Finish Griding - Next Grit When?

[boy&hisdogs]

When hand finish sanding a blade, you alternate the direction of your sanding motion to cross the scratch lines, once the old scratch lines disappear, you can move to the next grit.

But how do you know when to move up a grit on a belt sander when they are all going the same direction? Especially if you are using a bevel jig and the scratch lines are in exactly the same direction.

Searches keep steering me towards threads about sharpening with a belt sander. I'm trying to find out about the faces of the knife, bringing them on up to 400 or 600 on the machine instead of starting right off the 60-120 lines.

 

[Tyshoots]

I use blue dykem in between the different grit belts. When you cannot see any more blue it's time to move to the next grit.

 

[Matthew Gregory]

Tilt the blade, even just a little bit, while you're grinding with the next grit. The disparity in angle of each grit's 'pattern' will stand out.

 

[Geoff Flato]

Even on a hollow grind you can tilt the blade some. I do iron all of mine, and it makes a huge difference in ease of finishing. It just makes the wheel act a bit bigger than normal. My hollow grinds on a 12" usually look more like what would be expected from a 14

 

[coldsteelburns]

If it's too hard for you to tilt the blade using your jig, another method is to jump up to a high grit such as 400 after 120, as this will usually show any remaining deep scratches. Then go back to the grit you need to remove any deeper scratches if needed.

I have messed around with using dykem to show scratches in the past, but in my experience it rubs off too easily before everything is taken down to the same surface level which can give "false readings".


~Paul
My YT Channel
Lsubslimed
... (It's been a few years since my last upload)

 

[Howard1]

Even on a hollow grind you can tilt the blade some. I do iron all of mine, and it makes a huge difference in ease of finishing. It just makes the wheel act a bit bigger than normal. My hollow grinds on a 12" usually look more like what would be expected from a 14

"Iron all of mine" how do you mean?

 

[Geoff Flato]

"Iron all of mine" how do you mean?

Supposed to be "do it on all of mine"
Sorry, the combination of a broken screen and unhelpful autocorrect has had me leave some rather big typos. I guess I didn't notice that one