How do you know you're done with one grit belt before you switch?

LX_Emergency

LX_Emergency

Joined
Jun 28, 2007
Messages
3,215
Hello gentlemen,
I'm asking the guys who do a lot of belt finished knives in particulair here. How do you know that you've gotten the grindmarks from the previous grinding belt out?

Because sometimes I find I really difficult to see whether the scratches are from the current belt or from the one I just finished...only to discover that I missed a few way back and I have to start all over again.

Just looking for some tricks and tips here.
 
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It heard of guys dipping in dykem which fills the scratches and you can watch them disappear. I tend to just wait till I move up a grit and then go back and correct them. I don't have dykem but I've used sharpie before.
 
if flat grinding tilt the blade at an angle to make the scratches go in a different direction then you can really see when all the odd scratches are gone
 
butcher_block said:
if flat grinding tilt the blade at an angle to make the scratches go in a different direction then you can really see when all the odd scratches are gone
Click to expand...

I've thought of this. But won't that mess with the plunge?

viral said:
It heard of guys dipping in dykem which fills the scratches and you can watch them disappear. I tend to just wait till I move up a grit and then go back and correct them. I don't have dykem but I've used sharpie before.
Click to expand...

Yeah. I've been trying the sharpie thing lately. Seems to work....ok I guess. It's not great so far.
 
I don't know that he does it on every blade, but MS Michael Rader made the suggestion here a while back of going straight from 60 to 400. He said it seems like it takes a long time to get the coarse scratches out, but if you watch the clock it's actually quicker than going through several grits.
Even doing that a time or two would really give you a new perspective on what it takes to make em go away.
My most common progression is 60, 120 Xwt ceramic, maybe 100 trizact, then 320 on the disk grinder. Since the disk is doing something totally different from the belt, it's really easy to see the deep scratches from the coarse belt. Obviously, hollow grinds are a different animal, and you have to have a plan to clean up the plunges.
 
Ive also been going straight from an 80 grit to a few quick passes on 320 to highlight where the deep scratches/low spots are. Then go to 150 grit and repeat with a kinda worn 320 to show where the deeper scratches are. Seems to work ok, sometimes the only really good way though is to hand sand lengthwise, this will really show you.
 
I have heard of the dykem and sharpie methods, but never used them. I usually start with a 60 grit or 80 grit ceramic belt, but from that point onward I hand sand starting with 80 grit at a different angle than the marks from the belt, switching direction with each grit. Sometimes I won't notice ALL of the belt scratches until I reach a high enough grit (this happened to me earlier today). Once I started 180 grit, there was a tiny remnant of a belt mark on the edge of one of the plunges. Just something else to keep watch for, and if it happens, it's far less time consuming to go back a grit or two over that area and remove it, instead of trying to be a hero and do the same with the grit you're already on (learned that one the hard way myself).
 
What Devin said!
Sunlight is great, my disk happens to be in a sunny spot in the shop, and getting an LED light bar over my main grinder really changed my game- it shows up the scratches almost too well!
 
Blue layout dye and paint markets and lots and lots of light. I have a 500w halogen work light, 2 bright LED lights by my grinder, and a cree head lamp that used double 18650 batteries, I use them ALL when im polishing. You can also buy spray cans of dykem dye in blue or red I just spray the whole thing down good and let it dry for a few minutes while I take a smoke break. If your trying to pinpoint a certain problem area or have some un-eveness on your grind and dont want to wash out your bevel scribe with more dye a paint marker works well, I've tried several brands and I've found dykem holds up best with water dipping and heat and oil ect.
 
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