Using a file on a lathe

[Pacer]

Using a file to sneak up on that final size is probably a personal choice, however its used by many.

My highly skilled machinist mentor/friend with some 50 yrs of experience probably uses a file on every piece he turns - a file and then finishing off with one of a dozen or so 1/2 - 3/4" strips of various grits of emery he has hanging just to the side of the lathe. As he puts it, "the only thing that will turn true - or at least close to it - is a CNC lathe" saying that while he has operated some very fine lathes that cut beautifully, they will all - at times - leave a bit of taper, or a high/low spot of so some varying thickness. And once youve run your lathe a while, it becomes glaringly evident that trying to turn .0015-.002 thou off to get that final dim can be a frustrating experience.

When Lane gets down to needing .002, or maybe even .003, he grabs a fine tooth file and quickly brings it within .0005 or so, and then the emery finishes it off. Often I find Im cutting some piece of "unknowium" (scrap yard stuff) over 3-4" and will get an irregular finish - striping? - and with out a file and emery the piece would likely be unuseable.

Its quite surprising what emery will take off also...

 

[radfordc]

author=DaveH link=topic=2547.msg17151#msg17151 date=1308837744

Using a file with one hand is a skill that takes some learning, and even then lacks total control.
So use two hands, your left hand and arm over the spinning chuck, not the best thing to do. One day it will get you

Do not use a file as described above. You should hold the file handle in your left hand and the tip of the file in your right hand. Now you can use the file without any part of your body over the chuck. When you use a file on a lathe you don't have to apply the same sort of stroking action you do for normal filing. The file becomes just another type of cutting tool. Same holds true for using emery or sandpaper. Back the paper up with flat metal bar (a 6" machinist ruler is ideal) holding the bar so that you don't reach across the chuck.

Charlie

 

[Tony Wells]

I used to regularly shoot down the manual machinists when I worked QC. Toss a part up on a good comparator and you'll see how difficult it is to file a 45 deg edge break per print.


Somewhere, I have a souvenir in my stuff. It's a file, in three pieces. I broke it with my finger, in 1979. Actually, my finger and a lathe, spinning an electric motor armature. The cast aluminum fins that protrude from the ends of the main body were a little too close to the bearing journal I was filing to size after a metallizing operation. I was holding the file what I consider normally (with my index finger on top, pointing towards to the work, and just swung my end of it over to the left a bit, SNAP! Lost a bit of finger. Well, really just pinched it good, and peeled the hide back. I still don't have feeling in the tip.

 

[Tony Wells]

Yeah, I can smell it burning when I solder before I feel it.

 

[Zigeuner]

You don't need much force when breaking an edge with a file. The file should have a handle on it so that there's no tang showing. I've watched people do this for many years and I've done it whenever I have a very small edge that I want to deburr.

It is important to focus, however. LOL.

 

[Tony Wells]

I'm surprised nobody suggested running the lathe in revers, and holding the end of the file with the tang pointing towards the wall behind the machine. It does seem to make it a bit safer, as it will just jerk it out of your hand rather than cram it into your palm.

Overall, I am against most filing on a lathe. If you have a decent machine, and know how to use it, you can hit a .001 tolerance or less by cutting. And I don't mean sneaking up on it and taking .001/.002 cuts. Those are unpredictable for the most part, unless you have a sharp point or very small radius. I regularly turn and bore hitting size within 0.0005 of size. Probably because that lathe is is good condition, but technique has a lot to do with it.

If I can't get the finish I need, I'll paper it, just for finish, not for size.

 

[Zigeuner]

Although I was never a professional machinist, I had a long background in the Aerospace companies and often spent time in machine shops as a mechanic, technical writer and editor and later as a safety consultant. I was employed at places such as Rocketdyne when it was a division of North American Aviation. They had a complete manual machine shop in several departmenrts. Then were was Lockheed, Litton and Rockwell on the first B-1. In all of them, I was involved in the machining of parts from a procurement and purchasing standpoint as well as writing manuals and technical illustration.

Having seen and observed the machinists in the manual era at all of those places and at vendor suppliers, I can tell you that files were commonly used. They have their place. When used properly, they can help to speed things up and make very nice parts at the same time.

While there are safety issues with use of files around rotating machinery, files are only one line item on a long, long list of safety considerations when using a lathe. I won't bother making a list. You all know about lathe safety, I'm sure.

 

[Tony Wells]

author=DaveH link=topic=2547.msg17254#msg17254 date=1308869927
Tony,
I have to say Mayhem was just asking about the edge.

To use a file to take off a couple of thou, to me is just shoddy.

If it was a good idea they would make them to fit in the tool post.

DaveH

Of course he was, Dave. But in our meandering way of tackling a subject, all sort of tangential information comes out. Usually it becomes interesting, and nobody really cares. It's all fun. No Nazis allowed.

 

[Zigeuner]

author=moe1942 link=topic=2547.msg17326#msg17326 date=1308933199
I think this site is getting too crowded with safety nannies and self proclaimed experts. There is a point where it goes beyond opinion and I see this site as going the way of too many others..It's getting hard to ignore the BS..

Paddy I've been riding longer than you are old and still at it..

And I've been using a file on the lathe for about fifty years and will continue to do so.. Mayhem you sound like a savvy man..file away..

Another biker......there goes the neighborhood! LOL.

I agree. There can be an influx of so-called "Machining political correctness". That's why I came over here. The other two main sites (we all know who they are) are full of that stuff.

I too have been using files on lathes now and then. If it works, I say do it!

Oh, here's a picture of my latest acquisition - a 2011 Harley-Davidson Street Bob (FXDB). Every man needs a good mate, a good shotgun, good machine tools and a Harley. LOL.

Happy Trails.

 

[Zigeuner]

author=moe1942 link=topic=2547.msg17329#msg17329 date=1308936493
Nice ride Zig.. I have two Road Kings.. My son rides one.

I'm old school. Man wants my advice he can ask.. He wants to dick up that's his business..

That sounds pretty reasonable to me.