Odd grind line

Metalhead0483

Metalhead0483

Joined
Jan 17, 2008
Messages
539
Hey guys, I'm working on a new project (mini cleaver/sheepsfoot pattern) and am running into an odd grinding issue. My right hand grind is lovely, nice and even. My off hand grind however, has a definite arc to it. I drew out a quick thing to demonstrate what I mean. Sorry I don't have actual pictures. I was in a hurry leaving the house this morning and forgot to grab the blank...

grind%20line.jpg

I'm trying to figure out what I'm doing to cause it. The edge looks great, it's just the grind line at the spine that is out of whack. I'm assuming it must be something I'm doing wrong technique-wise. Any ideas?
 
I run into this when I'm grinding my off side too. It's just using a different pressure and not always being flat on the platen. I clean it up with grinding in that spot to even it up. Takes a bit of practice.
 
You aren't holding the same pressure against the platen as you draw the blade across. You can do a "catch up" by simply starting part way through rather than from the end.
Frank
 
Hmmm, so it's just me not being consistent with my pressures huh? That makes a certain amount of sense I suppose, but if leaves me with a bit of a conundrum on this blade. while the actual grind line is a bit wonky, the edge is straight and true (and only about 0.005" off where I want it to be pre-sharpening. I need to decide if I should chase the grind0 to even the grind line and risk FUBARing the edge, or leaving it as-is on this one and doing better next time.
 
For me I chase it a little trying not to take material off the edge. I also find for some reason I can get it straighter after HT. I also try to fix it before I get to my pre HT grind so it's closer. It's a learning curve...
 
Let me guess... it's about a 4" blade? :p



You might find it helps to pull the blade along in only one direction from plunge to tip. I have a feeling you are changing direction as you grind. That is how you get the typical 2 inch dippedy-doo syndrome. As the blade stops to change direction, it hovers for a bit as the belt digs in. It is not too hard to overcome with a bit of practice. Keep at it.
 
Last edited:
It also appears you may be subconsciously focusing on the plunge line and getting "lazy" in the center then focusing toward the tip. I have had this happen as well. Like stated previously I fixed it post heat treat and grinder running slowly. The heat treat doesn't allow as much material to be taken off very quickly.
 
I hate to say this but you can always jig it up to fix it if the edge is that thin.

Lately, my arthritis is getting worst and I've had some issues with freehand, I've had to fix after with a jig or hand rubbing...
 
A push stick that is about half the width of the blade applying pressure near center will help keep even pressure.
 
How many knife have you made so far?
After awhile you get to the point where you can feel the the grind shape and just about see it in your minds eye. just keep working at it and it will click. I actually kinda ignore the plunge cut area while grinding the edge bevels in. I apply less pressure on the edge when coming into the plunge cut. This way it leaves me extra meat to dress it in after the bulk of the grinding is done.
 
Slow down the belt speed, put on a 100 grit belt. Get work rest set up. Now on low speed place the grind on the belt with the tip side 1/16" off the belt and use your thumb to apply pressure, with the tang hand pull straight across the belt and using the thumb pressure at the point of grinding.

The trick is a straight even pull with no hesitation and equal steady pressure ( mild) to get that top grind straight. Straight grind= straight pull
 
When first I started grinding I had that happen. Frank's advice is pretty much how I learned to correct that problem. Keep at it and be as observant as possible to every movement you make and how it translates to the steel and you'll be fine. And beware shop gremlins that steel your tools and drink your beer.....
 
Sorry guys, I haven't been on since Friday.

So to address a few of the questions/comments. People suggesting a jig, and to slow down the belt speed, I can only wish. I'm using a craftsman 2x42" grinder with a ceramic platen. So the rest is insufficiently stable and most definitely insufficiently true to the belt face to use a jig with any accuracy. Believe me, I've tried. Also, obviously no belt speed adjust...

Rick: Close, it's probably about 3.5" and while I understand what you're saying I definitely make a point of only pulling the blade on the belt, not doing the whole push/pull thing, which I figured out not to do pretty early on.

Alan: That's an interesting idea. I have a push stick, but it's nowhere near that wide. I might give that a shot.

JT: oh I don't know, probably fifteen or twenty in the past two years. It's just a hobby at this point, making them for myself and as gifts for friends. And we had a little girl last year, which has put a SERIOUS damper on my time in the shop... Also I've been primarily forging my blades pre-grind. This is probably only my fifth or sixth stock removal blade (which I completely understand is part of the problem) This is the first time I've noticed the weird wooble in the grind line though.


I'm hoping to get into the garage this afternoon to try and clean up the grind line. This is the first mini cleaver/sheepsfoot blade that I've done. I kinda like the look. We'll see how it performs when it's completed. I'll post pictured when all is said and done, promise ;)
 
I have this issue from time to time and usually on just one side - my strong side. It is generally caused from pushing too hard from the thumb. I like to reverse my direction - grind from tip to plunge, and press harder at the point where it needs to even up and then lighter as it gets to the plunge. I do not go back and forth, just like Rick states- Just tip to plunge and light at the end. This for me works to not keep digging into the plunge area. I like to do what Adam does and use a higher grit belt as well, seems to work better - albeit slower.
 
Happens to me on both sides when I get lazy or tired. One will be straight, the other dip, or curl, etc. Like everyone said it's about maintaining equal pressure, equal angle, and equal duration in contact with the belt. Learning to fix it by spot grinding is one of the tougher skills to learn in my experience. But once you can do it, it makes life a lot easier.
 
Yep the spot grinding and then evening things up with a nice even straight pull.


Or be a cheater and go to the disk like I do sometimes :P
 
I seem to only make things worse on the disc grinder. I bought a flat disc from Tru-Grit (as opposed to a 1 degree) and it doesn't seem to actually be flat.
 
I did some knives only on the flat disk ( takes a while ) so I got the hang of it that way.

I just have the 1 degree, forward and reverse but no variable speed.

I do have to move the knife up and down to get all of the scratches on the apex of the disk but it's tricky. Someday I'd like a variable speed one although I am still torn between the flat and 1 degree. Probably not the worst thing to have one of each set up.
 
You must log in or register to reply here.
Back
Top