded through use. A sheet of brass or aluminum pushed to follow the teeth works very well but in the end it's a little wearing on the edges. Do it but sparingly. A clean file cut cleanly and predictably. A plugged file is a PITA.

I make wooden chisel shapes from rippings left over from the table saw - a 1/4 x 1 stick a foot long with a chisel edge belt sanded on one end. Works great if you use it frequently and it keeps the teeth clear. The wood residue dusts the gullets and helps keep the sward fromaccumulating.

My ascerbic comments on file cards. The fiber brush is to me the sole reason for a file card's existance. Use only the fiber brush side to clean the file. The other features seem intended to destroy a file. Never use the wire brush side of a file card on a file. They are put there by file manufacturers to blunt the teeth and thus sell more files. There's a cruel looking fitting riveted to the end of the file card supposely there to pick out pinning. In fact it also damages the file teeth. I use a pointy hook scribe to eradicate stubborn pins.

The caustic (lye) bath trick Reb suggests to remove aluminum pinning works well. I've tried it in days of yore.

06-11-2010, 03:38 AM
Get a relatively large caliber spent brass. I have 357 Mag by buckets, and it fits nicely in a file handle. Flatten the first 1/4" or so in a vise, then rapidly heat to glowing and then quench to anneal. Now, run it with the grooves (brass blade width across roughly perpendicular to grooves) and it easily takes the set of the teeth, pushing out all pinning material. If its start getting work hardened (harder to clean as well), just anneal again.

Your Old Dog
06-11-2010, 07:18 AM
I feel so old fashioned.

I use a finely sharpened scribe and pic each groove one at a time. Takes but a minute to clean one up.

06-11-2010, 08:05 AM
I've heard a piece of bamboo works best for cleaning.

Like some others,I load the file with chalk.

Some people say a file card blunts files.

06-11-2010, 08:17 AM
Candle wax works too. Warm the file a bit to melt it in the grooves. Dunno if it's better than chalk, I've never tried chalk.

06-11-2010, 08:22 AM
before filing wet the file in parts washer (I use paraffin,) after filing wash file in parts washer...

06-11-2010, 09:11 AM
Can anyone explain precisely why a card file dulls a file? I must admit I was taught that way and have never heard of this until now.


06-11-2010, 10:12 AM
I use a lye solution to remove aluminum from files and rotary cutters or any metal surface the aluminum bonds to and it works.

I use pieces of 1/2" and 3/4" copper pipe flattened on one end to clean the file grooves like you would use a file card.

I've been using file cards since I was a teenager and I have a hard time believing that a file card will damage the cutting edge. That is, unless your using the file card the length of the file rather than across the file. The wires in the card would follow the grooves in the file and seldom if ever rub on the sharp edge. Even if they do I am sure the process of using the file to remove metal would do more damage to the cutting edge than a file card would.

On top of that the bristles of the file card are V shaped and lean back toward the handle so that they do not attack the groove. When the bristles go through the grooves they lean over much like the bristles of a paint brush on a stroke and follow the forward motion rather than leading.

I can't accept the concept that a file card does damage to a file.

Tony Ennis
06-11-2010, 10:35 AM
If a file card damages a file, I can only imagine what the steel I file must do.

Frank Ford
06-11-2010, 11:33 AM
I like bamboo.

I finally made myself a file cleaner tool that grips a piece of split bamboo (Bambusa oldhami from the back yard). It hangs right my file rack where it's always handy to keep files clean:


Forrest Addy
06-11-2010, 12:30 PM
A file's working surfaces consists of a hundred or more cutting edges made by succesive strikes of a chisel on a soft file blank. Later the incised file is hardened and the edges raised by the chisel are keen and sharp.

The metal file card bristles are spring steel wire. Scrub a hardened steel edge (like the hundreds on a file) with short spring steel bristles (like on the wire side of a file card) and what happens? Dullsville. Why delberately dull a cutting tool?

I was taught the conventonal widom of file cards and then as an apprentice I had to file for hours a day for rwo months. Went through a lot of files. I had plenty of time while fling to thnk about it. I noticed the file didn't cut as well after the first carding, and poorer yet after every subsequent carding. When I used the fiber bristle silde and a wood chisel to clean the stubborn accumulatons a file would cut well for days not hours. The files were good Nicholson and Simonds files. Uncle am bought the best in this case. The card was the standard file card you see today made for generations..

My conclusions are not frivolous. Anytime a cutting edge is scrubbed lengthwise with hardened stell the edge will be degraded. If you want to keep the file sharp don't scrub it with the wire side of a file card.

BTW, I use chalk sometimes but you have to be careful. Chalk sometimes carries an abrasive (possibly silica) and yu can't tell by looking at it. I once dissolved a hunk of suspect chalk in acid and got some geryish sediment. When filtered and washed t it and examined under 100X they looked like sand granules irregular but cystaline.

Wet filing works great if you want to avoid pinning but the swarf doesn't release from the file too well and tend to accumulate on the work. If you want to avout re-cuttng the swarf and scratching the work, you have to wipe, blow, and wrinse - a LOT.

I've tried chalk, solvent, soap, 409 cleaner, oil, steric acid, bee's wax, talc (a mild abrasive), corn starch, carnauba wax, soluable oil, alternate strokes on hardwood like maple or birch, water based coolants, and a dozen others as filing media but unless there's a special problem (dead soft aluminum - shudder) dry filing and brushing out the teeth every few strokes works the best for me.

06-11-2010, 02:55 PM
Which direction are we talking about here, regarding the file card strokes against the file?
I always thought you were to brush parallel to the teeth, i.e. at an angle to the long axis of the file.

Forrest's comment: "My conclusions are not frivolous. Anytime a cutting edge is scrubbed lengthwise with hardened stell the edge will be degraded. If you want to keep the file sharp don't scrub it with the wire side of a file card." suggests brushing down (or up) the length of the file.

Regarding the chalk: I've noticed that over time the chalk does tend to promote rust. I assume the chalk has an affinity for the atmospheric moisture.

06-11-2010, 06:53 PM
The best method I've found is to lightly coat the file with oil, it keeps the aluminum from sticking, and it can also flush any aluminum jammed into the file out.

06-11-2010, 07:42 PM
I'm sure Forrest means using a file card along the length of the teeth - ie across the file.

I do the same - dry filing, brushing out the file every twenty strokes in AL, every fifty strokes in Fe - brushing in the same direction you'd use a file card - but using a brass brush, one bought from a shoe shop for brushing up (blue) suede shoes.

If I don't brush often enough, I'll get some pinning from Al. Then it's emergency measures, starting with the thumbnail, and ending by digging the particles out one at a time with the rough sawn edge of a mild steel offcut.

My two everyday files, 14 inch coarse and 12 inch smooth, must be 30 years old now, and they're still quite serviceable. At least, they're good enough for me not to want to put my trust in something that might turn out to be rubbish.

I've never had a half decent round file - for filing out 6mm to 10mm holes. I just have no memory of ever owning a sharp one, and I've bought many.

(Edit to remove a bit about sharpening files that was made redundant by Joe's thread on the subject.)

Don Young
06-11-2010, 11:11 PM
For removing real stubborn pins, I find that the sharp point of a razor type utility knife carefully applied works well.

For soft aluminum, the real coarse curved tooth flexible files once used by auto body shops work well. We used to use them for filing the lead used for body filler.

06-12-2010, 01:24 AM
Which direction are we talking about here, regarding the file card strokes against the file?
I always thought you were to brush parallel to the teeth, i.e. at an angle to the long axis of the file.

Yeah, clearly I'm in the doo-doo here, because I've always carded parallel to the teeth, ie across the file. Followed by one of those little marking scribers out of the back of a combination square for the few stubborn remainders. So that's wrong? :confused:

I do like the wood idea though as clearly there's no chance of dulling a file that way.