First attempt at hollow grinding

G

Gossman Knives

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Apr 9, 2004
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I just finished my first hollow grind with the 10" wheel set-up on my KMG. I took a quick pic of it. Man after sweating it thinking it was gonna be tough, I think it turned out half way decent. :) It's not any harder then the other grinds, flat and convex. It's a rough grind with a 50 grit zirc. belt. I left it that way so you can see the grind line. It's a 3" semi-skinner profile. What do you think?

hollow.JPG


Scott
 
Lookin good, your already following the curve of the blade. Thats harder than doing it with a straight pass.
Once you figure out how to rock your pressure from edge to spine to adjust the grind its not too big a deal :cool:
Keep at it, let us see that one when its finished :)
 
Thanks Matt. I follow the same rule of thumb as I do while convex grinding and it worked like a charm. :) Both sides are pretty damn close. I still need to work on that. All in all, I'm pretty happy with it but there's always room for improvement. I always strive for improving.
Scott
 
Looks good from here! Hollow grinding is the only way I have tried to grind. Once you get the hang of it and can "feel" the hollow while you make a pass, it will track the blade for you, and then you have it licked. The hardest part for me is establishing that hollow, but after that it is a no brainer.

Nice work!
 
That's a dandy Scott. My 10 inch Coote wheel often asks me to hollow grind one but so far I have not. I am still a flat lander.

RL
 
Following the curve is nice for some knives, but taking the grind almost to the spine, and running it straight off the blade looks very good too.

Be careful when you get the groove going, a contact wheel will remove metal faster than a platen, so make sure you leave enough for the next grit. It's real easy to use up all the excess metal, and you'll have that famous 40 grit using knife finish. ;):D

It looks good!:D
 
Not bad at all. I noticed that if you start with 1/4 inch steel, the feel of the hollow lets you pratice more on the same piece. The first time I did 1/8 stock I went almost to the other side and had to convert the blade for a chisel grind. Just keep grinding. They say that it takes 100 blades freehand to get confindent. I think that you will beat those odds. :D
 
Mike Hull wrote:
"Following the curve is nice for some knives, but taking the grind almost to the spine, and running it straight off the blade looks very good too."


Hey Mike,
I'm trying to picture this. Probably seen it a lot, but don't realize it.
Would the grind line on such a knife, end up being PARALLEL with the spine?
It's funny,
Since I am learning to grind on my new BaderIII, sometimes I'm sitting in my shop, profiling out new blade shapes, and trying deperately to think of new grind patterns, and my mind will just draw a blank. Then, I go upstairs, hop online, and see all kinds of grinds online, and wonder why I didn't remember them while in the shop. LOL!
Thanks!
 
Thank you for the words of encouragement. Mike I know what your saying about the grit thing. It's hard to remember it's not a convex where I grind almost the the cutting edge before heat treat. Of course hollow grinding is the opposite so I need to remember not to grind off as much. I'm really getting the hang of the amount of pressure while grinding. Meaning when to press hard and when to use lighter pressure. Like I've said before, I'm not a big fan of the hollow grind for my own personal use, but it sure is fun making a knife this way. :D Roger, you ought to give it a whirl, I actually think it's easier then flat grinding. :)
Scott
 
Razorback - Knives said:
........Like I've said before, I'm not a big fan of the hollow grind for my own personal use, but it sure is fun making a knife this way...............
Scott
Click to expand...
It's actually an excellent grind. It got it's bad name from people that can't do it, or from knives with really radical hollows, like 2-6" wheels, and they aren't really practical.
Match the wheel to the height of the blade, and it's hard to beat it.

The historical knives were mainly hollow ground, and not on 6' wheels(that was one place in france) either. I've seen photo's of the old Sheffield grinders sitting in front of grindstones the size of many contact wheels now in common use, and they were grinding bowies. They didn't have flat platens back then.
The bad you hear about hollow grinding is mainly propaganda.
 
I understand what you mean. Maybe after I get the knack of doing the hollow grind, I'll come to appreciate it more. I don't plan on doing it as thin as some of the ones I've come to dislike.
Scott
 
Mike Hull said:
Following the curve is nice for some knives, but taking the grind almost to the spine, and running it straight off the blade looks very good too.

Be careful when you get the groove going, a contact wheel will remove metal faster than a platen, so make sure you leave enough for the next grit. It's real easy to use up all the excess metal, and you'll have that famous 40 grit using knife finish. ;):D

It looks good!:D
Click to expand...


Hey Mike,
Does this just mean a grind line that runs parallel to the spine???

"Following the curve is nice for some knives, but taking the grind almost to the spine, and running it straight off the blade looks very good too."

Thanks,
 
Thats about what it means Razor
Your plunge is pretty much perpendicular to the spine where it is and then your hollow goes straight forward all the way to the tip. As you move out towards the tip the grind will go above the spine. It gives you a really nice distal taper when you've done it right.
Here's an example:

attachment.php
 
Looks great Matt. The hollow grinds I do like are on Chris Reeve's hollow handle knives and Buck knives hollow grinds are good. Randall Knives have good grinds so do Ruana. I still like the convex grind the best, especially on large choppers.
Scott
 
Thanks guys
Not trying to hijack your thread Scott. Just thought that might help answer his question.

Yeah I don't like abrupt hollow grinds either. I try to run em full height or pretty close to it. And then on hard use knives I'll leave the edge a little thicker, and sometimes even convex it.
 
Ok guys, here is what I ended up with after going to 120 grit zirc and then finishing on a 220 ceramic. Does it look right? Did I take it to high? This is something I will need to practice, pratice, practice. It is pretty even on both sides, down to the point and along the cutting edge.

hollow2.JPG


Tell me if I need to do something different or am I on the right track. Thanks
Scott
 
Scott,
Looks good. I was wondering if you are straight free-handing, or are you using a work rest? Just curious.
 
razorhunter said:
Scott,
Looks good. I was wondering if you are straight free-handing, or are you using a work rest? Just curious.
Click to expand...
Razor, I'm straight freehanding. I don't want to start out with a crutch. I've been freehanding from the start with convex and flat grinding. The thing I'm finding with the hollow grinding is you need to use the same pressure when changing to another belt/grit. That's why the grind ended up higher then I anticipated. I wasn't holding/applying the same pressure when I switched to the 120 grit. I think it's actually better this way because the point is tapered more. This will be a trail and error learning experience. I've always liked teaching myself, but it tends to frustrate.
Scott
 
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