O.k. grinding help needed

Okay, I spend the last two days working on couple of big Bowies. Yesterday I ground off hand, which I always have. Today I use Johnny Stouts Hollow ground method, from his video. I won't ever Grind off hand again. I Find it much easier to grind with a rest with the edge up. Just saying.
 
Another thing to check is the blade straightness -- that can screw up grinds fast! Other than that; practice, practice, practice.
 
Alot of sound advice given here ! Weak hand first etc. etc.

Here's my take. It looks to me like an issue of PRESSURE. I grind freehand so there is the possibility that using the rest diminishes the FEEL. Alot of folks grind off a rest though so my guess is that it's not the rest giving you trouble and you just have to develop your FEEL for your grind and the pressure.

I like the lazer comment above so lets call that the X-axis. Grinding consistanly in the X-axis is only one part of the 3-dimentional equation. Pressure is IMHO fairly easy keep consistant while grinding down the lenth of your blade. As you gain experience and feel you'll magically stop getting the 2" divot caused from the side of the belt away from the plunge.

Now lets call the plane from edge to spine the Y-axis. Pressure on this axis is what we're using to walk the grind up towards the spine, IE we're using Pressure to remove steel from the top of our grind and not on the bottom. It's also this pressure that "mainly" controls the shape of the plunge.

Your Z-axis is being held consistant by the work rest. Think of holding your blade against the platen then turning it like the hand of a clock to undrstand the Z-axis.

All of 3 axis's work together to determine the 3 dimentional shape of your grind and understanding the cause and effect of pressure in each axis will allow you to troubleshoot your grinds as you go and thus let you know what you need to do to fix them.

This is how I think about my own grinding and it has helped me IMMENSELY !!! Let me also say that I'm no robot while grinding (although I wish I were, lol) and grinding a blade to me is taking a pass or 2 then troubleshooting. Fix any problems and then move on.

So I'll use this method to trouble shoot your grind as best I can from those pics.

Assuming you are grinding edge-up we'll use the grind you made left handed as the baseline for what we want. You've got a nice little sweep at the top of the plunge and the top of the grind is nice and straight from plunge to tip with no wobbles. This side looks great so now to match up the other side.

First is to determine where the problem/problems lie. You've got the dreaded 2" divot - X-axis problem. This is quite common and nothing a pass or 3 with even pressure and a SHARP belt wont fix.

The fact that the 2" divot scuffed up to the spine is caused by a wobble in the Y-axis. I'd speculate that in trying to get your plunge ground up to where it should be your sitting still right in the plunge and doing some funky stuff with your pressure. For me sitting still against the belt is a BIG no-no that will only cause problems so my blade is always moving in a left or right direction while grinding. FWIW, I always approach the belt in the middle of the blade with a light touch, get flat against the belt, run back into the plunge and THEN exert grinding pressure.

Judging by how the light from the flash is reflecting off the blade it looks to me like youve got 3 distinct facets on this side of the grind. You've got a wide flat right dawn the middle of the grind, a tiny flat down on the edge that is LESS of an angle than the center flat, and another thin flat on the top of the grind thats a stteper angle than the center flat. This is cause from a combination of a light pressure overall and a DULL belt. One trip with medium to firm pressure across a brand new belt would flatten things right back out.

To straighten this grind out I'd use the edge of the belt to HOG some steel from where the top of the plunge should be. I'd get it close to where it should be then get that new belt and work the center of the blade till I had a nice flat grind where the top of the grind line was nice an parallel to the edge then get on THAT flat and run it gently back into the plunge.

Keep a very good eye on your edge thickness, grind line, and plunge while grinding to diagnose if there's a problem and get it fixed as soon as possible. Leaving a problem like a divot or funky plunge will only seem to get worse if left un-fixed.

Kids are getting antsy so I'm gonna post this and come back to proof read myself. I should really quit replying with the quick reply box, lol.

Hope this help you some at least- Josh
 
I produced a DVD for Gil Hibben a couple of years ago showing how he does his freehand grinding. It is available on his website http://www.hibbenknives.com. If I do say so myself, it is a good DVD that clearly shows and explains eveything from layout up through the rough grind prior to heat treating.
 
Lots of interesting advice, Anthony.

Ditch the rest and/or jigs for grinding. If you're using a rest you can't really feel where your blade is in relation to the wheel and your hands and body. Correcting your grind line and making them even depends more on very fine adjustments to your body's position and less on sight. Imagining a laser sight is not the same as having one, and unless you're Steve Austin you won't have the ability to actually see what you're doing well enough to make those fine corrections. Setting the blade on a rest or holding it with a jig of some kinds keeps you from feeling where your blade is and making a tiny adjustment.

I don't think it makes any difference which hand you start with, strong or weak. You've got to learn to use both hands. I'm right handed and I usually start off holding with my right and supporting with my left just because that's how I've always done it. I grind equally well with my left because I've practiced for nearly 30 years. And that's the real key - PRACTICE! Yes, you may need to waste a few pieces of steel before you get it right, so do it. A good steel machinist's rule will help.

So go practice. Throw away the bad ones, keep the good ones.

David
 
Thanks guy's there is no substitute for practice , I think I am going to start trying free hand on a few peices and see how it goes.
 
I highly recommend Gil Hibben's DVD also. Gil's method of grinding is what allows him to do all the exotic grinds on the fantasy knives.

I can see where rests could be helpful on some grinds some of the time but you are so limited with them. I don't see anyone who's knives have the curved plunges like those you will see on David Broadwell's knives or exotic grinds like Gil's using a rest. I personally don't care for a square plunge line which is why you seldom see that on my knives. If I don't curve it I almost always at least angle the plunge.
 
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