How different is flat grinding than hollow grinding?

K

krept

Joined
Jan 14, 2002
Messages
568
Here is the situation:

I have a belt sander and a video I just ordered from Texas Knife Supply just arrived. It's volume 1 of something and is about hollow grinding. I have not watched it yet.

Problem is, the knife that I am working on I would like to flat-grind. I bought both the hollow grind and the flat grind video. How much can I learn from the hollow grind video that applies to flat grinding? Is it THAT different?

BTW, the belt grinder I have is 4" x 36". Low HP, but works much better than the Dremel. This should facilitate flat grinding, no?
 
The 4x36 I have,it has a hard time tracking the is that key to getting good lines.Hollow grinding and flat grinding are very different
one thing about hollow grinding that is different is when you get
a hollow started you can feel when the wheel is riding in the grove
Flat grinding on the other hand you can not feel much
and it is alot harder to control.
I know the video you have Johny Stout grinds nice he uses a rest
I see notting wrong with that.
Harvey Dean flat grinds one up and one side down.
I don't know if I answered your questions the only way I know
how to be able to grind is pratice


;)
 
Hey Nathan, thanks for the reply, I appreciate it.

I practiced on a small piece of 154CM and it came out faceted, meaning that I changed my angle many times during grinding I suppose.

I still need to check out the hollow grinding video. Might be a good project for a neck knife out of the smaller piece of CRUWARE I have.
 
Until a couple of years ago I only did flat grinding.Now I do almost all hollow grinding. The hollow grinding is easier to do, often looks better, and uses a lot less sandpaper. For sure there are some knives that work better flat ground such as fillet knives and large camp knives meant for use. Just my opinion of course. Frank Niro
 
I started out with a 4X36, it'll work just fine for the time being. One thing I did to to mine was to put a piece of 1/8 sheet metal of sorts about 4 1/8 inches wide by about 3 inches long on to the platen to give me an edge on the sides so I could do a fairly good plunge. I countersunk (countersinked?) some holes to bolt it on. It was "sacrificial" and I would hav to replace it every so often.\

I made a number of knives in this fashion until I moved up to a different grinder and of course, every knife was flat ground. Its not that difficult to do on a 4X36, it just takes a little more patience. I used to get so frustrated when I was first learning but its fun nevertheless. I still have a picture of my first one ever and it was done on a 4X36. The nicest thing about it is the handle material. This was 7 or 8 years ago...not the prettiest thing in the world but the one I still keep around and will not part with. Hang on to your first one so you can see where you've been and where you're coming from.
fdced160.jpg


C Wilkins
 
Thanks for the inspiration. I might just start out with hollow grinding this blade .

Nice knife, by the way.
 
Hey Mr Wilkins I did the same thing with a 4 x36 about 20 years ago. It was a way to get started and I had no idea whatsoever what might work or not plush I too had a very limited amount of funds to spend. Frank Niro.
 
I use a 4" X 36" craftsman belt grinder for all of my flat grinding. Being under powered isn't a problem for me because I take my time (I'm slow) and pay close attention to my hands. The faceting you mentioned can be avoided by starting each grinding pass at the edge and very gently 'finding' the flat spot you passed last time. Very much like hollow grinding only different. Sort of. I left my platen alone because I like rounded plunge lines instead of sharp 90 degree ones. I don't think sharp lines belong anywhere but on the edge.

I learned to hollow grind on a 10" stone grinder. It only took me about 3 months to grind a blade with even lines. Three months to grind one good blade. So, be patient and feel your way through. The main thing is not to get too hung up on pressing 'hard'. When you press too hard you lose control when you're first starting out. You'll learn to just 'lay' the blade on the groove and follow it. It will become second nature to you after a while. And if the blade gets too hot to hold onto then you're messing up or your stone is glazed or your belt needs cleaning. Stop after each pass and have a quick look at your blade. See where you hit and where you missed. On the next pass 'will' your hands to find the spot that needs work. Eventually, it will come. Trust me. You just have to be patient and really give yourself a chance. It's all about hand to eye coordination.

One thing that I'll say about hollow grinding is this. It should be done on top of the grinding wheel whether it's a rock or sanding belt. Well, let me back up and regroup. It's however you learn to do it really. But for me it was easiest on top of the wheel because it's easier to keep your eye on things and estimate the angles of attack with each pass. And unless you're ambidextreous you'll wind up pulling one side and pushing the other. If you don't think you know what I mean I'm sure you'll find out with practice. Good luck with your grinding.
 
M, thanks for the tips. After watching the hollow grinding video, I realized that the "wheel" on my belt grinder does not have a large enough diameter to do a good hollow grind on the blade I am making. It should be large enough for maaaaybe a 1" hollow grind on a neck knife, however.

Fortunately for me, the flat grinding video arrived yesterday. We'll see if my first true grind on a blade is a combo of flat, hollow and convex grinding all in one.

And yes, at this point I'm appreciative of the 1/3 or so horses that my inexpensive grinder cranks out... even though it goes relatively slow, it's better than a dremel or files, which are my only other options.
 
You must log in or register to reply here.
Back
Top