Rambling of an Idiot-knives-1

[rstegman]

Rambling of an Idiot-knives-1

The title tells you everything you have to know.

I am a wood carver. I learned how to make my own knives from files. When you purchase a commercial product, one is afraid of damaging it, so one does not want to make any changes whatsoever. Making one's own knife allows you to understand when and how to make repairs or corrections in the design.
This actually goes for any tool or equipment you use. If you built it once, you can build it again, better usually.

Knives generally use two kinds of edges. Each has their advantages and disadvantages.
One type has a generally steady slope, then sharp angle at the edge, usually twenty five degrees. This is a strong edge that is not likely to chip or break. It wedges materials to the side. an overall use knife like a pocket knife will do well with this type of edge. This edge needs to be sharpened often as there is very little depth to the "sharp" part of the edge.
The other type of edge is a continuous slope to the edge. This edge slices through materials. It is a fragile edge and will chip easily, but it can cut for a long time without having to be sharpened. the cross section that one would consider acceptable sharpness is quite long. Again, this is weak material too.
In my experience, I can never hold a consistent angle to a blade. sometimes it will be fifty degrees, other times it is ten degrees and sometimes the different angles in the same edge. Because of this, I personally avoid this type of edge.
On the other hand, the continuous angle is easy to sharpen. Lay the blade flat on the sharpening stone and stroke. the flat of the knife keeps the angle consistent. All my knives are sharpened this way, in spite the weak edge.

Now when sharpening a blade, I prefer take several strokes on one side, then flip it over and take several strokes. Usually no more than five on each side when I start sharpening, and down to one or two when I am at the edge I am after.
The reason for this is that the media draws some of the metal along the surface of the blade. This excess metal goes past the edge of the knife and becomes a "wire", a ridge of metal that tends to curl up. This wire, when it becomes big enough, can break, taking away your sharp edge.
By flipping the knife over every few strokes, the wire is worn down on each side until what is left becomes your fine edge. You save sharpening time.
I have a general preference of "trying to cut the stone" kind of stroke, where the edge leads across the stone. This also reduces the wire, leaving a sharp edge.
After the stones get the knife to the right shape, one needs to polish the edge so it will not catch. A leather strop or a metal strop is used for this. some people will use a rouge, which is a grit, to add teeth to their leather. I learned that this is not needed. The leather itself will smooth out the surface and remove the saw tooth profile the grind stone created.
Once a blade is sharp, for example when carving, one simply strops the blade when you stop to do something or set the blade down. The edge will remain for a long time. Eventually, though, because leather has give, the leather will round the edge and one will have to grind the surface again to straighten it out.

Grind stones, like sandpaper, are rated to the size of the grit. Basically they make a screen with a given number of fibers per inch of surface. they usually have several screens. A grit is classified as any grit that won't go through the screen. A sixty grit sand paper contains any grit that will go through a mesh with thirty fibers to an inch, but not go through a mesh with sixty fibers to the inch. An eighty grit will then have anything that will pass the sixty but not the eighty. A hundred will have any grit that passes through eighty but not a hundred. They will go beyond a thousand grit sand paper in some product lines. Old grind stones were simply sand stone or similar product chipped into shape. Nowadays, grindstones have some form of glue holding the stones in place. The strength of the glue and the hardness of the stone is indicated by numbers on each grind stone.
Course grind stones remove material fast, great for shaping. fine grindstones are great for creating fine finishes.

When using power grinders on blades, place your fingers on the back side of the blade, If the blade gets too hot to hold your hand on the surface, quench. this will prevent one losing the temper from the blade, if you are using files or something else as your material.

Enough rambling for now.

[Pault17]

rstegman
I think "knives - the cliff-notes version" would be a better title. thanks for ranting!"

[rstegman]

Rambling of an idiot - Knives - 1

The Title will tell you everything you need to know

Many of us use wood handles. The way to get the super fine finish everybody oo's and awes about, is to sand properly.

First, dull sandpaper is NOT a finer grade of sandpaper. Sandpaper is crystals of rock glued to a paper or cloth base. When the sandpaper is dragged across a surface, the sharp edges of the crystals will score the surface. When sandpaper gets dull, the edges of these crystals actually break off, become rounded, lose their grinding power. Some sandpapers use harder stone and glue them stronger to the base. The harder stones last longer and are held firmly until they get rounded. Others will use a softer stone and weaker glue so that the highest stones will eventually break off the base, allowing smaller stones to work. once all the grains are rounded, the sandpaper loses the cutting power.

When sanding, the grit scores the surface. Since sandpaper grit is all about the same, they will leave a given depth score based on the grit of sandpaper. What one does is to sand until the entire surface has an equal level of scoring over the surface. You start out with a grit just strong enough to remove any tool marks in the wood, or metal. Then one goes to the next grit sandpaper and remove all the scoring of the previous grit of sandpaper, making the surface with an equal amount of scoring over the entire surface.
It is best to work with sandpaper grits of the same manufacturer, as the grit, the glue holding the grit, and the screens used to filter the grit are different for every manufacturer.
When you are working with 32 grit, to 80 grit, the scoring almost hurts the eye. It is important to get the sanding even over the entire surface. You only use these grits when you need to shape the piece or remove tool marks.

Grits 100 220 are fine tuning grits, You are removing the damage of the previous grits and preparing the surfaces. Grits of 320, 400, 600 (don't skip grits) are your finishing grits. With these, you will see a fine finish appear and the piece really starts to look good.

Really hard woods can be finished beyond 1000 grit without any wax or varnish. Softer woods could use a protective coating to bring out a shine.
One can also buff such woods with a soft buffing wheel once you get to 600 grit and really built up a fine finish with some woods.

I do wood-turning, making bowls, vases and such. The way I finish these is to sand to 600 grit, then use wipe-on poly varnish. you apply it with a varnish dampened cloth (those lint free cloth based paper towels are good) and rub the varnish on the surface until it is completely dry. By rubbing it till it is dry, you won't get drips or nibs on the surface. Sand lightly with 600 grit and apply again. Even with rather poor looking wood, you will end up with a fine looking finish.

It should be noted that some woods have a strong oil in them. To finish these, shellac the surface, then add your varnish. The shellac seals the oils inside the wood and gives the varnishes something to bind to. I've not dealt with oily wood so I am going by memory of what I’ve been told several times. .

[leafshadow]

thanks for rambling dude, that actually helps... :)

[Blackbeard]

Hey rstegman would love to see some of your work! Please post some pics!
Bb

[rstegman]

Here are a bunch of my carving knives.
The one at the front is an older knife I have used for a few years. The two knives at the back have not been tested at the time this picture was taken. I would carve the wooden sheiths as the test to see how the blade was set up.

I don't recommend this, but on the back for knives, I used a strip sanding attachment on my angle grinder (harbor freight). I sanded from the back to the edge and it got rid of grinding errors beautifully, giving a pretty good edge. Of course I used a stone to grind the edge further and then stropped each of them. These were the best blades I have made in a long time.

[larry harley]

The reason for this is that the media draws some of the metal along the surface of the blade. This excess metal goes past the edge of the knife and becomes a "wire", a ridge of metal that tends to curl up. This wire, when it becomes big enough, can break, taking away your sharp edge.


a good sharpening always will produce a wire edge
but like u say it wont cut it rolls over
its not untill this wire is removed that the true edge is evident
it dont take the edge with it
thats part of the leathers job is to poilish and take away that wire
another way to git rid of the wife is on a buffer
w polishing compound
or like butchers do by backhoneing the blade
harley
LonesomePine Knives

[larry harley]

another way to git rid of the wife is on a buffer
i ment wire
.WIRE NOT WIFE
DANG OL FAT FINGERS OF MINE:(
sorry cat type
harley

[pete46]

:rolleyes:Larry !is Sweet Thang Rid'n Your Donkey;& Make'n U Take The Freaud'n
Roller Skates??????????