Freehand Grinding Question

[imill3567]

Alright so I’ve transitioned from jig to almost exclusively freehand grinding and I have it down pretty good now. There’s only one thing that I’m still chasing. I get these little errant scratches on the top of the bevel (see pic), worse at lower grits, most of the time by the time I finish the grind I’ve cleaned them up. But if they stray to the top of the bevel, as they do sometimes when I bring the bevel fairly high with 36 grit, then I have to either take the grind all the way to the very top or clean up my flats after. Any tips or recommendations for this other than just continue practicing? I don’t think I’m applying any more pressure to the spine than is necessary to work the grind towards the spine rather than the edge.

 

[DeadboxHero]

Just use 60grit belts for that work and the issue goes away.

View attachment 1429104 Alright so I’ve transitioned from jig to almost exclusively freehand grinding and I have it down pretty good now. There’s only one thing that I’m still chasing. I get these little errant scratches on the top of the bevel (see pic), worse at lower grits, most of the time by the time I finish the grind I’ve cleaned them up. But if they stray to the top of the bevel, as they do sometimes when I bring the bevel fairly high with 36 grit, then I have to either take the grind all the way to the very top or clean up my flats after. Any tips or recommendations for this other than just continue practicing? I don’t think I’m applying any more pressure to the spine than is necessary to work the grind towards the spine rather than the edge.

 

[JTknives]

I have only used 50-60 grit belts to rough in me edge bevels and I only see that issue with real shallow angles. But having a surface grinder makes fixing this issue easy. But I would also check your belt tension and make sure it’s running flat on you platten.

 

[imill3567]

DeadboxHero it gets better with 60 (that photo was 60 I believe) but does not entirely go away but I will try switching from the 36 earlier on. JTknives I usually do flat grinds on thin stock so angles are always low and I did start thinking about platen extension particularly the bottom not being too far back from the belt so I will check that on my next grinding session and see if it helps. Thanks for the input so far.

 

[Cushing H.]

Agreed that is just a shallow angle issue. As you get shallower, coarse grits will have some particles that are bigger, protrude higher above the belt, and hit the flat to do what you see. Sneak up on it... get most of the way there with 36, then shift up to 60, and so forth. Or do what JT said... but 36 grit gouges gotta be a bear to get out. Personally, 60 is the coarsest I use, but as the bevel gets shallow, this happens with 60 also

 

[Scaniaman]

Scribe your transition line and when you start closing up on it move to a 120 belt and then 240. This phenomenon is typical for high grinds on thin stock like 0.1" and down.

 

[Natlek]

Agreed that is just a shallow angle issue. As you get shallower, coarse grits will have some particles that are bigger, protrude higher above the belt, and hit the flat to do what you see. Sneak up on it... get most of the way there with 36, then shift up to 60, and so forth. Or do what JT said... but 36 grit gouges gotta be a bear to get out. Personally, 60 is the coarsest I use, but as the bevel gets shallow, this happens with 60 also

I don t think so . I make many kitchen knives from 1.5mm steel and never have that issue.Clean crisp line , always ! And only I have and use is 40 grit ceramic belts .Klingspor if that matter at all
I believe that belt tension and position of plate behind belt have impact on that.......and grinding jig which i use , maybe

 

[DeadboxHero]

The 36grit grains are so large they have a tendency to slide over the shoulder a little and make messy lines and "fuzz up" the shoulder line. I don't have that issue with a 60 grit in my experience, I stopped buying 36grits, not needed.

If fuzzing the line with a 60grit it's operator error.

One needs to "click" that bevel up on the platen and keep it flat on the platen or make a flat with some pressure otherwise it will convex over your shoulder.

Here is one I did, I grind all my knives freehand.


60 grit.

Knife is at 71.2hrc so it also more difficult to grind than most knives.

"Click" that bevel flat up on the platen better and don't lean back on the shoulder too much, lock that wrist.

DeadboxHero it gets better with 60 (that photo was 60 I believe) but does not entirely go away but I will try switching from the 36 earlier on. JTknives I usually do flat grinds on thin stock so angles are always low and I did start thinking about platen extension particularly the bottom not being too far back from the belt so I will check that on my next grinding session and see if it helps. Thanks for the input so far.

 

[Cushing H.]

Deadboxhero - what was the thickness of that stock?

 

[AVigil]

Is your platen perfectly flat?

I will take my grind to 75% with 50 grit and then walk it up to 100 grit, then finish with higher grits

The grind line will be smooth from plunge to tip

 

[imill3567]

Yeah my platen is as flat as a relatively new glass platen is. I increased the “proudness” of the platen into the belt making sure the bottom especially wasn’t backed off and that helped immensely. Right off the bat my 36 grit grinds were fairly crisp. I also ended the 36 grit grind earlier than usual maybe half or just over then went to 60 and finished that grit with only flat passes no “bevel climbing” type passes with pressure towards spine. Then all polishing grits were just flat bevel passes and the lines were pretty crisp. Thanks everyone for the tips I think I know how to make sure I get crisp lines freehanding or at least what to practice.

 

[LARRYZ10]

Use finer grit belts to start. I even start my grinds with a 60 grit belt and then switch to 80 grit ceramic. When you get top close to the top of your grind go up one finer grit like 120 and be sure to slow your grinder each time you use a finer belt. My way is slower but it has worked well for me. A clean grind always shows up in the end. Larry