Plunge lines

Tony Manifold

Tony Manifold

Well-Known Member
How do you get plunge lines and grinds so high up the blade. I have the blade as close to flat as I can make it with out putting it flat on the belt. Yet I still only get grinds that go halfway to 2/3 of the way up the blade.
 
Tony,
Perhaps the angle of your bevel grinds are too steep? With a full flat grind, I take my edge bevels to 0.025 for some very thin slicing culinary knives up to 0.40 for camp with others in the middle. What Bevel edge size are you grinding to?
 
rhinoknives said:
Tony,
Perhaps the angle of your bevel grinds are too steep? With a full flat grind, I take my edge bevels to 0.025 for some very thin slicing culinary knives up to 0.40 for camp with others in the middle. What Bevel edge size are you grinding to?
Click to expand...

I am talking pre edge. This is a typical example. Sometimes I can get the grind higher but this is typical.

avazahag.jpg


I am looking to get a plunge line that is almost all the way to the spine. The knife above would benefit from less meat on the blade. A skinning style blade doesn't need an eighth of an inch thickness 1/4 inch up from the edge.

Sorry, I just noticed how crappy that pic is. Hope it gets the point across.
 
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Well, From the looks of it, Just keep grinding the bevel higher. My plunge lines don't get to the top until I grind them there. DSCN5698.jpg

I guess i am just not understanding your issue?
 
It looks like you are using to steep of a degree.That looks like about a 15 degree beval or so and for a full grind I would say 2 - 3 maybe
4 at the most.
 
I guess I am asking how to get that acute angle. Is it just a practice thing or is there a special technique? Right now I just try to hold the blade at as narrow angle I can without laying the whole thing on the belt.
 
I'm trying to think of a simple way to explain it,I will try and draw you a illustration in my scetch book snap a pic with my phone and post it,I don't even think I have a ruler but I will see if I can give you a awnser that makes sense.
 
Ok first determin the total width of your blade and the thickness of your stock.Next illustration shows a veiw as though you were looking at the point.You can do this to determine what degree your final grind should be leaving whatever thicknes you want at the cutting edge before sharpening.So draw a 1/8 x1 1/2 inch cross section then lay a strait edge on it from the point you want your ground edge to start at the spine and draw a line to your termination point at the edge.Measure the deg with a deg scale or a protractor and do your grind at that deg, so can see from my illustration that for a full grind its a fairly shallow deg.If you don't have a bubble jig or some type of grinding jig then you have to keep it in mind that you need to stay on the shallow deg .If you don't and roll your edge in to say 10 deg your going to end up with more of a chisel grind.I hope this is making sense.
 

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Awesome. That is it exactly. One if the problems of doing this by myself is I often don't know if I am doing the wrong thing or the right thing wrong.

In this case it looks like I am on the right track, I just need more practice at keeping a very fine angle.
 
I'm a new guy in knife making. One of my biggest challenges is to have a nice deep grind. With 5/32" blade stock and a blade 1 1/8" wide. If I want my grind 1" tall, I find it takes a lot of practice to get a clean straight grind line. The less of an angle/ taller grind line, the tougher it is to keep from washing out your desired grind line. It is for sure possible to do, I've seen lots of makers do it all the time, but it's possible to learn. Would be easier with a jig, but I suspect you are free hand grinding like I do. Practice practice practice
 
Tape is your freind if you're just learning.
Quick and simple reference is to apply tape where you want your grind to end. Take out everything in between the edge and the tape without zero grinding your edge. 3 or 4 layers of tape will let you 'feel' when you're there and protect the spine. Stop using the tape when you can visualize what you want the belt to do. I've done this set up for a couple of people who wanted to learn freehand grinding, it saved me a lot of explaining things they didn't seem to understand.

Rudy
 
Agreed,

I've messed up a few blades where I didn't care to finish them after putting nasty scratches past my desired grind lines. The tape could for sure give something to slow that down, and perhaps feel it happening.

Great idea.
 
A word of caution...
The tape is no excuse not to visually check your progress every couple of passes. Most people catch on quickly having a visual cue like the tape or even a line in Dykem. Most beginers have a rigid mindset when at the grinder, almost like a robot or human jig. You are allowed to rock your blade to give the belt some meat to eat. As in the picture, if you lay that grind on the belt without the grinder running and rock the blade a few times, that will give you the feel for where you need to push and basicly take out that high spot on every pass. The high spot will progress up the blade with every pass. If using the tape or a line, allow for post heat treat clean up. Hope this is clear, simple and helps.

Rudy
 
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