If that went through a rolling mill then that might be the culprit.

There are so many variables you would have to give us all the details from beginning to end for a more accurate guess.

Thanks for the quick reply, Karl. I forged the 10" blade from 3/16" x 1-1/2" 1084. I normalized the blade and then full quenched in 130 degree F Parks 50. I drew the spine with a torch, while keeping the edge buried in wet sand. Tempered at 350 in a toaster oven. The spine and tang measured 44-46 Rc, mid-blade hardness was 58. The edge measures 60 - 64. I cleaned the tempered forging with a belt grinder, files, stones, and emery paper. The shadows only became relevant to me after hand polishing with Simichrome.

I just really don't know. But on a different subject, I have no idea why you're heating that #50 so warm. It only needs to be 80 or so degrees. It's designed to be a very fast quechant at "room temperature".

I can't really guess on those wobbles. What style is your platen? What grinder?

There are two things that I have noticed causing this type of effect in my production.

1. Surface grinding at 220 grit

2. Bevel grinding on the 2x72 at 220 or higher grit.

I think it's the seam in the belt that causes it. I have been able to erase these lines on the disc.

The "130 degree F Parks 50" too! grabbed my eyes too..... WHOA! Leave that stuff at room temp! Otherwise, sooner or later, a blade you're quenching will start talking to you....and not in a nice way.. something such as "ting!" "ting!" "TING!" <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />

Those "chatter" marks look suspiciously like they came from grinding..... were you holding the blade lengthwise on the platen? My guess is that it's either caused by belt joint, or it "fell off" the platen, and back on when grinding. Those little shadows/dips, almost look like the blade hit a contact wheel in the process?

Like Karl said..... to nail it down, we need a step by step of what you did to that blade.

Very hard to tell from just a picture; grinding artifact or very uniform alloy banding? But I will make it a third voice in the Parks/Heatbath #50 temperature. Going above 120°F will not yield better results in the blade, but it will eventually degrade your #50. The Manufacturers give very specific warnings about the max temp of 120°F to avoid thermal breakdown. I have found a sweet spot in this oil at around body temperature. It can be used at ambient (75°F) but it is capable of through hardening 1095 at .250" when heated to 98°F to 100°F.

I apologize, because I know you didn't ask for this input, but one other thing makes my teeth itch when viewing your image. When going forward, if you want to go for a JS rating, never allow your grind plunge lines to move that far behind the choil notch formed by your heel. If you are not into the whole JS testing idea than fee free to ignore this added advice, but if you are thinking of trying for it in the future, it is something you should be aware of.

|quoted:

I just really don't know. But on a different subject, I have no idea why you're heating that #50 so warm. It only needs to be 80 or so degrees. It's designed to be a very fast quechant at "room temperature".

I can't really guess on those wobbles. What style is your platen? What grinder?

Thanks, Karl. I must have had the Parks 50 temperature written wrongly in my notes. I was using a flat platen on a Burr King grinder. Thanks for your replies.

Lots of good replies. Thank you all. Keep 'em coming. Joshua, the fact that the lines are so uniform, makes me doubt the belt grinder. Oh, that my grinding skills were so uniform. :0) Kevin - thanks for the plunge advice. On the Parks 50 temperature, I have had several breaks on thin chef's knives. Maybe the oil temperature contributed. I'll keep the oil at ambient temperature except in winter.

Jesse,

Diagnosing finish issues in steel is difficult at best with blade in hand and almost impossible from a picture. Best advice I can give is to look in the Master & Journeyman Smith list on the main web site and find someone close you can contact and go to their shop for one on one input, I realize with the current virus situation it maybe difficult arranging this. FYI - the closest Masters to me are a three hour drive away and I consider myself lucky they are that close but I would drive further if necessary.

If that is not possible, I would get my finest grit paper and back it up with a hardened flat ground piece of steel or some other hard flat surface with the widest combination I can come up with I would just lightly sand diagonally across the blade in an area the flaws are most pronounced. This is going to help you decide if it is in the steel or in the finish, if the scratches pattern 100% of the surface sanded it is in the steel, if the scratches hit peaks and do not touch in valleys it is in your finish.

If it is in the steel, try to document your process as detailed as possible: where material came from, forging process ( tools used - press, power hammer, rolling mill etc..., temperature range, number of heats and material left for grinding before heat treating ), pre-heat treat process ( normalize, anneal temps & times and equipment - forge, oven ), grinding ( stock left to grind after heat treat, grind 100% or minimal cleanup, final grit pre heat treat ), heat treat processes ( time & temps and equipment ).

If it is in your finish, try to give the same detail, belt grits, do you check your belts for buildup front and back, brand new belts or used belts for finishing, platen buildup or flatness, belt tension, type belts. Do you grind edge up horizontally or tip down vertically or both? Do you angle your blade across the belt occasionally while grinding to check flatness? You mentioned stones and sand paper, what directions do you go with them, what backing material do you use for sandpaper? Are the stones used still flat after using them? What brand sand paper do you use? It could be an infinite amount or combination of things I am sure you can work thru and find help on this forum to figure it out.

Hope this helps some or points you in a direction to get some help.

|quoted:

Very hard to tell from just a picture; grinding artifact or very uniform alloy banding? But I will make it a third voice in the Parks/Heatbath #50 temperature. Going above 120°F will not yield better results in the blade, but it will eventually degrade your #50. The Manufacturers give very specific warnings about the max temp of 120°F to avoid thermal breakdown. I have found a sweet spot in this oil at around body temperature. It can be used at ambient (75°F) but it is capable of through hardening 1095 at .250" when heated to 98°F to 100°F.

I apologize, because I know you didn't ask for this input, but one other thing makes my teeth itch when viewing your image. When going forward, if you want to go for a JS rating, never allow your grind plunge lines to move that far behind the choil notch formed by your heel. If you are not into the whole JS testing idea than fee free to ignore this added advice, but if you are thinking of trying for it in the future, it is something you should be aware of.

Thanks for the plunge line comment, Kevin. A JS stamp is a goal of mine, but I doubt that I have twenty years left to learn, so any information I can use to shorten my learning curve is welcomed. Beyond more practice and a fresh belt, do have suggestions or suggested resources on how to make acceptable plunge lines? I use a Burr King grinder with a flat glass platen. I try to "sneak up" on the plunges, but invariably, I chase the plunge lines from side-to-side towards attempting to keep them even and clean. I suppose I could file the plunges in, but wouldn't this present greater cleanup challenges?

Thanks.

I hope this isn't butting in, and I don't mean to replace Kevin by any stretch of the imagination. There is more than one way to skin that rabbit, so I'll just throw my way out there.

Whether I file them in, or do them on the grinder, I use one of those nifty carbide faced file guide/jig tools to make sure they are aligned properly and a mirror to ensure that they will be square to the spine (if you want them square).

On the grinder, I made a special work rest so I can get the guide right up against the side of the platen. You can also do it freehand, but I don't. Use a J-weight belt, get it to roll a little bit over the edge of the platen. and you will grind the plunges down to the carbide face. Using a file post heat treatment will require you to draw back the tang and ricasso area to get it soft enough for the file to cut. A mill file leaves a pretty nice finish that cleans up fairly easily.

|quoted:

I hope this isn't butting in, and I don't mean to replace Kevin by any stretch of the imagination. There is more than one way to skin that rabbit, so I'll just throw my way out there.

Whether I file them in, or do them on the grinder, I use one of those nifty carbide faced file guide/jig tools to make sure they are aligned properly and a mirror to ensure that they will be square to the spine (if you want them square).

On the grinder, I made a special work rest so I can get the guide right up against the side of the platen. You can also do it freehand, but I don't. Use a J-weight belt, get it to roll a little bit over the edge of the platen. and you will grind the plunges down to the carbide face. Using a file post heat treatment will require you to draw back the tang and ricasso area to get it soft enough for the file to cut. A mill file leaves a pretty nice finish that cleans up fairly easily.

Joshua. Yes, different ways to skin a cat..., but thanks. I'm trying to make my first dagger, at present. If I understand your file guide suggestion, so long as the ricasso is square across the blade, I should be able to grind all four plunges using this method. Do you usually begin grinding beyond towards the point and then ease into the ricasso or do you hit the plunge initially?

Setting up for your plunge line location must begin in the forging. Once again, many ways to do this. Lin Rhea has a method where he forges the plunges at an oblique angle so he can pull the heel down and backward past the bottom edge of the ricasso. This allows for a variety of choices in plunge line shape and orientation. You can see his method in a photo documentary here.

If you are on FaceBook, I highly recommend following Lin.

I am not anywhere near as competent as Lin is forging to finished shape, so I tend to forge my piece with enough room to grind small areas away, and "push" my plunges to where I want them.

The flat of the ricasso will protrude below the bottom line and slightly curve downward to follow the plunge line.

I rough grind my plunges and try to get them very close to final location while leaving a little bit of the ricasso flats still below the bottom line. In the finished grind, I can "push" the plunge backward, and the ricasso line forward until they meet and that little protrusion goes away. I don't know if that makes any sense without seeing it.

Hopefully, someone else will offer you more methods and you can find one that you like.

Jesse, by all means get as much input as you can from as many helpful folks as you can. Methods of finishing and shaping blades are as numerous as makers doing them, and the steel doesn’t know by who, or how it was shaped while cold. During heat treatment conversations, my standard reply to the old “skin a cat” adage, is that we are not skinning cats we are heat treating blades. But heat treatment is different from other aspects of knifemaking in that the steel does indeed know, and remembers, what you did to it when you heated it. But how you achieve a nice finished look to a knife is the fun part because there is no right or wrong to any method that gets you the desired results, so I like it when many people join in the conversation because I just may find a new way to do things as well.

If somebody is not asking for help with the ABS rating program, I would normally just overlook something like this and focus on the good things I see. But if somebody is thinking of going for a JS rating, I feel it is only right to help them avoid the pitfalls. I say this because when I am judging, the choil notch being forward of the plunge lines makes my job VERY easy; as soon as I see it I can write “fail” on the card and move onto the next applicants knives. This is because there are only two explanations for that particular problem- 1. The applicant isn’t aware that it is a problem, which means they may not be ready for JS or, 2. The applicant lost control of the grind shoulders and ended up chasing them back behind the choil, where they intended to stop. The first is an easy fix, let them know that it is a problem, knowledge is power. The second is by far the most likely situation, as we have ALL done this at one point or other in our knifemaking career, and know the problem quite well.

Here is my fix for avoiding it; once it is done it is done, but it can be easily avoided:

When I teach grinding to my students, I will have them first clean up (descale) and profile the blade, but the one area that I tell the completely new grinders to leave alone in the profiling is the heel and choil area. In other words, leave that inside heel corner until you have the shoulders done, and you can then put it in wherever it needs to go.

But more importantly is keeping the shoulders even and clean, and this starts on the anvil. Do not wash out this area with the hammer, and keep your ricasso clean, flat, and thick. When the student has the blade cleaned and profiled, I will take a marker or layout die and mark an area 3/8” in front of where those plunge shoulders will be, ¼” down from the spine, and ½” back from the tip. I then instruct them to grind the bevels, with one, flat and even grind line, but they are forbidden to erase any of my marker. They will now have a nice, flat track to work off from as a foundation for their grind. Once that is established, I allow them to begin to advance into marked areas with the very first being the ¼” at the spine. They will slowly walk their flat grind, pass by pass, towards the spine until only a thin sliver, 1/16” or less, of my mark is left. This almost guarantees that they will maintain the spine without a blow out and they will quickly get the idea of how that little radius at the top of the grind is to be maintained in avoiding a blowout.

At this point, none of the 3/8” forbidden zone in front of the ricasso has been touched. How you lose control of those is putting them to the grinder repeatedly, as every time you touch the shoulders to the belt you change them a little. Most people lose control of them by engaging them on every pass while grinding the edge bevels, thus grinding and regrinding them needlessly. I have the student save them until the bevels are done and you are not juggling too much by worry about grind lines or bevel angles while you are also trying to precision cut those shoulders.

Now, using the already finished edge bevels as their track to work on I have the student nibble the plunges back to where they are exactly where we want them and matched on both sides. Then we stop! With that one last pass that evens them all up, we are done with them, and we move on to roll in our marked off tip area to finish the grinds with the same idea, saving the tip for last do that we don’t grind it with every pass until it is too thin.

At this time, if the student left the choil area unground, they can cut in that inside heel corner exactly where they want it in relation to the plunge shoulders. Using this method there should be very little chance of chasing those plunges to your ruin.

I strongly encourage students to learn to cut the plunge shoulders on the grinder, as it is just a good grinder skill to develop and it is the most efficient way to do it. But there are those times when it is too scary and touchy for some, such as the four tight plunges on a dagger. Then I advise that they can use a file guide to evenly cut them in with a round file, but the problem is that a belt grinder will still be the most efficient way to clean up the file scratches, and a 220X belt will blow those shoulders just as quickly as a 40X, if you haven’t developed some plunge grinding skills.

I have grips and techniques for freehand grinding of those shoulders, such as the double OK grip that I teach, but it would be too much to explain in a forum post. Let me just say that, with the right techniques, and practice, it is possible to nibble those shoulders in with absolute precision by hand alone.