Hollow Grinding techniques

D

Destraal

Joined
May 28, 2008
Messages
135
So I've now seen 3 different hollow grinding techniques and am trying to decide which one I should practice first.

Technique 1:
This is where you rotate the blade to follow the curve of the blade.

Technique 2:
In this technique you pull the handle away from the belt as you near the tip of the blade. The blade stays parallel to the floor throughout this technique, and the distance from the floor to the spine of your blade remains constant.

Technique 3:
Instead of either of the above, as you approach the tip you move the blade vertically while keeping the spine parallel to the floor and blade tangent to the contact wheel.

So what's the advantage of each of these? Trying to decide which technique to learn first, as I'm still quite inexperienced when it comes to grinding the bevels. Any advice would be greatly appreciated.
Kevin
 
There are far better experts than me on this forum, but I have a moment to give you an answer... so here goes.

When I grind I break the bevel up into different areas to work on. I would first grind a straight bevel the full length of the blade. Then I would work on the curved tip. I believe that "Technique 2" and Technique 1" are actually the same thing. When you are following the curve, you must also tip the blade into the grinder or else you will lose contact with the wheel.
You want the deepest point of the grind to follow the edge of the blade all the way out to the tip... or at least that is what I usually do.
I use a work-rest and a push-stick to do my rough grinding. That allows me to really lay into the grinder and let the blade get very hot. I use 60 grit Blaze belts for rough grinding. After rough grinding, I switch to finer grit belts and grind and polish freehand.

When I was learning to grind, I sometimes practiced on clear acrylic (Plexiglass) I learned alot when I could see thru the blade and see what the grinder was doing on the opposite side... that side is usually hidden from view while grinding. Acrylic is very fast and easy to work with.
 
I use Technique 2 but i started with 1. i find that i order to get a flawless grind you need to be as ridged as possible with as few movements. i love Technique 2. if you have not seen the how to videos on my site you should there is on just on hallow grinding.
 
1 and 2 aren't the same. If you look at the reflection of light on a blade ground using technique 1, the highlight wraps around the belly when you view it. If you look at a blade ground using technique 2 the highlight runs straight off the end. It appears that Chris Reeves and many manufacturers uses technique 2, and I feel it is an easier way to do it. I prefer the appearance of technique 1 but like JT said it is more difficult.

I hope one of the masters with mad grinding skills will chime in here.
 
Kevin you are about two hours from me. Ride over one day and I will see if I can help you with your grinding. Mike
 
im by no means a pro but i move the blade around the wheel on the curves

lucky for me razors don't have curves and i don't do many hunters and things like that
 
JTknives said:
I use Technique 2 but i started with 1. i find that i order to get a flawless grind you need to be as ridged as possible with as few movements. i love Technique 2. if you have not seen the how to videos on my site you should there is on just on hallow grinding.
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Indeed I have seen your videos and they certainly improved my grinding instantly, but I got more out of the way you widened your grind. However, you are where I really learned about technique 2.

WilsonKnives said:
Kevin you are about two hours from me. Ride over one day and I will see if I can help you with your grinding. Mike
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I will most certainly have to take you up on that sometime soon. Just need to find a day that I have a minimum of 5 hours at once that I can spare.

So from what I've heard here:
Technique 1 looks nicer
Technique 2 is easier

I'm also guessing that technique 2 probably creates a more sturdy point, since it would seem more like a flat grind there.

I guess I'll practice 1 for now, if it's more difficult then I suppose it's better to get a start on it first. Finally went out and got some of those paint stirrers and ill practice on that. Maybe try the acrylic idea if I don't make fast enough progress on the stirrers.
 
JTknives said:
thanks, i put alot of work into them and love sharing them as i like helping people learn to do knifemaking.
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Just wanted to say thank you for the videos JT. The Hollow grind was a big help to me. I hope it shows when the Christmas knife exchange photos are posted.
 
I stumbled across this old pict that illustrates nicely what I was talking about.

16.jpg


This it technique 1, notice how the light and reflections wrap around the belly of the blade. Technique 2 the reflections run straight off the end. It is my opinion that this way looks better.
 
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