Help with plunge lines

T

Technohedge

Joined
Sep 9, 2018
Messages
84
Hi guys,

Been getting my grind on this afternoon, full flat grind on a kitchen knife.

Question on the plunge line, In the images below the first one shows one side and the nice curve I managed to achieve. The second is the other side where I have taken it a little too far. Can I move the plunge further back and redress it?

Also would changing to a different belt (this was all done so far with a 60grit) be easier to do plunges with? Im a bit of a noob so any help appreciated

Thanks

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The way I get a sweeping/ curved plunge line is by tracking the belt off the platen by 3/16-1/2 inch, depending on how much curve you want. I don't do plunge lines until 200 grit. I use a home made file guide up until that point. Remove guide and then track wheel off to the side the desired amount I also tend to grind slowly. I tend to ruin less steel that way
 
Just a thought. You have your plunge line extending all the way down to the edge. Although this is done on some kitchen knives it's usually cheaper ones. I do own a Henkel with this. The problem is that it makes it hard to sharpen in that area. As the blade gets sharpened you may end up with an edge that's higher than than thick heel and therefore you'll get a gap just in front of the heel when cutting as well.

That being said, some people like the blunt section at the heel for safety.

Don't let me change your mind or design. I just want to make sure you have considered this so you don't end up with something you don't like.
 
yes, you can move it back to help match the other side. i personally do not do plunges until i am at 220 grit. i slightly rough them in with 120 grit, but most of the shaping is with 220. if i used a 60 grit i would only get one or two passes because the 60 removes so much metal. the higher grit gives you more passes or chances to develop the feel and fix any errors.
 
Some advice I read here, was to not go to full grind height with the coarse belts. Stop well before your final height with the 60grit, then with 100g walk it up higher but not to final height. Then with 200g, 400 or whatever finer belts you use walk it to the final height. This gives much more control and helps avoid over shooting which is so easy to do with aggressive belts.

Another piece of advice that was helpful is to keep the belt tracked close to the platen for the early grits. This leaves no or a tiny radius, then with the finer belts, track the belt off to make a nice radius. This applies more to smaller fillet radius, and I have not advice for those sweeping ones you might be after.
 
Looks like you're changing angles slightly when grinding one side or the other, or at the very least, putting more pressure against the edge of the platen when you were grinding the "full height" side. Even plunges are just something that have to come with practice, but my advice is not to worry about getting them even until the very end, then use a fresh belt when you grind them in. J-Flex belts curled just over the corner of the platen do a nice job. Heavy belts tracked off the platen just a little bit will work too, but sometimes it helps to "break" the edges so they have a little more flex. I use a ceramic rod for this.
 
As others have said only ho about half way up the bevel with 60grit, then 85%with 120 then finish it with 220. I personally do my plunges at 120 then refine with 220.
To get a slightly rounded bevel you need to track the belt off each side the same amount, and be very cautious of your pressure, this is something I really struggled with.
With a kitchen knife I PERSONALLY take the edge all the way to the heel.
 
Technohedge said:
Some really good info here guys, many thanks!
Click to expand...
You can try this one too .Split one belt in two , one part you can use for slack belt work on handle and other part only for finishing plunge . Leave them about 2 mm from where you want them so you have more chance to get them right.Inch and half wide belt will be more , far more forgiving then 2 inch belt , if you miss approach angle ....
 
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