Help needed on sharpening blades please

G

godogs57

Joined
Apr 16, 2004
Messages
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Stupid question but I sure could use some help here...I am primarily stock removal and utilize CPM 154CM. Normally, things go just fine with respect to sharpening a knife once I am finished with it. But occasionally lately I have had some that will not shave in the curved part of the blade, but will scalp you on the straight part. The part that sometimes gives me fits is shown in a pic of one of my knives below. My method, as taught to me, is as follows: After finishing I take it to the 120 grit on the flat platen and get my initial bevel of 20 degrees, on to 220 and 320 and then either a diamond stick or crock sticks. I always take my time and make dang sure the blade never heats up. Some of my counterparts then take their blades to a soft wheel buffer a whip on a feather edge which I know wont last two seconds, but appears scary sharp to a potential customer...I try to shy away from that and get my edge the correct way.

I have progressed years ago past that beginner stage where your blades are thick in some areas & thin in others, too thick at the tip, etc...I am able to keep 'em consistant throughout their length, as they should be. No problems with heat treat, blad geometry, etc as far as I know... I don't have any problems with keeping a consistant 20 degree angle, etc...The picture shown below is one of my "old" knives from years ago just to show what I am talking about. I hate it that I have a problem every now and then with some blades and hope some suggestions can be made to help things out....any comments are sincerely appreciated.

Everybody drive safe to the Blade Show next week!

Thanks in advance,

Hank
PicforBladeforum.jpg
 
Okay, let me preface this by saying that I am only 6 months old when it comes to making knives. However, I have found I have the opposite problem where I get the curves razor sharp and flats only moderately. What I have done to correct this is to set the bevel as you do, but use a 15 or a 9 micron 3M belt after that on the slack portion of the belt. I'm sure at a micro level this gives it a slight convex, but we're talking the 600 / 1200 grit level. I do hit it with a super fine sharpener just to debur after the whole process. Like I said, I am new, but this has worked for me wonderfully.
 
Purdy nice knife, there!

Anyway, I don't/can't use those stick to set an edge. For 40 years I have alwasy used a flat honing surface. Early on, a natural stone, lately a diamond stone followed by a stropping. You can also use a piece of glass with some wet/dry paper just laying on it damp. (it will stick).

That tip area needs to be kinda "swirled" around as you're drawing the knife toward you at the end of the stroke. You can feel it pretty well after some practice. Try like 400 grit paper, followed by 800 and then 1200.

The first time, you need to establish this edge for your customer, as he won't know how to use those sticks..........

Me neither:D
 
Some times there is a tendency to slightly turn your hand when stroking around the curve. This can either result in more or less sharpening in that area. A look with a 20X loupe at the edge will tell you a lot about what is going on there.
Stacy
 
Morning Hank,

That transition area, around the nose of the knife, is always the hardest

part for me to achieve a fine edge.

Is the 20 degree angle you refer to the sum of both sides, Or is that per

side?

Fred
 
I use the knife sharpening wheels available from Jantz supply
http://jantzsupply.com/cartease/item-detail.cfm?ID=WKS800.
This 2- wheel system mounts to a buffer, and has worked extremely well for me on every blade shape I make. It leaves an insanely sharp, polished edge with just a little practice. One note: be prepared to refinish the wheels often if you do a lot of recurve edges- the recurve wears the corners of the wheel quicker.
The method I use is to begin near the ricasso and run the blade lightly on the wheel towards to the point, keeping the knife paralell to the floor (edge down)the whole time. When the point begins, I turn the blade into the wheel a little and ride the edge around the curve and up to the point.
 
Hey Fred....

That is the standard 20 degrees per side...sometimes I get it down to 18 degrees or so as well.

JB Knives: I appreciate your help suggesting the wheels...I got some at the last Blade Show and have not really gotten the hang of using them yet...they just did not seem to do the trick for me. I am sure it was me and not the wheels.

Thanks again for all your suggestions
 
This is just here at my shop; but, I use an angle of 12 degrees per side and have found that much above that does not give as keen and edge. I'm not looking to make the edge thinner, but less steep.
I have found I can produce a sharper edge out along the transition at the nose of the blade when I make the edge, less steep.

Fred
 
Can somebody explain to me how they sharpen on the Wheels that JB referenced please? I tried it and apparently I was not holding my tongue right or something....

Many thanks.
 
i have been using the same wheels since the early 90's. i plan on making a short video of how to use these wheels when i get some help. godogs57, i sent you an email that i hope helps.
 
I recently bought a #1000 Shapton water stone along with the flattening plate and it works really, really well. Much better than any oilstone I have encountered. I am able to shave with the entire edge even though it's only 1000 grit. Today I ordered two more stones- 5000, and 8000. Expensive but worth it.

Good luck,
Alex
 
I just started using those wheels and a 1800 rpm bench grinder within the past 2 weeks , I love it !

I always sharpened on the contact wheel , which never came out the way I liked since my contact wheels are all serrated.

Something Tom Mayo told me , when sharpening with your elbows locked at your side , instead of lifting your elbow when you get to the tip , move youer elbow back , it has made my sharpening skills 10x better.

next up is a 8" leather wheel to suppliment this setup :)
 
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