Filing a Flat Surface

[rhmc24]

Probably not news to old timers but reducing a flat surface & keeping it flat takes care, skill, judgment, etc.  Not being especially so gifted I use this aid:  Score the surface with cuts or depressions of guestimated similar depth & file to remove them.

I use a tool made from a triangle file with one side ground smooth, which gives two cutting edges. I try to score the same depth, lines about 1/8" or less apart, judging the depth of my scorings by their width.  Similar method could be used with punch marks, drill starts, etc.

This is an aid to skill & judgment rather than a substitute for them.  It has been especially useful to me where accurate measurement is difficult or impossible such as setting the BC gap after installing a barrel on a solid frame revolver.  (BC gap = gap between barrel & cylinder.)

[Chris Treichel]

Another little trick for once you get close to even or in a delicate spot... is to take a sharpie and color the area that you want effected... that way you can really see what your file/stone is doing on each pass and any high or low spots really stick out.

[kutter]

Things like screw heads or the threaded end, any other small flat surface that needs a bit of trimming down flat can be guesstimated first and a quick chamfer swiped accross one or more of the outside edges with the file.
Now file the surface down till the chamfer (bright spot) is gone. You've gone no further than the depth of that chamfer cut. If done carefully (chamfer(s) and stock removal) the surface will remain as flat as you started with.
Especially helpful when shortening up a threaded end of a screw. Trying to eyeball a certain # or portion of the threads usually leads to failure.  All done with just a file, no solar powered measuring devices.

[D. Taylor Sapergia]

Your method is well received.  I use a similar system, for example, on the base of a sight, to reduce the thickness and still keep the surface flat and an even thickness.  On a gun stock I use a pencil to draw lines about 1/4" apart over the surface I want to reduce, then scrape/sand/etc to remove just the pencil marks.  It can be a curved surface, either concave or convex, and work just the same.  The point is that you remove only the marks, thus controlling the amount of stock removed and keeping the plane intact.  Great Post Mr. McC.

[jerrywh]

 Old time gunmakers never think much about stuff like this but they do it all the time. When I am draw filing a barrel or sanding it to final finish I will swipe my file across the barrel at a 90° angle a few times every several  strokes to make shiny marks on the surface. This allows me to see where the file is taking off the metal when draw filing. I do this alternately during the process. The same on locks when or any other similar process. Also I chalk the surface on wood with colored chalk.
  These are the trick that never get put in books because it becomes so automatic one ever thinks about it.
  Good thread rhmc24.  Old guys know stuff--- right?

[rhmc24]

jerrywh  -- I think that's what this is all about, exchange of info & letting new people know about ways to do it. Here for example several variations on the basic idea.

[Mike Brooks]

I have taught gun building classes for years. You wouldn't believe the number of people who can't run a file, or any hand tools for that mater.

[Acer Saccharum]

There is a lot of truth in the mundane not getting passed on, because 'everyone knows THAT part'.

No more erasers to be clapped. No more files to be chalked. Things won't be made by taking material away, buy by building the material up, one dot at a time.

The faster this stuff goes away, the more important is our task of preserving the technology.

[flehto]

When I was serving a tool and diemaker apprenticeship in the late 50s, some of the toolmakers of German decent  who had served their apprenticeship in Germany mentioned that they had to file a square block of steel so that it was indeed  square and all the surfaces were flat.  This was a one of the req'd "tests" to bcome a journeyman.

I agree w/ Jerry that filing a flat surtface was an " every day task" of the gunsmiths of yore and  it's just something that requires practice if a person wants to achieve this skill in this modern age.   Of course...for some it's easier than for others....but that's life......Fred

[David R. Pennington]

The same type of technology applies to hand planning a board to get a flat level surface. I use a straight edge and wind sticks to find the highs, lows and twists. I will mark the high spots with chalk and plane till they are gone and test again. Once one surface is perfect I can set my marking gauge to the desired thickness scribe all the way round the edges and true the opposite side. Then just square up edges.
We do take for granted some things that we think every one knows. I was recently helping my son in law with a project at his house. We went to the big box store to get some lumber and as I was picking through the kindling they sell for 2 by 6's he wanted to know why I held the boards up and looked along the edge. I showed him one of the boards that he had picked had almost a 1/4 turn twist in it!

[jerrywh]

 Talk about tough hand work.  Try hand scaping lathe ways so that they are perfecly true.  By the way that thing about filing a perfect square bock is very hard to do. It is also hard to file a perfect square hole in a hammer so I broach them. It is easier to make the broach.

[Flint62Smoothie]

When I was serving a tool and diemaker apprenticeship in the late 50s, some of the toolmakers of German decent  who had served their apprenticeship in Germany mentioned that they had to file a square block of steel so that it was indeed  square and all the surfaces were flat.  This was a one of the req'd "tests" to bcome a journeyman.

When I went through GE's (aircraft turbines) machinist apprentice 3-1/2 year program, we had to study up on other apprenticeship history and a German apprentice spent their first year using files. We had extensive pictures and samples of their work and it was simply amazing ... all by hand.

[Sawatis]

When I was serving a tool and diemaker apprenticeship in the late 50s, some of the toolmakers of German decent  who had served their apprenticeship in Germany mentioned that they had to file a square block of steel so that it was indeed  square and all the surfaces were flat.  This was a one of the req'd "tests" to bcome a journeyman.

Yep, my high school machine shop teacher had us do that for the first month of class...Hmmm. Old German guy...but so am I...must run in the blood... .  But I think if you gave a kid a file and told him (/her...got to be pc) to do that today he'd throw it at you...oh, but then they don't have shop classes much in highschools anymore...too many kids making weapons...

[D. Taylor Sapergia]

This same concept applies to polishing too, a flat surface or a curved one.  After filing, I use 80 grit abrasive cloth (made in Holland), and I change the angle of the previous marks left by the file so I can see when they are all gone.  then 120 grit, again removing the marks left by the 80 grit, at a different angle to those marks, and so forth until I get to 1200 grit paper, that I apply parallel to the longitudinal direction of the part - polish lengthwise on the last grit.  This system helps keep edges sharp without rounding them over, and ensures that each successive grit of abrasive removes the scratches left by the previous one.
Although I understand that where this makes perfect sense to some, it is a mystery to others.  But I also think that some folks would rather ask for direction than to step out on the limb and give things a try, perhaps learning the hard way.
As far as using hand tools is concerned, I'm amazed sometimes when someone is in the shop and hasn't the foggiest notion of how to use a file, preferring to go to the belt grinder where mistakes happen a lot faster.

[kaintuck]

When I was showing a rifle to friend, he heldit, and his first words outta his mouth was, " they got computers that can makes this"

Getting fewer and fewer folks that can appreciate hand done work.......
Marc

[westbj2]

I recall chatting with an acquaintance years ago who while serving an apprenticeship at  Westley Richards as an action filer told an interesting story. 
This fellow was reluctant in his filing efforts to take off too much material.  The shop foreman came by his bench regularly and when appropriate, the foreman would grab ‘the big file’ and rap him on the knuckles with it saying “use this one”.
It has taken many years for me to understand why the foreman was insistent about the big file.  Using an aggressive file, large or small  in size but appropriate for the job allows for time efficiency and better accuracy.  Think in terms of using an aggressive file to achieve the desired shape and size so that the only remaining work is to take out the file marks left behind.
When I get close now and start to get a bit nervous about the last stroke or two not much material remains to be cleaned up.  If the work is properly positioned and you watch the angle of the file body, ‘high centers’ or incorrect angles seldom occur.

A few years ago, my neighbor who runs a mid size machine shop was down in the shop.  He made the observation that “you know files are obsolete now”.  That may be in the world of CNC machining centers but no one in that world has figured out how to make sharp corners in an acute angle with a rotary tool.

Keep filing!
Jim
               

[Bob Roller]

Kaintuck,
I'd tell that guy that he will be able to push a watermelon thru a key hole before any CNC or other electrowidget will make even the simplest rifles.

Bob Roller

[shortbarrel]

I gotta question. talking about filing a square. Did they require you to file the cube by eye, or did they give you the opportunity to make a try gauge to measure  your filing process. Filed a 1\2 inch square and its in two 2 tenths using a try gauge I made. Filed many bullet cherries. some rotated by hand and some rotated in a treadle  lathe. I have to know how it was done in years past, then sometimes I'll do it on my whizzing machines. BTY I'm mostly germane . Scrapers and arced files work wonders in this work.

[thecapgunkid]

I am a cordwainer ( shoemaker) because I can butcher metal work in a hurry. The only way I can survive metal work is with a sharpie.  It seems to work better that candle soot, and in the limited work I just did in a rescue rifle project ( where I learned to stick to shoes, by the by) it made a big difference.

Don't  shoot yore eye out, kid

The Capgun Kid

[David Rase]

Another secret to filing an object flat is to be sure you lift up the file after the forward stroke vs. dragging it back over the surface an the back stroke.  I have found that when you drag the file back over a work piece you have a tendency to round the object.  If I push and lift vs. push and pull I get a much flatter surface.
David

[ironwolf]

  Yes, files don't cut on the back stroke anyway.
    Kev.

[greywuuf]

I know I recall reading  that creating a cube with files by hand was one of the requirements for being a master blade smith? it was a "current" requirement ( that i read somewhere in the last 20 years)

[Dan Fruth]

 I made my first lock 42 years ago under to instruction of a machinist, and the first thing I had to do was learn to use a file. He made me file till he could mike the thickness and not find more than a .002 difference. I was young and gun-ho, so I filed and filed. Now I still file and file, but I also bought a milling machine! But learning how high to mount your vice is crucial so your arms don't pull the file up or down, but the natural movement of your arms is parrel to the top of your work piece. Makes a big difference....Dan