gene-pavlovsky
Plastic
- Joined
- Apr 24, 2019
Dear all,
As a hobbyist, I learned how to file from books and online articles, rather than in a class/shop setting.
It's always mentioned that the file should only cut on the push stroke, the pressure should be taken off or the file lifted off the work on the return stroke. This is due to the cutting teeth geometry, the sharp teeth edges would roll over if pressure is applied on the return stroke. That part is quite clear to me.
What is not quite clear is the proper technique for draw filing.
Simonds' Files Facts says:
Single-cut files are used for sharpening tools, finish filing and draw-filing.
...
Draw-filing. This is an operation in which the file is grasped
at each end, and with an even pressure alternately pulled
and pushed over the work. The file remains perpendicular
to the direction of motion.
Nicholson's Guide to Files and Filing says
Drawfiling consists of grasping the file firmly at each end and alternatively
pushing and pulling the file sideways across the work. Since files are made
primarily to cut on a longitudinal forward stroke, a file with a short-angle cut
should never be used, as it will score and scratch instead of shaving and
Shearing. When accomplished properly, drawfiling produces a finer finish than
straight filing. Normally, a standard Mill Bastard file is used for drawfiling,
but where a considerable amount of stock has to be removed, a Flat or Hand file
(Double Cut) will work faster. However, this roughing down leaves small ridges
that will have to be smoothed by finishing with a Single Cut Mill file.
So it seems that when draw filing, equal pressure is applied on forward and return strokes.
I don't really understand why is this ok when draw filing? To me it seems that when you draw
file, the teeth are presented to the workpiece at a smaller angle, slicing rather than shearing (like holding a woodworking plane at an angle to the direction of travel - reducing the "angle of attack"). This would be true only in one direction (push or pull - depending on which hand holds the file's handle), the other direction would drag the teeth backwards over the work (again, at a smaller angle) - why would this be effective at cutting, and why wouldn't that dull the teeth?
Just trying to understand...
--Gene
As a hobbyist, I learned how to file from books and online articles, rather than in a class/shop setting.
It's always mentioned that the file should only cut on the push stroke, the pressure should be taken off or the file lifted off the work on the return stroke. This is due to the cutting teeth geometry, the sharp teeth edges would roll over if pressure is applied on the return stroke. That part is quite clear to me.
What is not quite clear is the proper technique for draw filing.
Simonds' Files Facts says:
Single-cut files are used for sharpening tools, finish filing and draw-filing.
...
Draw-filing. This is an operation in which the file is grasped
at each end, and with an even pressure alternately pulled
and pushed over the work. The file remains perpendicular
to the direction of motion.
Nicholson's Guide to Files and Filing says
Drawfiling consists of grasping the file firmly at each end and alternatively
pushing and pulling the file sideways across the work. Since files are made
primarily to cut on a longitudinal forward stroke, a file with a short-angle cut
should never be used, as it will score and scratch instead of shaving and
Shearing. When accomplished properly, drawfiling produces a finer finish than
straight filing. Normally, a standard Mill Bastard file is used for drawfiling,
but where a considerable amount of stock has to be removed, a Flat or Hand file
(Double Cut) will work faster. However, this roughing down leaves small ridges
that will have to be smoothed by finishing with a Single Cut Mill file.
So it seems that when draw filing, equal pressure is applied on forward and return strokes.
I don't really understand why is this ok when draw filing? To me it seems that when you draw
file, the teeth are presented to the workpiece at a smaller angle, slicing rather than shearing (like holding a woodworking plane at an angle to the direction of travel - reducing the "angle of attack"). This would be true only in one direction (push or pull - depending on which hand holds the file's handle), the other direction would drag the teeth backwards over the work (again, at a smaller angle) - why would this be effective at cutting, and why wouldn't that dull the teeth?
Just trying to understand...
--Gene