dang grind angles.....

[exsanguinate]

I am still trying to flat grind my blade using the platen. Every time I think I have it down, I run the blade across the belt/platen and dang, I was off on my angle by a tiny bit. The blade is getting smaller

If I try to dress it up on a slack belt, it seems the angle is not so crucial.

My question is, when flat grinding, is it best to use the platen initially and then dress it up on a slack belt, or just keep trying to get the angle right on the platen? If I am using the slack belt (after getting the master grind angle), am I getting more of a convex grind?

 

[Rob!]

Don't know if this will help or if it's even what you were looking for. I flat grind with the edge up and the tool rest in place. I draw the blade across the belt once, holding a fairly steep manual angle. This gives me a grind line that is probably only 14" up the blade and invariably, pretty uneven. I then do all the rest of my passes with that bevel flat against the platen. The grind line isn't moved by holding the blade at a different angle, but rather by the position of your push stick. As you hold the push stick closer and closer to the spine, the grind line starts moving that direction even though you're holding the blade flat against the platen. If the grind line line gets near where you want it and the edge is still not down far enough, just move the push stick pressure toward the edge and the upper grind line will stop moving while the edge grinds down further.

Another good piece of advice I got was "know when to quit". It takes time and many knives to get really good grind lines (so I'm told - I'm not there yet.) Have the courage to accept a few as they get better so you can watch your growing skill rather than a growing pile of grindings on the floor.

Hope this helps.

Rob!



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Rob Ridley
Ranger Original Handcrafted Knives

 

[Bruce Bump]

I dont use the slack belt unless I want a convex grind. For flat grinding, I grind with the edge up so I can see better. Take your time and feel for the flat spot. It has no flat spot at first but will develop one soon. apply more pressure in the needed places untill the grinds look the same on both sides of the blade. Watch where the sparks are coming out, that is where its grinding. It all comes with practice, pracrice, practice. One more thing, You have to hold your mouth just right, Bruce

 

[peter nap]

I kinda hate to tell you how I do it because I learned to grind by trial and error. The internet didn't exist then. Anyway...

I start making a 45 degree cut on both sides using a tool holder. This allows me to see where my error is.

I go to the belt grinder and carefully start the angle the way I want, checking every two strokes. When I have enough flat, I put on a pair of cotton gloves to keep from burning my fingers and use four fingers to keep that flat against the belt.

I swap ends of the knife and do thew opposite side the same way. You can see the grind lines grow and gauge the bevel that way.

 

[C L Wilkins]

When I first started I tried to use a tool rest. It just made sense (at the time) to use one but if it is not exactly squared or perpendicular to the belt then the plunges are never even. I removed it. The darn thing just got in the way. Nowadays I just swing it down out of the way and use it to square things un when I need to.

For flat grinding this is what I do. Whether it is right or wrong I don't know, it just works for me. I use a file guide clamped on to the blank at the plunge area. This is my guide so to speak. I do the plunge with this starting with a 60 grit belt. To get the grind even on both sides what I do is grind the one side to about where I want it and then measure the distance from the spine to the top of the grind line. I measure this with a simple compass and mark the other side after spraying dykem on it and re-check it for it being even on both sides. I will leave the file guide on the blade when I move up to 120 grit and take it off after that.
I will go up to maybe 320 or 400 grit then the hand sanding begins. I will go back to 220 grit to start the hand sanding. Use cutting fluid and back your sandpaper with a piece of hardwood or micarta. Don't use just your fingers. If you are going to go to higher grits, glue a piece of leather onto your sanding block. It makes a difference.

Hand sanding is a requirement when flat grinding with a belt. A disk setup may be another story.

I also have lights on both sides of the platen to eliminate shadows.

One other thing, I only grind in one direction and edge up. Basically it is from plunge to tip, never back and forth. I run my belt about 1/8 to 3/16 inch off the side of the platen.

Remember, elbows in, sway those hips and eat lots of meat and potatoes to build up that "organic tool rest".