Distal Tapers

Jerry, the discussion on flat - vs.- hollow ground blade strength generated a question that I have slept on for a day or two, but I'm still puzzled so I thought I'd ask.

You commented that HG blades don't have distal tapers. I have tried to put one in on every blade I have hollow ground, and as you can imagine, it is the most difficult part of blade grinding for me, since it involves a *very* slight, sort of intuitive shift in the position the blade is held as it crosses the contact wheel. This manuver has generated more scrap than anything else along the learning curve. If others aren't going through that angst, I wonder if I'm doing work that isn't necessary.

I don't taper. Instead I angle the grind so the apex of the hollow is just below the point. This gives me a thin area on the edge where it does the most good, and leaves a little extra beef on the point to make that stronger.

You have to remember though, I grind completely wrong - upside down! I pretty much ignore the edge while I'm hollow grinding, so the apex/center of the hollow is well above the center line. After I get everything where I want it, I then go back and thin the edge to suit me. It is often thicker than the center of the blade, especially on large blades where I want a robust edge for chopping or incidental contact.

Many makers, just follow the edge profile completely and hollow grind the point just like it were any other part of the edge.

I know; I'm weird!

Allright, another upside downer you think you have problems, I right with the wrong hand too.

hey 2 wrongs may not make a right, but 3 rights make a left ! :

Jerry and Terry,
Did you guys ever consider that maybe you are the only two who know how to do it right, and everyone else just hasn't caught on yet?

I'll tell you someone who is interesting to watch. I'm sure you've both seen some of the beauties Harvey Dean puts out. He grinds one side edge up and the other side edge down. He never has to change hands.

I do some of my rough grinding on large blades that way. I wear a glove only on my left hand, and keep the point in that direction. Yeah, I'm weird...

It's not impossible to incorporate a distal taper into hollow ground blades, I've never understood why some think you have to forge or flat grind to get distal taper.

If you grind your hollow all the way to the top (spine) and parallel to the cutting edge as you go, the spine will automatically taper from guard to point as the blade width narrows (assuming the blade width narrows from guard to point as is usually the case). Also, you don't have to grind a perfect 8"hollow groove just because you only have an 8" wheel. You can fudge toward the top or bottom side of the grind and feather the grind out to your final desired thickness at any point. It doesn't matter whether you grind upside down or right side up- I think this is sort of what Jerry is doing when he first grinds the bulk of the hollow then works the edge down to the final thickness he wants.

When people use an 8" wheel to grind very wide blades they must also do this feathering or they would grind a hole in the middle of the blade before the edge reached final thickness (or thinness?)This assumes they want the grind to go from edge to spine, or nearly so. It doesn't apply if they want a sabre type grind only going part way up the blade. If you want to distal taper this type of grind, you must taper the bar by flat grinding an overall taper first, then hollow grind. There are several ways to get a taper.

If you stay perfectly parallel to the edge, the knife will get too thin near the point for some applications, as Jerry pointed out, so you must back off some as you near the point to obtain a more practical taper and retain strength. Part of this grinding thing is art as well as science and just takes a little practice and experience.

All those who've ground a hole in the middle of a blade say, aye!

AYE!!!! yi yi yiiii............

Been there. Hope I don't go back.

A hole in the middle!?! No problem, mon. I've also gotten it so thin that it was like aluminum foil!

As far as the distal goes, on the few hollow grinds that I have done, I just moved the steel straight across the surface of the contact wheel. The geometry of the drop point took care of the rest. I do use a 10" wheel if it makes any difference.

A very good friend of mine just can't get the concept down since he arcs his steel as he moves towards the tip. In other words, as he grinds towards to tip, the tang is moved down. He also grinds sitting down which I just can't do. Although we both make blades in a different fashion, there is nothing wrong with either of our blades. I must say my friend makes a fine knife but I just can't do it "his way".

That is one of the most interesting aspects in this thing we call knifemaking. There's at least a hundred different ways to get there. This is truly intriguing to me. Each of us has a "signature". I get excited just thinking about it! What a craft! I am sorta "ate up" with it.

Craig

If you parallel grind then form the drop point afterwards, doesn't this upset the geometry of the taper?

I would hate to be restricted by this phenomenon, as such I grind the way Don's been trying, but I take small bites at the required angle, changing sides often & smooth things out afterwards.

Someone has probably already answered this question, but it's difficult for me to unravel the mysteries of replies, so pardon me if I've covered old ground, or not explained myself properly.


Colin

Remember that the way I grind is completely WRONG, but it works for me.

Once I lay in some initial bevels and get some groove established, I turn the blade egde down and grind up to a point where I want the grind line to be. In the case of the point, I place the grind line above it sufficiently to make it reasonably thin. Still the apex of the grind where the blade is thinnest is usually about 1/4" below the point, so that is really the thinnest spot on my edges. To then make the point thinner, I rotate the tang up and away from the wheel just as I slide over the point until it is as thin as I want. After all that is done, I go back and blend everything into the edge, using up and down motions, to a final thickness I want the edge to be.

The distal taper is actually in the hollow, but I retain as much spine thickness as possible for lateral strength.

I don't expect anyone to grind blades like I do. It took a whole lot of years and LOTS of scrap steel to get pretty good at doing it wrong.

Jerry, what you must remember is that it is only wrong for other people. Apperantly it is right for you. I have looked at a good number of your blades and afew were very long and ground very well. I usually put a distal taper of 3" on a 4/5" blade. I grind with the edge up and usually all the wat to the back spline.Regards--Rade