progression, strokes, and pressure

Anonymous wrote:

If achieving a straight and sharp edge…and this has been the result of many strokes with various stones. while the stone progression to getting a good edge, can be achieved according to experts here , even at # 600 grit. IM trying to see what is the progression of stones grits and strops by pressure and number of strokes ( ball park ).. I know all knives are different. given me some sort of estimate when trying to achieve a mirror image once an edge is sharp, are we talking heavy pressure at first, or light pressure through out the process… I know that visuals play a big part in going to the next level. But I have no idea what experience has taught the Pros here. what grit, what strop, how many strokes, how much pressure. what is your finally progression, final polish, strokes and pressure before calling it a day. Thanks Bill aka ET

Aloha Bill,  Im no expert but I hope to share what Ive learned and how i do just that in a video over the next couple days.

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Alan

As to your question of strokes and pressure, I use medium pressure from start to finish and I alternate my strokes at each grit level going like this ///// at 100 grit. like this \\\\\ at 200 grit and so on up to 1000 grit checking quickly with scope to make sure previous grit scratches are gone.

3 things Immediately come to mind that make your question of “time” hard to answer.
The type of steel, the length of the blade, and the thickness of the bevel.  All of these factors can change the time it takes to get a uniform scratch pattern at whatever grit stage you are currently at.  The easy answer is do it until its done, by which I mean that I have a routine I personally use that doesn’t take too long and then I check with scope.  If Im seeing this XXXX instead of this ///// or this \\\\\ I do a little more and adjust at the next grit with a few more passes and check.

Again my personal routine, but after 1000 grit I go laterally with 1500 grit wet/dry and wipe the slate totally clean with a close inspection that ALL scratch lines now are going this way =====.  You could do the same at this point with ceramics but it may cause grooving in the stones.  This is my transition point to lapping film so a few moments more under the scope or an extra piece of film will ensure that I dont have a nasty ///// surprise appear faintly later and harsh my vibe.

Lapping films go very quickly from grit to grit if they are spaced appropriately close together.  Each stage takes under 1 minute.  So lets say 2 minutes for each of the first 6 grits, and 1 minute for the following 7 lapping films, plus transition time and Id estimate a smaller, thin bevel knife could be done in 30 minutes under the right conditions.  Id still probably alternate between //// & \\\\\, then finish the last 2 final grits both going the same ===== direction.

As a final note just going laterally after the 1000 grit paddles is a marked improvement in the finished look of the bevel.  Simply doing that step and maybe applying a micro-bevel on top is an excellent choice for a functional and beautiful look to the edge.

Aloha, Cliff

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Gib Curry, Alan

Im currently not a huge fan(subject to change) of stropping and try to minimize it for a couple reasons…

The more stages of stropping the more rounded the apex bevel will become.

Stropping can scratch up a mirror polish.  One tiny piece of contaminate has several times ruined my day.  Just a few days ago I spent a bunch of time “disinfecting” all my strops and then sealing then in ziplock baggies before I start new testing on a finishing ultra light couple of passes with different substrates.

I believe from reading here on the WE forum that stiction is desirable and it is then burnishes and blending the scratch lines smoother.  The problem I have faced with sticky paddles is that it then leans me towards using more force to move the paddle across the bevel, which if the angle is not kicked down a couple degrees the leather can roll right over the apex and round it off significantly reducing the sharpness.

There are 2 aspects we are dealing with here, looks and performance, and they kinda go together.  In seeking a higher keenness to the apex, a mirror bevel is a nice side result.  Inversely if you do a careful grit progression down to a perfect mirror, then a refined smooth apex should form as well.

Dealing with the final treatment of that apex for the most ultra refined edge possible is what I am currently focusing my own studies and experiments on.  Here is what I tried with the .03 micron lapping film as a reverse alternative to stropping:

Results were inconclusive beyond it would wittle a hair…. due to not having a high enough power magnification(the reason I started the other thread on that btw).

Id also like to do some experiments with different higher (+1500 grit) micro-bevels just to see how they “bite the finger” so to speak.

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Alan

ET, I am only 3 months old in WEPS age.  I like to keep a dish of water on the side and do a finger dip onto my diamond stones.  I find it very effective at moving metal especially if it is the first time for a particular knife.  In setting the burr I am very aggressive and will use firm vertical strokes up to 25 per side then switch sides.  After the burr set I get less aggressive with each grit.  As far as pressure I tend to favor the lighter side.  As I move up the grit scale I start to almost feel the metal moving while tuning into the sounds.   I generally keep my nose behind the handle and try to watch the stone move for each respective side to minimize left/right biases.  Techniques similar to woodworking body motions help.  After the burr set, I alternate single side strokes 50 per side while counting to 100.

I’ve been trying to use the full stone during a stroke which I think puts more diamond across the full edge for more efficient stroke.  What stroke do you use near the tip especially if it flexes ?

I use isopropyl on my strops as a gentle lube and find that it works nice.  I don’t change the angles at all because duplicating that on the next sharpening would cause me to redo the burr (which isn’t too bad I guess). I do not have the time to go beyond the 3.5 um green paste.

Also, remember I only do kitchen knives, the material hardness makes a difference. I have a Shun Blue Steel Knife (low carbon).  The feel while sharpening it is completely different than the stainless ones.  It can diagonally chop gently folded tissue paper and almost the same with toilet paper.