Newbie file question

It's probably the mill scale finish that was too hard to cut through, which is why after you stoned it off you were able to file the fresh steel. Also, with aggressive files (double cut bastard) if the surface is too smooth it can be difficult to get the cut going since the teeth aren't really able to bit into anything since there is too little surface area, so it will mostly just slide over the surface.

Soaking you knife blank in vinegar overnight to soften the mill scale and then removing it with some sandpaper or a wire brush (or stone, or scrotchbrite pad etc.) can help a lot when you're only using hand tools. Also, when starting your cuts at the bevels for example, start the cut at a steeper angle, like filing the edge at ~45 degrees and then progressively shallower angles until you reach the final bevel angle, then finish by draw filing. This will increase the amount of pressure at the point where the file is actually cutting. Another thing that can help is beginning your file cuts with a semi draw-filing motion to get into the the fresh steel below the surface as opposed to trying to cut straight into it at a 90 degree angle, because the teeth are able to more gradually begin their cut into the surface of the steel.

What I mean by "semi draw-filing": just imagine you are draw-filing regularly by holding the tang of the file in your left hand and holding the top of it in your right hand, but as you pull the file towards yourself you would also be pushing (or pulling) it to the right a bit. So the file will begin it's cut a bit to the left and will finish a bit to the right, if that makes sense.

You'll find that on hardened blades (steel), pretty much only draw-filing with fine single cut smooth mill file will be able to shave some of the steel away, which shows that the larger the teeth are, the softer the steel should be since each file tooth is trying to remove a lot more material at once on a coarsely cut file than on a fine file. You may find it helpful to begin your filing by using finely single cut file to help get into the fresh steel a bit as before switching to a coarse file for faster stock removal, which will also help roughen up the surface to give the coarse file something to 'bite' into.

I have a decent belt grinder, but I still enjoy using files, especially when I want a nice clean and swedge or false edge on a blade, which a fine single cut works great for by draw-filing; it goes pretty fast and gives me much more control with the angle and the blending of the plunge area for the swedge (or if it fades seamlessly into the spine) than I feel I have with my grinder for such a small bevel.


~Paul
My Youtube Channel
... (Just some older videos of some knives I've made in the past)
 
Last edited:
coldsteelburns said:
It's probably to mill scale finish that was too hard to cut through, which is why after you stoned it off you were able to file the fresh steel. Also, with aggressive files (double cut bastard) if the surface is too smooth it can be difficult to get the cut going since the teeth aren't really able to bit into anything since there is too little surface area, or rather it's too smooth, so it will basically slide over the surface.

Soaking you knife blank in vinegar overnight to soften the mill scale and then removing it with some sandpaper or a wire brush (or stone, or scrotchbrite pad etc.) can help a lot when you're only using hand tools. Also, when starting your cuts at the bevels for example, start the cut at a steeper angle, like filing the edge at ~45 degrees and then progressively shallower angles until you reach the final bevel angle, then finish by draw filing. This will increase the amount of pressure at the point where the file is actually cutting. Another thing that can help is beginning your file cuts with a semi draw-filing motion to get into the the fresh steel below the surface as opposed to trying to cut straight into it at a 90 degree angle, because the teeth are able to more gradually begin their cut into the surface of the steel.

What I mean by "semi draw-filing": just imagine you are draw-filing regularly by holding the tang of the file in your left hand and holding the top of it in your right hand, but as you pull the file towards yourself you would also be pushing (or pulling) it to the right a bit. So the file will begin it's cut a bit to the left and will finish a bit to the right, if that makes sense.

You'll find that on hardened blades (steel), pretty much only draw-filing with fine single cut smooth mill file will be able to shave some of the steel away, which shows that the larger the teeth are, the softer the steel should be since each file tooth is trying to remove a lot more material at once on a coarsely cut file than on a fine file. You may find it helpful to begin your filing by using finely single cut file to help get into the fresh steel a bit as before switching to a coarse file for faster stock removal, which will also help roughen up the surface to give the coarse file something to 'bite' into.

I have a decent belt grinder, but I still enjoy using files, especially when I want a nice clean and swedge or false edge on a blade, which a fine single cut works great for by draw-filing; it goes pretty fast and gives me much more control with the angle and the blending of the plunge area for the swedge (or if it fades seamlessly into the spine) than I feel I have with my grinder for such a small bevel.


~Paul
My Youtube Channel
... (Just some older videos of some knives I've made in the past)
Click to expand...
Thanks Paul, that is a lot of great information. I will try some of those different file techniques.
 
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