bottom of grind

M

magnum .44

Joined
Jun 12, 1999
Messages
1,110
how do you guys make the bottom even, i'm having trouble getting the edges correct. also for future reference how do i square off the bottom of the grind, it always tends to round off.
 
Magnum,
I think that if you scribe double centerlines, that my help. By setting my height gage for .050, scribing the edge of the blade, then flipping it over and scribing it again, gives me double center lines that are .025 apart on 1/8 material. Now, the important thing is when you grind your blade, try to split the scribe lines!! This means grinding half way through each one!
I know this sounds hard but even if you are close, the edge will be pretty straight.
As far as keeping the edge square, I think I would have to see you actually grind! Is the wheel catching and "rolling" over the top of the blade????
I have to agree with George about the practice thing! I bought about a ton of 01 material from the company I work for. I think about half of it went in the trash the first year I had my belt grinder! Now that I can grind my standard knives with pre-determined results, I started making these Hawbill Neck Knives..... Grinding inside curves is like learning all over again!
Neil
PS I should have pics of the Neck Knives on monday!!!

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Just updated 10/31!! New Knives, New Pics!!!
http://www.geocities.com/Eureka/Meeting/5520/index.html

 
Like Dr. Lathe, I also use the double scribe line method. It eliminates a lot of guesswork. As far as rounding off the edge, it sounds like you might be getting too low on your grinding wheel.
Steve


 
i think you guys miss understood me, the end of the grind near the tang is were i'm having trouble. the grinds them selves are alright, even and flat. i use the platen on my grinder though. dr. lathe, i can't wait to see the knives.
 
are you talking about where the grind ends at the ricasso? If you are, I scribe bothe sides of the blade where I want the grinds to stop at the ricasso, then use these as a guide.
 
I think your problem is caused by having the belt overhang the platten too far, and maybe a too flexible belt. If the belt overhangs too much, it sort of runs over the bottom edge of the ricasso and cuts the bottom back towards the handle. I cut my plunges with a 120 grit belt overhanging the platten by about 3/32". I don't just lean in and try to cut the radius of the platen into the ricasso, but actually use the little bit of belt overhang as a carving tool to cut the radius I want, which is much, much bigger than the radius on the edge of the platen.

It takes some practice to get this technique right, but once mastered, it gives you great control over the shape of the plunge from ricasso to blade. I finish the plunge cut by hand because I cannot keep finer grit belts from screwing up the effect I'm looking for. It takes longer, but looks way better.

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Matt Harildstad
Knifemaker
www.planet.eon.net/~matth
matth@planet.eon.net

 
Magnum, for flat grinds, Barry Jones has an excellent method of getting the plunge ctus done accurately. He made a file guide with two pieces of bar stock that are bolted together on the ends. and one edge ground dead straight and flat. He clamps the guide bars on the blade with the bolts, and lines the ground edges up with where he wants the plunge cut to be. Then he takes a file, round if you want a soft plunge, flat if you want a sharp plunge, and simply files down to the scribed grind line. I have seen in books where people use these guides as stops for grinding on a platen too. They align them and just let them ride on the edge of the platen as they grind the plunge. If you want a set, I would be happy to make them for you. Just pay for the shipping. Take care!! Michael

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"Always think of your fellow knife makers as partners in the search for the perfect blade, not as people trying to compete with you and your work!"
 
thanks guys this really helped, but l-6 could you post a pic, so that i could see the set-up i'm confused a little on were to put the bars.
 
Magnum, I'll get a picture for you here asap, but its very simple. Just put the ground side of the guide bars where you want the ricasso, ie.. plunge cut to be.
 
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