Even plunge depths with file guide?

M

matthewhoffman

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Nov 19, 2016
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Hoping someone can help before I pull all of my hair out. I keep a file guide (post-HT) in place through 120 grit while I work up my bevels. It's worked wonders for keeping my plunges straight, but I'm having a bear of a time getting the depth of the plunges equal on both sides. I've tried to compensate with a little extra time/pressure on the side that tends to be shallower, but without great success. Is there a trick for managing this? Free-hand plunges are beyond me at the moment. Any advice would be welcome!
 
Do you scribe a center line on the blade edge before starting the plunge? That really helps. Paint the blade side and edge both with a magic marker (or better yet persian blue) and scribe lines where you want the cut to end, both on center of edge and up on the blade side.
 
The sides of the blade being flat and even thickness is important, otherwise the blade will lay at different angles on either side. If you are forging, that may be the problem.

If you have a flat and even piece and cant get it even, then i would say use some calipers and measure the edge thickness down the length of the blade and make sure you take the same amount off both sides.
 
I must have done a poor job explaining the issue. My apologies.

The depth of the plunges are how deeply they cut into the sides of the blade--into the thickness (not speaking of the width). I've found that the plunge on one side of the blade isn't as pronounced as the plunge on the other. With the file guide in place, I find it difficult to gauge how deeply I've gone. Once I've removed the guide, the discrepancy is obvious--and not so easy to correct at that point.

I do scribe a center line, but perhaps I'm losing the geometry more on one side than the other?? Calipers might a solution, if I can manage some addition and subtraction!
 
matthewhoffman said:
......With the file guide in place, I find it difficult to gauge how deeply I've gone. Once I've removed the guide, the discrepancy is obvious--and not so easy to correct at that point.......
Click to expand...

With the scribe line in center of blade edge, and scribed line where you wish the grind line to be on the blade will help with that problem. Using both lines as a guide, file until the depth is touching the line at both blade edge center line and the grind scribed line and the depth will be the same on both sides. I should say here to scribe TWO lines on blade edge, with perhaps .015" between the lines for amount you wish to leave on blade edge. OR - file to a spot just before the center line.
 
Ken, I understand what you're saying, and it makes sense--although the plunge might still be invisible with the guide in place. I'll have to take a look. I didn't mention that I'm using the guide while using the 2x72. Appreciate your thoughts!

Pictures sure make things easier. I'll borrow a camera and throw up some pics, if these snafus don't somehow magically disappear.
 
What hand is the more "pronounced" or the better looking side? I know a lot of folks have issues using their offhand starting out. I did and still can have some trouble when grinding with my offhand. But I can say over time and for me some instruction with the pros, helped things to balance out. Either I got better with my offhand or I learned how to compensate in some fashion.

If I had to guess based on what you said I would say you are cutting crisper or sharper lines with your dominant hand and more of a sloped plunge with your offhand or one is almost perpendicular to the edge and the other is curved toward the tip if you were looking down and the knife is edge up. You can fix this, i.e compensate by just kissing the belt in front of the plunge and grinding back towards the plunge line with the belt wrapped around the edge of the platen. That is, if I understood your issue :D

Eyes and finger tips are a knifemakers best friend when finishing a knife. But they don't always tell you what the problem is!

-Clint
 
Ain't it the truth. My eyes go one way and my hands go somewhere else. I'm counting on practice--a helluva lot more than I have--to even out that particular issue. And knowing a problem exists isn't the same as knowing how to fix it.

Actually, my plunges are straight, thanks to the file guide. But anticipating the depth on either side remains hit or miss. I got off the grinder an hour ago, and both plunges were equal and clean. It was a mistake, no kidding! Haven't a clue what I did right.
 
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