Bill Amsterlaw on tue 17 apr 01
I make trimming tools out of old metal files. The steel is hard and =
brittle. You have to be careful not to drop the cutting tools after you =
make them because the business end can break off. However, they will =
hold an edge even against heavily grogged clay for quite a while.
You can often pick up old files at a flea market for less than $1 each. =
You can find them in a wide variety of sizes. Try to pick the size =
according to the size of work you will use them on. (However, with the =
right technique, it is possible to trim very small forms with the same =
tool you would use on a much larger form.) It takes about 30 minutes to =
make an old file into a durable cutting tool.
Stick the ends into a kiln port at the next firing to get them red hot =
so they can be bent and forged without snapping off. (If you are using =
an electric kiln, play it safe and flip off the power for a while before =
you stick metal anywhere near the coils.) Pull the red-hot file out, =
quickly clamp it in a vise and put a 90-degree bend in the file about an =
inch from the end. Get it red hot again and bang it into good shape =
with a hammer. (Don't bend or bang unless it is red hot ... or the =
steel is liable to crack.) Then use a grinder to shape the steel and =
put a cutting edge on it.
The part of the process that takes up most of the time is the shaping of =
the blade. I usually make two beveled, slightly convex edges that come =
to a point. I also grind away some of the steel at the bend to form a =
corner where the handle meets the blade. You have to experiment to get =
the angle of the bevel right; you need a fairly acute angle (maybe 25 =
degrees) before the tool will cut well.
I use an angle grinder with a metal cutting disc to do both the shaping =
and the sharpening. When they get dull, it takes about 30 seconds, =
using a light touch with the angle grinder, to put a decent edge on them =
again. After many sharpenings, you may want to break off the blade at =
the 90-degree bend and make a new, slightly shorter, cutting tool out of =
the remainder.
Bill Amsterlaw
Keene, NY, USA
http://amsterlaw.com
wamster@amsterlaw.com
Bruce Girrell wrote:
<< I just recently had a major snit about dull trimming tools. The =
Kemper ones are pure junk in my humble opinion. They are dull when you =
get them and they are made of cheap steel. They dull very quickly even =
after sharpening.>>
Bill Amsterlaw on thu 19 apr 01
Hi Clive:
I really know very little about the physical properties of metals. I =3D
observed that the steel that files are made of, when heated orange-hot, =3D
becomes very hard and brittle (ie will break if you drop the tool). I =3D
assumed that this hardness is a desirable feature in that the blade =3D
should hold its edge longer than a softer steel. Maybe this assumption =3D
is incorrect. The trimming tools I have made from this material do seem =
=3D
to hold an edge for quite a while, but I have not tried to compare them =3D
with other tools. Do you think that spring steel, properly tempered as =3D
you described, would hold an edge equally well? or better? Would the =3D
spring steel be easier to sharpen?=3D20
Are metal files brittle because they were heated to a higher temperature =
=3D
before being quenched ... or is the alloy different from what you call =3D
spring steel? ... or both? If you heat file steel to a dull red before =
=3D
quenching it, will it be springy and less brittle?
Cheap new or used files seem to be readily available. Can you recommend =
=3D
a source for spring steel in convenient sizes and amounts?
Bill Amsterlaw
Keene, NY, USA
http://amsterlaw.com
wamster@amsterlaw.com
Clive Tucker wrote:
>spring steel is also good for trimming tools and comes in more readily
>useable sizes. And if you have a blow torch, it makes the whole heating =
=3D
up
>business quite a bit easier. and you have to retemper the metal after
>heating. i.e quench it in water before it cools. different metal
>temperatures before quenching give different hardnesses.bright cherry =3D
is too
>hot and though hard, tool will be brittle. try quenching just as red =3D
glow is
>fading.
>so bend, shape, sharpen, temper, final sharpen.
>or ask a blacksmith.
>Clive Tucker.
>Vancouver,Canada.
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