Hollow Grind Help...

D

DEwing

Joined
Dec 15, 2013
Messages
11
I just upgraded from a Grizzly to a 3 speed KMG (good move). I am following the practice, practice, practice method to get my hollow grinding technique down. I am closer but not quite there...

The image below shows my latest knife grind line sloping consistently and of course I am looking for a grind line parallel to the spine then arcing down to match the arc of the blade.

The opposite side shows a more parallel grind line but it has a slight bump in the middle.




Any advice as to how I can get the grind line parallel to the spine???

Thanks

Dan
 
Might want to ask this over in the Knifemaker's section - you'll get help there, I'll wager!
 


I am looking for some technique advice on hollow grinding. I have been practicing quite a bit and while I am close I am still not getting the grind lines the way I want them. Namely I am struggling to get the grind line to parallel the spine of the blade. On one side I get a sloped grind line and on the other I get an uneven but more parallel grind line...

I am using a KMG, 3 speed with a 10" contact wheel...

And advice as to how I can get control over that grind line would be MUCH APPRECIATED!

Thanks

Dan
 
You just have to practice. Your right hand and your left hand are working differently. After each pass look at your grind line and remember where you have to put a bit more pressure on it for the next pass. Eventually you will get it. Even after hundreds of ground blades.....you just have to look and see what you are doing after each pass. You will get more mechanical but never to the point of being a machine. Machines do not need to look after each pass....but we do!

John Lloyd
 
I have found a consistent depth results in a nice line, not the other way around if that makes any sense....I'm no expert but I like doing hollow grinds.
James
 
What I do is lock my elbows to the side then use my body to control the movement of the blade on my grinder which results in more stability and better control. I've found that I get better results when I check every few passes instead of every pass because the more often you stop and look..the higher the chances of you placing the blade on the wheel where you don't want it to be placed.
 
I was flat grinding a couple of blades yesterday and getting much the same results as you have when it occurred to me that I was moving the blade from left to right, or vice versa, at a different rate on one spot than on another spot.

I started trying to more carefully control the speed of side to side movement and things started improving. Not great yet, but better.
 
I ground another blade today and figured out that with my left hand grip I need to apply more pressure to the edge of the blade but with my right hand grip I need to apply more pressure towards the spine of the blade... When I did this I got straighter lines on both sides. I have NO IDEA why this is the case - makes no sense to me but seems to work better. Having said that I still have a slight hump in the middle of the grind line - it's VERY slight but still there...
 
Using a very light touch, bring the knife to the wheel making sure that the edge touches the wheel first, then pivot it so that the entire bevel is being ground. If you try to bring it in so that it hits right on the bevel, it's so easy to wipe out the nice crisp line you worked so hard to establish.
This motion gets more important the closer to finished you are.
 
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