I am a woodworker and I have never really done any smithing or metal work.
But I just purchased some 01 precision ground steel 1/4" thick and 1.5"
wide. I am interested in making several high quality wood hand plane. My
question is after I from the plane iron to rough shape. Should I completely
sharpen the iron before heat treating? Also what temperatures should I use
and how should I go about the heat treating and tempering? I will be
purchasing a small electric kiln for the heat treating process. the max
temperature of the kiln is about 2300 degrees F.
Any help would be grate full,
Kris
Greetings and salutations.
On Thu, 15 Jan 2004 03:04:54 GMT, "speedbuggy"
Well, what the heck, I may as well snap at the bait.
First off...O1 is already pretty much where you need it to
be in terms of heat treatment, I think. Also, I am not really
all that thrilled about a 1/4" thick chunk of steel for a blade...but,
at least you REALLY will not have to worry about chatter (*smile*).
I would suggest this: Grind an appropriate edge on it, being
careful to keep the metal cool enough to touch with your fingers while
grinding. Sharpen to Scary Sharp standards. Build a wooden plane
body to fit it and see how it cuts. If it dulls too quickly...consider
retempering the steel...or...running by the local WoodCraft store
and picking up a Hock blade *smile*. The nice thing about making
a wooden plane is that...well...it's wood. The only metal in it
is the blade, so, it is a good project for a woodworker, and, when
done, you WILL have a very useful tool.
Wile there is (theoretically) nothing complicated
about tempering steel, it actually can be quite a challenging process,
requring fairly exacting timing and control of heat. Unless you have
a *lot* of disposable income burning a hole in your pocket, perhaps it
would be better to experiment with some smaller pieces of steel,
heating them with a MAPP torch to tempering temperatures, and,
annealing as necessary on the burner of your stove. I would suggest
starting with a knife blade that is 1/8" thick or so...
I would also suggest that you visit the local library or
used book stores, and, get some books on metallurgy, to start
getting an idea of what happens to the internal structure of metals
when they are heated, and, how tempering and annealing changes
that structure. Getting a little knowledge first will lead to
a much happier and productive time.
Regards
Dave Mundt
Hi guys,
I am a blacksmith and used to specialize in cutting tools.
First thing you should know is that precision ground flat stock comes
annealed, meaning as soft as it ever will be. This makes it easier to
cold work (file, saw, grind) So first thing will be to shape the plane
as close to finished as possible. Do not however take the edge down to a
sharp edge. If you do, you risk cracking during the hardening phase of
the heat treat cycle. Instead, grind a nice clean bevel but leave the
very edge square and about .?" thick. Do not polish it but go to 220grit
finish. I am assuming you will not be forging this blade to shape but
even still the finished blade should be re-annealed before hardening.
This is because stresses are imparted to the steel during heavy grinding
operations. I suppose if you are careful to keep the heat down when
shaping the blade you might choose to skip this step. I am not exactly
sure of the hardening temperature for 0–1 but it is probably between
1450?f –1550?f. Bring your electric furnace up to temperature then place
your blade inside. It should take about 1/2 hour to get the steel to the
same heat. grab blade with tongs and quickly plunge edge first into your
oil bath. Drugstore mineral oil works well. Oh, warm up the oil first
to about 120?f this lowers viscosity and actually is safer than cold
oil. The steel should now be harder than the hubs of Hell. Test it with
an old file, it should skate right off the blade and leave no scratches.
If it does then you hardened at to low a heat. The steel is hard but
also under a LOT of stress and must now be tempered. DO NOT WAIT as the
steel will sometimes just pop apart. If you have an oil deep fat frier
you can set it at about 400?f and toss the hardened blade in it for
about 1 hour. You can also do this in the kitchen oven. Yer done except
for the clean up and sharpening. Good luck, expect some scrap metal
before you get a keeper.
Glen G.
I will not go into the heat treating cycle for O-1, that is easily obtained
from the Internet or a handbook, but I did want to comment about the
actually operation when you harden it. One thing to absolutely do is to get
some stainless steel foil and make a foil bag just big enough for the blade
to go into it, leaving enough on the opening end to make a tight double fold
closure. When you are ready to do the hardening, wrap the blade in several
layers of paper towel, insert it in the stainless steel bag,.and fold it
tightly closed. Then do your hardening procedure, allowing extra time for
the heat to get through the steel foil and the paper. The paper intercepts
the oxygen as it chars, preventing the metal from getting any scale on its
surface. Once you have run your hardening heat long enough, and I add about
30 minutes for the bag and paper wrap, then working very quickly (have
everything ready and placed for rapid access, including a screw driver or
other similar tool to help opening the bag) grab a set of tin snips and very
quickly cut the end off the foil bag and dump the contents, unburned paper
and all, into your oil quench. If you try to separate the paper and the
blade you will lose your heat and it will fail to harden, especially so with
a thin 1/4" blade. Dump it straight down in so the blade enters the oil
vertically, and have the foil bag right close to the oil so there is no
splash.
Then, reach in with some fine pointed tongs, so as not to cover up much of
the blade with the tongs, and swish the blade around in the oil. Once it has
lost most of its heat, you can just barely touch it with bare skin, then
move it rapidly into your tempering oven, which was preheated to the
temperature you need. If you allow the blade to go completely cold, and go
off and eat lunch or something, you may find it will self destruct.
The stainless foil bag does several things for you. It prevents any fire
scale from forming, which means the blade will be clean and shiny when its
done, without any grinding or other treatment. It also slows the heat entry,
reducing stresses, and it evens the heating so that the whole blade will
come up to temperature more evenly. Doing fine blades by any other means,
other than in an inert gas atmosphere, is a waste of time, and the results
will be dubious at best. The stainless steel foil can be obtained through
McMaster Carr, or a variety of other sources...don't try using your wife's
aluminum foil.....won't work. The foil is expensive, so you may want to ask
around and find someone who will sell you just what you need, not a whole
roll. I am fortunate enough to have a local machine shop that makes the bags
up in various dimensions and sells them to make a little extra money, so I
just buy the premade bags. They generally cost between $3 and $4 each
depending on size. The foil is very hard and its edges are like a razor, so
if I don't have to handle it to make the bag I am happy to pay the shop for
them to do it.
I will also say that the second reply you received was dead on correct. The
O-1 comes in a dead soft annealed state to make grinding or machining easy.
If you are going to use it without any hardening and tempering you may as
well use mild steel instead, and not waste your money on tool steel.
Yours,
Ron
Golden Age Forge
http://www.reil1.net/gallery.shtml
E-mail: snipped-for-privacy@reil1.net
Boise, Idaho
Dear Ron,
Personally I think the stainless steel wrap is a pain in the
butt and not worth the bother and expense. Come on Ron, fine tools were
and are still made with out the foil wrap. Unless you are hardening
chunky dies or something it is almost impossible to get the wrap off of
a plane blade or knife before losing the critical hardening temp. Plus,
if you are hardening in a forge it is next to impossible to judge
hardening heat/color when the tool is wrapped in foil. I tried this
stuff and did nothing but curse it. If you are careful and you are at
the right heat almost all of the light scale that forms on a blade will
pop off when it's quenched anyway. Another cheap and easy solution is
to make a watery paste from wood ash, charcoal dust and table salt.
This is painted on the blade just prior to hardening. It lessens scale
formation and leaves a relatively clean surface after quenching. I
learned this from a Japanese tool maker. When I asked how much salt to
add he said, "till it tastes like sea water" He also said he quenched
at a heat the color of a monkeys butt.
Why make things complicated? It really isn't that hard to learn
to judge hardening and tempering colors. There will be failures sure,
but how else do you really learn anything.
Let's KIS eh?
Glen
If you are really going to make a high end plane, you may be interested in
making a laminated blade like the old original plane irons. It isn't hard to
do, and it will be a pretty special piece of work when it's done, one that
you will be proud to pass on to your son some day. Also, it will have the
qualities of strength and hardness that are not available in a solid tool
steel blade, although this really isn't an issue today with modern steels. I
am a member of an old tools group, the vice president in fact, and am one of
only three smiths in the group. All the rest are wood workers, and most
collect old planes. I have made laminated plane irons several times for guys
to replace badly pitted and rusted originals. If you do the forge welding in
a gas forge it is very easy, in a coal forge it is very easy too...to burn
the tool steel away...grin. Use gas. You could use the tool steel you have
and weld a thicker back to it and draw it out to the correct thickness,
certainly less than 1/4", to make your blade. If you decide to make one, I
recommend 1095 for the tool steel because it forge welds easily, also I
don't have any experience forge welding O-1 so can't speak about its
qualities. If you have a good anvil surface, and have, or make, a good
surfaced flatter, when you finish the blade you will not need to do any
grinding other than the cutting edge itself, although I do take a light
sanding on the faces after I remove it from the pickle tank to remove the
fire scale. You do need to remove the fire scale.
Yours,
Ron
--
Golden Age Forge
http://www.reil1.net/gallery.shtml
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