We had to draw file the sides and backs of the recoil lugs we welded onto NM M14 receiver’s at the RTE Shop at Quantico. These surfaces had to be DEAD flat so they wouldn’t hang up on the bedding when taking the receiver out of the stock. We checked them by placing a precision ground block on them and if we saw light between the block and the surface, they weren’t flat enough and had to be draw filed some more. That ground block was one of the most hated items in the shop because it never lied. Grin.
The way I draw file is sort of a combination of how Don Getz and Dphariss do it, though I don’t use a plexiglass file. First I file it the way Don mentioned, then I wrap garnet paper around the file and hold it tight on the file with the two fingers Don mentioned. That way you don’t get the buckling you can get with the plexiglass and you don’t have to worry about scarring the surface if you lift the edge of the file. I’m not saying Dphariss is wrong, but I have tried that and it didn’t work for me.
Someone correctly warned about draw filing the sides of a barrel that has already been inletted. Drawfiling will open up the space between the barrel and stock REAL quick. MAYBE I might draw file just the portion that rises above the stock, but if you REALLY want to do that, learn to draw file on the top three sides first. .
I also taught draw filing to our OJT’s (apprentices) so I have a few more tips.
1. Take a piece of the barrel you cut off (if you did) or another piece of another barrel to practice your technique till you get it down pat. Lacking that, a piece of un hardened scrap steel is a good way to learn. (I learned to draw file by filing a piece of 3/16” 01 tool steel into a knife blade, though I will NEVER do that again. Grin.) Lacking that, draw file the bottom sides of the barrel first as they will be covered by the stock.
2. Do NOT touch the draw filed surface with your bare fingers especially if you sweat a lot with your hands. If you leave sweat on the barrel, that can cause the file to skip or cause you to pin the surface. I clean the surface with a paper towel dipped in acetone and should I even think I touched it, I clean it again.
3. Start with SHORT strokes first, maybe only an inch or two until you develop the feel for it and GO SLOW. Make sure the file is in contact with the surface throughout the file cut. Longer strokes when beginning to learn allow you just too much chance to mess it up and make a wobbling cut surface. As you learn the technique, you will feel just how long a surface you can draw file before you start to wobble. Everyone I ever taught had a different length for that and that’s normal and natural. Just learn how far you can do it and stay inside that length.
4. I prefer to lift the file off the surface at the end of the stroke, no matter if you pull or push it. (I found pushing works better for me, but some folks could control pulling better.) I don’t like to lightly draw or push the file back over the draw filed surface after the cutting stroke. I found it was too easy to “pin” or score the clean draw filed surface. Getting that pin gouge always seems to come right when you are close to having the surface filed and then you have to draw file more. .
5. Here is the “secret” of what I called “Zen Draw Filing” for my apprentices. You have to THINK about putting more pressure where you want the draw filed surface to move. Not much pressure, just keep thinking about putting a little more pressure towards that side while you keep the file flat on the surface. This is important and it really does work.
6. Maybe when you are first starting out and you have the surface where you think it is flat, but not sure, use some cold blue on the surface. Just DON’T touch or oil the surface after you cold blue it. I wipe it hard with a clean paper towel so there is no liquid left on the surface, though. Try another very light/soft draw file cut to verify it is flat. If not, the cold blue left will tell you where it is not flat.
Gus
