# Lathe filing. Is long angle file useful?



## alexmin (Jan 5, 2010)

I've read in an old machinist book(1940-something) about filing on a lathe with long angle file but don't see anyone mentioning it on any forum.

How practical is it? Is it worth even buying some long angle files?


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## mossyoak (Jan 5, 2010)

Ive used my standard files on the lathe with no problems what so ever, only thing is you gotta keep them clean, they fill up so fast when using them with a lathe.


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## will (Jan 5, 2010)

+1

invest in a file card - this is the tool that will clean out the metal from the file.

safety tip - make sure you have a handle on the file. Hold it so the end does not rest in the palm of your hand, kinda like a tennis racket or golf club..


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## precisionworks (Jan 5, 2010)

> Ive used my standard files on the lathe with no problems what so ever





> make sure you have a handle on the file. Hold it so the end does not rest in the palm of your hand,


+2 

I've also read about long angled files, which are single cut (versus the normal double cut machinist file). But I don't believe there's one in my shop (might be, as there are quite a few dozen files in total). Filing to final diameter is commonly done when a very tight final diameter is needed - when the print calls out +/- .00010 or +/- .00015, there's hardly any other way to reach that diameter on a manual machine.

The ******* cut mill file is aggressive, and isn't a great choice for filing unless it's pretty worn. The second cut or smooth cut mill file are a better choice.


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## wykeite (Jan 5, 2010)

Never heard of long angle files. Single cut files which I think you're referring to I know as mill files. They are less aggressive and leave a finer finish. Less prone to pinning they give a better finish. 

The files shown above are not mill files but cross or double cut.


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## chew socks (Jan 5, 2010)

will said:


> +1
> 
> invest in a file card - this is the tool that will clean out the metal from the file.
> 
> safety tip - make sure you have a handle on the file. Hold it so the end does not rest in the palm of your hand, kinda like a tennis racket or golf club..



+2 on the file card...makes cleaning so easy

Good safety tip. ive also found that, depending on the size of the piece, spinning the lathe backwards and then holding the file in reverse and filing in reverse, can also protect you. That way i the file catches, it will be flung away from you instead of toward.


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## Fred S (Jan 5, 2010)

I have used long-angle fis a bit, and they do seem better than regular files. They seem to cut a litte smoother.


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## StrikerDown (Jan 5, 2010)

+1 on the file card. If you don't keep the file real clean the chips on the file mess with finish quality.

The "long angle file" sometimes called a Lathe File seems to be more common in gun smith circles. It produces a somewhat finer shearing action on the part you are filing. They are a bit on the expensive side though and you can simulate the shearing action by turning the standard file so it has the same angle cut on the part.

http://www.brownells.com/.aspx/pid=25663/Product/LATHE_FILES


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## brickbat (Jan 5, 2010)

will said:


> +1
> 
> invest in a file card - this is the tool that will clean out the metal from the file.



I'm going against the flow on this one. Don't bother with a file card. Great thread here: See posts 4 and 10, especially.

http://www.practicalmachinist.com/v...2628.html?t=192628&highlight=clean+file+brass

The brass stock is amazing at cleaning single cut files...


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## darkzero (Jan 5, 2010)

brickbat said:


> I'm going against the flow on this one. Don't bother with a file card. Great thread here: See posts 4 and 10, especially.
> 
> http://www.practicalmachinist.com/v...2628.html?t=192628&highlight=clean+file+brass
> 
> The brass stock is amazing at cleaning single cut files...


 
Good idea, I'll have to try the brass & bamboo/wood.

I have one of those file cards too. Don't know if it's just a psychological thing but I always felt like they make my double cut files dull, especially my smaller double cut hobby files. I use mostly single cut mill files & these are the only files I use the file cards on, going with the teeth of course. 

For double cut files I prefer to use a semi stiff short bristle (not metal) brush. On the smaller ones I use a very fine & dense stainless steel bristle brush that is used supposed to be used for electronics.


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## precisionworks (Jan 5, 2010)

Chalking a file is another great way to extend file life. The chalk keeps the filings from packing between the teeth. And it's dirt cheap, considering how long it lasts.

http://www.brownells.com/.aspx/pid=785/Product/FILE_CHALK


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## will (Jan 6, 2010)

It looks like there are several ways to clean up a file. The main thing with all this, the file will work better and faster if it is clean.


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## precisionworks (Jan 6, 2010)

> The files shown above are not mill files ...


You're correct, those are flat files ...






Source: Machinery's handbook for machine shop and drafting-room


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## wykeite (Jan 6, 2010)

One of the points I should have made in my earlier post and in reply to using a mill/long angle file on a lathe is that a double cut file can start to what can only be described as 'screw cut' especially if the file is held still. I think it's important to keep the file moving in a filing movement. This can also happen when filing a flat surface, the file will wander off and start making deep grooves, never happens with a mill file though. The mill file is my favorite for lathe work.

At work our stores still carry rough block chalk though seldom gets used for it's original purpose, with the quality of files we get these days it's a waste of time chalking them. If they haven't snapped, they're blunt, all in the cause of economy. We used to get Nicholson, Stubbs etc. good quality tools, now we get totally unmarked rubbish.

The brass bar, in my case about 3/8 square and as hard as possible is what I use. Even a large csk brass screw in the end of a dowel is good. In fact a piece of round bar can be good for that stubborn 'pin'. Bamboo and hardwoods I've just got to try that. File cards I did use as an apprentice many years ago, I've given up for many of the reasons stated here. They weren't designed for files but for 'carding' sheep wool. Not exactly a purpose made tool.

A potentially great thread, the file along with the hammer, cold chisel and hacksaw are skills that should be learned if you wish to work in metal.

Perhaps we should discuss the file taper's use in filing flat:tinfoil:


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## wykeite (Jan 6, 2010)

*Re: Lathe filing. Warning*

Please when filing on the lathe wear good eye protection.

A lathe tends to have a suction at the work end, if hollow, swarf can travel down and exit via the chuck jaws. It's only with a short piece that's shorter than chuck jaws and leaves an opening. 

Luckily mine was steel but took 3 years to get rid of all the bits. EYE PROTECTION MANDATORY please.


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## darkzero (Jan 6, 2010)

*Re: Lathe filing. Warning*



wykeite said:


> Please *when filing* on the lathe wear good eye protection.


 
More like "when always".  Swarf can be very unpredictable.


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## precisionworks (Jan 6, 2010)

> the file along with the hammer, cold chisel and hacksaw are skills that should be learned



Every now and then, a print would come out of engineering with these initials:

PTF/FTF/PTM

Meaning?

Pound to fit, file to finish, paint to match


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## wquiles (Jan 7, 2010)

wykeite said:


> Perhaps we should discuss the file taper's use in filing flat:tinfoil:


I most definitely would like to hear more about this - please?


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## wykeite (Jan 8, 2010)

wquiles said:


> I most definitely would like to hear more about this - please?


 

Traditionally files have tapered in thickness over about the front third of their length. The most common files for filing a flat surface is the flat file and the hand file. The difference in the two being the flat file tapers in thickness but is parallel in width. The hand file tapers both in width and thickness. I hope these terms agree with US terms, I'm not quite up to the files chapter in Machinery's Handbook. Most other files have these tapers which are more visible in round,square and three square.

That covers what and where the taper is but before we pursue that let's look at vice (vise:tinfoil height. It needs to be at elbow height, do an Arnie and flex your bicep with the elbow pointed down, if the vice is higher you're on a loser. Ideally you want to be at or very slightly below the elbow, it's all part of the geometry that will be the filing machine.

How to hold the file with it's correct size handle: feet apart at shoulder width, right angles to the bench. Grasp the file handle in the favoured hand and lay the file on the work. With the other hand place the thumb on the top of the file and grasp the underside with the fore and middle finger tips. 'Theoretically' now the geometry is about as good as it gets for the human form and if we move our arms backwards and forwards will get a flat filed surface:nana:. You forgot to keep your body still:devil:.

Test your results by placing a rule on the 'flat' surface and holding up to a light. If you see no light try engineers blue on a surface plate.

Still not quite getting there?

That's where the taper comes in. Our abysmal efforts have produced curved surfaces due to the numerous slack linkages in our bodies. The file has a sweet spot where the taper starts that allows us to file a concave surface. Judicial use of this allows us to get a flat surface by removing the dome. Try blackening the surface with a magic marker and taking out only the centre.

One of the well known tricks of chalking the file will also give you an indication of where you are removing the metal as the shed chalk dust will appear matte whereas metal removal will be brighter.

Anyone care to explain how to make a surface plate without reference to a flat plane?


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## wykeite (Jan 8, 2010)

*Re: Lathe filing. Warning*



darkzero said:


> More like "when always".  Swarf can be very unpredictable.


 
You are of course absolutely correct. The point I was inadequately trying to make is that when using a file on a lathe there generally isn't a lot of visible swarf produced. I was filing a hollow fitting and the swarf was sucked into the end and came out at great velocity between the chuck jaws. Painful for three days and was told I was lucky it was ordinary mild steel. That was many years ago now though.


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## gadget_lover (Jan 8, 2010)

Thanks for the explanation. I need to practice more. (of course).



wykeite said:


> Anyone care to explain how to make a surface plate without reference to a flat plane?



Oh, you mean the 3 plate trick? Start with three reasonably flat plates. You lap plate a and b till they match, then lap b and c together, then lap c and a . Then back to a and b. When the level of flatness meets your need, you stop.

Sell the one that was not lapped in the last batch to a buddy. 


Daniel


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## Bruceter (Jan 8, 2010)

precisionworks said:


> Every now and then, a print would come out of engineering with these initials:
> 
> PTF/FTF/PTM
> 
> ...



My favorite saying along that line is: Measure it with a micrometer, mark it with a crayon and cut it with an axe.

Bruceter


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## precisionworks (Jan 8, 2010)

> Measure it with a micrometer, mark it with a crayon and cut it with an axe.


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